Laboratory Evaluation of the Effect of Insecticides on Non-target Organisms: 1- The Predatory Green Lacewing, Chrysoperla carnea (Stephens) (Neuroptera: Chrysopidae)

A study purposed to evaluate the acute residual toxicity of six insecticides (different groups); Dursban and Malathion (OP), Chess (Selective feeding broker), Spintor (bioinsecticide), Biogard: (Bacillus thuringiensis) (bacteria), and Biover: (fungus) on immature stages of the predator, Chrysoperla carnea (Stephens) (Neuroptera: Chrysopidae) was carried out under laboratory conditions. Lethal and sub-lethal effects of the tested insecticides (4 concentrations each) on the development of the eggs (3 ages) and the 2^nd instar larvae of the predator were assayed. The eggs were treated using the dipping method, while the larvae were treated using the residual film contact method. LC₅₀, LC_90, LC₉₉ and the sub-lethal concentration (LC₂₀) for each insecticide were estimated. Hatchability values, percentages of the treated eggs as well as percentages of larvae were calculated. Pupation and adult emergence percentages were estimated and compared with those of the untreated check to study the residual effect on the treated larvae, using LC₂₀ of each insecticide. The dose-mortality responses of theeggs were compared in terms of differences in slopes and LC₅₀ values. Data showed that the 3-day old eggs were more tolerant to the tested insecticides than the newly ones. The mean mortality percentages of treated larvae were: 100, 100, 55, 50, and 20% for Dursban, Malathion, Biogard, Chess and Spintor, respectively. According to the classification of (IOBC/WPRS), Dursban and Malathion were classified as harmful insecticides, Biogard and Chess as moderately harmful, and Spintor as harmless insecticde. C. carnea larvae showed a relative tolerance to the insecticides tested as they pupated and developed successfully to the adult stage. The highest larval mortality (24%) was recorded for Dursban, while the lowest one (18%) was for Spintor compared with (10%) for the control. Statistical analysis of accumulated larval mortality indicated that there were insignificant differences among the mortality percentages in any of the studied insecticides and also between the treated larvae with each insecticide and the control. Spintor was the most suitable insecticide recommended to be used in IPM programs as it is safe for different stages of C. carnea.