Effect of Temperature and Length of Exposure Time on Percent Egg Hatch of Cactoblastis cactorum (Lepidoptera: Pyralidae)

Abstract

The oligophagous cactus moth, Cactoblastis cactorum (Berg), has been recognized as a serious and immediate threat to Opuntia cacti in Florida and the southeastern United States. The moth has successfully colonized new geographical ranges with lower annual temperatures north of the Florida Keys where it was first detected in the continental United States in 1989. This study evaluated the effect of temperature on egg development and egg hatch of C. cactorum by utilizing various treatment temperatures, exposure times, and egg ages. The temperatures used in this study ranged from a low of -20°C to a high of 50°C, thus encompassing the potential range of temperatures that eggsticks may be exposed to in potential new host areas. One-d-old eggs held at a constant temperature of 30°C resulted in the highest percent hatch and shortest time to egg hatch. Eggs did not hatch when held at constant temperatures =15°C or =35°C. Furthermore, one d of exposure at -10°C and 4 d of exposure at -5°C were 100% lethal to one-d-old eggs. Eggs that were 7- and 14-d-old before exposure to cold temperatures were generally more resistant to temperature effects than one-d-old eggs.

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