The effects of Varroa destructor infestation and botanical oils on physiological characteristics and mechanism of defensive behavior of Carniolan and Italian Apis mellifera

Abstract

The purpose of this study was to assess the physiological and behavioral reactions of Italian and Carniolan honey bees (Apis mellifera) to botanical treatments and infestations of Varroa destructor. Measurements of amino acid profiles, enzyme activities, nutrient contents, grooming, and hygienic practices were used to evaluate the effects of infestation and treatments (formic acid, apricot seed extract, garlic oil, and camphor oil). In both bee subspecies, Varroa mite infestation markedly changed the levels of amino acids, especially lowering proline, alanine, and methionine. Essential amino acid levels were higher in uninfested bees, whereas methionine and glutamic acid levels were higher in bees treated with formic acid. In general, the lowest concentrations of amino acids were found in apricot oil. The untreated controls had the highest levels of total carbohydrates, proteins, and lipids, while the bees treated with garlic oil or formic acid had the lowest levels. While invertase activity peaked in bees treated with apricot oil, the enzymatic activities of GOT, GPT, amylase, and esterases decreased when exposed to formic acid and garlic oil. The enzyme levels of Italian and Carniolan bees varied, with the latter typically exhibiting greater activity. Grooming responses changed over five days after treatment, according to behavioral assays. Apricot extract and garlic oil significantly influenced grooming behavior in colonies, with the highest levels of hygienic behavior observed within the first 24 h. These findings suggest Varroa infestation impairs bee physiology, but certain botanical treatments especially apricot and garlic oils may enhance bee resilience through improved biochemical balance and behavioral defenses.