Abstract
Sensitivities to β-hydrastine, strychnine and picrotoxinin were compared between two populations of western corn rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), differing in their susceptibility to cyclodiene insecticides. The antifeedants are antagonists of γ-aminobutyric acid (GABA) neuroreceptors that may mediate gustation and, in the case of picrotoxinin, interact directly with the target site for cyclodiene insecticides. In combination with cucurbitacin B, a specific Diabroticite phagostimulant, cyclodiene-resistant beetles were two- to four-fold less sensitive to hydrastine and strychnine. The discrimination threshold for picrotoxinin was higher for resistant beetles; however, overall dose-response profiles were similar. Beetles were more sensitive to hydrastine and strychnine in combination with L-alanine, a general phagostimulant of less potency than cucurbitacin B. Dose-response slopes for the alkaloid-alanine combinations were double those of respective cucurbitacin B slopes, which indicates that phagostimulatory input from L-alanine was more negatively affected by the alkaloidal antifeedants than the respective cucurbitacin B treatments. Picrotoxinin sensitivity was similar in mixtures with either phagostimulant. Comparison of chemosensillum responses to strychnine was inconclusive. Results are discussed in context of GABA receptor pharmacology.
Original language | English (US) |
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Pages (from-to) | 220-226 |
Number of pages | 7 |
Journal | Physiological Entomology |
Volume | 23 |
Issue number | 3 |
DOIs | |
State | Published - Sep 12 1998 |
All Science Journal Classification (ASJC) codes
- Physiology
- Ecology, Evolution, Behavior and Systematics
- Insect Science