Zonal Agriculture Research Station, J.N.Krishi Vishwa Vidyalaya, Khorgone-451001 (M.P.).
Influence of meteorological factors on the incidence of pod fly, (Melanagromyza obtusa Malloch); its larval parasites and their distribution pattern within the pods of medium maturing pigeonopea (Cajanus cajari) variety Khargone - 2 were studied during two cropping seasons of Kharif 1991–93. The pod fly was first noticed in the 43rd Standard Week (SW). The average temperature (3rd degree best fitted polynomial) which was 20°C, coinciding with proper podding stage of the crop was found to be favourable for egg laying i.e., during 48th - 50th SW. Highest pods (28.8%) were also oviposited during this period. The female fly preferred four locule pods for oviposition (51.9%), followed by three locule pods (43.9%). Further, 97% eggs were laid in ventral sutures and 3% in the dorsal sutures. Middle-second locule were highly preferred for oviposition (36%), followed by middle - first locule (27.4%) and basal locule (19.1%). Similar distribution trend was recorded for larvae and pupae. Low temperature had significant effect on larval and pupal population. There was gradual increase in larval population with decrease in average temperature from 20°C to 18°C. Average temperature 20”C was found to be conducive for larval development which attained peaks in 49th and 5th SW. Average temperature 24.15°C (2nd degree best fitted polynomial) was found to be deleterious for larvae. Maximum pods (16%) infested with larvae were observed during 5th S W. Average temperature 19 - 20.5°C (3rd degree best fitted polynomial) was found to be most favourable for pupal development and population build - up with peaks at 50th and 5th SW. Highest pods (6.9%) were harbouring pupae during 50th SW. Euderus sp., Ormyrus sp., Eurytoma sp. and Antistrophoplex sp. were the four parasites of pod fly larvae identified. Cumulative extent of parasitism ranged from 4.1 to 49.8% (51st SW). With the decrease in average temperature from 20.5°C to 18.5°C (3rd degree best fitted polynomial), there was a gradual and significant increase in parasite population, with peaks at 51st, 2nd and 7th SW. Maximum population of parasites were recorded in middle - second locule (37.7%), followed by basal locule (32.9%), middle - first locule (23.2%) and middle third locule (6.2%). Of the total eggs observed, only 49% and 17% successfully reached the larval and pupal stages respectively. The curvilinear equation (Y=8.46 - 0.21 xl + 0.72 x2) revealed that the parasites and the temperature were the major factors for larval mortality.
