Comparative Acaricidal Responses of Five Species of Spider ...

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1956

Comparative Acaricidal Responses of Five Speciesof Spider Mites.Mohammed Ramadan Abo-el-gharLouisiana State University and Agricultural & Mechanical College

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Recommended CitationAbo-el-ghar, Mohammed Ramadan, "Comparative Acaricidal Responses of Five Species of Spider Mites." (1956). LSU HistoricalDissertations and Theses. 162.https://digitalcommons.lsu.edu/gradschool_disstheses/162

COMPARATIVE ACARICIML RESPONSES OF FIVE SPECIES OF SPIDER MITES

A Dissertation

Submitted to the Graduate Faculty of the Louisiana State University and

Agricultural and Mechanical College in partial fulfillment of the requirements for the degree of

Doctor of Philosophyin

The Department of Zoology, Physiology and Ehtomology

byMohammed Ramadan Abo-El-Ghar

B. Sc. Ein-Shams University, Cairo, Egypt, 19U7 August, 195>6

ACKNOWLEDGMENT

The -writer wishes to acknowledge gratefully the efforts of the following in their guidance and interest in the problem:

Dr. L. D. Newsom who suggested and guided the problem and gave helpful advice and suggestions throughout the study; Dr. H. B. Boudreaux for supplying, identifying and checking species of mites; and Dr. J. S. Roussel for giving the advice for calculating dosage mortality curves and the statistical analysis.

TABLE OF CONTENTS

PageACKNOWLEDGMENT ................................................. iiLIST OF TABLES............................................... ‘ ... vLIST OF F I G U R E S ...............................................viiEXPLANATION OF FIGURES .......................................... ixA B S T R A C T ..................................................... ...INTRODUCTION ................................................. IREVIEW OF LITERATURE.............................................ilMATERIALS AND METHODS............................................11

Method of rearing mites .........................11Method of application of acaricides.....................13Tests with adults, ................. l)|Tests with nymphs. . . . • . • . • • • . 1 5Tests with eggs . . . . . . . . . . . 1 6Comparison of susceptibility of developmental stages • . 17

Results........................................17Discussion................... ... . . . 17Conclusion . . . . . . . . . . 2 0Comparative effectiveness of four

acaricides, two containing sulphur compounds and two phosphorus com­pounds, against five different species of spider mites of the genus Tetranychidae • U2

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PageResults, . . . . . . . . h2Discussion . . • • • • • • U3Conclusion • • • • • • • • Ia7

Effectiveness of acaricides tested • • • . h9Conclusion...................• . . . . 50

Susceptibility to acaricides of T. cinnabarinusreared on roses and cotton ........................ 65

Procedure . . . . . . . . . . 6 5Results .................65Discussion....................................66Conclusion .................... 67

SUMMARY AM) CONCLUSIONS............................................ 70BIBLIOGRAPHY .................................................. 72autobiography: ................................................... 75

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LIST OF TABLES

II.

in.

IV.

V.

VI.

VII.

VIII.

PageThe response of adults, nymphs, and eggs of

T. tumldus to parathion, Niagara ExperimentalCompound., aramite, and sulphur dusts appliedat the rate of 10 pounds per acre. . . • „ . 22

The response of adults, nymphs, and eggs ofT. gloveri to parathion, Niagara ExperimentalCompound, aramite, and sulphur dusts appliedat the rate of 10 pounds per acre. . . . . . 2f>

The response of adults, nymphs, and eggs of T, cinnabarinus to parathion, Niagara Experimental Compound, aramite, and sulphur dusts applied at the rate of 10 pounds per acre . . 28

The response of adults, nymphs, and eggs ofT. lobosus to parathion, Niagara ExperimentalCompound, aramite, and sulphur dusts appliedat the rate of 10 pounds per a c r e . ............. 31

The response of adults, nymphs, and eggs ofT. deseretorum to parathion, Niagara ExperimentalCompound, aramite, and sulphur dusts appliedat the rate of 10 pounds per acre................. 3k

Comparative susceptibility of adults, nymphs, and eggs of Tetranychus spp. to parathion,Niagara Experimental Compound, aramite, andsulphur dusts. 37

Comparative susceptibility of adults, nymphs,and eggs of Tetranychus spp. to each acaricide 51

Comparative effectiveness of parathion, Niagara Experimental Compound, aramite, and sulphur dusts against adults, nymphs, and eggs of Tetranychus spp. .......................52

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PageIX* Summary of susceptibilities of various stages

of the five species of mites to theacaricides indicated. 53

X. Evaluation of similarity in response of allstages of all species to all acaricides tested • • 5U

XI, Comparative mortality of T. cinnabarinus rearedon cotton and roses and treated with parathionat the rate of 10 pounds per acre « . . . , 68

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LIST OF FIGURESPage

1. Dosage mortality curves for the toxicity of parathion to adults, nymphs and eggs of mites indicated. • . • . . * • • * 3 8

2* Dosage mortality curves for the toxicity ofNiagara Experimental Compound 1137 to adults,nymphs and eggs of mites indicated • • . • * 3 9

3. Dosage mortality curves for the toxicity of aramite to adults, nymphs and eggs ofmites Indicated, . . « • • • • • • Uo

U. Dosage mortality curves for the toxicity of sulphur to adults, nymphs and eggs ofmites indicated. • • • • • • • • • hi

£• Comparative susceptibility of adults, nymphsand eggs of mites indicated to parathion • . • 55

6. Comparative susceptibility of adults, nymphsand eggs of mites indicated to NiagaraExperimental Compound 1137 • • • • • • • 5 6

7. Comparative susceptibility of adults, nymphsand eggs of mites indicated to aramite • • . • 57

8. Comparative susceptibility of adults and nymphsof mites indicated to sulphur • • • • • • 58

9* Comparative effectiveness of acaricidesindicated against adults, nymphs and eggs ofT. tumidus • • • • • • • • • • • 5 9

10. Comparative effectiveness of acaricidesindicated against adults, nymphs and eggs of T. gloveri • • • • • • • • • * • 60

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Comparative effectiveness of acaricides indicated against adults, nymphs, and eggs of T. cinnabarinus.......................

Comparative effectiveness of acaricides indicated against adults, nymphs, and eggs of T. lobosus . . . . . . . .

Comparative effectiveness of acaricides indicated against adults, nymphs, and eggs of T. desertorum • • ...............

Comparison of susceptibilities of the five species (over-all) based upon similarity of response (see text, p. u7 for discussion) .

Dosage mortality curves for the toxicity of parathion to adults of T. cinnabarinus on cotton and roses , 7 . . . . . .

EXPLANATION OF FIGURES

A * AdultsAR = AramiteC ® T, cinnabarinusD » T. desertorumE *» EggsG = T• gloveriL “ T* lobosusN ® NymphsNG » Niagara Experimental Compound 1137P = ParathionS « SulphurT « T. tumidus

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ABSTRACT

A laboratory study was conducted to conpare the to:<±city of two products containing sulphur and two containing phosphorus compounds to adults, nynphs and eggs of five species of spider mites attacking cotton in Louisiana.

An e:xperiment was conducted also to investigate the response of spider mites to acaricides when reared on cotton and roses.

The five species were: Tetranychus tumldus Banks, T. gloveriBanks, T. cinnabarinus Boisduval, T. lobosus Boudreaux, T. desertorum Banks.

The two products containing sulphur were aramite and sulphurj the two phosphorus compounds were parathion and Niagara Experimental Compound 1137*

Mites were reared in the laboratory on seedling cotton and treated in a dusting chamber.

Based on response to acaricides, species tested were grouped as follows:

1. Tetranychus tumidus Banks and Tetranychus gloveri Banks2. Tetranychus cinnabarinus Boisduval and Tetranychus

lobosus Boudreaux3. Tetranychus desertorum Banks

x

In general, T. desertorum was the most sensitive mite to parathion, but it was less sensitive to Niagara Experimental Compound 1137* aramite and sulphurj T. tumidus was the most resistant mite to the acaricides tested. The three other species were intermediate in response. Susceptibility of mites tested varied with their developmental stages.

Parathion was highly effective against the five species, followed by Niagara Exp erimental Compound 1137, aramite and sulphur respectively. However, aramite and Niagara Experimental Compound 1137 showed the same toxicity in many cases.

Adults of T. cinnabarinus reared on roses were about 2^ times more resistant to parathion than those reared on cotton.

ad.

INTRODUCTION

Spider mites are among the more serious pests of cotton wherever it is grown. During recent years economic entomologists have been increasingly concerned with these mites, partly because many of the new insecticides are often detrimental to predaceous enemies of spider mites, or render the plants more susceptible to the mites (Baker and Pritchard, 1953)•

There are at least seven species of spider mites which attack cotton in Louisiana all of them individually capable of damaging the plant. These are: Tetranychus telarius (L.), T. tumidus Banks,T, ludeni Zacher, T. cinnabarinus (Bois.), T. desertorum Banks,T. gloveri Banks, and T. lobosus Boudreaux. Tetranychus cinnabarinus,T. lobosus, T. desertorum, and T. tumidus are the most widely distributed species in Louisiana. The other species seem to be of local importance only in cotton: T. telarius at Baton Rouge, T. gloveriin the vicinity of New Roads, and T. ludeni in central Louisiana.T. tumidus has not been found in the northern one-third of the state (Boudreaux, 195U-1955)•

Work during the past four years to evaluate the effect of spider mites on cotton growth, yield, and quality of lint and seed in Louisiana has demonstrated that these pests are capable of causing

1

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serious reduction in yield when conditions are favorable for rapid development of mite populations* Reduction in yield averaged 30 per cent over the past four years in infested plots, and ranged from none to 77 per cent (Roussel, 1933-193U).

