Author
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JACKSON, CHARLES |
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Submitted to: Southwestern Entomologist
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 7/1/2003 Publication Date: 9/1/2003 Citation: JACKSON, C.G. OVIPOSITION BY LYGUS HESPERUS AND ITS EGG PARASITOID, ANAPHES IOLE, IN COTTON, ALFALFA, AND A WILD MUSTARD.. SOUTHWESTERN ENTOMOLOGIST. 2003., pp. 167-176. Interpretive Summary: Lygus bugs are important pests on a number of crops and ornamental plants. They build up large populations on other plants, like weeds, and then move to the crops where they cause losses in yield. I determined 1) where the western tarnished plant bug, Lygus hesperus, lays its eggs in three different plants and which of these plants it prefers and 2) where the tiny wasp, Anaphes iole, searched on these plants and parasitized lygus bug eggs. The lygus bugs showed a preference to oviposit in alfalfa over cotton in choice tests, but showed no significant preference between alfalfa and London rocket. Anaphes iole parasitized lygus bug eggs in all three plant types. The number of eggs parasitized was greater in alfalfa, where the larger number of eggs were deposited, than in cotton, but the percentage of eggs parasitized was higher in cotton than alfalfa. There was no difference in the number of eggs deposited in alfalfa or London rocket, nor was there a difference in the percentage of eggs parasitized. However, a larger number of the eggs in London rocket were parasitized. Lygus hesperus tended to oviposit in the top one-third of cotton plants and the top two-thirds of alfalfa and London rocket. Anaphes iole searched and parasitized eggs in all parts of the plants. Technical Abstract: Oviposition patterns of Lygus hesperus Knight and its parasitoid Anaphes iole Girault were observed in three host plants. The majority of the L. hesperus eggs were deposited in the upper third of cotton, Gossypium hirsutum L., Var. Deltapine 16, and alfalfa, Medicago sativa L., mixed cultivars, and in the upper 2/3 of a wild mustard London rocket, Sisymbrium irio L., plants in cages. In choice tests, L. hesperus deposited significantly more eggs (78%) in alfalfa than in cotton but did not show a significant preference between alfalfa and London rocket. Anaphes iole readily parasitized eggs of L. hesperus in all three plant types, but appeared to search and parasitize eggs on all sections of the plants rather than restrict searching to the areas where most of the host eggs were located. Significantly, more L. hesperus eggs were parasitized in alfalfa than in cotton, but a greater percentage of eggs were parasitized in cotton. More eggs were parasitized in London rocket than in alfalfa, but the percentages parasitized were not significantly different. |
