Phytochemical composition and acaricidal potential of Argemone mexicana and Ricinus communis extracts against Varroa destructor in Apis mellifera colonies

Abstract

The ectoparasitic mite Varroa destructor is one of the main sanitary threats to Apis mellifera colonies worldwide, prompting the search for sustainable alternatives to synthetic acaricides. This study evaluated the effects of hydroethanolic extracts from Argemone mexicana and Ricinus communis on phoretic V. destructor infestation and mite fall under field conditions. Extracts were applied at concentrations of 10%, 15%, and 20%. In addition, total phenolic compounds, flavonoids, condensed tannins, and antioxidant activity were quantified to further characterize the phytochemical profiles of the extracts. The effects of these extracts on mite fall, reduction of phoretic infestation, and honey production were evaluated in thirty-five productive honey bee colonies, which were randomly assigned to seven experimental groups, each consisting of five colonies. Six groups received botanical treatments, while one group served as a vehicle control and received 70% ethanol without plant material. Our results showed that botanical treatments increased mite fall and significantly reduced phoretic V. destructor infestation compared with the vehicle-control colonies, demonstrating a clear concentration-dependent response. A. mexicana exhibited the highest concentrations of phenolic compounds, flavonoids, and condensed tannins as well as the strongest antioxidant activity. However, plant species did not significantly affect the estimated effectiveness in reducing phoretic infestation. Honey species did not significantly affect honey production or extract concentration (p = 0.088); however, acaricidal effectiveness was positively correlated with honey production (r = 0.794, p < 0.0001). These findings demonstrate the biological activity of the tested botanical preparations against V. destructor under field conditions and support further investigation into their use in integrated management strategies.