In a small field plot test conducted at Baton Rouge, Louisiana, during 1930 injury to cotton resulting from infestation by the spider mite Septanychus tumidus (Banks) ( = T. tumidus Banks) caused a U3 per cent reduction in the amount of seed cotton produced* This injury reduced vegetative growth as measured by the amount of dry matter produced, number of leaves per plant, and size of leaves* In addition to these effects several characters of the seed and lint were adversely affected. There was also a reduction in length and maturity of fibers which was attributable to spider mite injury (Roussel et al., 1931)*

Control of mites, therefore, has become an important problem confronting cotton farmers in Louisiana.

In the last few years many new acaricides have been developed e.g«, parathion, malathion, systox, aramite, neotran, chlorobenzilate, ovatran, demeton, diazinon, and karathane. Apparently no comprehensive investigation of the relative susceptibility to these new acaricides of the developmental stages of different species of mites which infest cotton has been reported in the literature. Field experience has demonstrated that some acaricides are primarily effective as ovicides, while others with practically no ovicidal effect may be highly toxic to the newly hatched young.

3

The objectives of this study were?1. To compare the effectiveness of four acaricides, two

containing sulphur compounds, and two phosphorus compounds, against five species of spider mites of the genus Tetranychus and against the developmental stages of each species (adults, nymphs, eggs).

2. To investigate the difference in susceptibility to acaricides of T. cinnabarinus (Boisduval) reared on rose and cotton.

REVIEW OF LITERATURE

It has been reported that an insect species causing damage should be determined before remedies are recommended. Failure to recognize the importance of an exact determination is a frequent cause of failure in control (Isely, 195U).

Gaines et al. (1950) have shown that sulphur compounds (aramite and sulphur dusts) proved more toxic to Septanychus texazona McG. ( ° T. desertorum Banks) than to T. bimaculatus Harvey while the phosphorus compounds were nearly equal in effectiveness against both species. It seems probable that they were dealing with either T. cinnabarinus (Boisduval) or T. lobosus Baud, instead of T. bimaculatus (See Boudreaux, 1956).

Mistric and Rainwater (1952) showed in their work with S. texazona and T. bimaculatus that adults of S. texazona were significantly more susceptible to all sulphur and phosphorus compounds tested than were adults of T. bimaculatus.

Melvin and Earle (19̂ *8) found that a 3pecies of Paratetranychus •was approximately five times as resistant as was T. bimaculatus Harvey to tetraethyl pyrophosphate0

Newcomer and Dean (19U9) reported that the Pacific mite,

U

Parate t r anychus pilosus (C, & F,), differed in its susceptibility to several acaricides,

German (1950) has shown that certain colonies of the green­house spider mite became resistant to parathion, but that resistance did not appear when several other acaricides were used.

Entomologists often utilize only the adult mite as a test animal in the evaluation of acaricides. However, Ebeling and Pence (l95U) have demonstrated that it is misleading to evaluate a group of acaricides on the basis of their effectiveness against a singledevelopmental stage. They have reported also that insects may vary

1greatly in their susceptibility to insecticides during their developmental stages.' With aramite and some of the organic phosphates they found the LD 50*s for the larvae higher than for the adults. In their experiments, eggs were the most resistant stage to most of the acaricides tested,

Mistric and Rainwater (1952) concluded that eggs and immature stages of S. texazona were significantly more susceptible to materials containing sulphur than were the same stages of T, bimaculatus. In these stages they found that both species of mites were equally susceptible to parathion, but T, bimaculatus was significantly more susceptible to merthon. They found also that, when the two sulphur compounds were applied, the significant difference in susceptibility remained constant for all stages of the mites. But when the two phosphorus products were applied, the stage of development greatly influenced their relative susceptibility.

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Only a little information is available on the relative resistance to the action of insecticides on eggs of insects, but it is often supposed that the egg is the most resistant stage. Furthermore, it has been demonstrated that the age of the egg may have a direct bearing on its susceptibility to most insecticides. Hintz (1953) found that the stage of the European red mite most difficult to kill was the egg* He concluded also that average dosages of the organics did not prevent development of the eggs, but they often killed the larva before it could rupture the egg shell*

Potter and Tattersfield (19)43) carried out laboratory spraying and dipping experiments with pyrethrum on the eggs of Pieris brassicae (L.), Ephestia kuhniella, Sitotroga cerealella (C. L.), and Plutella muculipennis (Curt.). They noticed that a high proportion of the unhatched eggs contained embryos that were either fully developed or highly developed before dying, but that some eggs were killed with partially developed embryos indicating that a toxic action was exerted before full development had been attained*

Mukerjea (1953) determined that the susceptibility of the medium varied with the age of eggs of Tenebrio L., Diataratia oleracea, and Periplaneta americana L. He found that the susceptibility increased rather sharply from the one-day egg (youngest egg) to the two-day egg, and then gradually increased to the five-day old egg (oldest egg) which wa3 the most susceptible* He also noticed that the pyrethrins had an effect on the development of the embryo and that in some cases further embryonic development was inhibited after the application of the

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insecticide.A few experiments in which DDT was tested as an ovicide have

been reported and it appears that, in some cases, no difference in susceptibility with the age of egg was noticed. It has been pointed out by Speyer and Parr (19)-i5) that they found no difference in the sus­ceptibility of various age3 of eggs of Diataratia. oleracea when they were dusted with 5 per cent DDT powder or when sprayed with a DDT emulsion.

Salkeld and Potter (1953) noted that under a given set of conditions and with a given insecticide both the magnitude and the pattern of resistance could vary with the species of egg.

The results of tests with oil and dinitro-compounds against winter eg :s of the European red mite have been reported by Chapman and Pearce (19^9) and Chapman and Lienk (1950). It was demonstrated that while dinitro-ortho-cresol was relatively ineffective, othor dinitro materials, such as dinitro-sec-butyl phenol and dlnitro-amyl phenol were quite toxic to the eggs.

Lienk and Chapman (1951) reported that all the organo- phosphorus compounds tested were highly effective in killing hatched forms of the European red mite and the two-spotted spider mite.

Iglinsky et al. (19U9) found that parathion dusts at a concentration.of 0.5 per cent or more were effective in controlling red spider mites. They noted also that this material did not have residual or ovicidal properties.

Petty (19U8) found that HETP used as a spray was not effective in killing the eggs of T. bimaculatus Harvey.

Zimmerman and Hartzell (19b7) found that the eggs of the same species were not killed in fumigation tests with HKTP and TEPP in the greenhouse*

It seems that the resistance of an insect egg to a toxic material may depend not only on the susceptibility of the embryonic material, but also on the ability of the toxic material to penetrate through the shell layers to the embryo.

Experiments on the penetration of some type3 of oil through the shells of several species of insect eggs have been done. In con­sidering the ovicldal action of parathion to eggs of the peach tree borer Smith (195$) showed that egg3 treated at all stages of development continued to respire normally until the seventh day declining progressively thereafter for several days beyond bhe normal time of hatching. He proposed that young eggs are more permeable to parathion vapor, and the extended sub-normal respiratory rate is likely a secondary effect of poisoning. Smith (19$b) noticed that exposure of 2 - 6 days were required to cause mortality of eggs deposited on the sprayed surface with parathion. He concluded also that in all cases where mortality occured, the embryos developed apparently normally to the point of hatching, but failed to emerge from the chorion.

Fox (193P) O’Kane and Baker (193$)> and Blickle, O'Xane aid Baker (19U2) found traces of oil in the chorion, in the layers underlying the chorion, and surrounding the yolk, and in the developing embryo in the eggs of Oecanthus niveus, DeG., Anasa tristis, DeG.,

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Dilachnus pini L. Chrysopa occulata Say., Platysamia cecropia L., and Epilachna corrupta, Muls.

Blickle (19U2) using oil saturated with a dye found that the oil (as judged by the presence of the dye) penetrated the shell of the older eggs of the same insect species more quickly than that of the younger. This indicated that some change was taking place in the protective envelopes of the egg as hatching approached.

Only a little information is available on the resistance of spider mites to the action of acaricides when fed on different host plants.

Neiswader et al (1950) concluded that Hie two spotted mite,T. bimaculatus, is influenced by the host plaits on which the mites feed. For example, a mite population feeding on roses was usually more resistant to acaricides than one on beans.

German and Kennedy (19U9) reported that mite populations may fluctuate with the vigor of the host plant, as affected by the amount of soil fertilization.

Compton aid Kearns (1937) suspected the texture of the rose leaf to be in part responsible for the difference. However, when they took equal numbers of mites from roses and snapdragons and transferred them to cotton cloth and sprayed them with a selenium compound "selocide", it was found that 100 per cent of the mites from snapdragon were killed and only 2 per cent of those taken from roses were killed.

Cole et al (1955) reported that a red form of spider mite population from squash when tested on bean in comparison with the red

form from bean was less susceptible to DM3 but equally susceptible to malathion.

