Biological quality assessment of different generations of the parasitoid, telenomus busseolae Gahan (Hymenoptera: Scelionidae) reared on eggs of the sugarcane stem borer sesamia nonagrioides Lefèbvre (Lepidoptera: Noctuidae)

Abstract

The present study evaluated the biological parameters (parasitism rate, fertility, emergence rate, adult longevity, and offspring sex ratio) of seven generations (F₀, F₁, F₃, F₅, F₇, F₈, and F₁₀) of the parasitoid wasp Telenomus busseolae Gahan (Hymenoptera: Scelionidae) reared on eggs of the sugarcane stem borer Sesamia nonagrioides Lefèbvre (Lepidoptera: Noctuidae) under laboratory conditions. A host colony was established from field-collected S. nonagrioides, and fresh eggs were provided to T. busseolae females from generations F₀ (field-collected), F₁, F₃, F₅, F₇, F₈, and F₁₀; 30 female wasps per generation were randomly selected for the parameter recording. Significant declines were observed across generations: parasitism rate decreased from 85.2% (F₀) to 61.3% (F10), fertility from 42.1 to 25.7 parasitized eggs/female, emergence rate from 92.3 to 71.8%, female longevity from 9.2 to 5.8 days, representing an a approximately 37% reduction. The offspring sex ratio shifted from 75% female (significantly female-biased) to 45% female, which did not differ significantly from a 1:1 ratio. The results demonstrate a gradual decline in the biological quality of T. busseolae under laboratory rearing. Consequently, periodic introduction of field populations, optimization of rearing diets, and stringent environmental control are recommended to sustain the efficacy of T. busseolae in biological control programs.