Parasitism potential of Dirhinus giffardii (Silvestri) (Hymenoptera: Chalcididae) on pupae of the fruit fly species, Zeugodacus cucurbitae (Coquillett) and Bactrocera dorsalis (Hendel) (Diptera: Tephritidae), during variable exposure durations

Background Fruit flies are important insect pests of horticultural crops. Pesticides used to control them which cause environmental and health hazards; therefore, other alternative sustainable management measures are required. Main body Successful implementation of an integrated pest management program, using biological control agents, needs synchronization of parasitoids with hosts selection and exposure time. The present study was conducted to assess the biological activity of the parasitoid species, Dirhinus giffardii (Silvestri) (Hymenoptera: Chalcididae), against the melon fruit fly, Zeugodacus cucurbitae (Coquillett), and the oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae), at different exposure durations (24, 48, and 72 h). The experiments were conducted under standard laboratory conditions. Significant differences in the parasitism rate of D. giffardii were observed for both species at different exposure durations. The maximum parasitism rate of D. giffardii (52.60 +/- 2.84%) and (42.73 +/- 2.74%) was observed at 48-h exposure period for Z. cucurbitae and B. dorsalis, respectively. Also, a comparison between both species showed a difference in parasitism rate at 24 and 48 h and a positive correlation between percent parasitism and exposure duration. Adult emergence of D. giffardii showed a maximum emergence rate from pupae of Z. cucurbitae (63.55 +/- 4.02%) and B. dorsalis (51.61 +/- 2.33%) at 10 days interval, respectively. However, the daily emergence of the parasitoid was not correlated to exposure duration in both species. The results of the present study may serve in the mass rearing of D. giffardii. Conclusion The biological activity of D. giffardii was maximum at 48 h of exposure for both fruit fly species, and this important information may improve the mass rearing technology of D. giffardii.