Submitted to: Journal of Insect Behavior
Publication Type: Peer reviewed journal
Publication Acceptance Date: 8/1/2004
Publication Date: 1/1/2005
Citation: Manrique, V., W. A. Jones, Jr., L. Williams, III & J. S. Bernal. 2005. Olfactory responses of Anaphes iole (Hymenoptera: Mymaridae) to volatile signals derived from host habitats. Journal of Insect Behavior 18: 89-104. Interpretive Summary: Plant bugs are serious pests of many crops, including cotton, in the United States. We conducted behavioral experiments to determine if crop plants damaged by plant bugs produce odors that attract a beneficial insect that attacks plant bugs. Experiments with Anaphes iole, an insect that kills the eggs of plant bugs, demonstrated that this beneficial insect is attracted to plants on which plant bugs have fed and laid eggs. We discovered that A. iole were consistently attracted to odors derived from different crop plant-plant bug complexes, while odors from uninfested plants were not attractive to this beneficial insect. These findings indicate that A. iole uses plant odors released after plant bug feeding and oviposition to locate suitable areas in which to search for plant bugs. Our results suggest that manipulation of plant biochemical pathways that regulate production and release of odors can be used to enhance attack of plant bugs by beneficial insects.
Technical Abstract: Anaphes iole Girault is a frequent parasitoid of Lygus spp. eggs in the U.S., and has potential as a biological control agent against Lygus hesperus Knight in different crops. Feeding and oviposition by L. hesperus induce emission of plant volatiles, but studies to date have not addressed the role of plant volatiles in the host-searching behavior of A. iole. In this study, a four-arm olfactometer was used to test the responses of female parasitoids to odors emanating from cotton plants damaged by L. hesperus females, L. hesperus males, larvae of the non-host Spodoptera exigua Hubner, or mechanically, or odors from L. hesperus females alone. In addition, various plants infested with L. hesperus eggs were evaluated in the olfactometer: cotton (Gossypium hirsutum L.), alfalfa (Medicago sativa L.), common groundsel (Senecio vulgaris L.), annual ragweed (Ambrosia artemisifolia L.), and redroot pigweed (Amaranthus retroflexus L.). In all olfactometry bioassays, treatment odors were compared against three controls (humidified air). Results showed that A. iole females were consistently attracted to odors derived from different plant-L. hesperus complexes, while odors from plants subjected to non-host (S. exigua) or mechanical damage and L. hesperus females alone were not attractive or variably attractive. These findings suggest that A. iole females use specific plant volatiles released following L. hesperus feeding and oviposition to locate host habitats. It was suggested that future research should seek to identify the chemical elicitors involved in the release of plant volatiles attractive to A. iole females.