Deterring and inhibiting effects of quinolizidine alkaloids on spruce budworm (Lepidoptera: Tortricidae) oviposition

Although alkaloids are known feeding deterrents for lepidopteran larvae, including the spruce budworm, Choristoneura fumiferana (Clemens), few studies have investigated their effects on lepidopteran oviposition. Quinolizidine-containing alkaloid extracts and isolated quinolizidine alkaloids were obtained from 2 Chinese plants, Sophora alopecuroides L. and Thermopsis lanceolata Robert Brown, to evaluate their effects on spruce budworm oviposition. Application of extracts from either plant on Parafilm substrate significantly deterred oviposition at dosages as low as 4.7 and 7.9 mu g/cm super(2), respectively, in dual-choice bioassays. Of 9 quinolizidine alkaloids produced by these plants, 6 deterred oviposition on Parafilm substrate treated at 7.9 mu g/cm super(2) or less. The most effective compounds were aloperine (0.3 mu g/cm super(2) = 1.3 nmol/cm super(2)), sparteine (1.6 mu g/cm super(2) = 6.8 nmol/cm super(2)), and cytisine (1.6 mu g/cm super(2) = 8.4 nmol/cm super(2)). Oviposition was deterred also on fresh host foliage, 8-cm twigs of balsam fir, Abies balsamea (L.) Miller, which had been sprayed with either a 1-ml aliquot of alkaloid extract (10 mg/ml) of S. alopecuroides or 1 ml of an aloperine solution (1 mg/ml). There was no effect on longevity of males or females continuously exposed to artificial substrate treated with aloperine or alkaloid extract from S. alopecuroides in no-choice bioassays, nor was the ability of males to inseminate females affected. However, female production of egg masses was inhibited, although clutch size (eggs per egg mass) was not affected. These results are the 1st demonstration of the behaviorally deterring and physiologically inhibiting effects of quinolizidine alkaloids on lepidopteran oviposition.