Impact of Adult Size and Sib, Conspecific, and Random Mating in Trichopria Sp. on Progeny Production and Sex Ratio

Abstract

The gregarious endo-pupal parasitoid, Trichopria sp. (Hymenoptera: Diapriidae) was evaluated for progeny production and sex ratio as influenced by adult size and sib, conspecific and random mating. Trichopria sp. is a parasitoid of the tachinid fly, Exorista bombycis (Louis), which causes a reduction of 10–20 % in silkworm (Bombyx mori L) cocoon yield in south India. Two-day-old virgin females and unmated males of Trichopria sp. were categorized into big and small and were allowed to mate in the following manner: (1) big female × big male, (2) big female × small male, (3) small female × big male, and (4) small female × small male. With regard to sib, conspecific, and random mating, the following mating combinations were set up: (1) mating among the progeny of the same mother (sib mating), (2) mating between the female progeny of one mother (A) and male progeny of another mother (B) (♀A × ♂B) and vice versa (♀B × ♂A), and (3) mating between the progenies of several mothers (random mating). Observations were made on the number of pupae parasitized, parasitoid developmental duration, progeny production, and sex ratio. Both big and small females of Trichopria sp. produced significantly more progenies when they mated with big males. Random mated females produced significantly higher progenies than those from sib and conspecific mating.