Thermal responses in the citrus fruit fly, Dacus tsuneonis: evidence for a pupal diapause

Abstract

AbstractThermal responses controlling pupariation and adult eclosion in a citrus fruit fly, Dacus tsuneonis (Miyake), were studied to understand the winter biology of this species. When mature larvae were exposed to various temperature conditions, the highest percentage of pupariation was obtained at 15°C, although the variance at this temperature was greater than at 20C or 25°C. Pupariation occurred most rapidly at 20°C and an alternating temperature with a mean of 15°C. At constant 15°C, pupae failed to emerge as adults. Pupae were characterized by a reduced respiration rate, which is typical of a diapausing pupa. When insects were stored at different temperatures for 45 days after pupariation, and then transferred to 25°C, adult eclosion occurred earlier when the initial temperature was 10°C than when it was 5°C or 15°C. Adult eclosion occurred most synchronously and pupal mortality was lowest when insects were stored at 15°C for 90 days before incubation at 25°C. These results strongly suggest that D. tsuneonis enters a pupal diapause.