Biology of the Parasitoids and Predators of Tribolium spp. (Coleoptera: Tenebrionidae)

Abstract

Two parasitoids and one predator were recovered from the red llour beetle, Tribolium castaneum (Herbst) and the confused flour beetle, T. confi,sum Duval infested wheal flours. lbe larval-pupal parasitoids are Rhahdepyris zeae Waterston and !Iolepyris sylvanidis Brethes (Hymenoptera: Bethylidae) and the predator is Xylocoris jlavipes (Reuter) (Hemiptera: Anthocoridae). Some ac;pects of biology of these parasitoids and.predator were investigated in the laboratory condition on the above two species of Tribolium. R. zeae although a larval-pupal ectoparasitoid showed a decided preference towards the fourth instar larvae and early pupae of the host. The developmental time varied in the male and female adult parasitoids. The male and female of R. zeae completed <.lt:velopmcnt within 19.06:1:0.59 um.I 20.14±0.58 days in 'I: castmwum while in T. confu.mm it was 20.10±0.77 and 21 .20±0.92 days, respectively al 30 ± I °C and 70% R. H. The males are polygamous but the females arc always monogamous. Both the sexes of R. zeae lived maximum days when host was supplied continuously. The female deposited maximum number of eggs when hosts were abundant. The sex ratio of R. zeae always showed female biased and dependent on the size of the host. Ji sylvanidis is also a primary larval-pupal ecloparasitoid of T. castaneum and T. confusum. After emergence the male took the initiative in mating and courtship. The fourth instar larvae were preferred for oviposition. The male of fl. sylva11idis completed life cycle within I 5.50±0.62 and 16.00±0.47 days in T. castaneum and T. confusum whereas the female required I 6.66t:0.72 and 17.15±0.80 days. Females are monandrous while males are polygynous. The hosts fluids were necessary for greater longevity in both the sexes. H. ,\ylvanidi.\· is arrhenolokous. Xylocoris jlavipes (Reuter) is a predator of different larval and pupal stages of Tribolium. The early stage was most preferred than that later stages. The male of X flavipcs completed life cycle within 16.99±1.86 and 17.80±1.30 days in 7'. castancum and T. confusum whereas the female required 16.00± 1.63 and 17.00±1.63 days. The female biased sex ratio of X jlavipes was noticed.-----