Oviposition Response of Spruce Budworm (Lepidoptera: Tortricidae) to Aliphatic Carboxylic Acids

Abstract

Abstract We investigated the effects of carboxylic acids on the oviposition behavior of the spruce budworm, a major defoliator of coniferous forests in North America. Carboxylic acids have been implicated as semiochemicals involved in lepidopteran host finding and oviposition, and they occur as free acids in the epicuticular wax of host (Picea and Abies spp.) foliage where spruce budworm lay eggs. In a dual-choice laboratory bioassay, several straight chain and cyclic monocarboxylic acids, and two dicarboxylic acids, significantly enhanced oviposition. Peak activity was associated with saturated acids having 8–12 carbons. Unsaturated oleic and linoleic acids were also preferred. The lowest effective dosage occurred at 7.8 nmol/cm2 (1 mM solution). At higher dosages (≥780 nmol/cm2), C9–C10 acids became strongly deterrent and some shorter-chain and longer-chain acids became stimulating. Electroantennogram responses to C6–C16 acids indicated that behaviorally active acids are detected by olfaction. The most ...