Seasonal incidence and effect of weather parameters on insect pests of linseed

Abstract

The most destructive enemy of linseed in India are insect pests. Twelve insect pests that caused damage inlinseed under Hyderabad (India) conditions were recorded during 2020-2021. Percent incidence and population (per 10 plants) of Liriomyza trifolii varied from43.2±7.20 to 69.7±5.53 and 0 to 2.8±0.20, respectively. Populations (per 10 plants) of Bemisia tabaci, leafhopper, Nezara viridula and Creontiades sp. reached maximum during first week of January 2021 (22.2±3.18), last week ofJanuary 2021 (13.6±0.68), first week ofJanuary 2021 (2.6±2.36) and last week of February 2021 (2.2±0.37), respectively. Dasyneura lini population (per 10 plants) varied between 0 to2.2±0.49 and reached maximum during second week of February 2021 (2.2±0.49). Spodoptera exigua populationreached maximum during third week of January 2021 (2.0±0.89 per 10 plants), whereas population (per 10 plants) of Helicoverpa armigera reached highest during third week ofJanuary 2021 (2.6±0.98). Other insect pests such as Aulacophora sp., Monolepta signata, Hyposidra talaca and tussock caterpillar also caused more damage to linseed. Among abiotic factors, the maximum temperature showed a negative correlation with all insect pests except Creontiades sp. and H. talaca. The abiotic factors jointly had a highly significant impact on population of insect pests. The model to predict insect pests incidence in linseed was developed by linear regression model which would offer forecasting for short term period.