Perception of aspen and sun/shade sugar maple leaf soluble extracts by larvae of Malacosoma disstria

We investigated the behavioral feeding preference and the chemoreception of leaf polar extracts from trembling aspen, Populus tremuloides, and from su n and shade sugar maple, Acer saccharum, by larvae of the polyphagous fores t tent caterpillar, Malacosoma disstria, a defoliator of deciduous forests in the Northern Hemisphere. Three polar extracts were obtained from each tr ee species: a total extract, a water fraction, and a methanol fraction. M. disstria larvae were allowed ad libitum access to an artificial diet from e closion to the fifth instar. Two-choice cafeteria tests were performed comp aring the mean ( SE) surface area eaten of the total extracts, and the foll owing order of preference was obtained: aspen > sun maple > shade maple. Te sts with the other fractions showed that M. disstria larvae preferred the t otal aspen extract to its water fraction, and the latter to its methanol fr action. The response to sun maple was similar to aspen. However, for the sh ade maple experiment, there was no difference between the total extract and its water fraction. Electrophysiological recordings for aspen showed that the sugar-sensitive cell elicited more spikes to the water fraction, follow ed by the total extract, and finally the methanol fraction, Spike activity to stimulations of sun and shade maple extracts revealed a similar trend, w here methanol fraction > water fraction > total extract Our findings are di scussed in light of previously known information about this insect's perfor mance on these host plants.