Biology and natural parasitization of Gall Fly Lasioptera Falcata Felt and Lasioptera bryoniae Schiner infesting bitter gourd

Abstract

The gall midge Lasioptera spp belonging family Cecidomyiidae, Diptera is one of serious pest of bitter gourd causing yield loss. Recently, the occurrence of the pest in bitter gourd crop was noted in Coimbatore and Tiruppur districts of Tamil Nadu during 2015 – 16. The adult midges collected from the gall shoots of bitter gourd were identified as L. falcata and L. bryoniae. The parasitoids associated with gall midge were collected from the parasitized maggots and identified as Aprostocetus diplosidis and Bracon sp. The biology of gall fly studied in bitter gourd under laboratory condition using the variety CO1 indicated L. falcata had a duration of 16-25 days where as L. bryoniae spent 18-26 days for the development from egg to adult. The adults of L. falcata recorded a fecundity of 98.3 eggs as against L. bryoniae which had a fecundity of 104.2 eggs. The natural parasitization of A. diplosidis and Bracon sp. was high during April and May with a parasitization of more than 80 per cent whereas incidence of the gall damage in shoots during these months was low averaging 32.28 per cent. The occurrence of gall shoots was maximum in November (77.7) which recorded low level of parasitization of A. diplosidis (20.13) and Bracon sp (22.48).