Toxicity of azinphosmethyl, methyl parathion, and oxamyl against the boll weevil (Coleoptera: Curculionidae) in Texas, Mexico, and Guatemala

摘要

abstract_textpThe toxicity of azinphosmethyl, methyl parathion, and oxamyl was tested against bell weevil populations from Texas, Mexico, and guatemala. The LD50 values of topically applied azinphosmethyl against field-collected bell weevil, Anthonomus grandis Boheman, from the Lower Rio Grande Valley of Texas were 0.16, 0.42-0.74, 0.43, 0.23-0.25, 0.043, 0.059-0.13, and 0.0011-0.14 mu g per weevil in 1983, 1985, 1986, 1988, 1989, 1990, and 1991, respectively. Even though LD50 Values showed 127-fold difference in 1991, only variation in susceptibility was indicated during the 8 yr of testing. The LD50 value of topically applied oxamyl was 0.31 pg per weevil against field-collected weevils in 1990 from the Lower Rio Grande Valley. The LD50 values of topically applied methyl parathion were 0.081-0.0091 mu g per weevil in Lower Rio Grande Valley and in Mexico (Rio Brave, Tamaulipas) in 1990 and 1991, respectively. These LD50 values indicate variation in susceptibility. A strain from Tiquisate, Guatemala, had a LD50 of 0.44 mu g of methyl parathion per weevil in 1991. This LD50 is the first shown from that country, and it was greater than LD50 values for weevils collected from the Lower Rio Grande Valley and Mexico in 1991./p/abstract_text