News on the flying paddy field dragons Jürgen Ott - L.U.P.O. / UFZ
News on the flying paddy field
dragons
Jürgen Ott - L.U.P.O. / UFZ
Why are dragonflies part of the project ?
• complex behaviour
• complex ecology
• aesthetic + attractive
insects
• good indicators for:
• biotopes / biotope quality / biotope complexity
• impacts
• climatic and global changes
reason to use them in LEGATO …
Dragonflies in LEGATO
• Philippines: > 300 species
• Vietnam: about 235 species (Do & Dang 2006)
– autumn 2013 > 280 species (Do pers. comm. 2013)
– spring 2014 > 310 species (Do pers. comm. 2014)
• many undescribed, some/many still undiscovered
• literature available, but still many gaps to fill
• rice fields as biotopes for dragonflies:
• special coenosis, mostly euryoecious species, in
mountain areas also forest species
• very important in / for the food chain
Dragonflies in LEGATO Species found in the rice fields and nearby: Variable Whisp (Agriocnemis femina) (Brauer, 1868) 4 Zygoptera
Pygmy Whisp (Agriocnemis pygmaea) (Rambur, 1842)
Common bluetail (Ischnura senegalensis) (Rambur, 1842)
Orange-faced Sprite (Pseudagrion rubriceps) Sélys, 1876
Trumpet tail (Acisoma panorpoides) Rambur, 1842 21 Anisoptera
Blue Darsher (Brachythemis chalybea) Brauer, 1868
Common Amberwing (Brachythemis contaminata) (Fabricius, 1793)
Black-tipped Percher (Diplacodes nebulosa) (Fabricius, 1793)
Blue Percher (Diplacodes trivialis) (Rambur, 1842)
Scarlet Grenadier (Lathrecista asiatica) (Farbricius, 1798)
Common Parasol (Neurothemis fluctuans) (Fabricius, 1793)
Russet Percher (Neurothemis fulvia) (Drury, 1773)
Pied Percher (Neurothemis tullia tullia) (Drury, 1772)
Scarlet Skimmer (Orthetrum testaceum) (Burmeister, 1893)
Spine-tufted Skimmer (Orthetrum chrysis) (Sélys, 1891)
Common Red Skimmer (Orthetrum pruinosum neglectum) Rambur, 1842
Variegated Green Skimmer (Orthetrum sabina) (Drury, 1773)
Wandering Glider (Pantala flavescens) (Fabricius, 1798)
Common Scarlet (Crocothemis servilia) (Drury, 1773)
Common Redbolt (Rhodothemis rufa) (Rambur, 1842)
Yellow-Barred Flutterer (Rhyothemis phyllis) (Sulzer, 1776)
White-barred Duskhak (Tholymis tillarga) (Fabricius, 1798)
Common Chaser (Potamarcha congener) (Rambur, 1842)
Indigo Dropwing (Trithemis festiva) (Rambur, 1842)
Pale-spotted Emperor (Anax guttatus) (Burmeister, 1839)
• typical species
Agriocnemis femina
Dragonflies in LEGATO
• typical species
Neurothemis fulvia
Orthetrum pruinosum + O. testaceum
Dragonflies in LEGATO
• typical species
Ischnura senegalensis Orthetrum sabina
Dragonflies in LEGATO
• typical species
Diplacodes trivialis
Dragonflies in LEGATO
simplified food web
from Koch et al. 1990
Dragonflies in LEGATO
simplified food web
from Koch et al. 1990
Dragonflies in LEGATO
„dragonfly food web“: who feeds on what ?
following „actors“ involved:
- leafhoppers und planthoppers
- damselflies
- dragonflies
study carried in September 2013 in PhilRice
Dragonflies in LEGATO
„dragonfly food web“: who feeds on what ?
Dragonflies in LEGATO
GLH /BPH
7 – 12 minutes
„dragonfly food web“: who feeds on what ?
Dragonflies in LEGATO
GLH /BPH
3 – 5 minutes
„dragonfly food web“: who feeds on what ?
Dragonflies in LEGATO
BPH < 0,5 minute - damselfly / dragonfly 3 / 5 minutes
„dragonfly food web“: who feeds on what ?
results:
- BPH and GLH are preyed by all damsel- and dragonflies
- damselflies prey also on sitting BPH + GLH, dragonflies
only on flying insects
- small damselflies are preyed by bigger damselflies
- all damselflies are preyed by all dragonflies
- smaller dragonflies are preyed by bigger dragonflies
-> damselflies and dragonflies are very important and
effective predators in rice fields – very beneficial !
Dragonflies in LEGATO
Northern Vietnam:
Lowland and hilly
areas:
intensive land use
(1 crop x year) and
intensive pesticide
use
Dragonflies in LEGATO
Northern Vietnam:
Lowland and hilly
areas:
intensive land use
(1 crop x year) and
intensive pesticide
use
Dragonflies in LEGATO
pesticide use – worldwide literature review:
- effects are shown, but no or only little effects on
damselflies and dragonflies
- more severe effects on amphibians, e.g. tadpoles
- sometimes even „positive“ for dragonflies
- not investigated effects are e.g. fluctuating assymetry
- study on the literature will be continued …
Dragonflies in LEGATO
pesticide use – worldwide literature review:
- general effects are shown in a new publication (2013)
- organic based rice fields vs. chemical based rice fields
- significantly higher invertebrate diversity
- but the dragonflies are the same in
both types:
- Agriocnemis pygmaea
- Ictinogomphus rapax
- Diplacodes trivialis
- Neurothemis tullia
- Diplacodes sp.
- Neurothemis sp.
Dragonflies in LEGATO
Effects of intensive land use on dragonflies:
- reduced rice field-coenosis:
max. 4 – 8 species found
- only very few species can tolerate this land use
and survive, e.g.:
- Ischnura senegalensis
- Agriocnemis femina
- Orthetrum sabina
- Brachythemis contaminata
- Pantala flavescens
Dragonflies in LEGATO
Effects of intensive land use on dragonflies:
Substrates are necessary !
Dragonflies in LEGATO
Effects of intensive land use on dragonflies:
Substrates are necessary !
Dragonflies in LEGATO
Intensive use of rice fields in
Vietnam + Philippines
Management for dragonflies: habitat enrichment
Dragonfly diversity in the
surrounding of rice fields
… good diversity only where woodland plots and small
streams are left
Paplopleura sexmaculata Heliocypha perforata
Copera marginipes
Trithemis aurora Mnais mneme
Euphaea guerini
What did not work too well until now:
- feeding experiments in cages
- cultivation of Orthetrum sabina-larvae
(as predators on golden apple snails)
Dragonflies in LEGATO
Conclusions:
- damselflies and dragonflies play a prominent role
as predators in the paddy fields (larvae/adults)
- they are good indicators for the habitat diversity
- easy management measurements through
ecological engeneering can improve their
diversity and abundance (effectiveness)
- they are beneficial, as they are relevant for pest
control and also economically of interest
Dragonflies in LEGATO
Dragonflies in LEGATO sociocultural aspects
protection campaign
in Vietnam:
„save the flying dragons“
instead of
“chuồn chuồn”
Dragonflies in LEGATO
see and save the
flying dragons
in the rice fields !