Effect of high temperatures on survival and longevity of the predator Cryptolaemus montrouzieri Mulsant

The effect of high temperature on survival and longevity of Cryptolaemus montrouzieri Mulsant (Coleoptera: Coccinellidae) female adults was studied in the laboratory by daily exposure of the beetles to 35°C (mean r.h. 52%) combined with 1-, 2- and 3-h intervals of thermal treatment at 38, 40, 42 and 44°C (r.h. 46–48%). Fifty percent of females survived until the 12th–13th day of the thermal treatment at 38°C (depending on the exposure time), the 2nd–10th day at 40°C for 1–2 h exposure and the 4th–5th day at 42°C for 1 h exposure. Survival was 25–38% on the 1st–2nd day of the thermal treatment at 40, 42 and 44°C for 3, 2 and 1 h of exposure, respectively. Three hours of exposure of female C . montrouzieri at 42°C and 2 h exposure at 44°C were lethal for the beetles. Mean longevity of the predator was 33.13 ± 1.22 days at 35°C and was significantly shorter as the temperature of the thermal treatments increased from 38 o to 44°C. These results suggest that daily temperature regimes of 35°C combined with 38–40°C for 1–3 h are marginal for the survival and longevity of the C . montrouzieri , whereas temperatures above 42°C are lethal even at short exposure. These results can partly justify the inability of C . montrouzieri to be permanently established in Pakistan environments and could contribute to a pre-evaluation assay of its potential adaptability in such environmental systems.