Reproductive performance of Nesolynx thymus (Hymenoptera: Eulophidae) as influenced by host (Musca domestica) size

Abstract

An investigation was conducted to understand the influence of host size on the reproductive performance of Nesolynx thymus, an ecto-pupal parasitoid of the uzi fly, Exorista bombycis, inflicting 10-20% loss to silkworm crops in the southern silk producing states of India. Two day-old adults of N. thymus were allowed to parasitize pupae of M. domestica, categorized into big and small at a parasitoid-host ratio of 1:20. After parasitoid adult eclosion, data on parasitization rate, developmental duration, male, female and total adult recovery per pupa and per female, sex ratio, adult size and adult longevity were recorded. The performance of first generation adults as influenced by host size was also recorded by allowing the first generation adults to parasitize three day-old pupae of E. bombycis. The parameters female and total progeny production per female, sex ratio, longevity, body length and wing span of males, females, head width of male, and abdomen length of female increased significantly with host size. No impact of host size was observed on performance of first generation adults.

Host factors influencing the parasitism by Nesolynx thymus (Girault) (Hymenoptera: Eulophidae) on housefly, Musca domestica L.

“…Increased parasitism resulting with the increased exposure time of parasitoid to host pupae observed in our study was also reported in Oomyzuz sokolowskii (Kurdjimov) where the parasitism rate doubled from 40% after 24 h exposure to 80% after 72 h of exposure to third-instar Plutella xylostella (L.) (Torres et al, 2010). Variation in parasitism level ranging from 20-80% in T. howardi on Chilo partellus (Swinhoe) was mainly due to exposure period (Baitha et al, 2004). In our study, 48 h exposure period showed higher level of parasitism and the with higher female progeny.…”

“…The reduction in parasitisation in exposure period beyond 48 h may be due to occurrence of superparasitism. A condition that was reported when T. howardi against Chilo partellus (Baitha et al, 2004). This study clearly indicates that 24-48 h is a suitable exposure period to adopted during mass production of parasitoids.…”

Trichospilus diatraeae (Hymenoptera: Eulophidae): development and reproduction in Lepidoptera palm oil pests

“…The shortest duration from egg to adult T. diatraeae in O. invirae pupae than in those of B. sophorae can be attributed to the shorter pupa stage of the host, because the faster metabolism of the host can reduce the parasitoids (Smethurst et al, 2004). Moreover, competition among immature T. diatraeae in the smaller O. invirae pupae and consequently the lower food resources available compared to larger B. sophorae pupae may also resulted in the development duration in that host (Aruna and Manjunath, 2010). The longest duration of T. diatraeae development in B. sophorae pupae can reduce the chances of host survival by it increases the period vulnerable to predators, pathogens or the host response (Benrey and Denno, 1997).…”