Author: Gagandeep Singh, Vijay Kumar and Amit Kumar
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The present investigation on population dynamics of different insect pests of maize viz., maize stem borer (Chilo partellus Swinhoe), maize aphid (Rophalosiphum maidis Fitch), grey weevil (Myllocerus discolour Bochemann), maize cobworm (Helicoverpa armigera Hubner) and the abundance of natural enemies in the maize field was conducted during Kharif, 2018 at Instructional Farm, Rajasthan College of Agriculture, MPUAT, Udaipur. Results of the study revealed that the maximum leaf injury (8.30 mean LIR) by C. partellus was recorded in the second week of August at 30th days after sowing. The dead heart incidence first appeared during last week of July and reached to its peak (3.00 per cent) during second week of August at 30th days after sowing. The peak infestation (96.50 /plant) of Rhopalosiphum maidis was observed in the second week of August. The maximum population of Myllocerus discolour (5.50 /plant) was noticed during third week of August. The incidence of Helicoverpa armigera larvae began in third week of July and reached to its peak (3.30/plant) in the first week of August. The H. armigera larvae population showed a significant negative correlation with mean relative humidity (-0.764). Natural enemies’ viz., coccinellids and green lacewing reached to its peak respectively, 7.50/plant and 2.50/ plant in the second week of August. The coccinellids beetles (0.914) and green lacewing (0.938) population showed a significant positive correlation with R. maidis population.
Insect pests, natural incidence, population dynamics, seasonal incidence
The population dynamics of different insect pests and their natural enemies were observed significantly influenced by weather parameters and the damage caused by these insect pests are affected by fluctuation in abiotic factors.
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