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Fieldwork fun with Bracon parasitoid wasps: on the hunt for wild wasps
ESR update – How different are parasitoid wasps between different populations? Individuals from one species might look alike, but can display quite different traits. If you want to use them as biocontrol agents, it is important to choose the ones that perform best under specific circumstances.
Simone Ariëns MSc.
My project is about figuring out the genetic basis of life-history traits of Bracon parasitoid wasps. These wasps are important candidates to control the European corn borer, Ostrinia nubilalis. The corn borer has recently drastically increased its destructive potential by producing two generations per year, instead of only one. However, we don’t yet know a lot about the life-history traits of these parasitoid wasps, such as the number of eggs a female wasp lays or how long she lives. One of the things that we aim to find out, is whether individuals from different populations vary in these traits.
Therefore, I will collect wasps along a cline through Europe. In a couple of weeks, I’ll be going on a field trip to catch these small wasps in their natural habitat. This will be done by hanging traps containing live host larvae in trees. The wasps can then parasitize them by stinging through the fabric. The traps will be sent back to Bremen, and all our fingers and toes will be crossed that they arrive safely, and on time! Packages that travel for too long might contain only dead insects in the end. When they do arrive at the university, the job of painstakingly identifying all hatching wasp species will fall in the hands of my supervisor Andra, the lab technician Laura, and my student assistant Thalea. Not an easy job, if you keep in mind that my two Bracon species can only be told apart by counting the number of segments of their antennae. Concerning the females, Bracon brevicornis has between 13-15 segments and Bracon hebetor between 17 and 19. And as for the males, we will have to count between 20 and 27 segments for the former and 18-23 segments for the latter.
Once I myself am back, the real experiments can begin. How much do the populations differ from each other? And how much do the individuals within each population differ? Can we find any relationship with latitude, or trade-offs between traits? Only time and thorough experimentation will tell…