Influence of physico-chemical traits of bitter gourd, Momordica charantia L. on larval density and resistance to melon fruit fly, Bactrocera cucurbitae (Coquillett)

Melon fruit fly, Bactrocera cucurbitae (Coquillett) is one of the most important pests of bitter gourd, Momordica charantia L. Because of the difficulties associated with chemical control of this pest, it is important to identify the traits associated with resistance and their influence on pest multiplication. There were significant differences in test genotypes for fruit infestation and larval density/fruit. The wild accessions, IC 256185, IC 248256, IC 213311, IC 248282, IC 256110 and IC 248281 were identified as resistance sources to melon fruit fly. There was a significant and positive correlation (r = 0.96) between percentage fruit infestation and larval density/fruit. Percentage fruit infestation and larval density/fruit were positively correlated with depth of ribs, flesh thickness, fruit diameter and fruit length, and negatively associated with fruit toughness. Flesh thickness and fruit diameter explained 93.0% of the total variation for fruit fly infestation, and flesh thickness and fruit length explained 76.3% of the variation for larval density/fruit. Ascorbic acid, nitrogen, phosphorus, potassium, protein, reducing sugars, non-reducing sugars and total sugars were negatively correlated, while the moisture content showed a positive association with fruit fly infestation and larval density/fruit. Moisture, potassium and reducing sugar content explained 97.4% of the total variation in fruit infestation, while moisture, phosphorus, protein, reducing and total sugars explained 85.7% variation for larval density/fruit.