Effects of Lime Hydrate on the Growth and Development of Darkling Beetle, Alphitobius diaperinus

Abstract

The addition of hydrated lime to poultry litter to control insects and pathogens has a history of support. We examined the effects of hydrated lime litter treatments on the darkling beetle, Alphitobius diaperinus and the fungal pathogen Aspergillus. Hydrated lime application rates were calculated as poultry house equivalents; 22.6, 45.4, 56.7, 90.7 kg per 93 m² (50, 100, 125 and 200 lbs per 1,000 ft²), ground limestone; 22.6 kg per 93 m² and an untreated control. Among treatment groups, mortality was significantly higher for larvae than for adult beetles. Hydrated lime at the highest rate (90.7 kg per 93 m²) produced 59.1% and 24.6% mortality for larvae and adults, respectively. Limestone did not increase beetle mortality. Darkling beetle mortality was moisture dependent with greatest larval mortality (100%) observed at 90.7 kg/93 m² and 68% moisture while adult mortality was 58.8%. Effects of lime hydrate on the number of bacterial and Aspergillus colony forming units (CFUs) in treated litter was inconclusive. The impact of hydrated lime on beetles and perhaps pathogens in litter is likely the direct effect of increased pH, however the numbers of beetles, and fungal or bacterial CFUs may increase as pH levels become more neutral.