Assessing the Effects of Thymol and Oxalic Acid on Honey Bee Colony Condition Using Ratiometric Spectral Indicators...

Over the past 20 years, honey bee colony declines have been driven by multiple factors, notably diseases and parasites. The parasitic mite Varroa destructor, which weakens the bees' immune systems, has been particularly harmful. While various synthetic acaricides are used, the chemicals may accumulate in the beeswax, endangering colony health and allowing Varroa populations to develop resistance to these acaricides. These problems have prompted interest in organic alternatives like thymol and oxalic acid. In this study, colony health was assessed through the proteins-to-phenolics spectral ratio in honey and beeswax, determined by fluorescence spectroscopy, as a ratiometric indicator of infection level in treated hives. Over two months, hives were treated with either oxalic acid, thymol, or remained untreated as controls. Neither treatment significantly affected the proteins-to-phenolics ratios in honey, ranging from 0.30 to 0.83, or in beeswax, ranging from 1.40 to 1.83, suggesting that the incorporation of these vital constituents remains stable despite acaricide application. While thymol demonstrates potential adverse effects on bee health, careful management of treatment concentrations is essential to ensure both the efficacy of Varroa control and the preservation of honey quality. These findings provide valuable insights for beekeepers regarding the safe application of organic acaricides.