MATERIALS AND METHODS• I

The sulphur-containing materials tested were:1. Aramite 2-Cp-tert-butylphenoxy)-l-methylethly-2-chloro-

ethyl sulfite2. Sulphur powder

The phosphorus materials were:1. Parathion : 0-0 - Diethyl O-p-nitrophenyl Thiophosphate2. NiagaraExperimental Compound 1137

The five species of spider mites were:1. Tetranychus cinnabarinus (Boisduval)^• Tetranychus lobosus Boudreaux3. Tetranychus tumidus BanksU. Tetranychus gloveri Banks

Tetranychus desertorum Banks Method of rearing mites:

The method used in these experiments was developed by Dr, H, Bruce Boudreaux in the entomological laboratory of the Agricultural Experiment Station at Louisiana State University (un­published), This method permits the mite to feed on the same leaf for periods up to one month.

A three-eighths inch hole is bored in the center of a petri dish, and a short piece of rubber tube is fitted tightly in the hole, its upper end protruding slightly above the rim of the dish.

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This is placed over a plywood sheet, bored to accommodate several dishes. Below each hole in the plywood is a bottle of water. Cotton is used as the host plant, since cotton is suitable for all the species tested. When cotton seedlings are about 6 to 8 inches high, the cotyledons are nearly two inches across. The true leaves are not yet developed. The seedling at this stage is inserted through the rubber tube so its roots are immersed in the water below. The mites are confined to the upper surface of the cotyledon with a tanglefoot barrier. The culture is covered with a crystallizing dish two inches deep. The mites may be easily examined without disturbance if the glass stage of a binocular stereoscopic microscope is replaced with a piece of wood with a large hole cut out of the center. Such a technique allows the microscope to rest upon a table with a cutout so that the culture dish can be placed under the microscope for examination.Several generations of mites may be reared on such cultures, and large populations may be maintained. The cultures were maintained in the laboratory at 85-90° with fluorescent tubes furnishing about l£0 foot- candles illumination to t he plants for 2k hours daily.

Pure cultures are difficult to maintain without contamination, especially in a laboratory where more than one species is cultured. The larvae apparently can be carried by air movements. It was decided, therefore, to maintain and test only one species for all the acaricides at one time. After finishing testing one species a pure culture of a different species could be maintained and tested, and so on. However, cultures were examined frequently for contamination.

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Method of application of acaricides:The dusting chamber, gun, and air pump used in these tests

were similar to those described by Waters in a publication edited by Campelland Moulton (1<?U3), and by Ivy (19UU)*

A celluloid-dusting cylinder 29 inches high and 12.2£ inches in diameter was used. This size cylinder was mounted on a cabinet 35»5 inches high, 15»2£ inches long, and ll*.5 inches wide. The cabinet was furnished with removable shelves, to accommodate different sizes of plants. The top sheet with a center hole was cut in half, the two pieces fitted together around the base of the plant which rested on the petri dish (in this kind of experiment). The plant was placed in the cabinet under the celluloid cylinder for dusting. Measured quantities of acaricides were calculated on a per-acre basis from the area of the dusting chamber. For instance if dust was to be applied at the rate of 10 pounds per acre (which was used in these tests),82 mg. of dust was required. Different concentrations of each acaricide were applied at'his constant weight* A number of preliminary experi­ments were made to ascertain the approximate dosage range for each acaricide. The dosage mortality regression lines were based on Ij. points. Dosages required to give mortalities of 5>0 per cent were calculated from the dosage mortality relationships according to the method of Bliss (1938).

The measured quantity of each dosage was discharged from.a glass gun into the top of the cylinder by means of an air pump apparatus. The dust was allowed to settle two minutes and the treated leaves were

ih

immediately removed. The gun was cleaned after each application by pouring sufficient clean sand in the gun, and shaking it back and forth vigorously. The sand was poured out and the process was repeated two more times.Tests with adults:

Twenty-five adult females were transferred to each leaf of a cotton seedling that had been treated in the described dusting chamber. The mites were confined on the upper surface of each leaf by a tanglefoot ring around the edge. However, some of the toxicants, e.g. parathion, made the mites very active for the first few hours, and in their efforts to escape from the poison, some tried to cross the ring, and consequently were trapped in it and died. In some ex­periments trapped mites reached 20 in number thereby rendering the results unreliable.

It was, therefore, decided to follow the petri dish method developed by Ebeling and Pence (19510. This method was satisfactory.In this method detached green cotton cotyledons were used instead of the whole seedling. Leaves were placed on wet cotton in a petri dish covered with a crystallizing dish two inches deep. This kept the leaves fresh for 5 days, and served also to keep all but a few of the mites confined to the leaves. However, such a technique allowed fumigation. Twenty-five adult females were placed on each treated leaf. Each experiment was replicated four times to obtain 100 mites for each dosage. Counts were made h8 hours after dusting. If there was a very little or no movement of the legs, such a mite was recorded

as dead. If the mite was still able to crawl about, it was taken to be alive. It should be noticed here that adults made contact with the acaricides only by crawling over the residues. Untreated checks . were used in each test.Tests with nymphs:

In these experiments, it was planned first to test the protonymphal stage. Morphologically, there is no way to differentiate between protonymphs and deutonymphs except by size. It was decided then to test the nymphal stage in general, since such differentiation was almost impossible.

Ten adult females were placed on t he upper surface of each leaf ringed with tanglefoot. Mites were left for twenty-four hours to lay an average of 60 - 100 eggs. After this period mites were removed and eggs were examined daily till they reached the nymphal stage.. Nymphs were distinguished from larvae by the fact that the latter have three pairs of legs. Leaves were detached from the seedlings, placed on wet cotton in petri dishes, and dusted in the dusting chamber. Four re­plications were made for each dosage. The total number of tested nymphs for each dosage was between 100-it00. Counts were made !|8 hours after treatment.

At the time the counts were made, some nymphs had already reached the adult stage, but since they had continuous contact with the residues during the nymphal stage, the experiment was considered to be an evaluation of the susceptibility of the nymphs. It should be noticed in this test that acaricides contacted nymphs directly when

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applied.Untreated controls were used in all replications.

Tests with eggs:In these experiments ten adult females were placed onihe

upper surface of each leaf. Animals -were forced to lay eggs on the upper surface of the leaves by surrounding them by tanglefoot. After 2k hours, mites were removed from the leaves. Detached leaves were put on wet cotton in petri dishes and treated immediately. Four re­plications were used for each concentration. The average number of eggs for each dose was lOO-ljOO. Counts were made after six days. Partly hatched eggs, larvae, nymphs or adults were recorded as hatched eggs, no matter if they were dead or alive.

Untreated controls were used for all replications. As with nymphs the acaricides contacted eggs directly when applied.

PART I

Comparison of susceptibility of developmental stages

ResultsThe results in Tables I, II, HI, and V show mortalities

of the developmental stages as observed a nd as computed according to the method of Bliss (1938).

Figures 1, 2, 3j and U present the dosage mortality curves for the toxicity of acaricides tested. In these curves per cent dosages were plotted against computed per cent mortalities obtained from Tables I, II, III, IV, and V.

LD^O's for acaracides against developmental stages are given in Table VI. These LD^O's were obtained from dosage mortality curves shown in Figures 1, 2, 3, and U, and consequently represent per cent concentration. In this table the test for significance was measured by the standard error based on the calculation of the fiducial limits from the dosage mortality relationships according to the method of Bliss (1938).

DiscussionFrom data presented in Figure 1, it is seen that adults

of both T. tumidus, and T. gloveri were more susceptible to parath'ion than were the nymphs. On the other hand, adults of T. cinnabarinus,

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18T. lobosus, and T, desertorum were shown to be the mork resistant to parathion than were the nymphs. Eggs were shown to be the most re­sistant stage for all species tested with parathion. However, the test of significance showed that there was no significant difference between the susceptibility to parathion of both adults and nymphs of T. tumidus, T. cinnabarinus, and T. desertorum.

Data given in Figure 2 show that the five species exhibited the same response to Niagara Experimental Compound (which is a phosphorus compound like parathion, but contains sulphur) as they did to parathion. However, this similarity in the mode of action of both acaricides did not show the same similarity in their LD $0's which will be discussed later on. Statistical analysis did show here that there was no signi­ficant eifference between the adults and nymphs of T. desertorum in their susceptibility to Niagara Experimental Compound 1137•

The response of the five species and their developmental stages to aramite is presented in Figure 3. From these data it is clear that adults and nymphs of T. tumidus, T. gloveri, and T. desertorum were almost equal in their susceptibility to aramite. On the other hand, nymphs of both T. cinnabarinus and T. lobosus were more suscep­tible to aramite than were the adults. Eggs were still the most resistant in all specied tested with aramite* There was no significant difference between adults and nymphs of T. gloveri and T_. desertorum in their susceptibility to aramite.

Results presented in Figure U show that nymphs of T. lobosus and T. gloveri were more sensitive to sulphur than were the adult3.Adults of T. tumidus were more sensitive to sulphur than were the

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nymphs. Achilts and nymphs of T. cinnabarinus and T. desertorum were similar in their susceptibility to sulphur. On eggs sulphur was ineffective except for T. desertorum. However, eggs were still much more resistait to sulphur than the other developmental stages of this species. Statistically there were no significant differences between adults and nymphs except between T. gloveri and T. lobosus.

