Trans-anethole is a potent toxic fumigant that partially inhibits rusty grain beetle (Cryptolestes ferrugineus) acetylcholinesterase activity

Abstract The safe storage and protection of grain includes the exploitation of plant-based fumigants as a green control technology. This study first determined the fumigant toxicity of 12 traditional Chinese medicinal plants against adults of the rusty grain beetle, Cryptolestes ferrugineus (Stephens), one of the most ubiquitous and pestilent grain storage pests worldwide. Exposure to volatiles released from Illicium verum Hook. f. powder was found to be by far the most lethal. Illicium verum power and its volatiles eluent were then confirmed to be highly effective in killing both larvae and adults of C. ferrugineus. Star anise volatiles also showed good biological activity against Lasioderma serricorne (Fabricius) and Sitophilus zeamais Motschulsky, but not Tribolium castaneum Herbst. No significant differences were found in mortality of the adults of the rusty grain beetle when exposed at different temperatures ranging from 15−35°C. Gas chromatography-mass spectrometry (GC–MS) analysis showed that the main components of the eluent of star anise powder were trans-anethole (62.60%), estragole (23.70%), linalool (3.66%) and d-limonene (2.15%). In the fumigation test using synthetic standards of these four chemicals, only trans-anethole showed effective biological activity with exposure to 30 mL/L trans-anethole for 24 h resulting in 100% mortality of rusty grain beetle adults. Estragole did significantly enhance fumigant efficiency of trans-anethole. We further found that trans-anethole affects the beetles acetylcholinesterase activity, which was inhibited and decreased by 64.48% within 24 h. The results therefore show that trans-anethole, the major component of star anise volatiles contributes to its fumigant toxicity against C. ferrugineus by, at least partly, affecting its insect nervous system. Hence, star anise or its biologically active substances show very good potential to be used as a botanical insecticide to control C. ferrugineus.