Comparison of baiting strategies in common vole management

BACKGROUND: Worldwide, pest rodents can cause extensive damage to agriculture, forestry, food storage, and infrastructure and pose a risk to public health and livestock due to the spread of zoonotic pathogens. In Europe, the most common pest rodent species is the common vole (Microtus arvalis). Management during periodic outbreaks largely relies on rodenticidal bait with zinc phosphide. Efficient baiting with rodenticides or possibly anti-fertility products in the future require baiting methods that allow a sufficient proportion of the population to consume an effective dose of bait. We used a bait with the quantitative marker ethyl-iophenoxic acid (Et-IPA) to evaluate baiting strategies in enclosure experiments. This wheat-based bait with Et-IPA was placed in bait boxes or directly into the tunnel system entrances in different seasons and common vole abundances. Voles were live-trapped, individually marked and blood samples were collected to relate Et-IPA blood residues to bait uptake.
RESULTS: The percentage of animals consuming bait was not heavily affected by the baiting strategy but voles had higher Et- IPA blood residues if tunnel baiting was used in autumn and if bait boxes were used in winter. Non-reproductive as well as ligh- ter animals tended to have higher Et-IPA blood residues than reproductive individuals, whereas sex had no effect. Population density had a negative effect on the probability of residues present as well as on Et-IPA blood concentration.
CONCLUSION: The results of this study might help to improve baiting techniques to manage overabundant rodent pest species regardless of the compounds to be delivered.