From these results it is clear that with parathion and Niagara Experimental Compound 1137 the LDJjO's for the nymphs of

tumidus and T. gloveri were hi^ier than for the adults, while those for T. lobosus, T . cinnabarinus, and T. desertorum were equal or lower than those for the adults.

To aramite, the LD^O’s for the nymphs of T. tumidus,T. gloveri, and T desertorum were similar to those for the adults, while those for T. lobosus and T. cinnabarinus were lower than those for the adults.

With suphur the LD50’s for the nymphs of T. lobosus and T. gloveri were lower than for the adults, while those for T, tumidus T. cinnabarinus, and T. desertorum were similar to those for the adults.

It is of great interest to emphasize the fact that the susceptibility of spider mites varies with their developmental stages. In their work with the two-spotted spider mite, Ebeling and Pence (195U) have shown that with aramite, parathion, and malathion, the LOGO’S for larvae were higher than those for adults. The results of the present experiments showed that with aramite, parathion, and

20

Niagara Experimental Compound 1137 > the LD^O's for nymphs of T. cinnabarinus and T. lobosus were lower than those for adults.

Dosage mortality curves of Figures 1 through U illustrates the fact that T. tumidus and T. gloveri show a great deal of similarity in their response to both phosphorus and sulphur compounds. The same thing can be said for T. lobosus and T. cinnabarinus. These findings agree with those of Dr. H. B, Boudreaux who has found evidence in un­published experiments that T. gloveri is a species distinct from .T. tumidus although they closely resemble each other. He gave evidence also (1956) that T. cinnabarinus is a species distinct from T. lobosus, again in spite of difficulty in distinguishing them.

ConclusionIt Can be concluded that adults of T. tumidus and T. gloveri

were more susceptible to phosphorus compounds than were the nymphs.For sulphur compounds adults and nymphs of both species had similar susceptibility except for sulphur which was more effective on the nymphs of T. gloveri.

Differing from T. tumidus and T. gloveri nymphs of the other two species, T. cinnabarinus and T. lobosus, were more susceptible to both phosphorus and sulphur compounds than were the adults.

Adults and nymphs of T. desertorum have shown the same difference in susceptibility to both phosphorus and sulphur compounds except for Niagara Experimental Compound 1137 which was more effective on nymphs than it was on adults.

feggs of all specied tested were much more resistant to all

acaricides tested than were the nymphs and adults* no effect at all on eggs except for T. desertorum.

Sulphur had

22

Table I.- The response of adults, nymphs, and eggs of T. tumidus toparathion, Niagara Experimental Compound, aramite, andsulphur dusts applied at the rate of 10 pounds per acre.

Acaricides bosage No. of Wo, No. dead Observed Confutedpercent mites

treatedsurvivors after I48 hours

after b.8 hours

mortalitypercent

mortalilpercent

Parathion 0.010 100ADULTS79 21 21 27.3

0,030 100 25 75 72 56.80,060 100 21 79 79 7ii.50.100 100 11 09 89 8)4.6

Niagara 0,050 100 72 28 28 26.8Experimental 0.100 100 52 ii8 I18 li9.UCompound 0.250 100 16 8U 8ii 85.il

0.500 100 6 9k 9k 91.8

Aramite 0.075 100 81 19 19 20.50.100 100 59 ill ill 2i;.60.250 100 5U U6 i}6 U5.80.500 100 38 62 62 63.1

Sulphur 1.000 100 100 00 00 00.05.000 100 52 H8 U8 U8.010.000 100 2h 76 76 7 6.325.000 100 k 96 96 95.8

23

Table I0- (Continued). The response of adults, nymphs, and eggs ofT. tumidus to parathion, Niagara Experimental Compound, aramite,and sulphur dusts applied at the rate of 10 pounds per acre.

Acaricides Dosage No’. of Jio3 No. dead bhserved ^Computedpercent mites survivors after mortality mortality

treated after lj.8 hours percent percent ___________ ____ 1)8 hours ___________________________

NYMPHSParathion 0.010 H53; 325 128 28 21.0

0.030 377 290 87 23 Uo.e0.050 336 189 ll*7 1* 51.50.050 275 1*6 229 83 7U.7

Niagara 0.100 U30 312 118 27 23.3Experimental 0.250 3U7 231 116 33 39.6Compound 0.500 lj.28 210 218 51 53*3

o;75o 377 127 250 66 61.7

Aramite 0.075 U78 370 108 22 25*50.100 U1|6 259 187 Ul 29.90.250 I|l6 298 118 28 1*5.30.500 U37 137 300 69 57*7

Sulphur 5.000 13U 80 51* 1*0' 1*7.110.000 131 78 53' l*o 66.015.000 1U6 m 102 70 75*725.000 I9h 9 185 95 85.U

2l*

Table I.- (Continued)# The response of adults, nymphs, and eggs ofT. tumidus to parathion, Niagara Experimental Compound, aramite,aid sulphur dusts applied at the rate of 10 pounds per acre.

Acaricides bosage percent

too. ofeggstreated

too.hatched eggs after 6 days

No.unhatched eggs after 6 days

Observedmortalitypercent

Computedmortalitypercent

Parathion 0.100 186EGGS

181 5 3 11.?0.250 1U3' 116 27 19 23.00.500 U27 II46 281 66 65.10.700 307 U5 262 85 81.5

Niagara 1.500 93 73 20 22 2i*.ljExperimental 2.500 136 96 1*0 29 38.9Compound 3.000 82 1*7 35 1*3 l*l*.5

5.000 20l* 63 11*1 69 60.7

Aramite 1.500 376 333 1*3 11 11.92.500 398 318 80 20 as .65.000 330 1U9 181 51* 1*3.27.500 373 201 172 1*6 56.5

Sulphur 25.000 286 21*9 37 13 «• «*

50.000 1*52 381* 68 15 - -

75.000 1*33 3U8 85 20 - -

100.000 1*81* 333 151 31

25

Table II.- The response of adults, nymphs, and eggs of T. gloveri to parathion, Niagara Experimental Compound, aramite, arid sulphur dusts applied at the rate of 10 pounds per acre.

Acaricides Dosage No. of 'No. No. dead Observed Computedpercent mites survivors after mortality mortality

treated after 1*8 hours percent percent1*8 h o u r s _______________

ADULTS

Parathion 0.010 100 72 28 28 26.30.030 100 28 72 72 72.10.060 100 8 92 92 91.30.080 100 5 95 95 95.8

Niagara 0.050 100 61* 36 36 37.0Experimental 0.100 100 1*0 60 60 50.9Compound 0.500 100 27 73 73 79.7

1.000 100 1* 96 96 88.5

Aramite 0.050 100 6 9 31 31 37.80.100 100 58 1*? U2 1*6.90.500 100 1*0 60 60 67.71.000 100 17 83 83 75.6

Sulphur 5.000 100 66 31* 31* 31.67.500 100 55 1*5 U5 50.7

10.000 100 Itl* 56 56 61*. i25.000 100 22 78 78 93.2

26

Table II.- (Continued). The response of adults, nymphs, and eggs of T. gloveri to parathion, Niagara Experimental Compound, aramite, aid sulphur dusts applied at the rate of 10 pounds per acre.

Acaricides Dosagepercent

'To. of" nymphs treated

'"To. ." 'survivors after I4.8 hours

No. dead after U8 hours

Observedmortalitypercent

Computedmortalitypercent

Parathion 0.010 156NXMFHS

120 36 23 1U.50.030 225 189 66 29 U6.10.050 150 5U 96 6U 63.70.080 7U k 70 95 80.6

Niagara 0.050 215 192 23 11 18.5Experimental 0.100 217 132 85 39 32.UCompound 0.500 215 72 1U7 67 71.61.000 212 28 18U 87 8U.5

Aramite 0.050 118 8U 3U 29 2t| .2 .0.100 113 51 62 55 Ii6.70.250 130 U6 8U 65 76.80.500 100 k 96 96 91.2:

Sulphur 5.000 111 62 h9 hh 50.27.500 55 16 39 11 55.210.000 60 12 U8 80 58.815.000 75 111 61 81 63.3

27

Table II,- (Continued). The response of adults, nymphs, and eggs ofT« gloveri to parathion, Niagara Experimental Compound, aramite,and sulpKur dusts applied at the rate of 10 pounds per acre.

Acaricides Dosage No. of NoT Hoi observed Computedpercent eggs hatched unhatched mortality mortality

treated eggs after eggs after percent percent __________________________ 6 days 6 days______ __________________

EGGSParathion 0.10 121* 102 22 18 H.7

0.25 nil 72 I*2 37 38,50.50 158 80 78 ii? 65.2;0.70 n8 20 98 83 76.5

Niagara 1.00 138 n? 21 15 15.7Experimental 1.50 96 73 23 2h 22.1Compound 2.00 69 U5 2k 35 32.)*

3.00 156 102 5U 3.6 39.9

Aramit® 2.00 127 98 29 23 22.32.50 99 73 26 26 29.95.00 218 90 128 59 57.57.50 128 31 97 76 73.5

Sulphur 25.00 96 81 15 15 «• tm

50.00 12i* 99 25 20 tm tm

75.00 161 126 35 21 tm tm

100.00 157 in i+6 29 - -

28

Table III,- The response of adults, nymphs, and eggs of T. cinnabarinusto parathion, Niagara Experimental Compound, aramite, andsulphur dusts applied at the rate of 10 pounds per acre*

Acaricides Dosagepercent

Ndo ofmitestreated

No.survivors after U8 hours

Wo. dead' after h8 hours

Observedmortalitypercent

Computedmortalitypercent

ADULTS

Parathion 0.010 100 8U 16 16 9.50.030 100 68 32! 32 U8.60.060 100 20 80 80 77.80.100 100 h 96 96 91.8

Niagara 0.100 100 72' 28 28 2U.2Experimental 0.230 100 la 59 59 65.0Compound 0.500 100 12 88 88 88.6

0.750 100 2 98 98 95.U

Aramite 0.075 100 73 27 27 31.20.100 100 5h U6 k6 ho.20.250 100 33 67 67* 69.80.500 100 12 88 88 86.U

Sulphur 1.000 100 88 12' 12 10.05.000 100 7h 26 26 36.2

10.000 100 52 U8 hQ 52.025.000 100 16 8U 8b 71.8

29

Table III.— (Continued) The response of adults, nyrtphs,and eggs ofT. cinnabarinus to parathion, Niagara Experimental Compound, aramite,' and 'sulphur dusts applied at t he rate of 10 pounds per acre.

