Influence of Photoperiod on Larval Growth Indices and Energy Budget for Metamorphosis in Culex quinquefasciatus Mosquito (Diptera: Culicidae): its implication in Integrated Vector Management

Abstract

This study was designed to elucidate, for the first time, the effects of photoperiod on mosquito larval growth indices and energy reserve utilised for metamorphosis, using Culex quinquefasciatus as a model vector. Approximately Day-old larvae of the mosquitoes were exposed to different photoperiodic regimens, ranging from zero to 24-hours of Light (hL) and reared using standard protocols. Analyses revealed significant effect of photoperiod on mosquito larval growth rate. This decreased as the duration of photophase increased, with range of values of 0.0412±0.0023 to 0.1044±0.0021 mg/day. It was also discovered that, the effects of photoperiod on Total Larval Body Size (TLBS) were not significant at the first larval instar, L1 (range=0.84±0.05 to 0.88±0.02 mm). However, as the mosquitoes progressed from L2 through L4, there were significant reductions in TLBS, with respective values at 24 and 0 hL, ranging from 2.29±0.14 to 2.73±0.10 mm, 2.55±0.64 to 3.18±0.08 mm, and 3.86±0.46 to 4.53±0.10 mm, respectively, for L2, L3 and L4. Total Teneral Reserve Component utilised for the processes of pupation and eclosion, were significantly affected by photoperiod. As there was increased utilisation of teneral reserves as the duration of photoperiod increased from 0 to 24 hours, with range = 7.07±1.31 to 11.59±2.04 μg nutrient/ mosquito and 5.78±2.19 to 12.28±3.33 μg nutrient/ mosquito, respectively, for pupation and eclosion. This study, thus, revealed critical information on these important aspects of bio-ecophysiology of mosquitoes, which will be invaluable in the development of a robust, cost-effective, and eco-friendly integrated mosquito management protocols.