Lithium Chloride Shows Effectiveness against the Poultry Red Mite (Dermanyssus gallinae)

SIMPLE SUMMARY: The poultry red mite (Dermanyssus gallinae) is the major pest of poultry and a vector for many animal and human pathogens. Control is limited, and alternative substance efficacy may imply resistance and inconsistency problems. As a consequence of this, there is an increasing demand for alternative substances. In this pilot study, we report for the first time that lithium chloride, a currently promising potential miticide for Varroa mite (Parasitiformes) control in bees, showed effectiveness against poultry red mite in vitro. However, further comprehensive studies are needed to reveal whether lithium compounds can be considered an alternative miticide to control Dermanyssus gallinae. ABSTRACT: The poultry red mite (Dermanyssus gallinae) is the main pest of poultry, causing severe problems by being a vector of several animal and human pathogens. The number of miticides is few, and their efficacy in practice implies problems of residues and resistance; therefore, the demand for a new and safe agent is constant. The present publication investigated the effectiveness of lithium chloride under in vitro conditions on poultry red mites. This chemical currently appears to be one of the most promising alternatives to study amongst potential applicants to treat varroosis, a fatal disease of honey bees. In Experiment I, the previously used experimental doses (5.52 M, 2.76 M, 1.38 M) on Varroa mites confirmed their in vitro activity on the poultry red mite. Three event times (uncontrolled movement, immobilisation and death) were recorded to base the response to treatment for each concentration. In Experiment II, the LD 50 value was calculated, i.e., the value at which 50% of the mites were killed by the treatment. This Experiment showed that the LD50 of lithium chloride = 0.265 M in the poultry red mite. It is to note that the study remained restricted to in vitro confirmation of lithium chloride’s effectiveness on the parasite. Thus, further extensive studies are needed to decide whether it has any relevance in practice against D. gallinae, and also to assess potential residue problems that could affect poultry products.