Bio ecological approaches for management of major insect pests in rice ecosystem

Abstract

newline As biotic stress, especially insect pest is one of the most considerable newlinelimiting factors of rice productivity, a field study was carried out in the rice field of newlineRegional Agricultural Research Station, Assam Agricultural University, Titabar, Jorhat newlineto investigate the relative abundance of major insect pests as well as the effects of newlineabiotic factors on their damage incidence in seven high yielding varieties, Ranjit, Ranjit newlineSub-1, Bahadur, Bahadur Sub-1, Gitesh, Swarna Sub-1 and Shraboni in kharif and rabi newlineseason during 2018-2020 with an aim to formulate sustainable management strategies newlineagainst major insect pests in rice. White stem borer (47.49%) was the most newlinepredominantly abundant species followed by yellow stem borer (41.97%) among seven newlinemajor insect pest species including leaf folder, gall midge, caseworm, whorl maggot and newlinegundhi bug observed throughout all the growth stages of rice both in kharif and rabi newlineseason. Both the species of stem borer gradually increased and reached peak at newlinereproductive stage due to availability of enough food and then decreased and again newlineincreased in the ripening stage during both the season. The relative abundance of white newlinestem borer varied from 38.23 per cent to 47.49 per cent in the seven varieties recorded newlinehigher population in rice variety, Shraboni and lower in Gitesh at reproductive stage in newlinerabi season. Rice leaf folder was the most abundant leaf feeder and its population newlineabundance varied from 6.30 per cent to 6.61 per cent in Ranjit Sub -1, Ranjit and Gitesh newlinewithout significant difference to each other and higher leaf folder population was newlinerecorded in Shraboni (9.89%) followed by Bahadur (9.67%), Bahadur Sub-1 (9.61%) newlineand Swarna Sub-1 (8.47%) at vegetative stage which reached peak at reproductive stage newlineduring kharif season. The population of caseworm and whorl maggot was higher in newlinevegetative stage and subsequently declined till the reproductive stage in kharif season. newlineNo caseworm population was observed during rabi season due to scanty rainfall. Spider newlinewas...