Comparison of Alternative Application Methods for Anti-Varroa Lithium Chloride Treatments

Abstract

Varroosis is one of the most dangerous threats to the bee industry but means of its treatment are still unsatisfactory. Lithium-based anti-Varroa treatments may provide an alternative, as this trace element can be a natural component of honey and is well tolerated by adult bees. However, it can be toxic to larvae and its use in beekeeping practice is not yet well understood. The present study aimed to investigate the efficacy of relevant application methods of acaricides used in beekeeping practice in brood-free conditions for lithium. Vaporisation proved to be an inefficient method of lithium treatment and killed only 9.9 ± 3.3% (mean ± SD) of mites in the hive. Lithium-impregnated paper strips showed moderate efficiency by killing 55.1 ± 26.2% of mites. The most effective way of applying lithium was the trickling method; different trickling treatments decreased the abundance of mites on average by 65 to 99.7%, depending on the applied dosage and the number of treatments. Repeated trickling treatments were more effective than single treatments, and they generally provided >90% efficiency. Experiments also proved that adding sugar to the trickling solution does not influence treatment efficiency. Thus, it is suggested that repeated and sugar-free trickling treatments with moderate lithium dosage could be the most rational methodology. Since lithium is not yet legalised in beekeeping practice, comprehensive studies are also needed to uncover the amount of lithium residue in bee products, depending on the treatment parameters.

Contact varroacidal efficacy of lithium citrate and its influence on viral loads, immune parameters and oxidative stress of honey bees in a field experiment

“…However, varroacidal efficacy (96.85%–96.80%) we achieved by single treatment of low concentrations (5 and 10 mM) of Li-cit was slightly higher than the efficacy of 95.6% that Kolics et al (2021a) achieved with much higher concentration (250 mM) of Li choride (also by single treatment). However, in most recent work of Kolics et al (2022) only repeated trickling treatments with a 500 mM of Li chloride provided >90% efficiency. Based on the results of Kolics et al (2021a , 2022) and the results of current study, it seems that the efficacy of Li salts is rather dependent on the mode of application (feeding vs. trickling treatment) than on concentration.…”

“…However, in most recent work of Kolics et al (2022) only repeated trickling treatments with a 500 mM of Li chloride provided >90% efficiency. Based on the results of Kolics et al (2021a , 2022) and the results of current study, it seems that the efficacy of Li salts is rather dependent on the mode of application (feeding vs. trickling treatment) than on concentration. On the contrary, in a work of Abd El-Wahab et al (2021) efficiency of two ‘hard’ varroacides, Vapcozin-20 (amitraz) and Mavrik 2F (fluvalinate), was not dependent on the mode of application.…”

“…Li-cit in this study was tested in the same way as Li chloride in studies of Kolics et al (2021a , 2022) , by trickling lithiated sugar syrup in broodless period. However, varroacidal efficacy (96.85%–96.80%) we achieved by single treatment of low concentrations (5 and 10 mM) of Li-cit was slightly higher than the efficacy of 95.6% that Kolics et al (2021a) achieved with much higher concentration (250 mM) of Li choride (also by single treatment).…”

“…New substances have been continuously sought for decades in order to find those that will exhibit high varroacidal efficacy at low doses/concentrations, without side effects on bees ( Stanimirović et al, 2019 ; Jack and Ellis 2021 ). Several studies have shown that lithium (Li) salts are good candidates for this purpose ( Ziegelmann et al, 2018 ; Kolics et al, 2020 , 2021a , b , 2022 ; Stanimirovic et al, 2022b ; Sevin et al, 2022 ). The varroacidal effect of Li salts was first described by Ziegelmann et al (2018) in which bees were fed different Li salts under both laboratory and field conditions (but on artificial swarms).…”

“…Honey originated from brood chamber was not affected with lower concentrations (15 and 20 mM) of Li-cit (Stanimirovic et al, 2022b), so concentrations in a range from 4 to 10 mM were declared promising (Stanimirovic et al, 2022b) and taken into account for contact efficacy testing in this study. When it comes to the method of application, we considered results of Kolics et al (2020Kolics et al ( , 2021aKolics et al ( , 2022 who concluded that trickling method is the most effective way of administration of Li chloride.…”