Positioning New Pesticide Chemistries in the Management of Pod Fly, Melanagromyza obtusa Malloch (Diptera: Agromyzidae) in Pigeonpea

Abstract

Background: Pigeonpea is an important pulse-cum-grain legume crop of India. Major constraint in its production is the insects damage. Pod fly, Melanagromyza obtusa is of regular occurrence in South and Central India causing yield loss to the tune of 60 to 80 per cent particularly in late maturing pigeonpea crop. Due to its feeding habit as an internal borer, cultural, biological and mechanical methods are ineffective in reducing the damage due to pod fly and insecticides play a paramount role in managing their population under field conditions. Hence, present study have been aimed to evaluate the efficacy of different new pesticide chemistries against pod fly in pigeon pea ecosystem. Method: Two field experiments were conducted during Kharif 2019 and 2020 in RCBD using pigeonpea cv. GRG 811 with 14 treatments replicated twice. Two sprays were imposed at 15 days interval initiating from pod initiation stage. At maturity, number of damaged pods were recorded and expressed as percentage. Grain yield was recorded and benefit cost ratio was also worked out. Results: Among the screened insecticides, fipronil 4+thiamethoxam 4 SC @ 40+40 g a.i./ha followed by thiamethoxam 25 WG @ 50 g a.i./ha and fipronil 40+imidacloprid 40 WG @ 160+160 g a.i./ha provided better control of pod fly in terms of reduction in pod damage (69.54, 62.13 and 62.57%) and seed damage (72.51, 71.35 and 70.39%) respectively over untreated check. The average grain yield of 1577 kg/ha was highest in fipronil 4+thiamethoxam 4 SC @ 40+40 g a.i./ha followed by fipronil 40+imidacloprid 40 WG @ 160+160 g a.i./ha (1555.5 kg/ha) and thiamethoxam 25 WG @ 50 g a.i./ha (1536.5 kg/ha). Whereas, B: C was higher in fipronil 4+thiamethoxam 4 SC @ 40+40 g a.i./ha (2.84) and thiamethoxam 25 WG @ 50 g a.i./ha (2.83). Therefore these insecticides can be used for effective management of pod fly.