Contact toxicities of oxygenated monoterpenes to different populations of Colorado potato beetle, Leptinotarsa decemlineata Say (Coleoptera: Chrysomelidae).
In the present study, 12 pure oxygenated monoterpenes at 2 different doses were tested for their toxicity against second and third instar larvae and adults of three different populations of Colorado potato beetle (Leptinotarsa decemlineata Say). Some of tested compounds were found to be toxic to larvae and adults, but the degree of toxicity was variable. The mortality range was 20-100%. In general, fenchone, linalool, citronella and menthone showed a strong toxicity against the tested developmental stages; camphor, carvone and linalyl acetate showed moderate toxicity against larvae and adults of Colorado potato beetle and some compounds like fenchol, isomenthol, menthol, nerol and neryl acetate showed the least or no toxicity against the tested developmental stages of L. decemlineata. Another important result was that although the tested populations of Colorado potato beetle showed some resistance to Endosulfan (50% WP), there was no resistance to tested oxygenated monoterpenes. The present results indicate that some of these compounds can be used as potential control agents against both larvae and adults of Colorado potato beetle.