Seasonal Abundance of Mustard Aphid, Lipaphis erysimi (Kalt.) and Saw Fly, Athalia lugens proxima (Klug) in Relation to Abiotic Factors and their Eco-friendly Management

Effect of weather on abundance of mustard aphid and sawfly and their eco-friendly management was studied during 2011–13. Mustard aphid, Lipaphis erysimi appeared first in 49^th and 50^th standard week and reached maximum in 2^nd standard week (49.07 and 63.48 aphids 10 cm⁻¹ central inflorescence during 2011–12 and 2012–13, respectively). Sawfly appeared in 45^th and 46^th standard week and attained maximum in 47^th standard week (1.57 and 1.42 larvae plant⁻¹ during 2011–12 and 2012–13, respectively). The correlation study revealed that minimum and maximum temperature had significant negative influence on aphid population (r=-0.64 to-0.83 during 2011–12 and 2012–13) whereas saw fly population was influenced positively by both temperature (r=0.62 to 0.67 in both the periods). Of 14 germplasm of rapeseed-mustard screened against mustard aphid and sawfly, Sikkim Toria-2, Sikkim Sarson Yellow-1, Sikkim Sarson Yellow-3 and TS-38 were found promising. Among the biopesticides evaluated against mustard aphid and sawfly, Bacillus thuringiensis @ 2 g l⁻¹ was found to be effective for management of sawfly population (68.60% larval reduction over control) while petroleum agro-spray @ 10 ml l⁻¹ and neem oil 0.15EC @ 3 ml l⁻¹ were most effective for controlling of aphid population. Among treatments the highest yield (7.8 q ha⁻¹) was recorded in the plot treated with petroleum agro-spray followed by neem oil (7.6 q ha⁻¹) and were on par with check oxydemeton methyl 25EC @ 1 ml l⁻¹. Coccinella septempunctata and Menochilus sexmaculata were recorded more (0.35–0.70 nos. plant⁻¹) with higher predatory efficiency (8.4–12.6 aphids day⁻¹) in comparison to syrphid fly.