BEHAVIORAL-RESPONSES OF LEAFROLLER LARVAE TO APPLE LEAVES AND FRUIT

Larvae of Epiphyas postvittana and Planotortrix octo were released ont o branches cut from apple trees, and allowed to colonize a range of ty pes of artificial nests. Both species exhibited similar strong prefere nces for nests comprising leaf-leaf or leaf-fruitlet combinations, fol lowed by nests comprising leaf-plastic leaf, leaf-plastic fruitlet or plastic leaf-fruitlet combinations. Nests involving fresh plant materi al alone (shoot, fruitlet or leaf alone) were also colonized to a less er extent, but no larvae were found on nests consisting of plastic lea ves or fruitlets alone or in combinations of the two. In another exper iment, more E. postvittana larvae colonized nests with leaf and fruitl et combinations, compared to leaf and glass ball, or leaf and treated wax ball combinations, where the wax had been in contact with fresh ap ples or fruitlets. Choice tests, conducted using larval traps, showed that larvae were caught in traps baited with odors collected and relea sed by wax which had been in contact with mature apples and leaves. Ch loroform extracts from apple skin also caught larvae in choice tests. These results suggest that both physical and chemical cues are importa nt to leafroller larval establishment.