Toxicity of diafenthiuron and imidacloprid to the predatory bug Podisus maculiventris (Heteroptera: Pentatomidae)

Susceptibility of the predatory pentatomid the spined soldier bug, Podisus maculiventris (Say), to diafenthiuron and imidacloprid was investigated in the laboratory. Adults and 5th-instar nymphs were exposed to formulated materials of each compound by direct topical exposure, residual contact, aid ingestion. The effects of sublethal doses were also evaluated. Diafenthiuron was practically nontoxic to P. maculiventris when applied topically. However, both ingestion and residual contact caused severe mortality. In general, adults were more sensitive to diafenthiuron than 5th-instar nymphs. For imidacloprid, toxicity decreased in order of topical exposure > ingestion > residual contact. Treatment with a sublethal concentration of diafenthiuron caused a high mortality rate during the 2 wk of treatment. Oviposition and egg hatch were not affected when treating female adults. Our data suggest that the use of these products, in combination with P. maculiventris in an integrated management program, should be carefully evaluated.