Response of three insects to sublethal doses of phosphine

Abstract

Sublethal treatments with phosphine produced cumulative effects when repeatedly applied to insects, and these effects differed with different species. Tribolium confusum adults recovered from a sublethal treatment in 10 days so that normal tolerance to further treatment was regained in that time. Sitophilus granarius adults recovered more slowly, and 40 days after initial sublethal treatment tolerance was still less than untreated insects. Tenebroides mauritanicus larvae treated with a dose that killed no insects in 2 weeks showed a varying response thereafter; some individuals died slowly over a period of weeks, some remained as permanent larvae, some developed to pre-pupae or pupae and died, some developed through to the adult stage but were deformed, while a few developed to normal appearing adults.