Lethality and kinetic of diatomaceous earth uptake by the bean weevil (Acanthoscelides obtectus [Say] Coleoptera: Bruchinae): Influence of short-term exposure period

Laboratory bioassays were carried out to assess the lethal effect of the diatomaceous earth (DE) formulation Fossil-Shield® against males and females of adult bean weevils (Acanthoscelides obtectus [Say]). Kinetics of the DE uptake experiment was determined by using manganese as a trace element. The adherence of DE to the common bean was also measured in this study. The mortality of weevils was evaluated after exposure to eight different DE dosages (400–4000 mg/kg) after 1, 2 and 4 days, respectively. DE dust was more lethal to male than female weevils within shorter exposure period at low DE dosages ( 0.05) between sexes. DE adherence ratio ranged between 73% and 98% at the highest (3600 mg/kg) and the lowest (400 mg/kg) DE dosages, respectively. The maximum saturated amount of DE retention on the bean surface was approximately 7.14 μg/mm2. The amount of DE uptake by a weevil was significantly increased (P