Release of Chrysoperla carnea (Stephens) ( Neruoptera : Chrysopidae) as a Biological Control Agent against Tetranychid Mites, Tetranychus urticae (Koch), on Phaseolus vulgaris L. Plantations under Semi Field Conditions.

Abstract

This study was outlined to evaluate the effect of releases second larval instar of Chrysoperla carnea (Stephens) at different predators: prey ratios (P:p) to control tetranychid mites on the kidney bean, Phaseolus vulgaris L. plants under semi field conditions during summer 2016. The results revealed that the effective control of Tetranychus urticae Koch was realized after six days from introducing C.carnea larvae when the P: p ratio was 1:10 or 1:20, while at higher ratios (1:40 and1: 50), the tetranychid mites numbers decreased after 12 days from the release. The results assured that the numbers of kidney bean tetranychid mites decreased after 6 days from release by 100 and 86.6% at 1:10 and 1:20 P: p ratios, respectively.While the larvae of C.carnea which released after nine days the percentage redaction of T.urticae was100,100, 93.3,90.2 % and 84.7 days with P:p releases of 1:10, 1:20, 1:30, 1:40 and1:50 , respectively. The obtained results showed that the number of tetranychid mites remained zero for a period of 12 days after the release. Regression analysis demonstrated a strong negative relationship between P:p ratios and reduction percentage of theKidney beantetranychid mites.