Cold hardiness and chill coma recovery dynamics in mealybugs species of citrus, and implication for pest management

Abstract

Cold stress influences insects by affecting their metabolic rates, reproductive success, distribution, and establishment. While insects develop inherent basal thermal tolerances to cope with variable extreme conditions, their fitness and survival are dependent on both the severity and duration of temperature exposure. In this study, we tested the effect of low temperature and exposure duration on the survival of six mealybug species: Paracoccus burnerae, Nipaecoccus viridis, Pseudococcus calceolariae, Delottococcus aberiae, Pseudococcus longispinus, and Planococcus citri. Using the F1 generation (3rd instar and adult female), we measured lower lethal temperatures (LLTs), critical thermal minima (CTmin), and chill coma recovery time (CCRTs). Temperature and exposure duration affected survival across life stages and species. CTmin and recovery times varied among species and life stages, with 3rd instar females exhibiting greater cold tolerance than adult females across all species. Notably, D. aberiae and P. burnerae demonstrated the highest cold tolerance, suggesting they have a survival advantage over the more cold-susceptible P. citri and N. viridis, especially during winter conditions and extreme cold exposure. These results indicated that such differences in cold response could influence the rate at which these mealybug species or life stages establish and distribute within and across orchards, hence impacting the effectiveness of the set management interventions.