Oviposition attractants for Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae) in the volatiles of whole wheat flour

Plodia interpunctella is attracted to whole wheat flour. Volatiles obtained from whole wheat flour by Porapak Q trapping were assayed using pitfall olfactometers, and were attractive to mated females (active at 10−1 gram/day equivalent, gde), but not to males or unmated females, suggesting that the volatiles are oviposition attractants for P. interpunctella. Silicon dioxide column chromatography of the crude volatiles revealed that the fraction recovered with 3% ether in pentane (3% EP) was active and contained at least 27 components, in which alkanals (C6-C10) and 2E-alkenals (C7-C11) were active as individual aldehydes or mixtures. Nonanal was most active (the lowest active limit, LAL: 10−2 μg), followed by 2E-nonenal and 2E-decenal (1 μg each). The synthetic mixture of the 27 components identified from 3% EP was attractive at 1.59×10−4 μg, which was equal in activity to the crude volatiles at 10−1 gde (LAL) for mated females. The ether fraction (E) showed no activity by itself but synergistically enhanced the activity of the 10% EP fraction (LAL: 10−4 μg). Alkanols (C5-C9), lactones and carboxylic acids (C5-C18) were identified from the E fraction, in which hexanol and hexanoic acid were the major components. Both hexanol and palmitic acid were synergistic in combination with the aldehyde mixture.