ECOLOGICAL STUDIES ON SOME INSECT PESTS ATTACKING COTTON PLANTS

Abstract

The present study was carried out at the Experimental Farm of the Faculty of Agriculture, Kafr El-Sheikh, Tanta University to study some insect pests attacking cotton plants and investigate the following objectives: 1. The relative susceptibility of certain Egyptian cotton varieties to bollworms infestation under natural conditions. 2. Population densities of the most common predaceous arthropods in treated and untreated cotton fields. 3. Relationship between the catch of pheromone traps and boll infestation with bollworms. 4. The effectiveness of the parasitoid, T. evanescens as a mean to control cotton bollworms.

The results could'be summarized as follows: 1. The relative susceptibility of seven Egyptian cotton varieties to infestation with bollworms, Pectinophora gossypiella (Saund.) and Earias insulana (Boisd.) under field conditions: 1.1. Percentage of infestation of cotton varieties with P. gossypiel/a and E. insulana during 1998 season: The highest percentage (39.3%) of the pink bollworm infestation was recorded for Giza 45... while the lowest one (26.8%) was found for Giza 88. The highest number of P. gossypiella larvae was recorded for Giza 45 (170 larvae/40 cotton bolls),while the lowest one was found for Giza 88 (112larvae/40 cotton bolls). On the other hand the tested cotton varieties were nearly equally susceptible to E. insulana infestation with no significant differences between varieties. The total number of that insect pest larvae were nearly the same among all the tested varieties with no significant differences.