The Overwintering Survival of Adults of the Queensland Fruit Fly, Dacus Tryoni, Under Natural Conditions.

Abstract

Estimates of the weekly survival rates of adult Dacus tryoni (Froggatt) in an overwintering site at Cam- den, N.S.W., indicated that the mortalities of males and females were similar and were related to the minimum temperatures the flies experienced. When minimum temperatures remained above 0ºC the weekly mortality rate remained fairly constant at an average of 8% of the population per week. When sub-zero temperatures occurred mortality increased. An apparent decrease in survival at the end of the winter, which coincided with the period when temperatures rose above the developmental threshold for maturation, was attributed to emigration of flies from the overwintering site. The results are discussed in relation to the ecology of D. tryoni in the southern parts of its range.