Abstract
Apprehensions are mounting about the effects of pesticides on human and environment. Therefore, interest is being revived to use biological control, which is recognized as an important component of sustainable pest management. Dirhinus giffardii has been effectively used as pupal parasitoid for the management of fruit flies. Experiments were conducted to determine the suitable host age for rearing of the pupal parasitoid on the two species of fruit flies, Bactrocera zonata and Bactrocera cucurbitae. Results indicated that D. giffardii preferred the pupae of B. zonata than B. cucurbitae at all the tested host (pupae) ages of the fruit flies. Maximum parasitism per female was observed at the age of 3 days old pupae. The parasitism increased significantly up to the pupal age of 3 days and then the parasitism started declining. Parasitism of the D. giffardii was recorded on fruit flies pupae up to the age of 5 to 6 days on both the fruit fly species and no parasitism was recorded from day 7 onwards. The results revealed that age of parasitoid, D. giffardii also had significant effect on pupal parasitism of B. zonata and B. cucurbitae. The mean parasitism per female was increasing with age of parasitoid and reached to its peak at the age of 5 days of parasitoids. Thereafter the parasitism started declining with the subsequent age of parasitoid and it reached lowest at the age of 30 days. The studies suggested that the parasitoids D. giffardii should be discarded after the age of 15 days for good mass rearing. Key words: Pupal parasitoids, fruit flies, host and parasitoid ages, parasitism.
Highlights
The insect pests adversely affecting agricultural productions are commonly controlled by the application of large quantities of pesticides
Results indicated that D. giffardii preferred the pupae of B. zonata than B. cucurbitae at all the tested host ages of the fruit flies
Parasitism of the D. giffardii was recorded on fruit flies pupae up to the age of 5 to 6 days on both the fruit fly species and no parasitism was recorded from day 7 onwards
Summary
The insect pests adversely affecting agricultural productions are commonly controlled by the application of large quantities of pesticides. Production is affected in the field, prior to harvest, and after harvest. 30 to 40% losses in field and post harvests by the insects are common (Mathew, 1999). Due to frequent and injudicious application of pesticides insect pests develop resistance that jeopardized their efficiency and deteriorate the environment. The urban public is fervently more disparate to the present control strategy of insect pests in the field crops and the fruit orchards.
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