Estimation of losses caused by Aphid (Rhopalosiphum nymphaeae L.), Case worms (Elophila depunctalis W. & E. crisonalis W.) and Rib borer (Chironomous sp.) in Makhana Crop

Abstract

Makhana (Euryale ferox Salisb.), also known as Fox nut or Gorgon nut is an important minor aquatic fruit crop in India including Bihar and a good source of carbohydrate, protein and minerals. It is cultivated over an area of 20,000 ha in Bihar which constitutes about 80 per cent of the Makhana crop in the India but the production (3.18 lakh quintals) and productivity (21.25 q/ha) of Makhana crop is low due to many constraints, of which insect pests viz., aphid (Rhopalosiphum nymphaeaeL.), case worms (Elophila depunctalis W.& E. crisonalis W) and rib borer (Chironomous sp.) under the changing cropping patterns and intensification of crop emerges as major constraints in getting maximum yield. Considering the economic losses caused by the insect pests, Field experiments were conducted under randomized block design (RBD) with four replications at Makhana research farm of Bihar Agricultural University, B.P.S. Agricultural College, Purnea during 2015and 2016 summer season. The Makhana Variety Swarna Vaidehi was transplanted in a plot size of 1000 square m by adopting standard production technology. Six treatments including untreated control were evaluated and protected plot having seed treatment with imidacloprid 70 WS @ 5 g/kg seed and root dip treatment with imidacloprid 70 WS @ 5 ml/Lt of water for half an hour at the time of transplanting along with three foliar spray of NSKE @ 0.5 per cent was found most effective in controlling the insect pests of Makhana as compare to unprotected plot. Seeds were harvested from 12 randomly selected spot from each of protected (best treatment plot) and unprotected plot by using quadrate of 01 sq. m for estimating the losses due to insect pest. The analysis of yield data of 2015 and 2016 summer season showed that the insect pests viz., aphid (Rhopalosiphum nymphaeae L.), case worms (Elophila depunctalis W.& E. crisonalis W.) and rib borer (Chironomous sp.) together causes yield loss to the tune of 17.04 to 23.66 per cent in Makhana crop.