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Comparison of trap designs against the Yellow-legged hornet (Vespa velutina)

Nevile MAHER & Denis THIERY INRA (French Agricultural Research Institute) Bordeaux – Aquitaine

Presented by Claire Villemant (MNHN)

European program for Apiculture 2007 - 2010 CNRS-MNHN-IRD-INRA

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Rortais et al. 2009.

ALARM Atlas

Vespa velutina

nigrithorax

Distribution ofVespa velutina

Native to South-East Asia, V. velutina was introduced to France

(Aquitaine) before 2004 presumably through horticultural trade

Shortly before 2004 ?

By the end of 2008, South-West France (130 000 km²) was completely colonised with over 1100 nests officially reported by INPN (Rome et al. 2009).

Invasion of Vespa velutina in France

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A new honeybee predator in France

⇒⇒⇒⇒ Vespa velutinapredation can lead to bee colony death.

1. Bee captured in flight 2. Hornet cutting up a bee before returning to nest

1. August : a few hornets hawking in front of the hive

3. Once bee colony defence collapses, hornets plunder hive provisions

2. October : over 50 hornets flying around the apiary

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Annual life

cycle of Vespa

velutina in

France

Emergence of

founder queens

Febr. -

March

September -

October

Mature nest (>1500 adults ?)

40 - 80 cm

October -

November ?

Emergence of sexuals

N + 1

Workers

May

5 cm

First

nest

April

Nest construction

Colony growth

Summer

Colony death

December

Trapping of founder queens

Trapping of workers in apiaries

Nest destruction

Trapping of young queens

CONTROL

LEVELS

Mating

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Specific traps are needed to monitor, manage and contain expansion of Vespa velutina populations to the rest of France and Europe

� Our aim is to develop chemically selective traps by identifying species specific attractants as baits

Such chemical lures should be:

- specific to avoid capture of non target species,

- highly attractive with a good diffusion rate,

- with long lasting attractiveness

non variable under different weather conditions,

needing few replacements

⇒ The first step was to chose an efficient trap design and perform bioassay setup to characterise such compounds for V. velutina.

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� Choice given between 4 items (trap designs or baits)

placed in shelters disposed between beehives.

� Each trial lasted 7 days with 3 successive

records of captured insects (on D2, D5 and D7).

� After each record, traps were replaced with new ones and

their positions rotated.

� Presented data are numbers of captured hornets per check

and per trap. On graphs, significant differences in captures are

indicated by different letters (P < 0,01, Kruskal-Wallis ANOVA

followed by a npmc test).

Multiple choice bioassay

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1. Comparison of trap designs using same attractant

Drowning liquid

Lateral tube

entrance

⇒⇒⇒⇒ Funnel trap most efficient trap design.

0

1

2

Glue-pan Water-pan Tubed bottle Funnel

Nu

mb

er

of

ho

rne

ts (

me

an

+ s

d)

/ ch

eck

2 - 9 july : apple bait

30 july - 6 aug : shrimp bait

a

a

ab

b

Top funnel entrance

Sticky surface

⇒⇒⇒⇒ Water-pan trap captures hornets.

⇒⇒⇒⇒ Glue and tubedbottle traps inefficient.

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2. Favouring inflow and limiting outflowfrom funnel traps

0

20

40

60

80

100

120

140

160

180

200

Large funnel Narrow funnel Large funnel +

talc

Dome

Nu

mb

er

of

ho

rne

ts (

me

an

+ s

d)

/ c

he

ck

17 - 24 sept : fish bait

b

c

a

b

⇒⇒⇒⇒ Ascending large entrance (dome trap) seems inefficient.

⇒⇒⇒⇒ Best trap design captured 400 V. velutinain a single trap / week with 20 g of fish bait.

⇒⇒⇒⇒ Descending large entrance with talc treated trap walls captured significantly more hornets.

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3. A dose-response experiment: attraction variesaccording to bait concentration

⇒⇒⇒⇒ Funnel traps captured significantly more hornets as the concentration of an apple juice bait (200 ml / trap) increased.

0

10

20

30

40

50

60

70

80

0 20 40 60 80 100

Apple concentrate dose (%)

Nu

mb

er

of

ho

rnets

(m

ean

± s

d)

/ ch

eck

4 - 11 nov

ab

c

bc

a

⇒⇒⇒⇒ Our field bioassay set-up proves to be adequate for screening attractive compounds for Vespa

velutina.

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Evaluation of a hive bottom-trap(in collaboration with A. Papachristoforou and M. Ifantidis, Aristotle University of Thessaloniki, Greece)

Experimental:

� The floors of 2 hives were replaced by bottom-traps during one

month (October 2008) at INRA of Bordeaux.

� A choice between 1 bottom-trap and 2 large funnel traps (baited

with honey + wax operculum and disposed on each side of a hive)

was proposed during 1 week.

� Total number of hornets in traps were counted each week.

The hive bottom-trap (named Apiburg) replaces the classical bottom of a

hive. Its side walls have two conic shaped entrances leading intruders into a

cage (Ifantidis et al 2005).

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0

50

100

150

200

250

300

350

400

Apiburg trap Funnel traps +

honey

Num

ber

of

horn

ets

(m

ean +

sd)

/ tr

ap

23 - 30 oct

a

a

• Number of V. velutina captured by bottom-traps after 1 month:

Bottom-trap hive 1 = 741 hornetsBottom-trap hive 2 = 378 hornets

•••• Comparison between hive bottom-trap (4 side entrances) and 2 funnel traps:

⇒⇒⇒⇒ Same number of hornets (approx. 200 in a week) captured by both trap designs.

⇒⇒⇒⇒ Hive bottom-traps could be complementary to disposable traps especially at the end of the season when V. velutina try to enter beehives.

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Conclusions

- Large funnel trap = best design tested for V. velutina.

- Experimental set up (replicates of four choices between hives)

is relevant to compare bait attractiveness.

- Concentrated apple juice efficiently attracts V. velutina with

limited effect on honeybees.

- We are currently progressing towards a higher bait specificity.

AcknowledgmentsMr Martrenchar (GDSA beekeeper) for kindly letting us carry out experiments

in his apiary.

Mr Bérard (beekeeper) for disposal of beehives.

Mr Barnier (President of Libourne beekeeper’s group) for advice on

beekeeping.

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Please accept our apologies for not attending the congress mainly due to financial restrictions.

You may contact us by email :maher@bordeaux.inra.fr or thiery@bordeaux.inra.fr

Beehive plunder (Bordeaux, 01/10/2008)