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Diptera have only one pair of wings; a second pair of wings evolved into small dumb-bell shaped "halteres", which are used for balance during flight. (The two-winged fly is an advancement in flight; that why flies can hover)
Some flies, such as syrphids, masquerade as bees and wasps. However, the pollinating flies can be distinguished with a sharp eye – or better yet, a camera.
The flies have only one pair of wings while bees and wasps have two pairs of wings.
Comical, robust and extremely hairy are the bee flies (bombylids), some with tongues as long as their bodies!
Pollinators are “keystone organisms” in most terrestrial ecosystems.
Pollinators are essential for maintaining the integrity, productivity and sustainability of many types of ecosystems: natural areas, pastures, fields, meadows, roadsides, many agricultural crops, fruit orchards, and backyard vegetable and flower gardens.
Without insect pollinators, many flowering plants would eventually become extinct.
Without the work of pollinators, many fruit- and seed-eating birds and some mammals, including people, would have a less varied and less healthy diet.
Why worry about Dipterans? Can’t the
bees do the pollination work?
Flies and bees are the two most important insect pollinator groups.
Over 71 families of Diptera are known to visit and pollinate flowers, linking the fate of plants and animals.
Depending on the region, the time of the day, the flowering phenology and weather conditions, flies may be the main or exclusive pollinators, or share pollination services with bees and other pollinator groups.
Dipterans are an extremely diverse group, varying in mouth parts, tongue length, size and degree of pilosity.
The diversity of flower-visiting flies is reflected in their effectiveness as pollinators. Some flies, such as long-tongued tabanids of South Africa, have specialized relationships with individual flower genera/species (much like some bees/butterflies)
Other flies are generalists, feeding from a wide variety of flowers. But they like to visit many of the same type while they’re in the neighborhood
In some habitats, such as the forest under-story where shrubs may produce small, inconspicuous, dioecious flowers, flies seem to be particularly important pollinators.
In arctic and alpine environments, under conditions of reduced bee activity, flies are often the main pollinators of open, bowl-shaped flowers, with readily accessible pollen and nectar.
Many flies are generalists; their contributions to plant reproductive success are sometimes discounted because of their reputation as ineffective pollinators.
However, the complexity of interactions in redundant pollination systems is little studied & deserves further attention.
When multiple pollinator species visit the same flowers, their respective value as pollinators is interdependent and may differ from year-to-year or even over the course of the flowering season.
Inefficient pollinators are needed when the more efficient pollinators are absent
Conditions affecting bee populations can be quite different from those affecting fly populations due to the great difference in larval requirements.
Many types of flies have few hairs when compared to bees, and pollen is less likely to adhere to the body surface. But under conditions when bees are scarce, an inefficient pollinator is better than none.
Presence of host plant pollen Bumble bee Syrphid flies
Present Absent
So what kinds of plants are known to be
Dipteran pollinated?
At least seventy-one of the 150 Diptera families include flies that feed at flowers as adults.
More than 550 species of flowering plants are regularly visited by Diptera that are potential pollinators. And that’s just the tip of the iceberg: few fly pollinator surveys exist!
Diptera have been documented to be primary pollinators for many plant species, both wild and cultivated.
More than 100 cultivated crops are regularly visited by flies and depend largely on fly pollination for abundant fruit set and seed production . Examples:
The cocoa tree (Theobroma cacao)
Tropical fruits such as Mango (Mangifera indica), Capsicum annuum and Piper nigrum, pawpaw (Asimina triloba)
Fruit-bearing Rosaceae: Apple (Malus domestica) and Pear (Pyrus communis) trees, strawberries (Fragaria vesca, F. x ananassa), Prunus species (cherries, plums, apricot and peach), Sorbus species (e.g. Rowanberry) and most of the Rubus-species (Raspberry, Blackberry, Cloudberry etc.) as well as the wild rose
Spices and vegetable plants of the family Apiaceae like fennel (Foeniculum vulgare), coriander (Coriandrum sativum), caraway (Carum carvi), kitchen onions (Allium cepa), parsley (Petroselinum crispum) and carrots (Daucus carota)
In addition a large number of wild relatives of food plants, numerous medicinal plants and cultivated garden plants benefit from fly pollination.
Western Yarrow – Achilla millefolia The Yarrows – horticultural plants extraordinaire
Family: Asteraceae (Sunflower family)
Cultivated in Europe ??thousands of years
About half a dozen species are commonly grown as garden plants
Natural variation in color has been exploited – many named cultivars – yellow, pink, red, purple
The species name, millefolium-of a thousand leaves-describes the fine, feathery foliage which resembles a fern. http://aggiehorticulture.tamu.edu/ornamentals/Cornell_Herbaceous
/plant_pages/Achilleamillefolium.html
1/6/2013
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Western Yarrow – Achilla millefolia
Found in most of CA
60-100 species of Achillia worldwide – northern hemisphere
In CA, found in seasonally wet places:
Meadows and pastures Along stream edges In sand dunes Along alkali sinks On coastal strand In coastal grasslands In Coastal Sage Scrub and
The most important fly pollinators are Hover Flies (Syrphid flies) and Bee Flies (Bombyliidae family)
There are many others that visit flowers to feed on nectar.
The common fly pollinators have developed yellow and black stripes on their abdomens, though they are not related to bees or wasps. This is probably a defense mechanism to deter predators; flies pretending to be stinging insects, though they cannot sting.
