Abstract:
Field studies were undertaken to assess the influence of insecticidal treatments on sucking and chewing insect pests and their natural enemies in cotton crop. Experiments were conducted to find out the effects of monocrotophos 36% SL and endosulfan 35% EC insecticides on the incidence of harmful insects and the beneficial insects. The data on the incidence of sucking pests were recorded on three leaves (top, middle and bottom canopy) per plant by randomly selecting five plants from each replicate. Similarly, observations on the populations of natural enemies were taken from whole plant basis at weekly intervals. The practice implemented for assessing infestation of chewing pests involved estimating of injury due to all kind of bollworms recorded on shoots, squares, flowers and bolls at regular intervals. Study displayed both the tested insecticides at their recommended doses statistically showed better control of the insect pests as compared to the control, and the pest infestations ranged 3.33-7.00 whiteflies, 0.55-1.99 jassids and 3.99-11.33 aphids per leaf; 2.88- 6.22% bollworms damage; and 2845.3-2433.0 kg yield ha-1 . The beneficial insects viz., coccinellid beetle (Coccinella septumpunctata [Linnaeus]), common green lacewing (Chrysoperla carnea [Stephens]), hover fly (Eupeodes confrater [Wiedemann]) and bigeyed bug (Geocoris ochropterus [Fieber]) were not so severely affected in the treated and control fields and no statistical differences noted in their densities. Concludingly, decline in abundance of pests and safety of natural enemies by tested pesticides may have important implications for the control of harmful insects in cotton areas and such chemicals can encourage biological control in an agricultural land.
Page(s):
131-136
DOI:
DOI not available
Published:
Journal: Pakistan Journal of Zoology, Volume: 48, Issue: 1, Year: 2016