Comparative susceptibility of two developmental stages of hide beetle (Dermestes maculatus Degeer, 1774) to ginger (Zingiber officinale Roscoe) essential oil

Abstract

The pesticidal effect of ginger (Zingiber officinale Roscoe) essential oil (GEO) against two developmental stages (adult and larva) of Dermestes maculatus De Geer, a key pest of African catfish (Clarias gariepinus) was evaluated under laboratory condition (32 ± 2 °C temperature and 70 ± 3% relative humidity). At 6 h after exposure (HAE), 25.80 and 36.23% mortality in 0.99 and 1.33 μl/ml air respectively was significantly (p < 0.05) higher than 9.2% mortality observed in 0.33 μl/ml air. Percentage mortality observed in 0.99–1.33 μl/ml air at 12 and 18 HAE was significantly (p < 0.05) higher than mortality observed in other lower doses of GEO. The results of the larval bioassay follow the same trend as observed in adult bioassay except that higher percentage mortality was observed in larva than in adult. At 6–18 HAE, 28.25–90.00% larval mortality at application doses of 0.33–1.33 μl/ml air was significantly (p < 0.05) higher than 4.60% mortality observed in the control. The LD50 of GEO against larva at 6 HAE {2.74 (2.17–3.81) μl/ml air} was different from 1.69 (1.32–2.03) μl/ml air and 1.36 (1.05–1.63) μl/ml air LD50 for 12 and 18 HAE respectively. For adult bioassay, 2.80 (2.50–3.19) μl/ml air was significantly higher than 1.85 (1.49–2.21) μl/ml air being LD50 for 12 and 18 HAE. The study reveals that D. maculatus larva was more susceptible to GEO than adult. Keywords: Ginger, Essential oil, Dermestes species, African catfish, Lethal dose