Daytime mechanisms of reaggregation in imported willow leaf beetle, Plagiodera versicolora, larvae (Coleoptera: Chrysomelidae)

摘要

The roles that leaf quality, the presence of siblings, trails, vision and touch play in reaggregation by imported willow leaf beetle larvae were examined. Larvae responded positively to the presence of siblings, their secretions, and faeces while reaggregating. Larvae do not have to see or touch siblings in order for reaggregation to occur and leaf quality does not appear to be involved in reaggregation. There were differences in behaviour of 4- and 8-day-old larvae: 4-day-old larvae responded positively to the presence of siblings whereas 8-day-old larvae did not, and under natural conditions 4-day-old larvae are found in aggregations whereas 8-day-old larvae are solitary.