Heat tolerance and thermal safety margins differentially influence the performance of co-occurring mealybug species (Hemiptera: Pseudococcidae) under climate warming

Ectotherms vary widely in thermal tolerance and exposure to temperature extremes, with sensitivity differing among species and life stages that can differentially influence their physiological and ecological performance under a changing climate. Using the F1 generation, we quantified thermal vulnerability for six mealybug species, Planococcus citri , Pseudococcus longispinus , Paracoccus burnerae , Nipaecoccus viridis , Pseudococcus calceolariae , and Delottococcus aberiae , by measuring their upper lethal temperatures, critical thermal maxima (CT max ), and heat knockdown times (HKDTs). We then calculated species’ thermal safety margins by comparing their absolute CT max and daily maximum temperatures (T max ) recorded in eight orchards over six years. Paracoccus burnerae , N. viridis , and D. aberiae exhibited higher heat tolerance and greater CT max (48.83 ± 0.15 to 49.65 ± 0.13) than Pl. citri , Ps. longispinus , and Ps. calceolariae (46.95 ± 0.17 to 48.32 ± 0.06). Although not all thermal traits differed significantly among life stages, adults had considerably longer HKDT than 3rd instar nymphs across species. Species differed in thermal responses and, in the context of microhabitat adaptations, produced vulnerability patterns consistent with each species’ thermal tolerance. Thermal safety margins declined as T max increased, especially for species with lower CT max . Combining species thermal rankings with environmental exposure revealed a complex, spatially variable risk landscape. These findings support incorporating thermal safety margin metrics into management strategies to enhance agricultural sustainability under climate warming.