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 ll/ml air respectively was significantly (p < 0.05) higher than 9.2% mortality
observed in 0.33 ll/ml air. Percentage mortality observed in 0.99–1.33 ll/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 mor-
tality at application doses of 0.33–1.33 ll/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)
ll/ml air} was different from 1.69 (1.32–2.03) ll/ml air and 1.36 (1.05–1.63) ll/ml air LD 50 for
12 and 18 HAE respectively. For adult bioassay, 2.80 (2.50–3.19) ll/ml air was significantly higher than 1.85 (1.49–2.21) ll/ml air being LD 50 for 12 and 18 HAE. The study reveals that D. maculatus
larva was more susceptible to GEO than adult.