Morphological alterations induced by boric acid and fipronil in the midgut of worker honeybee (Apis mellifera L.) larvae

Abstract

Morphological alterations, by means of histological and ultrastructural analysis, have been used to determine the effects of boric acid and fipronil on midgut tissues of honeybee worker, Apis mellifera L. larvae. In order to observe possible morphological alterations in the midgut, two groups of bioassays were performed. In the first one, the larvae were chronically treated with different concentrations of boric acid added to the food (1.0, 2.5 and 7.5 mg/g). In the second group, the larvae were fed with diets containing different concentrations of fipronil (0.1 and 1 microg/g) and compared with control groups without these chemical compounds. In the first bioassay, the larvae were collected on day 3 and in the second bioassay on day 4, when the mortality rate obtained in the toxicological bioassay was not very high. The larval midguts were removed and processed for morphological analyses using a light and transmission electron microscopy. We observed cytoplasmic vacuolizations, with the absence of autophagic vacuoles, and chromatinic compacting in most of the cells in the groups treated with pesticides. The morphological alterations were far greater in the larvae treated with boric acid than in the larvae treated with fipronil. Our data suggest that the midgut cell death observed was in response to boric acid and fipronil action. This study significantly improves the understanding of the toxicological effect of these insecticides from the ecotoxicological perspective.

Effect of boric acid on antioxidant enzyme activity, lipid peroxidation, and ultrastructure of midgut and fat body of Galleria mellonella

“…Perhaps increased midgut size was due to vacuolization of cells. Similar ultrastructural changes were observed by Sumida et al (2010) in ants and da Silva et al (2010) in bees exposed to BA. Midgut cells were vacuolized, membranes were ruptured, and myelinated figures were observed, too.…”

“…Additionally, in fat body cells, we focused on lipid droplets. These changes are frequently met when tissues are exposed to xenobiotics (Adamski et al 2005, Adamski 2007; da Silva et al 2010). …”

Exposure to Sublethal Doses of Fipronil and Thiacloprid Highly Increases Mortality of Honeybees Previously Infected by Nosema ceranae

“…In our study, fipronil and thiacloprid have antagonist effect on N. ceranae proliferation whereby fipronil decreases slightly spore production in honeybees. This effect can be attributed either to the cytotoxic effect of fipronil on the intestinal epithelium [55], [56] or to its pro-oxidant action [57] that may affect the reproduction cycle of N. ceranae , but this assertion should be confirmed by other experiments. In contrast, thiacloprid increased spore production in our study.…”

Loci Contributing to Boric Acid Toxicity in Two Reference Populations ofDrosophila melanogaster

“…Here, we complement this work by dissecting the genetic basis of resistance to boric acid, a common household insecticide. Boric acid has been shown to be effective against various ant species (Klotz and Moss 1996; Klotz et al 1996), and the larvae of both honeybees (da Silva Cruz et al 2010) and wax moths (Hyrsl et al 2007; Buyukguzel et al 2013). Boric acid administration has morphological effects on the midgut and malpighian tubules in leaf-cutting ants (Sumida et al 2010), leads to abnormalities in midgut cells in Argentine ants (Klotz et al 2002) and honeybee larvae (da Silva Cruz et al 2010), and promotes irregularities in both midgut tissue and the fat body in wax moths (Buyukguzel et al 2013).…”