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

Authors: Cornelius, Mary; Haber, Ariela; Weber, Donald

Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/16/2022
Publication Date: 4/16/2022
Citation: Cornelius, M.L., Haber, A.I., Weber, D.C. 2022. 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. Environmental Entomology. https://doi.org/10.1093/ee/nvac018.
DOI: https://doi.org/10.1093/ee/nvac018

Interpretive Summary: Egg parasitoids can be used in biological control programs to reduce pest populations in vegetable crops. Parasitoid foraging behavior is affected by habitat and host plant differences. Female egg parasitoids also use a combination of oviposition induced and host-derived cues to find host eggs. This study compared parasitism by Gryon pennsylvanicum on two squash bug species, Anasa tristis and Anasa armigera, by placing sentinel squash and cucumber plants with egg masses of either of the two squash bug species in squash and cucumber fields. 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 female 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. By increasing our knowledge of the foraging behavior of parasitoids, we can develop new methods to enhance their effectiveness as biological control agents of pests in vegetable crops.

Technical Abstract: Parasitoid foraging behavior is affected by habitat and host plant differences. Female egg parasitoids also use a combination of oviposition induced and host-derived cues to find host eggs. This study compared parasitism by Gryon pennsylvanicum on two squash bug species, Anasa tristis and Anasa armigera, 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. There was no difference in parasitism rates on eggs of the two squash bug species in an experiment where pairs of sentinel squash plants were placed only in squash fields. 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 female 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. Female G. pennsylvanicum parasitoids appear to utilize different combinations of host plant and host cues when searching for eggs of the two squash bug species.