Several projects of the Collaborative Research Centre 973 are currently studying the impact of insect egg deposition on the plant´s defence against hatching larvae.
In addition, we found that Pinus sylvestris defends against egg deposition by the herbivorous pine sawfly Diprion pini by changing the odour of pine needles; the egg-induced pine odour attracts egg parasitoids killing the eggs. We are currently studying how pine needles notice the egg deposition.
Cuticular hydrocarbons (CHC) of insects serve multiple functions. In leaf beetles, CHC may act as pheromones. Perception of cuticular hydrocarbons (CHC) of the mustard leaf beetle Phaedon cochleariae induces male mating behaviour in this species. We study the plasticity of the CHC profile and its role in speciation of leaf beetles.
It is well known that insect larval and adult stages show induced immune responses to attack by natural enemies like parasitoids and pathogens. However, so far little is known about induced defence of insect eggs against these attacks. To elucidate whether insects can respond to attack by natural enemies also during their very early life stage, the egg, we currently study(a) the differential expression of genes encoding proteins involved in immune response in parasitized and non-unparasitized insect eggs and (b) the impact of the parental immune state on the immune responses of insect eggs to parasitic attacks.
Olfactory orientation of herbivorous insects to their host plants and of parasitic insects to their host insects is affected by e.g. the age of the insect, its nutritional state and its prior olfactory experiences. Our studies aim to understand how these traits do affect the olfactory orientation.