Toshihiro Imai

Methyl anthranilate as an attractant for two thrips species and the thrips parasitoid Ceranisus menes.

The role of floral scents in host location by flower-dwelling thrips and a thrips parasitoid was investigated by experiment in the field. The scent of methyl anthranilate significantly increased the catches of Thrips hawaiiensis, Thrips coloratus, and Ceranisus menes, but had no effect on Thrips tabaci. Anisaldehyde increased the catches of T. hawaiiensis and T. tabaci, but had no such effect on T. coloratus and C. menes. Geraniol increased the catches of T. hawaiiensis, but not of T. coloratus, T. tabaci, or C. menes. Seasonal fluctuations of T. hawaiiensis, T. coloratus, and C. menes can be recorded by using methyl anthranilate as a lure for monitoring.

Field Attraction of Hoplia communis to 2-Phenylethanol, A Major Volatile Component from Host Flowers, Rosa spp.

The attractiveness of volatile compounds from the floral scent of Rosa, one of the most preferred plants for adult Hoplia communis, was evaluated under field conditions. The beetles were attracted to most compounds tested, but 2-phenylethanol exhibited the highest capture rate. Catches increased with increasing emissions of between 9.1 and 287.2 mg/day. Catches in white traps were significantly larger (17.4-fold) than those in green traps when both were baited with anethole, an already known attractant; however, the trap color was not significant when a more attractive lure, 2-phenylethanol, was used. The use of a single funnel trap baited with 2 g of 2-phenylethanol at a heavily infested nursery exhibited promising results for mass trapping. Approximately 90,000 beetles of both sexes, which nearly corresponds to the estimated maximum population per 1000 m2, were captured within six days.

Insecticidal activities of methyleugenol and β-asarone, from the herbal medicines Saishin and Sekishōkon, and other alkoxy-propenyl-benzene derivatives against the cigarette beetle Lasioderma serricorne (Coleoptera: Anobiidae)

The principal insecticidal compounds from the herbal medicines Saishin, the root of Asarum sieboldii Miquel, and Sekishōkon, the rhizome of Acorus gramineus Soland, were isolated by successive silica gel column chromatography and high performance liquid chromatography. The active components, which work against larvae of the cigarette beetle, Lasioderma serricorne (F.), were identified as methyleugenol (4-allyl-1,2-dimethoxybenzene) and β-asarone {1,2,4-trimethoxy-5-[(Z)-prop-1-enyl]benzene} by gas chromatography and gas chromatography/mass spectrometry analyses. These two compounds share some structural features, such as a benzene ring with o-dimethoxy groups and a propenyl group in the opposite position. Consequently, the insecticidal activities of 20 structurally related compounds were tested to evaluate their structure–activity relationship. We found myristicin (5-allyl-1-methoxy-2,3-methylenedioxybenzene) exhibited comparable insecticidal activity to methyleugenol and β-asarone, but the other tested compounds were less active. The lack of insecticidal activity of compounds with a hydrogen, hydroxy, or acetoxy substituent in place of one methoxy group indicates that o-dimethoxy groups are essential for insecticidal activity. The position and configuration of a double bond in the propenyl side chain affected the toxicity, but there was a lack of consistency in the structure–activity relationship for this.