IN-VITRO STUDY OF SUB-LETHAL EFFECT OF NEW CHEMISTRY INSECTICIDES ON THE ADULT CHRYSOPERLA CARNEA (STEPHENS)
Plant Protection Division, Nuclear Institute of Agriculture, Tandojam, Pakistan
Keywords:adult mortality, Chrysoperla carnea, insecticides, sub-lethal concentration
Four new chemistry insecticides viz. Bifenthrin (Talstar® 10% EC, FMC), Acetamiprid (Acelan®,20% EC, FMC), Imidacloprid (Imidacloprid®,25% EC, FMC) and Diafenthiuron (Polo®,100% EC, Syngenta Company) were evaluated against Chrysoperla carnea. Different concentrations (1.25, 2.5, 5, 7.5 and 10 µl/ml) of each insecticide were made in distilled water by serial dilutions tested to determine the sub-lethal concentration dose LC50 against adult’s C. carnea under laboratory conditions. Topical bioassay was performed against adult C. carnea. Adulticidal activity of insecticide in term of LC50 and LC90 with confidential interval was evaluated. The LC50 values of Acetamiprid, Bifenthrin, Imidacloprid and Diafenthiuron for adults C. carnea were 31.3, 96.1, 2.3 and 30.5 µl/ml, respectively. Toxicity of the tested insecticides to C. carnea form most to least toxic was Imidacloprid > Diafenthiuron > Acetamiprid > Bifenthrin. The 95% confidence intervals of Acetamiprid, Bifenthrin and Diafenthiuron overlapped, suggesting no significant difference in the toxicities of these three insecticides to the adult C. carnea. The adults were most sensitive to Imidacloprid and required low concentration (2.3 ± 0.25 µl/ml) to cause 50% mortality of the targeted adults compared to rest of the insecticide. Bifenthrin was found to be most tolerant and require high concentration to acquire LC50 that is 96.1± 28.6 µl/ml. The log concentration under directly proportional to the probability of adult C. carnea mortality. Increase in log concentration of Acetamiprid (0.894) resulted increase in probability (3.66). The decrease in the log concentration (0.854) of Bifenthrin decreased the (3.31) probability of mortality. Similarly the log concentration related to probability of mortality with the increase of log concentration (2.453) of Imidacloprid increased the probability (4.12). While the proportion of decreased log concentration of Polo (1.206) decreased the probability (3.120). The finding of this study proved that the above tested insecticides are harmful to adult of C. carnea. Generaly Bifenthrin causes less damage and may be included in the Integrated Pest Management (IPM) program with fairly adverse residual effect on bio-control agents.
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