Toxicity evaluation of cypermethrin, deltamethrin and diazinon with reference to Hyalomma anatolicum (Acari: Ixodidae)

Abstract

The present study was aimed to evaluate the relative bioefficacy of synthetic pesticides i.e. cypermethrin, deltamethrin and diazinon against different stages (adults, eggs and larvae) of Hyalomma anatolicum. Adult immersion test (AIT), Egg immersion test (EIT) and Larval immersion test (LIT) were conducted for determination of LC50 and LC90 values. The study showed that the bioefficacy was dose and stage dependent. In case of adulticidal bioefficacy, deltamethrin was found the most potent with LC50 value 49.28 ppm and LC90 value 182.58 ppm. While in case of ovicidal activity, cypermethrin was found highly effective and LC50 and LC90 values were 11.96 and 62.38 ppm. The larvicidal activity showed that cypermethrin had the effective exposure with LC50 value 17.0 ppm and LC90 value 54.96 ppm. The analyzed data showed all the synthetic pesticides had different efficacies on the adults, eggs and larvae but the diazinon was the least effective among all the stages followed by cypermethrin and deltamethrin. The effects of selected pesticides on fully engorged females were observed by the different parameters namely egg index, total weight of survived ticks after laid eggs, estimated reproductive factor (ER F), % inhibition of reproduction (IR). No survival rate of target organisms was found at concentrations 400, 500, 600 in case of cypermethrin. While in case of deltamethrin and diazinon complete mortality was found at concentration 300, 400, 500, 600 ppm and 400, 500, 600 ppm respectively. Inhibition of oviposition was observed in all treated groups in comparison to control. However, the hatched larvae were not affected and were similar to control groups. The value of % IR ranged in 99.07–99.77 (Cypermethrin), 99.75–99.75 (deltamethrin) and 98.98–99.76 (diazinon).