Comparative studies on populations of Pauesia juniperorum (Hymenoptera: Braconidae), a biological control agent for Cinara cupressivora (Hemiptera: Aphididae)

Abstract

Pauesia juniperorum (Starý), a solitary endoparasitoid which attacks several Cinara spp. in the subgenus Cupressobium, was introduced into Africa for the control of the cypress aphid Cinara cupressivora Watson & Voegtlin (previously identified as Cinara cupressi (Buckton)) and is now established. Data on its biology including a comparison of populations from different hosts and geographical locations are presented. From the UK this consisted of populations reared from Cinara cupressivora, Cinara fresai Blanchard and Cinara juniperi De Geer, and from France, Cinara ?fresai. Between different populations, the duration of development varied within a narrow range (15.5-18.1 days) at 22 degrees C. Data on duration of development over a range of temperatures (15-26 degrees C) for two populations, from the UK and France ranged between 14.0-31.4 days for males and 14.7-32.8 days for females. The threshold temperature for development was 6.2 degrees C and 4.1 degrees C for the populations from the UK and France, respectively. The mean egg load for different populations ranged between 46.4 and 78.5 eggs. The host species had a significant effect on egg load which was directly related to size of the respective host aphids. The lowest egg load was recorded on specimens reared from C. cupressivora which was the smallest aphid. The population from the UK had a higher intrinsic rate of increase (0.232) than the one from France (0.207).