Acaricides IJosage No. of IJoT No. dead 6bserved Computed'percent nymphs survivors after mortality mortality

treated after 1*8 hours percent percent____________________1*8 hours __________ ________

NYMPHSParathion 0.010 280 236 111* 16 12.0

0.030 292 168 121* 1*2' 5U.00.050 180 56 121* 69 75.50.090 1*12 12 1*00 97 91.6

Niagara o.5oo 283 123 160 56 50.7Experimental 0.750 308 112' 196 61* 62.2Compound 1.000 235 56 179 76 69.9

1.500 268 63 205 76 79.1*

Aramite 0.050 252 225 27 11 11.60.100 132 90 1*2 32 22.20.500 321 171 150 1*7 59.2:1.000 255 18 237 93 7l*.6

Sulphur 1.000 156 11*7 9 6 0.05*ooo 285 228 57 20 21*. 110.000 180 95 85 1*7 52.525.000 315 63 252 80 81**1

30

Table III.- (Continued) The response of adults, nymphs, and eggs ofT. cinnabarinus to parathion, Niagara Experimental Compound, aramite, and'sulphur dusts applied at the rate of 10 pounds per acre.

Acaricides Dosage No. of No^ Noi Observed. Computed 'percent eggs hatched unhatched mortality mortality

treated eggs after eggs after percent percent•_________________________ 6 days_____ 6 days________________________

Parathion 0.100 217EGGS167 50 23 15.10.250 128 85 1*3 31* 98.5

0.500 1# 191* 97 87J*0.700 136 0 136 100 9U.6

Niagara 2.000 251 205 1*6 18 19.9Experimental 2.500 283 189 91* 33 29.8Compound 3.000 188 126 62 33 39.8

5.000 217 85 132 60 67.1*

Aramite 2.000 31*0 309 31 9 11.22.500 271* 210 61* 23 20.35.000 206 61* 11*2 68 65.1

' 7.500 17 u 19 199 89 86.1*

Sulphur 25.000 11*3 126 17 1150.000 271 211 60 22'75.000 105 88 17 16 -100.000 186 11*2 1*1* 23 mm mm

31

Table 17,- The response of adults, nymphs, and eggs of T. lobosusto parathion, Niagara Experimental Compound,’"aramite, andsulphur dusts applied at the rate of 10 pounds per acre.

AcaricI3ei Dosage'™ NoV of fJol No. dead Observed 'Computedpercent mites survivors after mortality mortality

treated after 1*8 hours percent percent1*8 hours

Parathion 0.010 100

ADULTS

73 27 27 22.50.030 100 U7 53 53 61.60.060 100 17 83 83 83.00.090 100 u 96 96 91.0

Niagara 0.100 100 60 ho Uo 19.8Experimental 0.250 100 U3 57 57 65.0Compound o.^oo 100 30 70 70 71.1

0.750 100 8 92 92 7U.1

Aramite 0.100 100 60 uo Uo Ul.80,500 100 Uo 60 60 72.61.000 100 111 86 86 82.91.500 100 8 92 92 .87.5

Sulphur 3.000 100 68 32 32 29.75.000 100 50 50 50 U9.97.500 100 UU 56 56 66.310.000 100 16 8U 8U 76.3

32

Table 17.- (Continued) The response of adults, nymphs, and eggs of T. lobosus to parathion, Niagara Experimental Compound, aramite, and sulphur dusts applied at the rate of 10 pounds per acre.

Acaricides Dosagepercent

Wo. of nymphs treated

No.survivors after 1*8 hours

Wo. dead after 1;8 hour 3

Observedmortality-percent

Computedmortality-percent

NYMPHS

Parathion 0.008 115 72 U3 37 37.00.010 133 65 68 51 1*1*.80.030 lii3 21* 119 83 80.10.050 89 10 79 89 90.3

Niagara 0.050 119 9U 25 21 22.5Experimental 0.100 117 79 38 32 1*6.1Conpound 0.250 199 90 109 51* 77.8

0.500 126 10 116 92 92.2

Aramite 0.010 138 82 56 hi 38.2'0.075 108 1*2 66 61 70.60.100 176 1*2 131* 76 7l*.60.250 150 28 122 81 85.2

Sulphur 0.250 113 78 35 31 1*0.50.500 11*1* 77 67 1*7 1*7.81.000 138 62 76 55 51*.935.000 169 50 119 70 65.9

33

Table IV.- (Continued) The response of adults* nymphs, and eggs of T. lobosus to parathion, Niagara Experimental Compound, aramite, and sulphur dusts applied at t he rate of 10 pounds per acre.

Acaricides Dosage NoY of No. "too. Observed Computedpercent eggs hatched unhatched mortality mortality-

treated eggs after eggs after percent percent _________________________________ 6 days 6 days

EGGS

Parathion 0.100 100 82 18 18 13.90.2# 125 95 30 2l| U2.50.500 131 32 99 76 68.1+0.700 2 0l| 29 175 86 79.5

Niagara 1.500 106 76 30 28 2J+.6Experimental 2.000 110 76 31+ 31 38.6Compound 2.500 120 50 70 58 50.1

3.000 113 U6 65 58 59.9

Aramite 1.500 137 97 l+o 29 26.12.500 152 69 83; 55 5U.25.000 lli3 28 115 80 86.97.500 126 2 121+ 98 95.6

Sulphur 25.000 185 137 1;8 2550.000 137 90 U7 31+ mm75.000 12l| 68 56 h$ mm mm

100.000 102 1+7 55 5U -------

3k

Table V,- The response of adults, nymphs, and eggs of T. deseretorumto parathion, Niagara Experimental Compound,""aramite, andsulphur dusts applied at the rate of 10 pounds per acre.

Acaricides Dosage RoT'o? Do. dead Observed Computedpercent mites survivors after mortality mortality

treated after 1|8 hours percent percentU8 hours

ADULTS

Parathion 0.003 100 8U 16 16 10,90.005 100 76 21* 21* 31n 70.008 100 36 61* 6h 6U.70.010 100 18 82 82 77.1

Niagara 0.050 100 80 20 20 16.^Experimental 0,100 100 68 32 32 Uo.oCompound 0.250 100 23 77 77 76,2

0.500 100 tt 95 95 92.5

Aramite 0.075 100 80 20 20 21.90.100 100 6U 36 36. 30.60.250 100 liU 56 56 63.60.500 100 12 88 88 81*.0

Sulphur 1.000 100 100 0 0 0.05.000 100 8U 16 16 9.2• 10.000 100 32 U8 U8 1*9.6

25.000 100 6 9k 9k 95.8

35

Table V.- (Continued) The response of adults, nymphs, and eggs ofT. deseretorum to parathion, Niagara Experimental Compound, aramite, and sulphur dusts applied at-the rate of 10 pounds per acre*

Acaricides Dosage No. of Nou No, dead Observed Computed "percent nymphs 'survivors after mortality mortality

treated after l;8 hours percent percentU8 hours __

NYMPHS

Parathion 0.001 156 117 39 25 mm mm

0.005 126 8U U2 33 32.30.008 112 20 92 82 7U.80.010 252 27 225 89 88.6

Niagara 0.050 212 1U|. 68 3k 29.9Experimental 0.100 112 6k U8 U3 U3.8Compound 0.500 236 80 156 66 76.0

1.000 338 30 308 91 85.9

Aramite 0.080 81; 60 2h 29 2iw80.100 208 1U0 68 33 37.90.250 2811 116 168 59 57.lt0.500 312 88 221; 72 71.2

Sulphur 0.100 196 168 28 lit 15.71.000 220 181; 36 16 31.65*ooo 260 168 92 35 U5.7

10.000 372 108 26h 71 52.1

36

Table V.- (Continued). The response of adults, r.ymphs, and eggs ofT. deseretorum to parathion, Niagara Experimental Compound, aramite, and sulphur dusts applied at the rate of 10 pounds per acre.

