Pieris brassicae - Vlinderstichting
Pieris brassicae - Vlinderstichting
Pieris brassicae - Vlinderstichting
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No escape: how parasitoid wasps find<br />
<strong>Pieris</strong> eggs and caterpillars<br />
Joop van Loon, Nina Fatouros & Ties Huigens<br />
Laboratory of Entomology
Egg parasitoids are common natural enemies of butterflies and<br />
cause significant egg mortality ( ~ 30%)<br />
parasitization eclosion
How do tiny egg parasitoids find butterfly eggs?<br />
0.5 mm
Host location cues used by egg parasitoids<br />
• Pheromones/odors of adult host<br />
• Plant volatiles induced by host eggs or feeding<br />
• Combination of pheromones and plant volatiles<br />
• Short-range cues derived from the adult host<br />
Strong dependence on stimuli of adult host<br />
Photos: www.bugsinthepicture.com
<strong>Pieris</strong> <strong>brassicae</strong><br />
(Large Cabbage White Butterfly)<br />
Studied system<br />
Trichogramma <strong>brassicae</strong><br />
Photos: www.bugsinthepicture.com
Trichogramma egg parasitoids<br />
• predominantly attack eggs of butterflies<br />
and moths<br />
• extreme generalists, e.g. T. evanescens<br />
can parasitize up to 60 different hosts<br />
• often shown to rely on moth sex<br />
pheromones
(1) Research question<br />
Does Trichogramma <strong>brassicae</strong> use infochemicals<br />
of <strong>Pieris</strong> <strong>brassicae</strong> butterflies?
Virgin female<br />
Virgin female<br />
Mated female<br />
Virgin female<br />
Mated female<br />
Male<br />
200<br />
150<br />
(1) olfactory tests<br />
100<br />
Arrested to odours from mated female and male butterflies – virgin not attractive<br />
Which odors are involved?<br />
50 % 50 %<br />
50<br />
0 50 100 150 200<br />
Mean ( s.e.) residence time (s)<br />
*<br />
*<br />
ns<br />
*<br />
ns<br />
*<br />
Mated female<br />
Male<br />
Male<br />
Clean air<br />
Clean air<br />
Clean air<br />
Fatouros et al. 2005a, Nature 433, p. 704
(2) Research question<br />
Does Trichogramma <strong>brassicae</strong> make use of an anti-<br />
aphrodisiac of P. <strong>brassicae</strong> butterflies?
Anti-aphrodisiacs in <strong>Pieris</strong> spp.<br />
P. napi<br />
P. rapae<br />
P. <strong>brassicae</strong><br />
Anderson et al. (2003) J. Chem. Ecol. 29: 1489-99
GC-MS analysis of P. <strong>brassicae</strong> odors<br />
Anderson et al. (2003), J. Chem. Ecol. 29: 1489-99<br />
Male cloaks the female with its own odor > chemical mimic of male
esidence time [s]<br />
250<br />
200<br />
150<br />
100<br />
50<br />
0<br />
ns<br />
(2) olfactory tests<br />
+ benzyl cyanide<br />
** * ns ns<br />
10.0 2.0 1.0 0.2 0.1<br />
Applied benzyl cyanide [μg]<br />
Mated female<br />
Fatouros et al. 2005a, Nature 433, p. 704<br />
Arrested to virgin females treated with the anti-aphrodisiac
(3) Research question<br />
Does Trichogramma <strong>brassicae</strong> hitch-hike with <strong>Pieris</strong><br />
<strong>brassicae</strong> butterflies to the host eggs?
