Corn semiochemicals and their effects on insecticide efficacy and insecticide repellency toward western corn rootworm larvae (Coleoptera: Chrysomelidae)
1989
Hibbard, B.E. | Bjostad, L.B.
Volatile corn seedling (pre-stage 0 germinated seed) semiochemicals are attractive to larvae of the western corn rootworm, Diabrotica virgifera virgifera LeConte and were evaluated with insecticides in laboratory soil bioassays to determine attraction and increased mortality of larvae. Insecticides from four different chemical classes were tested. These were carbofuran (carbamate), fonofos (organophosphate), tefluthrin (pyrethroid), and 2'-bromo-4'-nitro-perfluorocyclohexane carboxanilide (EL-499, experimental, Eli Lilly Company). For each of the four insecticides tested in bioassays in soil with insecticide present in a central core, significantly more larvae were killed after 24 h when corn seedling volatiles were present in the core than when they were not. The enhanced rate of mortality was the result of larval attraction. In bioassays without soil present, significantly more larvae contacted an insecticide source after 30 min when corn seedling volatiles were present than when they were absent. Insecticide repellency was evaluated in soil bioassays (24 h) and in Petri dish bioassays (30 min) in the presence and absence of volatile corn seedling semiochemicals. Only fonofos was repellent, but the attractiveness of corn seedling semiochemicals overcame that repellency.
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