Observations of Aphelinus gossypii (Hymenoptera: Aphelinidae) reproduction, a parasitoid of Aphis gossypii (Hemiptera: Aphididae) on cotton.

摘要

This paper reports the reproduction of Aphelinus gossypii in CAR (Central African Republic). Some 500 Aphis gossypii of all stages and 100 aphid mummies were collected from a cotton plot in Bangui [see J. Appl. Entomol. (2004) 128, 1-7]. Collected aphids were transferred to potted cotton plants and maintained in screened wooden enclosures in ventilated shelters at 25-27 degrees C on 12:12 h photoperiod. Aphid mummies were isolated singly in gelatine capsules. When the wasp emerged from the mummified aphid, identity of the parasitoid was confirmed as Aphelinus gossypii, sexed and released into the enclosures. Virgin females (n=23) produced a mean of 5.2+or-4.6 mummies per female (range=1-16), while mated females (n=15) produced a mean of 14.1+or-5.6 mummies per female (range=2.28). These differences were statistically significant. Wasp emergence from the mummies produced by virgin females ranged from 45 to 75%, while emergence from mummies produced by mated females ranged from 35 to 76%. The sex ratios of offspring produced by virgin versus mated females were significant different. Virgin females produced male and female progeny, suggesting the occurrence of deuterotokous parthenogenesis. The offspring of mated female Aphelinus gossypii produced a male-biased sex ratio with a proportion of 0.75 up to 0.93.