The temperature has the greatest effect on the development and survival of mosquito larvae. The efficiency of insecticides relies not only on the active ingredient but also on the insect's environment. Variations in ambient temperature may thus impact the toxicity of the compounds to mosquitoes. The present study was undertaken to study the effect of temperature on Culex pipiens response to Commiphora molmol resin, Mirazid, crystalline and pharmaceutical form of acetylsalicylic acid. Bioassay tests were carried out on the 3rd instar larvae under laboratory conditions. The LC50 of the tested compounds were used to study the temperature-toxicity relationship, while the LC50 of Mirazid and pharmaceutical form of acetylsalicylic acid, as the most potent compounds, were used for further biochemical studies. Results indicated that, Mirazid was the most potent compound, with LC50 of 28.3 ppm followed by C. molmol resin with LC50 of 41.6 ppm while the crystalline acetylsalicylic acid was the least effective compound with LC50 of 799.7 ppm. The temperature has a considerable impact on Cx. pipiens larvae's susceptibility to the tested compounds. High temperature (36 0C) resulted in high mortality rate (72.88, 78.20, 58.8 and 62.12 % for of C. molmol resin, Mirazid, CASA and PASA, respectively. Moreover, there were significant changes in α- esterase, β–esterase and glutathione -S-transferase levels as well as the total protein content in the treated larvae due to the change in temperature. These findings show that temperature is an essential factor to consider in the management of Cx. pipiens. |