Acaricides Bosage Mo. of Mfo". No. oFservect Computecr-percent eggs hatched unhatched mortality mortality

treated eggs after eggs after percent percent______________________________ 6 days_____ 6 days________________________

EGGS

Parathion 0.008 377 335 U2 11 13.60.010 399 310 89 22 18.80.030 1+38 207 231 53 56.50.060 538 100 1+38 81 79.3

Niagara 1.500 51+1 1+51+ 87 16 16.0Experimental 2.500 381 2 95 86 23 37.5Compound 3.000 189 Uo 11+9 79 52.2

5.000 270 U8 222 8 2 86.5

Aramite 1.500 1+1+9 351+ 95 21 21.02.500 292 166 126 1+3 1+3.05.000 31k 69 305 82 71.1+7.500 162 25 137 85 81+.8

Sulphur 25.000 337 2ljl 96 27 25.050.000 266 1U5 121 1+5 52.175.000 280 85 195 70 68.li100.000 367 73 291+ 80 78 JLj.

Table VI.- Comparative susceptibility of adults, nymphs, and eggs of Tetranychus spp. to parathion, Niagara Experiment Compound, aramite, and sulphur dusts.

Acaricides Develop- T. tumidus T. gloveri T. cinnabarinus T. lobosus T. desertorummental LD 50 LB 50 LD LD 50 LD 50 ’

____________ stages_____________________________________________________________________________Parathion Adults 0.023 + 0.007 0.180 + 0.007 0.031 + 0.0100 0.022 + 0.010 0.0061} + 0.0020

Nymphs 0.0U0 + 0.016 0.032 + 0.008 0.027 + 0.0050 0.118 + 0.002 0.0059 + 0.0020Eggs 0.390 + 0.077 0.350 + 0.09U 0.210 + 0.0630 0.290 + 0.082 0.0250 + 0.0002

Niagara Adults 9.100 + 0.029 0.09U + 0.037 0.180 + 0.0001} 0.180 + 0.050 0.1300 + 0.0200Experiment­ Nymphs 0.U00 + 0.058 0.200 + 0.005 0.0li7 + 0.0120 0.110 + 0.021; 0.1050 + 0.0290al Compound Eggs 3.k 00 + 1.11U U.200 + 2.128 3.700 + 0.6610 2.500 + 0.695 2.9000 + 0.6600Aramite Adults 0.270 ± 0.052 0 j.30 ± 0.021} 0.139 ± 0.00l}0 o.ii}5 ± 0.020 0.1750 ± 0.00i}0

Nymphs 0.320 ± 0.003 0.110-_ -r 0.001 0.062 + 0.0170 0.021 ± 0.002 0.1800 + 0.0003Eggs 6.000 + 0.020 li.100 ± 0.037 i}.000-± 0.8320 2.3l}0 ± 0.686 3.0000 ± 0.0230Sulphur Adults' U.950 0.590 7.1}00 + O.OliU 9.200 + 3.1930 5.000 + o.oUli 10.0000 + 3.1060

Nymphs 5.300 + 1.015 U .500 + 2.060 9.800 + 2.5150 0.680 + 0.196 8.1}000 + 0.0690Eggs - + - - + - - + - - + - U8.0000 + 0.2850

* LD 50 is based on per cent dust concentrate at a 10 pounds per acre rate of application.

TUM ID U S

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T O A D U L T S , N Y M P H S , A N D EGO O F M IT E S IN D IC A T E D .

Comparative effectiveness of four acaricides, two containing sulphur confounds and two phosphorus compounds, against five different species of spider mites of the genus Tetranychidae.

ResultsData are presented in Tables VII, VIII, IX, and X and in

Figures $ through lU• These tables and figures were established and rearranged from Tables I through VI and Figures 1 through h so that such a comparison would be possible.

Table VII shows a comparative susceptiblity of species to acaricides tested. Table VIII, on the other hand, shows the affective­ness of acaricides on species. Figures 5 through 8 are spplementary to Table VII, while Figures 9 through 13 supplement Table VII.

It should be mentioned that dosage mortality curves for susceptiblity of eggs to sulphur were omitted from Table VIII since sulphur was practically ineffective on eggs except on those of T. desertorum.

1*2

Discussion Susceptibility of species to acaricides Parathion;

Figure 5 shows that adults of T. desertorum were the most sensitive to parathion among the species tested. It can be noticed from the dosage mortality curves in Figure 5> and from the LD 50 values in Table VII that adults of the rest of the 3pecies are quite different in their susceptibility to parathion. However, the test of significance did not show any significant differences between adults of T. tumidus, T. gloveri, T. cinnabarinus, and T. lobosus in their susceptibility to parathion.

Resistance of adults of the five species to parathion can be arranged in an increasing order of resistance as follows:

T. gloveri

T. desertorumT. lobosusT. tumidusT. cinnabarinus

As seen' in Figure 5, nymphs of T. desertorum, as its adults, were still the most susceptible ones to parathion. There was no significant difference in susceptibility to parathion between nymphs of T. cinnabarinus, T. gloveri, and T. tumidus, but the difference between their nymphs and nymphs of T. lobosus was significant. The final picture for resistance of nymphs to parathion is in increasing

hh

order of resistance:T. cinnabarinus

T. desertorum ^ T. lobosus ___* T. gloveri T. tumidus

Eggs of T. desertorum react similarly to the adults aid nymphs, in being most susceptible to parathion of the species tested. The test of significance showed a rather peculiar situation between eggs of T. cinnabarinus, T. lobosus, T. gloveri, but the difference between eggs of T. cinnabarinus and eggs of T. lobosus was insignifi­cant. Similarly, there was a significant difference between eggs of T. tumidus and eggs of T. lobosus, but the difference between eggs of T. tumidus and T. gloveri was insignificant. Therefore, any arrange­ment of the eggs of these species according to their susceptiblity to parathion will conflict between the test of significance and the actual values obtained. However eggs of T. lobosus and T. gloveri can be considered as intermediate between eggs of T. cinnabarinus and eggs of T. tumidus in their susceptiblity to parathion. This is drawn from the fact that the dosage mortality curve of eggs of T. lobosus is closer to that of T. cinnabarinus, and the dosage mortality curve for the eggs of T. gloveri is closer to that of T. tumidus. On the basis of this discussion the resistance of eggs of the five species can be arranged in the following order of increasing resistance to parathion.

T. desertorum — >• T. cinnabarinus*T. lobosusT. gloveri -> T. tumidus

b$

Niagara Experimental Compound 1137’Data of susceptiblity of species tested with Niagara Experi­

mental Compound 1137 are presented in Figure 6. Thi3 Figure shows that adults of T. lobosus and T. cinnabarinus had the same dosage mortality curve. There was no significant difference between adults of T. desertorum, T. tumidus, and T. gloveri. The susceptiblity rank of adults to Niagara Experimental Conpound 1137 is written below:

T. desertorumT. tumidusT. gloveri

T. lobosusT. cinnabarinus

Nymphs showed 'statistically the same order of increasing re­sistance as appeal's in Figure 6, namely:

T. lobosusT. cinnabarinus

T. desertorumT. gloveri -y — • tumidus

Susceptibility of eggs to Niagara Experimental Compound 1137 was practically the same for all species tested.

Aramite and Sulphur:Figures 7 and 5 present susceptibility of species tested with

both aramite and sulphur. Following the same order used in the previous discussion for parathion and Niagara Experimental Compound 1137 the sensitivity of species tested is listed below:

AramiteAdults

T. gloveriT. cinnabarinusT. lobosus

T. desertorum T. tumidus

U6

Nymphs

T. lobosus T. cinnabarinus T. gloveri T. desertorum T. tumidus

EggsT. lobosusT. desertorum

Sulphur:Adults

T* lobosus

T* cinnabarinusT. gloveri

^ T . tumidus

T. tumidus

Nymphs

T. lobosus

Eggs

T. gloveri T. cinnabarinus T. desertorum

T. gloveri T. desertorum

T. cinnabarinus

T. desertorum

T* tumidus

T. lobosus

T. cinnabarinus T. gloveri T. tumidus

Each time two species show no significant difference in susceptibility to any acaricide, a value of one is assigned to their association together (Tables IX and X). Thus the more times they are associated, the more similar they are considered to be in response to the overall acaricide program. If expressed as a reciprocal, this

1*7

reciprocal may be taken as an indication of dissimilarity if it is large, and closer affinity if it is small. Figure ll* shows the various species placed at distances to each other equivalent to the reciprocal number of the times there was no statistical significance in their response to any acaricide at any stage, and in all combinations. The spread of the position of each species is indicated by the histogram below the figure. The indication is that desertorum is the most susceptible, with lobosus and cinnabarinus as intermediate, tumidus as the most hardy, x-rhile gloveri lies between the last two groups in suscep­tibility.

ConclusionA review of the previous discussion will lead to the conclu­

sion that:1. Adults of T. desertorum are more susceptible to parathion

than are adults of both T. gloveri, T. lobosus, T. tumidus, and T. gloveri. The last four show the same susceptiblity to parathion.

Similarly nymphs of T. desertorum are more suscepti­ble to parathion than are nymphs of T. lobosus, which in turn are more susceptible to parathion than nymphs of T. cinnabarinus, T. gloveri, and T. tumidus.

