Seasonal incidence of major insect-pests on mustard (Brassica juncea L.) and their correlation with weather parameters

Abstract

Investigations on seasonal incidence of major insect-pests on mustard (Brassica juncea L.) “(Brassica juncea L.)” were conducted at research farm of Department of Entomology, V.N.M.K.V., Parbhani during Rabi 2022-23. Mustard aphid Lipaphis erysimi appeared from 17-23 December (51st SMW) to 19-25 March (12th SMW) in the range of 22.12 to 90.25 aphids/10 cm twig with the peak activity on 29 January-04 Feb (5th MW). Meanwhile Leaf webber Crocidolomia binotalis had shown its presence from 24 Dec -31 Dec (52nd SMW) to 05-11 March (10th SMW) in the scale of 1.35 to 6.45 larvae/plant and it found that 19 Feb-25 Feb (9th MW) was a preferable pace for the pursuit of leaf webber. Mustard Sawfly Athalia lugens proxima (Klug) infestation was initiated from 24-31 Dec (52nd SMW) and continued till 19-25 Feb (8th SMW) in the range 2.90 to 7.45 larvae/plant and the peak incidence was observed on 12-18 Feb (7th MW). In natural enemies, lady bird beetles were recorded in the range of 1.20 to 7.34 grubs and adults/plant and Syrphid flies in the scale of 1.00 to 2.60 maggots/plant. Lady bird beetles, Green lacewing in the scale of 0.20 to 2.20 larvae/plant. Ladybird beetle Syrphid fly and Green lacewing had their peak activity during the 5th SMW. Aphids showed negatively significant correlation with rainfall (r=-0.60*), minimum temperature (r=-0.61*), wind speed (r=-0.55*) and EVP (r=-0.73*). Leaf webber showed negatively significant correlation with minimum temperature (r=-0.55*), rainfall (r=-0.52*) and EVP (r=-0.80*). Mustard sawfly had positively significant correlation with morning relative humidity (r=0.72*) and negatively significant correlation with EVP ((r=-0.69*).