Efficacy of diatomaceous earth in controlling major store product pests: Plodia interpunctella, Tribolium confusum and Acanthosclides obtectus

Abstract

Diatomaceous earth (DE) is a dust formed from fossilized skeletal remains of single-celled algae – diatoms. Diatoms have a fine skeleton made of amorphous silicon dioxide (SiO2), as a major constituent of DE, which additionally contains minor amounts of minerals (aluminium, iron oxide, calcium hydroxide, magnesium and sodium). Insecticidal activity of DE is a result of desiccation that occurs after the particles of DE absorb the waterproof lipids from the arthropod cuticle (destroy epicuticular lipid layers) leading to high rate of water loss. Efficacy of DE depends on chemical composition, particle size and geographic origin. This work aimed to assess the efficacy of DE originating from Kolubara open-pit mine, Serbia, in comparison to commercially available preparation SilicoSec®. Efficacy was assessed in contact toxicity test, against indian meal moth (Plodia interpunctella) larvae and confused beetle (Tribolium confusum) and bean weevil (Acanthoscelides obtectus) adults. DEs were applied at rates: 5, 10, 15 and 20 mg-2 and mortality was recorded after 24, 48, 72 h and seven days.