Population Dynamics of Zeugodacus cucurbitae and Zeugodacus tau in Bitter Gourd

Field studies were conducted during kharif 2024 and 2025 at the Vegetable Research Farm of Acharya Narendra Deva University of Agriculture and Technology, Kumarganj, Ayodhya, to assess the population dynamics of fruit flies in bitter gourd (Momordica charantia L.) in relation to weather parameters. Weekly mean incidence was recorded from cue-lure based Rakshak traps. Two species, Zeugodacus cucurbitae (coquillett) and Z. tau Walker, were observed throughout the cropping period. The activity of Z. cucurbitae commenced from the 30th SMW and remained predominant throughout the observation period, showing relatively higher abundance between the 30th and 40th SMW, whereas Z. tau occurred in comparatively lower numbers. Correlation analysis based on pooled data indicated that maximum temperature exhibited a significant positive association with Z. cucurbitae (r = 0.75**), while minimum temperature also showed a positive relationship (r = 0.55*). In contrast, rainfall showed a weak negative association (r = −0.05) with Z. cucurbitae. Weather parameters showed comparatively weaker relationships with Z. tau, although rainfall exhibited a positive association (r = 0.56*). Multiple regression analysis further revealed that meteorological variables explained a higher proportion of variation in Z. cucurbitae (R² = 0.79) compared to Z. tau (R² = 0.53), indicating that temperature played a dominant role in regulating fruit fly abundance in the bitter gourd ecosystem. The study highlights inter-annual variability in climatic influence and indicates greater temperature responsiveness of Z. cucurbitae under bitter gourd ecosystem, which may aid in developing timely management strategies.