Presence and Abundance of Different Insect Predators Against Sucking Insect Pest of Cotton

摘要

The study on appearance and abundance of different insect predators against sucking insect pest of cotton in field conditions was conducted in the farmer's field, Kot Banglow District Khairpur, Pakistan. The population of sucking insect pests and insect predators were observed 20 days after sowing of the cotton crop. The insects were counted with the help of the magnifier lens. The analysis of data indicates that there was highly significant difference in days of observations, population of sucking insect pests and predator population. The mean maximum population of whitefly (31.98 plant~(-1)) was observed in first week of the September at relative mean temperature 32,60 deg C, however the maximum population of thrips (29.96 plant~(-1)) and jassids(3.93 plant~(-1)) was found in last week of the August at relative mean temperature 32.88 deg C. The maximum overall means of whitefly in various observation days were observed (15.90 plant~(-1)), followed by thrips (14.30 plant~(-1)) and jassid (2.08 plant~(-1)). The predator population of Green Lacewing, Chrysoperla carnea, Big eyed bug, Geocoris punctipes linearly increased but the population of Pirate bug, Orius insidiosus decreased in the last week of August at relative mean temperature 32.88 deg C. The maximum overall means of Green Lacewing in various observation days was 2.07 plant~(-1)), followed by Pirate bug (1.84 plant~(-1)) and Big eyed bug (1.28 plant~(-1)). The results indicated that the sucking insect pests were below the economic injury level at all phenological stages of the cotton plant due to the regular increase in predator population. The predators were active throughout the cotton season due to non-application of pesticides in and around the experimental area. The correlation coefficient (R = 0.563) showed a positive relationship between insect predators and sucking insect pest population. The increase in sucking insect population also exhibited an increase in predator population in observed days and trend line shows increase in insect predator population with sucking insect pest population during the growth stages of cotton crop.