Department of Entomology and Agricultural Zoology, College of Agriculture, Rajendra Agricultural University, Pusa, (Samastipur)-848125, Bihar, (India).
1A part of approved M.Sc. (Ag.) thesis submitted by Pawan Kumar to Rajendra Agricultural University, Pusa, (Samastipur)-848 125, Bihar, (India).
The infestation of rice leaf folder, Cnaphalocrocis medinalis Guen., varied from 1.4 to 33.2 per cent in rice from July to October. The minimum infestation was recorded in July (1.8 to 2.9%) and in the third and fourth weeks of October (1.4 to 6.3%), and the maximum during September (17.9 to 33.2%) followed by August (7.6 to 16.2%). The peak period of infestation coincided with the panicle initiation stage of the crop. The percentage of infested leaves having live caterpillars also revealed the maximum during the first fortnight of September and resulted in maximum damage in the second fortnight of September. Weather parameters, viz., temperature, relative humidity and rainfall failed to exhibit any correlation with the extent of damage. This might be due to narrow variation during the crop season, except rainfall. The population fluctuation of the pest was also influenced by predatory spiders, particularly Lycosa pseudoannulata, the population of which increased with the pest population resulting in decline in pest incidence.
