Effect of temperature on life cycle and behaviour of Aedes aegypti (Diptera: Culicidae)

Abstract

In this study, effect of increasing temperature on life cycle, mortality, and behavior of the mosquito species, Aedes aegypti was evaluated. Heat shock was applied at 32°C, 37°C and 42°C for 20 minutes, 1 hour and 2 hours for each temperature to egg, 2^nd instar, 3rd instar and pupal stage separately and changes in life cycle pattern was recorded on a routine basis. The control temperature was 27°C at which the mosquito was reared. When heat-shock was applied to eggs, the developmental period for each stage was found to be inversely proportional to temperature rise. The shortest embryonic developmental period was recorded at 32°C, and the shortest larval and pupal stages were recorded at 37°C (2h). The shortest full development period was also found to be at 37°C (2h). No hatching was recorded at 42°C. While heat shock was applied to 2^nd instar larvae, 3rd instar larvae and pupae, similar decreased pattern was observed. In this study, 100% viability was observed upon heat shock to eggs, larvae (2^nd and 3rd instar) and pupae at 27°C and 32°C. In case of 37°C, egg, 2^nd instar and pupal viability decreased. No egg hatched at 42°C, while few 2^nd instars survived. Lowest viability rate for 3rd instar larvae and pupae were counted at 42°C. Change in the rate of movement also decreased gradually with increasing temperatures in pupae. The change was irregular in case of 2^nd and 3^rd instar larvae. The highest movement was recorded for 2^nd and 3^rd instar larvae at 32°C and 27°C, respectively and lowest was recorded at 42°C.

Bangladesh J. Zool. 49 (3): 369-379, 2021