Cell death in honeybee (Apis mellifera) larvae treated with oxalic or formic acid

Abstract

-The effects of oxalic (OA) and formic acids (FA) on honeybee larvae in colonies were assessed and evaluated. Cell death was detected by the TUNEL technique for DNA labelling. In 3-and 5-day-old larvae exposed to OA, cell death was found in 25% of midgut epithelial cells 5 h after the treatment, using an "In situ cell death detection kit, AP" (Roche). The level of cell death increased to 70% by the 21st hour and the morphology of the epithelium remained unchanged. Fifty hours after the application, cell death was established in 18% of the epithelial cells of the 3-day-old larvae and had increased to 82% in the 5-day-old larvae. A "DeadEnd" apoptosis detection kit (Promega) showed sporadic cell death mainly in the larval fat body 5 h after treatment. Twenty-one hours after the OA application cell death was found in 4% of the larval midgut epithelial cells. Evaporated formic acid induced extensive apoptotic cell death in the peripheral, cuticular and subcuticular tissues that preceded the cell death of the entire larval body.Apis mellifera / cell death / oxalic acid / formic acid / immunochemical method

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

“…Normal cell turnover usually ranges between 5% and 10% (Gregorc and Bowen, 1997;Gregorc et al, 2004) which is consistent with the 8% cell death found in the control tissue when using a DeadEnd kit. Using an ISCDDK assay Gregorc and Bowen (2000) found that amitraz -another acaricide -increased the level of cell death in bee larvae and that an OA application triggered necrotic cell death in the midgut (Pulkkanen et al, 2000).…”

“…Programmed cell death in honeybees (Apis mellifera L.) has been revealed in the regressive hypopharyngeal glands (Moraes and Bowen, 2000) and in the midgut after a Paenibacillus larvae infection and an application of the acaricide amitraz Bowen, 1998, 2000) as well as in the isolated atria of the heart after exposure to the herbicide 2,4-Dichlorophenoxyacetic acid (Papaefthimiou et al, 2002). It has also been shown that an OA solution becomes distributed throughout the digestive system of an adult worker bee within 24 h (Nanetti et al, 2002;Nozal et al, 2003) and, when applied directly onto bee larvae, has an adverse effect on the midgut at the cellular level (Gregorc et al, 2004). Investigations into the effects of OA and rotenone at the tissue and cellular level are important in order to monitor their modes of acaricidal action and to study any preclinical symptoms, as their introduction into a honeybee colony may cause injury to its population and, therefore, negatively impact upon its development.…”

Oxalic acid for the control of varroosis in honey bee colonies – a review

“…Significantly fewer cells containing sealed brood were reported in treated colonies compared to the control groups (Wilcoxon-Mann-Whitney-test, P < 0.05; Higes et al, 1999). The effect of oxalic acid on bee larvae was investigated by Gregorc et al (2004). A solution of 6.5 g oxalic acid dihydrate / 50 g sugar/ 100 mL water sprayed on honey bee larvae (0.121 mg / larvae) affected the columnar cells of the midgut, leading to necrosis.…”

Organic acids and thymol: unsuitable for alternative control of Aethina tumida (Coleoptera: Nitidulidae)?

“…The measured formic acid concentrations in the atmospheres of the laboratory trials of ≥160 ppm would have been effective against varroa mites within beehives (Imdorf 2005). Values of ≥680 ppm would cause severe impacts on honeybee colonies, such as disorientation of bees (Przewozny et al 2003), queen loss, and/or dead brood (Gregorc et al 2004). Such concentrations should therefore not be applied in a colony.…”