TOXICITY OF TERPENES SECRETED BY THE PREDATOR XYLOCORIS-FLAVIPES (REUTER) TO TRIBOLIUM-CASTANEUM (HERBST) AND ORYZAEPHILUS-SURINAMENSIS (L)

Four terpene alcohols, linalool, geraniol, alpha-terpineol, and nerol, which are compounds produced by Xylocoris flavipes (Reuter), were tested for toxicity against adults of Tribolium castaneum (Herbst) and Oryzaephilus surinamensis (L,) using a Petri dish assay. Dose-response studies were conducted for each compound singly and in a combination that mimicked the concentrations of these volatiles in exocrine secretions of X, flavipes, Linalool and alpha-terpineol were toxic to T, castaneum in a dose-dependent fashion, but geraniol and nerol were not toxic during the 24 h bioassay, The mixture of the four compounds was several times less toxic than linalool and alpha-terpineol for T, castaneum, even when exposed to large amounts, All four terpene alcohols and the mixture were toxic to O, surinamensis, with alpha-terpineol proving most toxic and Linalool the least toxic, Toxic effects of linalool and alpha-terpineol against O, surinamensis occurred within very narrow ranges, suggesting the possibility of a threshold concentration, Variation in toxicity among similar compounds and between insect species for the same compounds should be examined in studies that assess terpenoids for toxicity against stored-product insects.