Occurrence and management of rice gall midge in transplanted rice (Orseolia oryzae Wood Mason)

摘要

For the study of occurrence of Rice Gall Midge in Transplanted rice three grasses Eeusine indica, Bothriochloa sp. and Paspolum sp. have been recorded as alternative host of rice gall midge. Highest infestation was observed on Eleusine indica in second week of July. Seasonal occurrence of Orseolia oryzae W.M. on kharif rice showed that pest infestation started in second week of August and continued upto last week of October, the peak activity was observed in last week of September. Parasite activityof Platygaster oryzae was started in the last week of August, at the minimum host infestation of 2.0%. The peak activity occurred during second week of October, consequently heavy (42%) mortality of gall midge due to this natural enemy was observed during this month. Field trial, for the management of gal! midge by insecticides, was conducted in transplanted kharif rice. The lowest incidence of rice gall midge was observed in the plots treated with Carbofuran 3G followed by Chloropyriphos 40EC and Phorate 10G. Highest grain yield was also obtained from the plots treated with Carbofuran 3G (3032.5 kg/ha) followed by Chloropyriphos 40EC (2910.0 kg/ha) and Phorate IOG (2832.5 kg/ha). The cost benefit ratio showed that Chloropyriphos was most economical.