ABSTRACT

An adult vial test was used to determine contact toxicity of technical dicrotophos (Bidrin ^® 8), acephate (Orthene ^®), imidacloprid (Provado ^® 1.6), thiamethoxam (Centric^TM 40 WG) and indoxacarb (Steward^TM ) to cotton fleahopper, Pseudatomoscelis seriatus (Reuter). These data are the first published for this species. Lethal concentrations [LC₅₀s(95% CLs)] at 24 h for dicrotophos and acephate were 0.1886 (0.1696-0.2066) and 7.6630 (5.9272-9.0815) µg/vial, respectively. These values were significantly different. For imidacloprid and thiamethoxam, LC₅₀s(95% CLs) at 24 h were 0.6583 (0.4422-0.9157) and 0.3855 (0.2724-0.5149) µg/vial, respectively. These values were not significantly different. Both imidacloprid and thiamethoxam were significantly less toxic than dicrotophos but significantly more toxic than acephate. Contact with indoxacarb did not significantly influence fleahopper mortality. Systemic toxicity of imidacloprid and thiamethoxam was studied by soaking green beans, Phaseolus spp. in water containing different concentrations of Provado 1.6 and Centric 40 WG. LC₅₀s (95% CLs) at 24 h for Provado and Centric were 74.8052 (54.9742-97.0045) and 36.0169 (20.8745-53.2132) µg/ml, respectively. These values were significantly different and were much higher than those for the same chemicals by contact.