EFFECT OF SEVEN ORGANOPHOSPHORUS INSECTICIDES ON THE LEAFMINER LIRIOMYZA TRIFOLII (DIPTERA: AGROMYZIDAE) AND THE PARASITE DIGLYPHUS ISAEA (HYMENOPTERA: EULOPHIDAE) IN COMMON BEAN FIELD

Seven organophosphorous insecticides were tested on common bean (Phasealus vulgaris) for the control of a serpentine-leafminer (Liriomyza trifolii) and the survival of the parasite Diglyphus isaea, in a trial to find out insecticides with selective properties for the use in integrated control program. Nasrcidol 20%, nasrcidol 60%, dianon 60%, metazon 60%, detrex 80%, agrothion 57% and profex 72% gave excellent control of leafminer with residual effect lasting for 15 days on treated foliage. Then effect decreased after the 15th day. So a second spray of treatments was done.
An interesting observation was noticed with agrothion 57% spray, that there was increased in pupal formation and lower rate of dead larvae, compared with the other compounds. Also there was a rapid decrease in the number of living parasitoid Diglyphus isaea in the treated fields till the 10th day of the first spray, then parasitoids regained its activity on the 15th day. However, detrex 80% has a little effect on parasitoid activity.Also In the second spray the number of mines gradually decreased in the control field and the treated fields reaching the maximum decline on the 15th day. After the second spray there was a marked drop in the number of living parasite reaching the maximum drop on the 15th day. From this study it could be concluded the insecticides applied are effective in controlling leaf-miners population but they reduced its parasitoids population.