Biochemical Resistance Traits of Bitter Gourd against Fruit Fly Bactrocera cucurbitae (Coquillett) Infestation

Host plant resistance is a key factor for management of the melon fruit fly, Bactrocera cucurbitae (Coquillett), due to difficulties associated with its chemical and biological control. Various biochemical traits including total sugars, reducing sugars, non-reducing sugars, silica, protein content, ash content, other elements and phenols, and moisture content of fruit were studied on 74 varieties/genotypes of bitter gourd (Momordica charantia L.), in relation to resistance against B. cucurbitae under field conditions. Seventy-four genotypes of bitter gourd were screened against fruit fly infestation. The correlation coefficients revealed that the larval density and bitter gourd fruit damage (%) had significant positive relationship (r = 0.99). The moisture content had significant positive effect on the fruit damage (r = 0.75) and number of larvae per fruit (0.80). Significant differences were found in tested varieties/genotypes for fruit infestation and larval density per fruit. The nitrogen, phosphorous, potassium and protein content (r = -0.87, -0.90) showed significant negative correlation with fruit fly infestation. The non-reducing, reducing, total sugars, total phenols, silica and ash content had significant impact on the fruit damage and showed significant negative correlation with fruit fly infestation. The ascorbic acid also had significant impact on the fruit damage and showed significant negative correlation with fruit fly infestation (r = -0.79), the chlorophyll ‘a’, ‘b’ and total chlorophyll content had non-significant negative effect on the fruit damage and number of larvae per fruit.