The influence of host plant species on the frequency of defensive behaviors exhibited by the Oleander aphid, Aphis nerii, in response to the parasitoid, Lysiphlebus testaceipes

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The oleander aphid, Aphis nerii Boyer de Fonscolombe, feeds on milkweeds in the Apocynaceae family. Characteristics including trichome density and leaf toughness vary among milkweed species. The hypothesis that host plant characteristics influence the frequency of defensive behaviors exhibited by this aphid against the parasitoid, Lysiphlebus testaceipes (Cresson), was tested in a laboratory experiment. Interactions between oleander aphids and L. testaceipes were investigated on four milkweed species with different physical characteristics. Aphids responded to parasitoid presence with spinning, kicking, bucking, a coordinated defense, and the excretion of cornicle wax. When excreted, cornicle wax reduced parasitoid foraging time regardless of host plant species. The most common response to parasitoid presence was a coordinated defense behavior on all host plant species. When spinning, kicking, bucking, and coordinated defenses were combined per host plant species, aphid defenses tended to be greater in frequency on Cynanchum laeve and Asclepias incarnata than on A. tuberosa with A. syriaca being intermediate. Our results suggest that aphids colonizing host plants with few physical defenses may exhibit a greater number of defensive behaviors than aphids on plants having rougher leaf textures and high trichome densities.


Author Institution: Department of Entomology, University of Kentucky, Lexington, Kentucky



The Ohio Journal of Science, v112, n2 (2013), 2-5.