Olfactory and aggregation responses of Oryzaephilus surinamensis (L.) to extracts from oats

Abstract Rolled oats and pentane extracts of rolled oats were attractive to the adult Oryzaephilus surinamensis (L.) when tested in a Y-tube olfactometer. Pentane and ether extracts of rolled oats caused aggregation of these beetles when tested in a two-choice petri dish bioassay. Responses to crude extracts obtained by 3 different extraction methods were not significantly different, but responses to various concentrations of these extracts differed significantly. When beetles were starved for periods of 4–7 days, responses were significantly higher than for those starved 1–3 days. Differences in lighting (subdued lighting compared to darkness) did not affect results significantly, nor did variations in the time of day between 0900 and 1700 hr. Fraction-ation of oat extract by column chromatography yielded a number of active fractions whose activity was enhanced by subfractionation. The nature of active constituents from oats are discussed in terms of whether they are attractants or arrestants.