Development of the predatory pentatomid Picromerus bidens (L.) at various constant temperatures

Development of the palearctic predatory heteropteran Picromerus bidens was assessed at constant temperatures ( 15, 18, 20, 23, 27, 32 and 35+/-1 degrees C) using larvae of the cotton leafworin Spodoptera littoralis as prey. All experiments were done at a 12:12 (L:D) h photoperiod and 65+/-5 \% relative humidity. The predator developed to maturity between 18 and 32 degrees C, but eggs failed to hatch at 15 and 35 degrees C. Duration of development of the different immature stages of P. bidens decreased with increasing temperature from 18 to 32 degrees C. The total development time for P. bidens ranged from 24.8 days at 32 degrees C to 85 days at 18 degrees C. The estimated lower thresholds for development varied between life stages and ranged from 8 to 16 degrees C. The thermal requirements for development of the egg stage, completion of the nymphal period and total development of P. bidens were estimated to be 208, 270 and 500 degree-days with lower thresholds of 10.5, 13.8 and 12.2 degrees C, respectively. Upper threshold temperature for development of eggs and nymphal stages was estimated to be between 32 and 35 degrees C. Egg hatch percentage, nymphal Survival and sex ratio were determined at each temperature. The data reported here should be helpful in predicting development of P. bidens Populations in the field and offer valuable basic information for the use of this native predator in biological control programs.