TEMPERATURE INDUCES TRADE-OFFS BETWEEN DEVELOPMENT AND STARVATION RESISTANCE IN AEDES AEGYPTI (L.) LARVAE

摘要

While heightened temperature increases the development rate of mosquitoes, for Aedes aegypti, larvae that commonly experience food limitation in urban habitats, temperature effects on adult production may also be influenced by changes in the capacity of larvae to survive without food. We carried out experiments at 2°C intervals between 20 and 30°C on the growth, maturation rate and the longevity of optimally fed larvae placed in starvation. Overall, both growth rate and starvation resistance were lower in the first three larval instars (L1-L3) as compared to L4, in which greater than 75% of growth occurred. While increased temperature reduced the duration of each instar, it had a U-shaped impact the effect of initial growth on starvation resistance, which increased from L1 to L2 at 20 and 30°C, remained constant at 22 and 28°C, and decreased at 24 and 26°C. Growth from L2 to L3 significantly increased starvation resistance only from 26-30°C. Increased temperature (above 22°C) consistently reduced starvation resistance in L1. In L2-L4, 2°C increments decreased starvation resistance between 20 and 24°C, but had weaker and instar-specific effects above 24°C. These data show that starvation resistance in Ae. aegypti depends on both instar and temperature, generating a tradeoff between increased development rate and reduced starvation survival of early instar larvae, particularly in the lower and middle temperatures of the dengue endemic 20-30°C range. We suggest that anabolic and catabolic processes in larvae have distinct temperature dependencies, which may ultimately cause temperature to modify density regulation of Ae. aegypti populations.