Environmental influences on fecundity, egg viability and egg cannibalism in the scale insect predator, Chilocorus nigritus

The effects of temperature on age-specific fecundity, egg viability and egg cannibalism were examined in the coccidophagous coccinellid, Chilocorus ni gritus being fed on the cyanophyllum scale, Abgrallaspis cyanophylli. There were no significant differences in lifetime fecundity or oviposition rate at constant temperatures in the range of 20 to 30 degrees C although there was a trend for both parameters to increase with increasing temperatures. T otal fecundity ranged from five to 1890 eggs per female whilst the oviposit ion rate varied from 0.2-12.1 eggs day(-1). Egg viability was significantly greater at 26 and 30 degrees C (63 and 74%, respectively) than at lower te mperatures (18 to 30%) whilst egg cannibalism was highest at 24 and 26 degr ees C (being the mid range of the temperatures tested). Mean pre-ovipositio n periods varied from 54 days at 20 degrees C to 8.2 days at 30 degrees C. The effect of relative humidities in the range of 33% to 75% on oviposition rate, egg viability and egg cannibalism was measured and found to have no significant effect on either parameter.