Effect of Adult Experience on the Host-Location Behavior of the Aphid ParasitoidAphidius colemaniViereck (Hymenoptera: Aphidiidae)

The effect of experience on the host location behavior ofAphidius colemaniViereck females was investigated by means of wind-tunnel bioassays and a glasshouse release experiment. In laboratory tests with bell pepper(Capsicum annuumL.), naive females showed little innate attraction either to uninfested plants or to plants heavily infested with the green peach aphid(Myzus persicaeSulzer). However, a brief preflight experience with this aphid/plant combination resulted in a significant increase in the proportion of females making complete upwind flights to such plants in the wind-tunnel. Subsequent experiments demonstrated that exposure to aphids alone, to uninfested plant material, or to infested plants of a different species (radish [Raphanus sativusL.]) was not sufficient to cause this increase in responsiveness: the effect was only seen in females that experienced the complete “target” aphid/host–plant combination. In the glasshouse experiment, females which were given a brief (15 min) exposure to aphid-infested plants before release subsequently found and parasitized significantly higher numbers ofM.persicaethan did naive females of the same age. The implications of these findings for applied biological control are discussed.