HOST-PLANT APHIDOPHAGA INTERACTIONS

Allelochemicals in the host plant can affect natural enemies adversely through the passage of plant toxins up the trophic pyramid. Additionally, the size of the host prey may be influenced through the plant, and this in turn affects the size and fecundity of parasitoids. The numerical response of natural enemies to prey density may also be affected by their attraction to plant volatiles, even in the absence of prey. Predators and parasitoids show different functional responses to prey on different host plants. This is related to prey size, to differences in defensive and other behaviours of the prey, and to effects on searching time of natural enemies. These influences are highly relevant to the use of host plant resistance as a pest control technique. The argument that natural enemies may accelerate the selection for plant-adapted biotypes of herbivores, and the production of pest-resistant crop varieties by genetic engineering are modern challenges to the practical exploitation of host plant-Aphidophaga interactions.