Efficiency of insect-proof screens in excluding three major pests of strawbeery into the greenhouse

摘要

 In recent years, the use of the insect-proof screens in protection of greenhouse crops has been increasingly recognized. In this study, the effectiveness of three types of insect-proof screens for their exclusion of Frankliniella occidentalis, Chaetosiphon fragaefolii and Tetranychus urticae have been evaluated in laboratory conditions (L:D 16:8, 27?b2 ￠XC Temp., and 60?b10% R.H.). The tested insect-proof screens were the 5??5 (5??5 threads per cm2), 13??23, 30??34 and Agryl p-17. In each cylindrical container, which was sealed by every one of the above mentioned insect-proof screens at one end, 50 individuals were placed. In this experiment, flowers and leaves of strawberry were used as an incentive for the insect to move through the openings of insect-proof screens. The control percent of screens was evaluated by calculating the number of insects in which were existed in the containers after 24 hours. The results of this experiment indicated that the 5??5 insect screen, which is widely used in greenhouses, did not exclude these pests really. Results also indicated that 94% of C. fragaefolii controlled by the 13??23 screen, compared to not efficient of this screen in excluding of F. occidentalis and T. urticae. 100% of C. fragaefolii, 46.66% of F. occidentalis and 13.8% of T. urticae controlled by the 30??34 screen. However, control percent was higher for C. fragaefolii than for F. occidentalis and T. urticae and this was related to the larger size of the strawberry aphid as compared to the western flower thrips and twospotted spider mite