To be in time: egg deposition enhances plant-mediated detection of young caterpillars by parasitoids
- 815 Downloads
Animals use information from their environment while foraging for food or prey. When parasitic wasps forage for hosts, they use plant volatiles induced by herbivore activities such as feeding and oviposition. Little information is available on how wasps exploit specific plant volatiles over time, and which compounds indicate changes in host quality. In experiments investigating the role of herbivore-induced plant volatiles in wasp foraging, induction of plant response is usually achieved by placing larvae on clean plants instead of allowing the natural sequence of events: to let eggs deposited by the herbivore develop into larvae. We compared the attraction of the parasitoid Cotesia glomerata to volatiles emitted by black mustard (Brassica nigra) plants induced by eggs and successive larval stages of the Large Cabbage White butterfly (Pieris brassicae) to the attraction of this parasitoid to black mustard plant volatiles induced only by larval feeding in a wind tunnel setup. We show that wasps are attracted to plants infested with eggs just before and shortly after larval hatching. However, wasp preference changed at later time points towards plants induced only by larval feeding. These temporal changes in parasitoid attraction matched with changes in the chemical compositions of the blends of plant volatiles. Previous studies have shown that host quality/suitability decreases with caterpillar age and that P. brassicae oviposition induces plant defences that negatively affect subsequently feeding caterpillars. We investigated parasitoid performance in hosts of different ages. Wasp performance was positively correlated with preference. Moreover, parasitism success decreased with time and host stage. In conclusion, the behaviour of Cotesia glomerata is fine-tuned to exploit volatiles induced by eggs and early host stages that benefit parasitoid fitness.
KeywordsHost quality HIPVs Host location Host suitability Cotesia glomerata
The authors thank Léon Westerd, Joop Woelke and André Gidding for rearing insects, Unifarm of Wageningen University for providing plants, and the Netherlands Organization for Scientific Research (NWO/ALW VENI grant 863.09.002 to N.E. Fatouros and NWO/ALW grant 820.01.022 to M. Dicke) for funding.
- Fatouros NE, Bukovinszkine’Kiss G, Kalkers LA, Gamborena RS, Dicke M, Hilker M (2005) Oviposition-induced plant cues: do they arrest Trichogramma wasps during host location? Entomologia Experimentalis et Applicata 115:207–215Google Scholar
- Harvey JA, Jervis MA, Gols R, Jiang N, Vet LEM (1999) Development of the parasitoid, Cotesia rubecula (Hymenoptera: Braconidae) in Pieris rapae and Pieris brassicae (Lepidoptera: Pieridae): evidence for host regulation. J Insect Physiol 45:173–182Google Scholar
- Harvey JA, Nouhuys S, Biere A (2005) Effects of quantitative variation in allelochemicals in Plantago lanceolata on development of a generalist and a specialist herbivore and their endoparasitoids. J Chem Ecol 31:287–302Google Scholar
- Ponzio CGR, Berhane TW, Dicke M (2014) Caterpillar-induced plant volatiles remain a reliable signal for foraging wasps during dual attack with a plant pathogen or non-host insect herbivore. Plant Cell Environ 37:1924–1938Google Scholar
- R Development Core Team (2008) R: a language and environment for statistical computing. R Foundation for Statistical Computing, Vienna. http://www.R-project.org/