news on the flying paddy field dragons ott... · 2015. 5. 12. · -damselflies prey also on sitting...

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


• typical species

Neurothemis fulvia

Orthetrum pruinosum + O. testaceum


• typical species

Ischnura senegalensis Orthetrum sabina


• typical species

Diplacodes trivialis


simplified food web

from Koch et al. 1990


„dragonfly food web“: who feeds on what ?

following „actors“ involved:

- leafhoppers und planthoppers

- damselflies

- dragonflies

study carried in September 2013 in PhilRice




GLH /BPH

7 – 12 minutes



GLH /BPH

3 – 5 minutes



BPH < 0,5 minute - damselfly / dragonfly 3 / 5 minutes


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 !


Northern Vietnam:

Lowland and hilly

areas:

intensive land use

(1 crop x year) and

intensive pesticide

use


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 …


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.


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


Effects of intensive land use on dragonflies:

Substrates are necessary !


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)


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 sociocultural aspects

protection campaign

in Vietnam:

„save the flying dragons“

instead of

“chuồn chuồn”


see and save the

flying dragons

in the rice fields !

news on the flying paddy field dragons ott... · 2015. 5. 12. · -damselflies prey also on sitting...

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