The diel oviposition periodicity of Aedes aegypti (L.) (Diptera: Culicidae) in the laboratory: substrate-movement effect

The diel oviposition periodicity of females of the LSHTM strain of Aedes aegypti was studied, under laboratory conditions, using one female/cage and monitoring, by changing the substrate, every 1, 2, 4 or 24 h. The individual females monitored at hourly intervals showed peak oviposition at 18.00-19.00 hours (a period when 44% of the eggs observed were laid) whereas the individuals monitored at two-hourly intervals showed peak oviposition between 16.00-18.00 hours (38% of eggs). The four-hourly monitoring gave a result that was similar to that of the two-hourly monitoring, with 79% of eggs laid between 14.00-18.00 hours, indicating an earlier peak in oviposition than seen with the one-hourly monitoring. Care should therefore be taken when conducting similar studies in the laboratory and when comparing or considering data derived from experiments in which different monitoring intervals have been employed.