Effect of Host Pupae Age and Depth in Plant Debris on the Searching Efficiency of Pupal Parasitoid Dirhinus giffardii (Silvestri) on Oriental Fruit Fly Bactrocera dorsalis (Hendel)

Abstract

lifestyle. However, insect pests, diseases and various other natural and unnatural factors affect both quality and quantity of the fruits and vegetables. Amongst the insect pests, fruit flies (Tephritidiae: Diptera) are most destructive insect pests, causing Abstract | This research study reports the effect of pupal parasitoid Dirhinus giffardii on oriental fruit fly Bactrocera dorsalis (Hendel) at various host pupae depths (0, 1, 2, 3, 4 and 5 cm) in plant debris and at different host pupae ages (24, 48, 72 and 96 h) in laboratory at 25 ± 2ºC, 60 ± 5% relative humidity and a photoperiod of DL 14:10 h. The observations indicated a significant effect of different depths of host pupae and its age on the amount of parasitism by parasitoid. Maximum significant (F = 10.78, P < 0.0001) parasitized pupae were recorded at 72 h of age at surface of the debris, while minimum number of parasitized pupae were recorded in a day old pupae at 3 cm depth. Correlation of percent pupal parasitism with depths of host pupae in plant debris, showed a negative linear trend. With increasing depth, the percentage of parasitism decreased, showing the lowest significant (F = 10.55, P < 0.0001) 38.74% pupae parasitized at 3 cm depth. Whereas, correlation of percent of pupae parasitized with the age of host pupae exhibited a positive linear trend. Older host pupae were more parasitized showing significant (F = 292.76, P < 0.0001) peak of 54.60% at 72 h of age. Since, pupal parasitoid D. giffardii mass rearing is helpfu l for decreasing oriental fruit fly population. Hence, it can be suggested that parasitoids exposed to older pupae have a greater parasitism potential. However, parasitization rate is adversely affected by the presence of plant debris.