FEEDING DETERRENCE OF VERBENONE TO THE PINE WEEVIL, HYLOBIUS-ABIETIS (L) (COL, CURCULIONIDAE)

Exposure to verbenone vapours did not cause any acute toxicity symptom s in the pine weevil, Hylobius abietis, whereas weevils exposed to hig her doses of both limonene and alpha-pinene exhibited signs of poisoni ng within a few h. Verbenone consistently suppressed feeding, while sy mptom-free weevils exposed to limonene or a-pinene fed as much as cont rols. Feeding in verbenone-exposed weevils remained suppressed 20 h af ter the insects had been transferred from the exposure vials, whereas weevils exposed to limonene and alpha-pinene resumed normal feeding so on after transfer. Feeding deterrence by verbenone was lost after 48 h , and starved weevils were less deterred than fed weevils. Feeding was also reduced by weevils offered food contaminated by verbenone, indic ating that acute toxicity effects were not responsible for the reduced feeding observed in weevils exposed to verbenone vapors. Feeding dete rrence by verbenone is hypothesized to be due to its association with microbial breakdown of host tissues, indicating sub-optimal food quali ty.