Journal of Economic Entomology (2010) 103, 448-459

Alicia K. Phillips, Arthur G. Appel and Steven R. Sims (2010)
Topical toxicity of essential oils to the German cockroach (Dictyoptera: Blattellidae)
Journal of Economic Entomology 103 (2), 448-459
Abstract: The toxicity of 12 essential oil components [carvacrol, 1,8-cineole, trans-cinnamaldehyde, citronellic acid, eugenol, geraniol, S-(-)-limonene, (-)-linalool, (-)-menthone, (+)-alpha-pinene, (-)-ß-pinene, and thymol] to adult male; adult female; gravid female; and large, medium, and small nymphs of the German cockroach, Blattella germanica (L.) (Dictyoptera: Blattellidae), was determined. Thymol was the most toxic essential oil component to adult males, gravid females, and medium nymphs, with LD₅₀ values of 0.07, 0.12, and 0.06 mg per cockroach, respectively. trans-Cinnamaldehyde was the most toxic essential oil component to adult females, large nymphs, and small nymphs, with LD₅₀ values of 0.19, 0.12, and 0.04 mg per cockroach, respectively, (+)-alpha-Pinene was the least toxic essential oil component to all stages of the German cockroach. The most frequently occurring susceptibility ranking for the stages was small nymphs > medium nymphs > adult males > large nymphs > gravid females > adult females. Adult females were the least susceptible to the essential oils, so they will be the determining factor when considering a rate for field application. Toxicity was positively correlated with essential oil component density and boiling point; however, there was no significant correlation between toxicity and lipophilicity. The effect of essential oil components on ootheca hatch was also investigated, S-(-)-limonene had the least effect on ootheca hatch, with 35.21 (mean) nymphs hatching per ootheca, (-)-menthone had the greatest effect on ootheca hatch with 20.89 nymphs hatching per ootheca. The numbers of nymphs hatching from each ootheca generally declined as dose increased. No essential oil component completely prevented ootheca hatch suggesting that multiple treatments might be required in the field to prevent reinfestation.
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Link to article at publishers website
Database assignments for author(s): Arthur G. Appel

Research topic(s) for pests/diseases/weeds:
control - general

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Blattella germanica