Host Discrimination

A behavior related to host seeking involves the discrimination between hosts that have already been parasitized and those that have not. Some parasitoid females, after they have successfully parasitized a host, deposit a chemical marker on the surface that serves to tell other parasitoids of the same or other species that the host is already parasitized. Such marking pheromones have most often been found in parasitoids that attack sedentary hosts, such as eggs or pupae. Often the oldest parasitoid in a host is the one that survives; consequently, host marking saves other parasitoids from wasting time and eggs on a host in which their offspring are likely to perish. Also parasitoids whose ovipositor has been inserted into a host are often able to distinguish parasitized from unparasitized hosts. Whether the cues perceived are the result of marking materials specifically injected by the first parasitoid or of chemical changes in the host resulting from parasitoid development is generally not known.

0 0

Post a comment