Effect of photoperiod and temperature on fatty acid composition of the mosquito Culex tarsalis

Abstract

A strain of Culex tarsalis from 35 N. latitude (not very cold hardy) was examined for the interplay of photoperiod and temperature on fatty acid saturation. At 22°C newly emerged females on 8 hr (short) photoperiod had 62 per cent unsaturated fatty acids compared to 52 per cent for those on 16 hr (long) photoperiod. The short photoperiod females reached a plateau at 1 week which was matched by the long photoperiod group at 3 weeks. Females on a complex low-temperature treatment had more unsaturated fatty acids than females at high temperature (30°C). Nevertheless the effect of short photoperiod was observed in the low-temperature females as the short photoperiod group had 43 and 26 per cent of palmitoleic and oleic acids versus 31 per cent and 20 per cent respectively for the long photoperiod group. Thus short photoperiod serves as a factor accessory to low temperature in the accumulation of unsaturated fatty acids. Males, which do not overwinter, accumulate lesser amounts of unsaturated fatty acids. Extreme temperatures (particularly high) caused the accumulation of large amounts of fatty acids of less than 14 carbon chainlength in males.