Effect of Temperature on the Parasitism Efficiency of Habrobracon hebetor Say against Brinjal Shoot and Fruit Borer

Abstract

In response to the ecological damage caused by conventional pesticides, bio-control agents offer a sustainable alternative for pest management. The brinjal shoot and fruit borer (BSFB), a devastating lepidopteran pest whose larvae bore into shoots and fruits, making it a critical target for effective bio-control strategies. As Habrobracon hebetor Say demonstrates high parasitism and host suppression efficiency against larvae of lepidopteran insect pests, this study investigated the temperature-dependent performance of H. hebetor against BSFB at 15°C, 20°C, 25°C, 30°C, and 35°C to determine the optimal temperature range for parasitism efficiency. The experiment was conducted following a single factor completely randomized design (CRD) with three replications. Temperature significantly influenced all assessed parameters: developmental time (DT), emergence success rate (ES), parasitism rate (PR), adult longevity (LR) and sex ratio (SR). DT differed significantly across all regimens and was inversely proportional to the temperatures, ranging 9.8 days at 35℃ to 48.5 days at 15℃. Emergence success was highest at 30℃ (70%), while the parasitism rate peaked at 25℃ (96.9%). Sex ratios (male: female) varied with temperature, reaching 0.35 at 30℃ and adult longevity was shortest at 35℃ (6.3 days). The highest parasitism at 25℃ and peak emergence at 30℃ suggests a trade-off between parasitism ability and successful adult emergence. These findings indicate that temperature significantly affects the biology and activity of H. hebetor against BSFB, with 25–30°C the optimal range for laboratory rearing and field application of H. hebetor. This optimum thermal range makes the parasitoid a viable and sustainable bio-control agent against BSFB.

SAARC J. Agric., 24(1): 87-98 (2026)