Do Size and Age of Female Trichopria Sp. Influence Longevity, Reproductive Performance, and Sex Ratio?

Abstract

The present study was conducted to record the effect of female size and age on the longevity and reproductive performance of Trichopria sp. (Hymenoptera: Diapriidae), an endo-pupal, gregarious parasitoid of Exorista bombycis Louis (Diptera: Tachinidae). Being an endo-larval parasitoid of the silkworm Bombyx mori L. (Lepidoptera: Bombycidae), E. bombycis causes a cocoon yield reduction of 10–20 % in south India. Two-day-old females of the wasp were segregated into big and small based on their size. The longevity of big and small females was recorded at 24 h intervals by feeding 30 % honey. The progeny production and sex ratio were assessed by allowing big and small gravid parasitoid females as well as 1–8 day-old females of the wasp to parasitize 3 day-old puparia of E. bombycis for 2 days at a wasp: host ratio of 1:4. Number of host puparia parasitized, parasitoid developmental duration, progeny production, and sex ratio were recorded. The longevity of big parasitoid female wasps was significantly longer than small ones. Similarly, big females of the parasitoid produced significantly more progenies with higher sex ratio compared to small females. With regard to parasitoid age, young females (1–3 day-old) produced significantly more progenies in comparison to old ones (7–10 day-old).