Again eggs of T. desertorum are much more sensitive to parathion than are eggs of T. cinnabarinus♦ The last are more susceptible to parathion than are the eggs of T. lobosus and T. gloveri. Egg3 of T. tumidus are the

most resistant ones to parathion among other species

tested.For Niagara Experimental Compound 1137 the susceptibility o.f developmental stages of the five species is quite different than that to parathion. In this particular case, it is noticed that adults of both T. tumidus and T. gloveri are shifted to join T. desertorum in its sensitivity to Niagara Experimental Compound 1137. The same thing can be said of nymphs of T. cinnabarinus which were more susceptible to Niagara Experimental Compound 1137 than nymphs of the other species. How­ever, eggs of all species tested have shown the same susceptibility to this substance.With aramite and sulphur, it is quite clear that adults and nymphs of T. desertorum are not the most sensitive mite compared with the other four species. However, eggs of T. desertorum are still the most susceptible ones to both aramite and sulphur. Adults and nymphs of T« tumidus are the most resistant to aramite among others, but they 3eem more susceptible to sulphur, T. lobosus has occupied the first place in being the more sus­ceptible mite to sulphur compounds. However, it3 eggs are less susceptible to sulphur than eggs of T. desertorum.

* h9

Effectiveness of acaricides testedData in Figures 9 through 13 and in Table XI show clearly

a comparative effectiveness of acaricides tested on adults, nymphs, and eggs of mj.tes in question.

It is evident in all the tables that parathion excels all the rest of the acaricides used in being the most effective acaricide on adults, nymphs, and eggs of mites tested. It is clear also that sulphur gives an inferior kill to adults, nymphs, and eggs of the five species tested. These results agree with those obtained by Matthysse and Naegele (l?£2) who state that parathion and aramite produced high mortality of motile mites. They concluded also that wettable sulphur gave inferior immediate kill. Gaines et al (195>1) reported also that parathion proved to be more toxic to spider mites than any of several experimental phosphorus compounds.

Both aramite and Niagara Experimental Compound 1137 proved to have an intermediate toxicity between parathion and sulphur. They showed the same toxicity against adults of T. gloveri and T, lobosus.They had the same ability to kill eggs of T. gloveri, T. lobosus,T. desertorum and T. cinnabarinus. Again, both acaridices exhibited the same toxicity against nymphs of T. cinnabarinus.

Niagara Experimental Compound 1137, however, was more toxic than aramite to adults, nymphs, and eggs of both T. tumidus and T. desertorum. On the other hand, aramite was more toxic than Niagara Experimental Compound 1137 against adults of T. cinnabarinus and against both nymphs of T. gloveri and T. cinnabarinus.

In general it seems that phosphorus compounds would give more

effective control on mites tested than would sulphur compounds. These results are in agreement with those obtained by Gaines et al (19$0).They showed that phosphorus compounds were more toxic than tho sulphur compounds when applied for control of spider mite3 and aphids. It must be remembered that the Niagara Experimental Compound 1137 also contai.no sulphur in addition to phosphorus.

Conclusion:It can be concluded that parathion is highly effective against

the five species tested.Niagara and aramite are le3s effective than parathion, and

are equally effective. However, Niagara Experimental Compound 1137 compared favorably with aramite for the control of T. tumidus.

Sulphur is the weakest toxicant among the acarides tested.

Table VU»- Comparative susceptibility of adults, nymphs, and eggs of Tetranychus spp. to each acaricide. *

Acaricides Species Adults Nymphs Eg~~s_______________________________ LD $0 _______ II)'$0 ID 50'Parathion T. tumidus 0.0230 + .0.0070 0 . 0U00 + 0.0160 0.3900 + 0.0770

T. gloveri 0.0180 + 0.0070 0.0320 + 0.0080 0.3500 + 0 . 09U0T . cinnabarinus 0.0310 ± 0.0100 0.0270 ± 0.0050 0.2100 + 0.0630T. lobosus 0.0220 ± 0.0100 0.0118 + 0.0020 0.2900 ± 0.0820T. desertorum 0.0061; ± 0.0020 0.0059 + 0.0020 0.0250 + 0.0002

Niagara T. tumidus 0.1000 ± 0.0290 o.Uooo + 0.0580 3.U000 + 1 .U U 0Experimental T. gloveri 0 . 09U0 ± 0.0370 0.2000 + 0.0050 u.2000 Hr 2.1280Compound T. cinnabarinus 0.1800 + o.oooU O.OltfO + 0.0120 3*7000 + 0.6610

T. lobosus 0.1800 + 0.0500 0.1100 4. 0.02U0 2.5000 -r 0.6950T. desertorum 0,1300 ± 0.0200 0.1050 ± 0.0290 2.9000 ± 0.6600

Aramite T. tumidus 0.2700 ± 0.052U 0.3200 + 0.0030 6.0000 + 0.0200T. gloveri 0.1300 + 0 . 02U0 o .n o o ± 0.0010 U .iooo ± 0.0370T. cinnabarinus 0.1390 + O.OOljO 0.0620 ± 0.0170 li.0000 + 0.8320T. lobosus 0.31*50 + 0.0200 0.0210 X 0.0020 2.31400 + 0.6560T. desertorum 0.1750 + O.OOUO 0.1800 -t. 0.0003 3.0000 0.0230

Sulphur T. tumidus U.9500 + 0.5900 5.3000 4- 1.0150 .. — — _ — —T. gloveri 7 .1;000 + 0 . 0UU0 U.5000 *r 2.0600 - - - - _ -T. cinnabarinus 9.2000 a. 3.1930 9.8000 + 2.5150 - - - . . .T. lobosus 5.00CO .1 O.OUUO 0.6800 t 0.1960 - - - _ _ _

T. desertorum 10.0000 + 3.1060 8.1:000 1 0.0690 US. 0000 ± 0.2850

LD 50 is based on per cent dust concentrate at a 10 pounds per acre rate of'application.

Table VIII.- Comparative effectiveness of parathion, Niagara Experimental Compound, aramite, and sulphur dusts against adults, nymphs, and eggs of Tetranychus spp, *

Species Acaricides Adults Nymphs EggsLD 50 LD 50 LD 50

T. tumidus Parathion 0.0230 0.0070 O.OliOO 0.0160 0.3900 0.0770Niagara Experi­mental Compound 0.1000 0.0290 O.UOOO 0.0580 3.U000 1 .11U0Aramite 0.2700 0.0520 0.3200 0.0030 6.0000 0.0200Sulphur U.9500 0.5900 5.3000 1.0150 ---- - - -

T. gloveri Parathion 0.0180 0.0070 0.0320 0.0080 0.3500 0.09U0Niagara Experi­mental Compound 0.09U0 0.0370 0.2000 0.0050 U.2000 2.1280Aramite 0.1300 0.02i|0 0.1100 0.0010 Uaooo 0.0370Sulphur 7.U000 o.oUUo u .5000 2.0600 - - - - - -

T. cinnabarinus Parathion 0.0310 0.0100 0.0270 0.0050 0.2100 0.0630Niagara Experi­mental Compound 0.1800 o.oooU 0.0U70 0.0120 3.7000 0.6610Aramite 0.1390 O.OOliO 0.0620 0.0170 U .0000 0.8320Sulphur 9.2000 3.1930 9.8000 2.5150 - - - ----

T. lobosus Parathion 0„0220 0.0100 0.0118 0.0020 0.2900 0.0820Niagara Experi­mental Compound 0.1800 0.6500 0.1100 0.02U0 2.5000 0.6950

Aramite 0.1U50 0.0200 0.0210 0.0020 2.3U00 0.6860Sulphur 5.0000 o.oUUo 0.6800 0.1960 - - - ----

T, desertorum Parathion 0.006U 0.0020 0.0059 0.0020 0.0250 0.0002Niagara Experi­mental Compound 0.1300 0.0200 0.1050 0.0290 2.9000 0.6600Aramite 0.1750 O.OOUO 0.1800 0.0003 3.0000 0.0230Sulphur 10.0000 3.1060 8.U000 0.0690 U8.0000 0.2850

LD 50 is based on per cent dust concentrate at a !L0 pounds per acre rate of application.

53

Table IX,- Summary of susceptibilities of various stages ofthe five species of mites to the acaricides indicated.

Ranis' Parathion NiagaraExperimentalCompound

Aramite Sulphur

Adults 1 desertorum desertorum gloveri lobosus]„2 gloveri tumidus 2 cinnabarinus 2 tumidus]c3 lobosus’ gloveri' JLob'osus gloverih tumidus 2 lobosus Ho clesertorum cinnabarinus5 cinnabarinus

jgm.n, i ■ ■■■■ ■ «•;cinnabar inujw tumidus desertorum

Nymphs 123U5

desertorumlobosuscinnabarinusgloveritumidus

cinnabarinus Lobosusdesertogloveritumidus

r jorurrT

lobosuscinnabarinusgloveridesertorumiumdus

lobosus[gloveriLItumidus

Eggs 123h5

desertorumcinnabarinuslobosus 2gloveriuumiidus

Lobosus Lobosus | desertorumdesertorum desertorunp Lobosusfcumldus 2 cinriabarinusj cinnabarinuscinnabarinus gloveri r gloverigloveri tumidus tumidus

12

The lower the number, the higher the susceptibility.Differences not significant. Rank within the group determined only by LD !?0.

