A novel parasitoid for an invasive mealybug: temperature-dependent biology of Anagyrus aberiae (Hymenoptera: Encyrtidae) and implications for the biological control of Delottococcus aberiae (Hemiptera: Pseudococcidae)

Abstract

Anagyrus aberiae (Guerrieri) (Hymenoptera: Encyrtidae), an imported parasitoid from South Africa, was released in Spain for the classical biological control of the invasive citrus mealybug Delottococcus aberiae (De Lotto) (Hemiptera: Pseudococcidae). However, limited information is available about the parasitoid’s biological traits. Temperature is a key factor influencing insect performance and population dynamics. This study examines the effect of 7 constant temperatures on the development and survival of A. aberiae and determines its developmental thresholds and thermal constants using linear and nonlinear regression models. The parasitoid successfully developed and survived at temperatures between 18 and 33°C but failed to develop at 36°C. Development time and adult longevity decreased with increasing temperature, from 58.15 d at 18°C to 19.27 d at 33°C. Female progeny production peaked at 24°C, whereas offspring production was lowest and male-biased at 18 and 33°C. The estimated lower and upper developmental thresholds were 11.4 and 36°C, respectively, with an optimal temperature of 32.1°C. The thermal constant was calculated as 250 degree-days (DD). A. aberiae can survive, develop, and reproduce within the typical temperature range found in Mediterranean orchards, suggesting strong adaptive potential in regions beyond its native range. These results should be considered when optimizing mass-rearing programmes and assessing the field adaptation and establishment of A. aberiae as a biological control agent of D. aberiae across different citrus-growing regions.