Tunnel Length as an Indicator of Feeding Damage in Soybean due to Bean Fly, Melanagromyza sojae (Zehntner) (Diptera : Agromyzidae)

  • B. K. Gyawali Entomology Division, Nepal Agricultural Research Council, P.O. Box 122, Patan Dhoka, Kathmandu


A total of 341 soyabean varieties and experimental materials were screened under field condition at Khumaltar from 1985 to 1990 against the bean fly, Melanagromyza sojae (Zehntner). The infestation of this fly was recorded 100 percent on 71 test materials. Yield loss was found in 149 test materials whereas yield gain was observed in ll6 experimental materials. Among 100 percent infested test materials B-3036, Chief, D84-6770, GM-3, GM-6, Jurnla black, Stuart TK No. 5 and UPSLY 2 showned positive correlation between tunnel length and plant height. Test material Fayette showed negative correlation between tunnel length and plant height. In both 149 (yield loss) and ll6 (yield gain) test materials, the relationship between weight of grain and number of grain on both damaged and undamaged plants were found positively correlated. Similarly, relationship between grain weight and pod number was also found positively correlated on damaged plants of 149 experimental materials and undamaged plants of 116 test materials.