FEMALE BEHAVIOR AND OVIPOSITION CHOICES BY AN ERUPTIVE HERBIVORE, DISONYCHA-PLURILIGATA (COLEOPTERA, CHRYSOMELIDAE)

The oviposition behavior of Disonycha pluriligata in relation to food plants for larvae was considered a critical link between generations i n the life history of this beetle relative to its population dynamics. Therefore, we undertook studies to clarify female behavior before and during oviposition and the consequences for larval establishment on t he host plant, Salix exigua. Field studies showed that females dig dep ressions in the soil, into which they lay a clutch of eggs, with some clutches covered with soil and others left uncovered. Therefore, first -instar larvae bad to find host plants and started feeding low on the foliage. An experiment using caged adults on potted willows showed tha t females always feed and copulate before oviposition, and they lay eg gs up to 15 cm away from a plant, which was the maximum radius availab le in the pots. In petri dishes, females oviposited in soil, on paper towel, and on bare plastic. Females demonstrated a relatively indiscri minate oviposition behavior, leaving larvae to forage independently fo r host plants. We hypothesize that this lack of linkage between ovipos itional preference and larval performance places strong selective pres sure on larvae to be relatively indiscriminate feeders, predisposing t hem to be generally able to eat any quality of leaves in a stand of wi llows and, as a consequence, to be damaging and eruptive in their popu lation dynamics.