Studies on the infestation levels by melon fruit fly, Bactrocera cucurbitae Coquillett, on pointed gourd (Trichosanthes dioica Roxb.) and bitter gourd (Momordica charantia Linn.) in new alluvial zone of West Bengal

Seasonal trends in level of infestation by Bactrocera cucurbitae Coq. were analyzed to determine the factors influencing the infestation by melon fruit fly in the field on pointed gourd and bitter gourd during pre-kharif and kharif seasons in 2012 and 2013. The highest fruit infestation i.e. 51.66% and 58.88% was recorded both during 25^th standard week on pointed gourd and 40.14% and 54.71% was recorded during 22^nd and 14^th standard week on bitter gourd during respective years. The correlation coefficient between per cent infestation by melon fly with weather parameters exhibited a significant positive correlation with maximum temperature and negative correlation with RH-II in 2012 and rainfall in 2013 on pointed gourd. But on bitter gourd a significant positive correlation was recorded with maximum temperature in 2012 and RH-I in 2013 and negative correlation with RH-II in 2013.