= attachment of one animal to another for transportation<br />
to certain location<br />
Phoresy<br />
Beetle larvae Mites Egg parasitoids
Virgin female<br />
Virgin female<br />
Mated female<br />
Virgin female + BC<br />
100<br />
80<br />
ns<br />
60<br />
Fatouros et al. 2005a, Nature 433, p. 704<br />
Preference for mated female butterflies<br />
Use benzyl cyanide to approach<br />
*<br />
(3) Mounting tests<br />
40<br />
20<br />
18<br />
9 23<br />
12<br />
20<br />
Mated female<br />
Male<br />
Male<br />
0 20 40 60 80 100<br />
Discriminate mated females from males at close range: male-specific cuticular<br />
hydrocarbons ? (Arsene, van Loon & Schultz (2002) J. Chem Ecol. 28: 2627-2631)<br />
21<br />
7<br />
7<br />
% first mounts<br />
*<br />
*<br />
Virgin female
Video
Landing on plant<br />
+ oviposition<br />
(3) Flight chamber tests<br />
n<br />
Reaches host -<br />
habitat (n)<br />
50 % back on the butterfly, landing on the host plant<br />
7 % parasitism (observed)<br />
Reaches host<br />
plant (n)<br />
Observed<br />
parasitization (n)<br />
Lost (n)<br />
28 8 4 2 14<br />
% 28.6 14.3 7.1 50.0<br />
Fatouros et al. 2005a, Nature 433, p. 704
Host location cues used by egg parasitoids<br />
• Pheromones/odors of adult host<br />
• Plant surface compounds induced by anti-aphrodisiac<br />
• Combination of pheromones and plant volatiles<br />
• Short-range cues derived from the adult host<br />
Fatouros, Broekgaarden, Bukovinszkine’Kiss, van Loon, Huigens, Dicke, Mumm & Hilker (2008)<br />
PNAS in press<br />
Photos: www.bugsinthepicture.com
Espionage-and-ride-strategy<br />
Espionage of anti-sex pheromones and hitchhiking on<br />
mated females could severely constrain evolution of<br />
<strong>Pieris</strong> sexual communication<br />
How common is it in nature?
Ongoing studies on Trichogramma - <strong>Pieris</strong><br />
Semi-field experiments<br />
Special nets<br />
Mounting tests<br />
Butterfly catches<br />
Olfactory tests
Brassicaceae – <strong>Pieris</strong> – Cotesia larval parasitoids<br />
Cotesia parasitism in cabbage crops can be as high as 95%<br />
Brassica nigra<br />
Brassica oleracea<br />
Arabidopsis thaliana<br />
Sinapis alba<br />
Tropaeolum majus<br />
<strong>Pieris</strong> <strong>brassicae</strong><br />
<strong>Pieris</strong> rapae<br />
Photo Hans Smid<br />
Cotesia glomerata<br />
Cotesia rubecula
Cotesia glomerata female attacking cluster of <strong>Pieris</strong> <strong>brassicae</strong> caterpillars
Herbivore-induced plant volatiles (HIPV)<br />
Common phenomenon (documented for dozens of<br />
plant-, herbivore and carnivore taxa)<br />
Volatiles are produced de novo<br />
Volatiles are produced systemically<br />
Volatiles are often herbivore-specific<br />
Influence herbivore-carnivore population dynamics
GLV<br />
HIPV from Brassica oleracea<br />
nitril terpenoids ITC<br />
GLV nitril terpenoids ITC<br />
Geervliet et al. (1994) JCE
Windtunnel set-up
Cotesia glomerata<br />
Cotesia rubecula<br />
Odour quality: plant level<br />
preference switch<br />
no change of preference<br />
Geervliet et al. (1998) Entomol. Exp. Appl. 86: 241-252<br />
***<br />
b
Chemical signalling: butterfly perspective<br />
Selective forces acting on oviposition behaviour<br />
Bottum-up forces<br />
food quality optimal for progeny<br />
optimal protein content; low in growth inhibitors and toxins<br />
food quantity sufficient: hostplant patch selection; no competitors<br />
Top-down forces<br />
chemical defense against natural enemies (aposematism)<br />
hiding from natural enemies<br />
- visually cryptic coloration<br />
- chemically low odour emission; cuticular chemistry<br />
resembles plant cuticle
Cotesia and Epicampocera parasitoids and their possible effect on <strong>Pieris</strong> host plant selection<br />
behaviour (Ohsaki & Sato, 1994)<br />
Species specialism main host plants/ intrinsic Cotesia/<br />
category characteristics nutritional Epicampocera<br />
quality parasitism<br />
<strong>Pieris</strong> napi monophagous Arabis spp. low < 3%<br />
unapparent (differential)<br />
permanent<br />
concealed<br />
shade<br />
<strong>Pieris</strong> rapae oligophagous Brassica spp. high > 80%<br />
cultivated<br />
ephemeral<br />
sun-exposed<br />
<strong>Pieris</strong> melete euryophagous Cardamine spp. high > 70%<br />
Brassica spp. 12-35%
Marcel Dicke<br />
Louise E.M. Vet<br />
Rieta Gols<br />
Hans Smid<br />
Colette Broekgaarden<br />
Maarten Posthumus<br />
Gabriella Bukovinszkine’Kiss<br />
spring<br />
3 rd<br />
2 nd<br />
1 st<br />
summer<br />
3 rd<br />
2 nd<br />
1 st<br />
Trophic levels<br />
3 rd<br />
2 nd<br />
1 st<br />
carnivores<br />
herbivores<br />
plants<br />
Sponsored by<br />
Monika Hilker<br />
Barbara Randlkofer
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