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

Housefly, Musca domestica is used as an alternate host to rear a eulophid, Nesolynx thymus (Girault), a pupal parasitoid of the tachinid fly, Exorista bombyci s (Louis) which in turn is an endolarval parasitoid of Bombyx mo ri (L.). An attempt was made to evaluate the host factors like pupal size, age and exposure periods of N. thymus for developing robust mass multiplication methods. The host size had significant effect on mean parasitism by N. thymus . Mated females of N. thymus when exposed to host pupae of varying size, revealed that mean per cent parasitisation was significantly higher (74%) in large sized pupae having a volume of 263.89 mm3. Regarding host age, 24 - 48 h old host pupae had higher level of parasitism (65%) by N. thymus . The parasitism rate declined with an increase in host age after 72 h. In field evaluation, release of N. thymus at weekly interval resulted in the reduction of housefly population as evinced from the higher parasitism (56 %) of the sentinel cards placed in the treated poultry sheds. The information on host factors generated will help to enhance the mass multiplication of parasitoid for the release of which would aid to bring down the M. domestica population in poultry and dairy units.