Host Finding Behavior of the Parasitoid Hadronotus pennsylvanicus (Hymenoptera: Scelionidae) for Egg Masses of the Squash Bugs Anasa tristis and Anasa armigera (Hemiptera: Coreidae) in Squash and Cucumber Fields.

Parasitoid foraging behavior is affected by habitat and host plant differences. Egg parasitoids also use a combination of oviposition-induced and host-derived cues to find host eggs. This study compared parasitism by Hadronotus pennsylvanicus (Ashmead) (Hymenoptera: Scelionidae) on two squash bug species, Anasa tristis (DeGeer) and Anasa armigera Say (Hemiptera: Coreidae), by placing sentinel squash and cucumber plants with egg masses of either of the two squash bug species in squash and cucumber fields in a 3-way factorial design. Host density of wild A. tristis egg masses in squash fields may have influenced parasitoid foraging behavior on sentinel plants. In the 3-way factorial design, parasitism was higher on sentinel squash plants and in squash fields overall. However, parasitism on A. armigera egg masses was highest on sentinel cucumber plants in squash fields and parasitism on A. tristis egg masses was higher on sentinel squash plants in either squash or cucumber fields and lowest on sentinel cucumber plants in cucumber fields. Results suggest that parasitoids were able to specifically orient to the combination of host plant and host cues associated with A. tristis egg masses on sentinel squash plants, but that they were more responsive to plant-induced cues associated with cucumber when searching for A. armigera egg masses. Parasitoids appear to utilize different combinations of host plant and host cues when searching for eggs of the two squash bug species.