Susceptibility of watermelon genotypes to fruit fly Bactrocera cucurbitae (Coquillett)

Host plant resistance is an important component for management of the melon fruit fly, Bactrocera cucurbitae (Coquillett) owing to difficulties associated with its chemical and biological control. A total of 27 watermelon varieties/genotypes were evaluated for their susceptiblity to the fruit fly in hot arid region of Rajasthan. The results showed that the varieties/genotypes viz. percentage of fruit infestation and larval population per fruit varied significantly. Pooled data showed that the varieties/genotypes viz., AHW/BR-60, BSM-1, IC 582909, AHW/BR-9, AHW/BR-137, Durgapura Kesar, AHW/BR-10, AHW/BR-18, AHW/BR-8, AHW/BR-21, AHW/BR-20 and YF-4 can be categorized as susceptible with considerable fruit infestation (55.72%, 59.28%, 53.05%, 67.20%, 60.43%, 61.83%, 63.87%, 63.62%, 59.45%, 59.62%, 62.52% and 55.68%, respectively) and with larval population per fruit viz. 17.12, 17.85, 16.45, 19.23, 17.90, 18.48, 18.38, 18.32, 18.40, 17.57, 17.93 and 17.70, respectively. The varieties/genotypes Asahi Yamato, AHW/BR-16 and Thar Manak had 12–18% fruit infestation (12.75%, 15.05% and 18.18%, respectively) with 1–1 lawal per fruit (10.13, 10.82 and 11.08, respectively) and declared which can be considered resistant. Lower values of host plant susceptibility indices based on fruit infestation (HPSI) were recorded on resistance varieties/genotypes, viz., Asahi Yamato, AHW/BR-16 and Thar Manak (28.85%, 34.05% and 41.14%, respectively). These could be used as a source of resistance for developing watermelon varieties/genotypes resistant to fruit fly.