Does diatomaceous earth (DE) cause mortality on Apis mellifera and Bombus terrestris?

Abstract

Bees play an essential role in the sustainability of terrestrial and agricultural ecosystems as pollinators. However, external factors such as pesticides can negatively affect both bees and plants pollinated by bees, as well as human health. Therefore, less toxic or non-toxic plant protection products have become a popular research topic for a sustainable environment. The purpose of this study was to determine the effects of four different commercial products of diatomaceous earth (Bio, Demite, Detech, Detech WP) on workers of Apis mellifera and Bombus terrestris under controlled laboratory conditions. Each diatomaceous earth product was sprayed on the bees as dust particles for 15 seconds at Maximum Field Dose (10 g/m2). While the worker bees in positive control groups (control +) were exposed to flour, those in the negative control groups (control –) were not exposed to any treatment. The highest mortality rates for B. terrestris and A. mellifera were 22% in Detech WP and 16% in Demite, respectively. However, since mortality rates were under 25% for all the tested DE products, they were classified as harmless for both bee species. Additionally, the direct effect of diatomaceous earth products on honey bees and bumble bees was revealed for the first time in this study.