Toxicological and immunohistochemical testing of honeybees after oxalic acid and rotenone treatments

Abstract

-Bees removed capped brood and young larvae from combs at a greater rate after a rotenone treatment than after an oxalic acid (OA)/sucrose treatment. Rotenone (1%) caused 75.2% of capped brood to be removed, OA (3%) 18.7% and a control treatment, 13.3%. Caged worker bees treated with a 1% rotenone powder, a 3% OA or with a control solution had mortality rates of 10.9%, 5.1% and 1.9% respectively. Rotenone (1%) significantly affected the mortality of brood and adult bees whereas OA (3%), did not. Solutions of 3% OA/32% sucrose, 3.4% OA/47.6% sucrose, 3.7% OA/27.1% sucrose (w/w) and a 32% sugar solution applied to adult bees resulted in death rates of 11%, 14%, 11.2% and 6.5% respectively. Individually treated bees consumed more of a 3% OA solution than solutions with higher OA concentrations. A TUNEL assay detected necrotic cell death in 69% of bee midgut cells 24 h after an OA treatment. Normal cell turnover is approximately 8%.Treatment / Apis mellifera / acaricide / TUNEL / cell death / mortality

Sublethal effects of oxalic acid on Apis mellifera (Hymenoptera: Apidae): changes in behaviour and longevity

“…It is known that a treatment with OA can cause permanent lesions in digestive and excretory organs (Martin-Hernandez et al 2007). Gregorc and Smodis Skerl (2007) detected necrotic cell death in 69% of bee midgut cells 24 h after an oral treatment with 3% OA (dosage 600 μg/bee). Tissue distribution of the acid was detected in bees that received a dermal application (dosage 1,320 μg/bee), so it was assumed that some of the acid is ingested by the bee (Martin-Hernandez et al 2007).…”

Effect of oxalic acid on Nosema ceranae infection

“…In spite of ingestion, therapeutic doses of OA are tolerated by the bees and are not associated to patent negative effects. In fact, although imunohistochemical analysis showed necrotic cell death in ventriculi of bees fed with oxalic acid (Gregorc and Škerl, 2007) and other studies put into evidence decreased bee longevity (Schneider et al, 2012), in an extensive investigation performed in several European countries obvious negative effects on the adult population of the colonies were not observed (Nanetti et al, 2003b).…”

Use of Thymol Formulations, Amitraz, and Oxalic Acid for the Control of the Varroa Mite in Honey Bee (Apis mellifera carnica) Colonies

“…Sublethal effects on honey bees and brood have been observed after the application of chemical or organic substances (Haarman et al, 2002;Gregorc and Smodiš Škerl, 2007). In order to eliminate the risk of mite resistance and to reduce residues in hive products (Bogdanov et al, 1998;Wallner, 1999), organic substances for the control of varroa mites have been applied with variable efficacy.…”