Hatchability of Eggs of Aedes taeniorhynchus (Diptera: Culicidae): Effects of Different Temperatures and Photoperiods during Embryogenesis

Eggs of Aedes taeniorhynchus (Wiedemann) were subjected to different photoperiod/ temperature combinations on days 0–5 postoviposition. At 22°C, those exposed on day 2 displayed the highest incidence of photoperiod-induced diapause. At 15°C, photophases <12 h produced a lower incidence of diapause when experienced by eggs from days 0–2 than from days 3–5 postoviposition. However, at both a constant 15 and 22°C and at a 21:5°C thermoperiod, percentage hatch tended to be inversely proportional to age for eggs that were 0–2 days old and directly proportional to age for those that were 3–5 days old on exposure to photoperiod. A combination of a 10.5:13.5 (L:D) photoperiod and 21:5°C (photophase/scotophase thermal regime) had the greatest effect when encountered by eggs 0–2 days postoviposition; the combination's effect on eggs that were 3–5 days old was similar to that of a 10:14 photoperiod and 15°C. Under a 11.3:12.7 photoperiod and a 24:9°C thermoperiod, a clearly defined hatching pattern was shown only by eggs subjected to the treatment 2 days after oviposition. A constant 5, 10, and 27°C suppressed the effect of photoperiod. Results suggest that photoperiod/temperature interactions were influential during embryogenesis.