Effect of temperature on the reproductive biology of Peristenus spretus (Hymenoptera: Braconidae), a biological control agent of the plant bug Apolygus lucorum (Hemiptera: Miridae)

Peristenus spretus Chen et van Achterberg (Hymenoptera: Braconidae), a parasitoid of the plant bug Apolygus lucorum (Hemiptera: Miridae), has been studied for use in augmentative biological control in China. Under laboratory conditions, we explored the development, survival, age-specific and potential lifetime fecundity, oviposition period and progeny sex ratio of P. spretus reared at six constant temperatures (15 degrees C, 19 degrees C, 23 degrees C, 27 degrees C, 31 degrees C, 35 degrees C) on the second instar nymphs of A. lucorum. At 15 degrees C, male and female P. spretus took 48.7 +/- 0.3 and 52.5 +/- 0.3 days to complete their immature development, while developmental time was reduced by more than half at 23 degrees C and 27 degrees C. The parasitoid can only develop to the larval stage at 31 degrees C and neither larva nor pupa survived at 35 degrees C. The estimated lower developmental threshold of the immature stage was 7.3 degrees C. When parasitoid adults were exposed at 15 degrees C, females laid 90% of their eggs at first 19 days of oviposition and had an extended reproductive life. In contrast, females held at 27 degrees C laid most of their eggs (90%) in their first of 10 days of oviposition and had shorter longevity. The highest potential lifetime fecundity of P. spretus was 671.2 +/- 34.7 SE eggs produced over 23.4 +/- 1.4 SE days at 23 degrees C. At 15 degrees C, 19 degrees C and 23 degrees C, sex ratios of reared parasitoids were male-biased, but at 27 degrees C there was no male bias.