Effect of BAY SRA-7660 on the Survival and Reproduction of Three Species of Stored-Product Insects in Laboratory and Small-Bin Experiments1

Abstract

In a laboratory experiment, BAY SRA-7660 [[(di-methoxyphosphinothioyl) oxy] imino] benzeneacetonitrile, was applied in hexane solution to wheat at concentrations of 1, 5, and 10 ppm. In a small-bin experiment, it was applied as an emulsion at 5 and 10 ppm. Adults of the rusty grain beetle, Cryptolestes ferrugineus (Stephens), sawtoothed grain beetle, Oryzaephilus surinamensis (L.), and the red flour beetle, Tribolium castaneum (Herbst), were exposed for 7 days to treated wheat at 1 or 2 wk after initial treatment, and at 10 or 11 other time periods thereafter, up to 23 wk. In both experiments, mortality increased and reproductive capacity decreased with increasing concentration. Sawtoothed grain beetles were the most susceptible, and red flour beetles the least susceptible species. The compound was more effective in the small-bin experiment than in the laboratory. In both experiments, progeny production in all species was drastically reduced. In the small-bin experiment, one larva of the rusty grain beetle was recorded at 10 ppm. No progeny was produced by red flour beetles even most of the adults survived after the 7th wk. In the laboratory experiment, the few progeny produced by beetles that survived treatment suffered retarded demortality.