Toxicity ofMyristica fragransSeed Compounds AgainstBlattella germanica(Dictyoptera: Blattellidae)

Abstract

The insecticidal constituents of hexane-soluble fraction from a methanolic extract of the seeds from Myristica fragrans (Myristicaceae) against adult females of Blattella germanica (L.) (Dictyoptera: Blattellidae) were analyzed by gas chromatography and gas chromatography-mass spectrometry. The insecticidal activity of 13 Myristica seed compounds against female B. germanica was examined by using the filter-paper contact toxicity and vapor phase toxicity bioassays. Results were compared with those of the other 23 known compounds of Myristica seed and currently used insecticides: dichlorvos, deltamethrin, permethrin, and propoxur. In contact toxicity tests using female B. germanica, (1S)-(-)-β-pinene (0.06 mg/cm2) was the most toxic insecticide, based on 24-h LD50 values. The insecticidal activity of this compound was comparable with that of permethrin (0.05 mg/cm2). (1R)-(+)-Camphor, (1S)-(-)-camphor, dipentene, (1R)-(+)-β-pinene, and (+)-α-terpineol (0.10–0.14 mg/cm2) were more toxic than propoxur (0.19 mg/cm2). (E)-Sabinene hydrate and propoxur were almost equitoxic. Potent insecticidal activity also was observed with (R)-(+)-citronellal, (S)-(-)-citronellal, (R)-(-)-α-phellandrene, (1S)-(-)-α-pinene, (1R)-(+)-α-pinene, and safrole (0.27–0.48 mg/cm2). In vapor phase toxicity tests, the compounds tested were effective in closed but not in open containers. These results indicate that the effect of these compounds was largely a result of action in the vapor phase. Myristica seed compounds described merit further study as potential insecticides or as leads for the control of cockroaches.