Seasonal incidence of mustard aphid, Lipaphis erysimi (Kalt.) and its relationship with weather parameters in western Uttar Pradesh

Abstract

A two-season field investigation was conducted during Rabi 2024-25 and 2025-26 at the Crop
Research Centre, Sardar Vallabhbhai Patel University of Agriculture & Technology, Meerut, Uttar Pradesh,
to determine the seasonal incidence of mustard aphid, Lipaphis erysimi (Kalt.), and its relationship with major
weather variables. Aphid population was recorded weekly from first appearance to crop maturity, and the
data were related to maximum and minimum temperature, morning and evening relative humidity, and
rainfall. During 2024-25, aphid incidence began in the 51st standard meteorological week (SMW) at 4.10
aphids/plant and reached a maximum of 112.67 aphids/plant in the 7th SMW. During 2025-26, the
corresponding population increased from 3.24 aphids/plant in the 51st SMW to 112.32 aphids/plant in the
7th SMW. Thereafter, aphid abundance declined toward crop maturity, reaching 4.84 and 1.47 aphids/plant,
respectively, in the 13th SMW. Reanalysis of the revised weekly data showed that, in 2024-25, aphid
abundance was weakly positively correlated with maximum temperature (r=0.170), weakly negatively
correlated with minimum temperature (r=-0.011), and negatively correlated with morning relative humidity
(r=0.425), evening relative humidity (r=-0.429) and rainfall (r=-0.122). In 2025-26, correlations were positive
with maximum temperature (r=0.347) and minimum temperature (r=0.212), and negative with morning
relative humidity (r=-0.082), evening relative humidity (r=-0.492) and rainfall (r=0.152). Multiple regression
explained 63.3% of variation in 2024-25 and 75.5% in 2025-26, with the latter model significant (p=0.013).
The repeated 7th-SMW peak indicates that late January to mid February is the critical surveillance period for
mustard aphid under the study conditions