Development of Diomus austrinus Gordon (Coleoptera: Coccinellidae) on two mealybug prey species at five constant temperatures

Diomus austrinus Gordon is a generalist mealybug predator native to southern Florida. The objective of this study was to provide information on the development and survival of D. austrinus when reared on two common mealybug species [the Madeira mealybug, Phenacoccus madeirensis Green, and the citrus mealybug, Planococcus citri (Risso)] at five constant temperatures (15, 20, 25, 30, and 35 °C). Results of this study demonstrated the efficacy of D. austrinus as an egg predator of mealybugs within the temperature range found in greenhouses. D. austrinus successfully completed development on both mealybug species, with larval development requiring 1–4 days longer on the citrus mealybug than on the Madeira mealybug. D. austrinus feeding on the Madeira mealybug completed development in 15 days at 20 °C, 22 days at 25 °C, and 39 days at 30 °C. The lower and upper larval developmental thresholds of D. austrinus appeared to be 15 and 35 °C, respectively. Estimates of lower developmental thresholds using a linear model agreed with the observed results. Survival of D. austrinus from egg to adult among temperature/prey species combinations ranged from 60 to 90%. In all temperature/prey species combination, the cohorts were slightly female-biased, with an average proportion females of 0.53. Females reared on Madeira mealybugs at higher temperatures were generally larger than those reared on citrus mealybugs.