Table Evaluation of similarity in response of allstages of all species to all acaricides tested,

Species group No. of times response Reciprocal ofwas similar (no sig. diff.) No. of times

similardesertorum - cinnabarinus 3 .33desertorum - lobosus 3 .33desertorum - gloveri 3 .33desertorum - tumidus 2 .50lobosus - cinnabarinus 5 .20lobosus - gloveri 5 .20lobosus - tumidus h .25cinnabarinus - gloveri 7 •1Ucinnabarinus - tumidus k .25gloveri - tumidus 6 .16

99.9

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55

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NYM PHS, AND EGOS OF M ITES INDICATED TO

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i 1.00

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56

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FIGURE 9 COMPARATIVE e f f e c t i v e n e s s CF

ACARICIOES INOtCATED A G A IN S T

A D U LT S , NYMPHS, ANO EGGS

OF X T JM lO U S

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FIGURE 9 COMPARATIVE EFFE C TIV E WES S OF

ACAAIC IDES INDICATED A G A IN S T

A D U LT S , NYMPHS, ANO EGGS

OF T T JM iO U S

100

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A C A R lC IO E S IN D IC A T E D A 6 A IN S T

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a c a r c o e s IN D IC A T E S a g a i n s t

A O U L T S . N Y M P H S , AND E S S S

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ACARIC'DES AOL'LTS, ST

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T. desert or vanT. lobosus T. cinnabarirrus

■» !£• glo^griT. tvimidus

Figure lli. Conparison of susceptibilities of the five species (over-all) based upon similarity of response (see text, p. Ii7 discussion).

PART II

Susceptibility to Acaracides of T. cinnabarinus Reared on Rose and Cotlion

Procedure

An experiment was conducted to investigate the difference in susceptibility to acaricides between T. cinnabarinus reared on cotton and T. cinnabarinus reared on roseso In this experiment mites were reared on roses in the laboratory under the same conditions used for rearing mites on cotton. Mites from the original stock were transferred from cotton seedlings to rose leaves. The method of rearing was described in Part I. When the fourth generation was reached, an equal number from both cultures was treated with parathion. The number of mites tested for each dosage was 25 animals. Each treatment was repeated i; times, so that the total number for each dosage was 100 mites. Parathion was applied at the rate of 10 pounds per acre, using the dusting tower described in Part I. Controls were used for all treatments.

ResultsThe results are presented in Table XI and Figure 15.

65

66

Discussion

Data presented in Table XI show that a dosage of 0*060 per cent parathion was enough to kill 80 per cent of mites reared on cotton.Such dosage gave £2 per cent mortality for mites reared on roses. Similarly a dosage of 0.100 per cent parathion gave a mortality of 96 per cent for mites on cotton, and a mortality of $3 per cent for mites on roses. LD 50's for both cultures were obtained from dosage mortality curves shown in Figure lf>. It is clear from both values that mites on roses were much more resistant to parathion than mites reared on cotton. The test of significance showed that such a difference was significant at the 5 per cent level. Similar results were obtained by Compton and Kearns (1937) who reported that mites on roses are more difficult to kill than are those on a number of other plants. They also suspect­ed the texture of the rose leaf to be in part responsible for the difference. Neiswander and Rodriguez (19!?0) concluded that a mite population feeding on roses is usually more resistant to the action of acaricides than one on beans. They assumed that a part of the difference in susceptibility can be attributed to the food. However,

i

the latter emphasized the fact that a study of the influence of host plant composition on susceptibility or resistance of mites to acaricides as well as a genetic study of the species should yield valuable information. Cole and Fish (19!?!?) showed that a red form

67

population (which probably was T. cinnabarinus) from squash when tested on bean in comparison with the red form from bean was less susceptible to malathion. This resistance may be attributed to the vigor of the host plant as reported by German and Kennedy (I9li9) *

ConclusionA mite population feeding on roses was about 2% times more

resistant to parathion than were mites feeding on cotton.

i

Table XI.- Comparative mortality of T. cinnabarinus reared on cotton and roses and treated with, parathion at the rate of 10 pounds per acre.

Dosage No. of T• cinnabarinus on cotton T,. cinnabarinus on rosespercent treated

mitesNo. of No. of survivors dead after after 1*8 hours 1*8 hours

Observedmortalitypercent

Computedmortalitypercent

No. of No. of survivors dead after after 1*8 hours 1*8 hours

Observedmortalitypercent

Computedmortalitypercent

0.010 100 81* 16 16 9.50.030 100 68 32 32 1*8.60.060 100 20 80 80 77.8 1*8 52 52 1*6.20.100 100 1* 96 96 91.3 1*7 53 53 52.60.2^0 100 31 69 69 66.20.500 100 9 91 91 71*. 3

LD 50 ® 0.031 Standard error ± = 0.010

LD 50 » 0.080 Standard error i = 0.030

O s03

% M

OR

TALI

TY

9 9 .9

FED ON COTTON

FED ON ROSES90

CINNABARINUS

0.1a , ° % CONCENTRATION K00 10-0

1

FIGURE 1$DOSAGE MORTALITY CURVES FOR THE TOXICITY OF PARATHION

CINNABARINUS

a i° % CONCENTRATION 100

FIGURE 15DOSA6E MORTALITY CURVES FOR THE TOXICITY OF PARATHION

TO ADULTS OF T. CINNABARINUS ON COTTON AND ROSES-

SUMMARY AND CONCLUSIONS

An accurate determination of both the species of mite and its host plant is of great importance for obtaining satisfactory control.

The toxicity of any acaricide cannot be evaluated from its effect on the adult stage only. An evaluation based on the relative toxicity of such an acaricide against the different developmental stages has yielded valuable information. For instance, if an infestation is known to consist only of T. desertorum, the acaricide recommended for its control would be sulphur which is very effective on eggs of T. desertorum. If an infestation consists of the five species, then the acaricide recommended for their control would be parathion, Aramite and Niagara Experiment Confound 1137 have shown the same toxicity in most cases.

There is a definite correlation between morphology and physiology of mites. Based on their responses to different acaricides, mites tested are grouped as follows:

I, T, tumidus Banks and T. gloveri Banks H , T, cinnabarinus Boisduval and T. lobosus Boudreaux

III, T. desertorum BanksPritchard and Baker (19$$) have 'this same grouping on a

morphological basis, except that T, gloveri is considered by them to be

70

71

a synonym of T. tumidus and they did not list T. lobosus, while T* cinnabarinus was listed as a synonym of T„ telarius (!.)• Boudreaux (unpublished data) consideres T. gloveri a distinct species closely related to T_, tumidus, and he also (19£6) has shovm that T* cinnabarinus and T* lobosus are species distinct from but closely related to T* telarius (L.).

Xt can be concluded, therefore, that physiology as well as morphology can be used fruitfully in the field of taxonony.

BIBLIOGRAPHY

Baker, E. W. and A. Earl Pritchard. 1953. A Guide tolhe Spider Mites of Cotton. Hilgardia 22(7), 203*

Blickle, A. L. 19k2. Penetration of Oils into Insect Eggs, (a)Influence of Oil Characteristics (b) Influence of Age of Eggs and of Species. Studies of Contact Insecticides XVI. Tech.Bull. N. H. Agr. Expt.Sta. No. 79, pp. lU.

Bliss, C. I. 1938. The Determination of Dosage-mortality Curve from Small Numbers. Quart. Jour. Fhar. and Pharmacology 11(2):192

Boudreaux, U. B. 195U-55* Summary of Investigations upon Cotton Spider Mites, 195%. L.S.U. Expt. Sta, Annual Report pp. 101-102.

Boudreaux, H. B. 1956. Revision of the Two-Spotted Spider Mite(Acarina, Tetranychidae) Complex, Tetranychus telarius (Linnaeus), Annals of the Ent. Soc. of Am. 1*9(1)sJU3—JU8•

Campell, F. L. and F. R. Moulton. 19l*3. Laboratory Procedures inStudies of the Chemical Control of Insects. Am. Ass. Adv. of Science Pub. 20 pp. 115 •

Chapman, P. J. and G. ¥. Pearce. 19h9* Susceptibility of Winter Eggsof the European Red Mite to Petroleum Oils and Dinitro-compounds. Jour. Econ. Ent. I(.2:UU—U7•

Chapman, P. J. and S. E. Lienk. 1950* Orchard Mite Control Experiments in Western New York. Jour. Econ. Ent. 1*3:309-11*.

Cole, Charles E. and E. W. Fish. 1995• Comparative Toxicity of CertainAcaricides to the Carmine and Green Forms of Two-spotted Spidermite. Jour. Econ. Ent. 1*8:85-87.

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AUTOBIOGRAPHY

Mohammad Ramadan Abo-El-Ghar was born in Shebin-EUcom, Egypt, August 2Y, 1922. He roccdved his high school diploma Prom Shebin- Jilkom High School in Juno 19U3* Ho soon entored Ein-Shams University, Cairo, Egypt. In June 19li7 ho obtained his B. Sc. from tho Colloge of Agriculture of this University. In November 19U7 he was appointed an instructor in Chemistry in the Collego of Agriculture of Ein-Shams University and continued teaching thero until he came to the United States September 3* 1953* He entered Oklahoma A. and M. College, Stillwater, Oklahoma in September 1953* and attended that college for the fall and spring semesters. In June 19$h, He entered Louisiana State University and continued studios toward the Ph. D. degree for which he is now a candidate.

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EXAMINATION ANI) THESIS REPORT

Candidate: Mohammed Ramadan Abo-El-Ghar

Major Field: Entomology

Title of Thesis: Comparative Acarlcldal Responses of Five Species ofSpider Mites

Approved:

M ajor Professor and Chairman

Doan of the Graduate School

EXAMINING COMMITTEE:

M I U :

Date of Examination:

3l1. !°l ^