Comparison of the developmental time of Bracon hebetor (Hymenoptera: Braconidae) reared on five different lepidopteran host species and its relationship with digestive enzymes

Bracon (Habrobracon) hebetor Say is a polyphagous parasitoid of lepidopteran larvae, including those of the family Pyralidae. There are many reports that this parasitoid attacks the larvae of stored product and field crop pests. However, there is little information on the biological parameters of this parasitoid attacking different lepidopteran hosts or the effect of the hosts on the digestive enzymes of the parasitoid. Hence, in the current study the effect of different lepidopteran hosts, Ectomyelois ceratoniae, Plodia interpunctella, Ephestia kuehniella, Helicoverpa armigera and Malacosoma disstria, on the biological parameters and digestive enzymes (α-amylase and proteases) of this parasitoid were investigated. The parasitoid performed better on stored product pests, such as E. kuehniella and P. interpunctella, than field crop pests, such as H. armigera and M. disstria. For example, in terms of percentage egg hatch, rate of development, off-spring sex ratio and adult dry mass Bracon hebetor did much better when it parasitized stored product insects than field crop insects (P < 0.05). Interestingly, the quality and quantity of the proteases and α-amylase of the parasitoid larvae parasitizing stored product and field crop pests differed. The greatest activity of these enzymes was recorded in the gut of those parasitoids that were reared on stored product insects (P. interpunctella and E. kuehniella). It is concluded that stored product insects, which feed on a diet rich in sugar and glycogen, provide physiological conditions that are more suitable for the parasitoid than field crop insects, which feed on diet rich in terpenes and tannins.