Abstract
Seasonal trends of feeding and oviposition activities of adults of the fleabeetle Argopistes coccinelliformis were investigated. Under field conditions, newly emerged adults showed a high feeding activity in early summer which soon declined and stayed at a low level during other seasons. These adults, collected in the field from early summer to autumn, needed a long period of time before ovipositing under laboratory conditions. On the other hand, the adults collected in late autumn or early winter showed a high feeding activity and required only a short period of incubation prior to oviposition. Feeding and oviposition activities were influenced by photoperiods, decreasing with short daylength. The overall results suggested that adults of this species were in a state of diapause during the period from summer to autumn, and that this state might be broken in late autumn or early winter in the field. However, the results also indicated that the species does not necessarily require a specific period of ‘late autumn or early winter’ to break the diapause. We speculated that conditions of short daylength and low temperature during the autumn and winter delayed ovarian development until the spring, and that this mechanism enhanced the alignment of the oviposition period to the time of the start of host plant sprouting.