Often called syrphids, hover flies, flower flies or sweat bees. Small/medium size
Occur in wide range of habitats worldwide: dunes, salt/freshwater marsh, all grassland ecosystems, scrub and forest-ecosystems
Lots of variability – example: short- and very long-tongued species
Visit wide range of flowers and can transport pollen long distances
Important pollinators: regional studies in Europe (Ssymank 2001) showed that up to 80% of the regional flora may be visited by flower flies. Important in local habitats.
Very convincing mimicry of bees and wasps: black with yellow or orange; narrow waist
The most important is for food : nectar and sometimes pollen. Pollen is rich in proteins, which is required by some adult flies before they can reproduce.
To lay eggs: the larvae feed on flower heads, developing fruits/seeds or insect pests
Because they’ve been tricked (scent/appearance that mimics the carcasses where they normally lay their eggs)
To keep warm: in arctic and alpine habitats, some flowers attract flies by providing a warm shelter.
As rendezvous sites for mating. Large numbers of flies will congregate at a particular type of flower
When we are concerned with the abundance of flower-feeding flies, we generally think of adults that feed at flowers.
However, larval food supplies could be more important in producing differences in fluctuations among species
Different life styles, different larval habitats, and differences in the regional distribution (broad or restricted ranges) could also result in different patterns of population stability.
If larval food is a key resource for most fly species, fly species may show significantly different patterns of fluctuation than bees whose larvae are all dependent on pollen for food, reinforcing the idea that different pollinator groups may respond differently to environmental change.
Ecologists are concerned that climate change may decouple the synchrony of inter-dependent organisms. For the majority of flies, we do not have even baseline phenology information.
There is evidence of parallel pollinator and insect-pollinated plant decline for flower flies and bees in UK and NL (Biesmeijer et al. 2006). The factors threatening the species are mostly unknown.
What consequences can we expect from the loss of pollinators? To what extent can any one pollinator be replaced by another? The answers to these questions are unknown and urgently need investigation.
There is an urgent need for networking among researchers, and for more fundamental and applied research toward improving our knowledge of pollination services. This knowledge is crucial for agriculture and wildland preservation efforts.
Second-largest family - > 10,000 species worldwide.
Adult tachinid flies known for their bristly facies and sometimes abdomens – though some only sparsely so.
Parasitoid habit - almost all are endoparasites of other insects; commonly the larvae of the Lepidoptera (butterflies and moths) and the adult/larval forms of beetles.
Other tachinids attack true bugs of the Hemiptera (Heteroptera), larvae of Hymenoptera (bees, wasps, ants, sawflies), and adults of Orthoptera (grasshoppers, katydids, crickets).
> 7,000 species world- wide; nearly 1,000 in North America.
Among the largest of the predatory flies; they can not only look like bumble bees, they can sound like them too!
Stout, spiny legs, bristles on the face (mystax), and 3 simple eyes (ocelli) in a characteristic depression between their two large compound eyes. The mystax helps protect the head/face in struggles with prey.
The short, strong proboscis is used to stab and inject victims with saliva containing neurotoxic and proteolytic enzymes which paralyze/digest the prey; the fly then sucks the liquefied meal much like we vacuum up an ice cream soda through a straw.
Fly Kachina (Hopi) The Fly or Sohonasomtaka Kachina can be a Chief, Guard, or Hunter depending on the ceremony. He may also appear as a warrior who punishes the clowns when they get out of hand during the ceremonies.
Insects and animals offer advice and teach life to the Hopi people. As a guard he would protect and keep ceremonies from outsider intrusions
The Robber Fly Kachina, Kuwaan Kokopelli, is named after a humpbacked fly that is always mating. Like Kokopell' Mana, this kachina represents fertility.
In an extensive 5-yr survey of syrphid flies in Poland
Found lower species diversity in urban and agricultural areas.
In comparison, natural habitats were species-rich and characterized by shifting proportions of species, as one moved from one habitat toward another. Syrphid fly species composition closely followed patterns of food supply and habitat condition.
The proportion of phytophagous and terrestrial saprophagous species dropped significantly, with only four species of phytophages present near the housing estates. These four were pests that eat ornamental plants, or weed-eating species. Urban areas were dominated by four syrphid species with broad geographic ranges
In Japan, a broad-scale, four-year survey compared all insect visitors to roughly 100 plant species in each of three different habitats: a university campus - mostly exotic vegetation,
an undisturbed oak forest, and
a botanically rich mosaic containing both native deciduous and planted coniferous forest.
The site of greatest human disturbance was poorest in species numbers . The total number of arthropod species on the
plants of the university campus was 37% of the total of the oak forest and 23% of the total mosaic of natural and planted forest.
Our understanding of pollination services is considerably hampered by a lack of some very basic knowledge.
Pollination services of flies are underestimated and functional relations poorly understood.
In the past, much pollination research has focused on bees, leaving a wide opportunity open for the study of other pollinator assemblages.
Although some types of fly pollinators have been well studied, as a group, fly pollination deserves far more research.
It is striking how large the gaps in species knowledge are: probably less than 10% of all Diptera species are named worldwide; considerable gaps exist even in Europe, where the fauna is generally well documented.
Big Fly, do'tsoh, is very important to the Navajo Indians in Northern Arizona and New Mexico. He is an intercessor, mentor and advise giver. He appears to have much of the capacities of the Spider Woman figure in the Navajo except to men, especially Holy Man. He is the daytime messenger to the Sun
In the Piman speakers of Southern Arizona and Northwestern Mexico, Blue-Green Fly teaches the Seris of the Sonoran coast and the Pima of AZ how to make fire.
Robber Fly is a hunter in Chiricahua Apache lore who carries his meat in a bag on his shoulder. Flies once were humans – they brought fire to all people