Field evaluation of imidacloprid as a systemic approach to flea control in black-tailed prairie dogs, Cynomys ludovicianus

Abstract

Epizootic outbreaks of sylvatic plague have dramatically influenced prairie dog (Cynomys sp.) populations across North America. While a great deal of debate surrounds the cause and persistence of plague, flea control can stop the spread of plague epizootic outbreaks and even increase prairie dog survival under non-epizootic conditions. We investigated a newly-developed imidacloprid-treated grain bait that could potentially reduce flea infestations and mitigate the effects of plague on black-tailed prairie dogs (C. ludovicianus). We used a study design involving randomly assigned experimental and control study plots to assess the effectiveness of the systemic flea control product. We observed a significant difference in flea prevalence and abundance between experimental and control sites on three of the four sites treated with a single application of imidacloprid-treated grain bait for up to 90 days post-treatment. We observed an even greater reduction in flea infestations following the double application of treatment bait on two of three additional experimental sites. While we were unable to reduce flea infestations to the extent reported for more commonly used topical insecticides containing deltamethrin, imidacloprid might still be effective at reducing the risk of plague and halting epizootics. In addition, this systemic product can be more rapidly applied than topical insecticides, providing managers with a tool to quickly reduce flea infestations. Future research is needed to evaluate the effectiveness of different application timing and rates, the utility of the product in limiting plague, and the potential effects on non-target species that might also consume the treated bait. Journal of Vector Ecology 36 (1): 100-107. 2011.

Mitigating plague risk in utah prairie dogs: Evaluation of a systemic flea‐control product

“…Captured prairie dogs were anesthetized using a specially designed isoflurane vaporizer and fitted mask (Seven and Seven Anesthesia, Fort Collins, CO). While a prairie dog was sedated, we sampled fleas by brushing the entire body of the individual for 30-60 s using a flea comb (Biggins et al 2010, Jachowski et al 2011. We weighed each prairie dog, measured its hind foot length, determined its age and sex class, and attached a uniquely numbered metal tag to each ear.…”

“…In May 2009, we established 2 study plots (treatment and control) at each of the 4 study sites. We selected study sites, and plots within sites, based on the expectation of capturing >50 prairie dogs within 5 consecutive trapping days based on visual assessments of prairie dog populations and our knowledge of likely trapping success (Jachowski et al 2011). For each plot, we attempted to select an entire colony of prairie dogs (i.e., an aggregation of adjoining family groups) or 2 colonies in proximity to each other, such that treatment and control plots within a site had similar soil, landscape, and vegetation conditions.…”

“…Given that imidacloprid reduced fleas on black-tailed prairie dogs, it might also be effective in treating Utah prairie dogs. However, reduction in flea prevalence, abundance, and intensity post-treatment with imidacloprid was less pronounced and more variable than is reported to occur with treatment using topical insecticides (Jachowski et al 2011).…”

“…Within 24-48 hr after a mammal consumes bait treated with imidacloprid, the compound resides in the animal's blood-stream and typically kills 96-97.3% of fleas that ingest blood from the treated animal for up to 30 days in a laboratory setting (Poché et al 2008). The product is a systemic flea-control agent that can be spread in a bait form above ground, and can be applied more rapidly than deltamethrin (Jachowski et al 2011). Given that imidacloprid reduced fleas on black-tailed prairie dogs, it might also be effective in treating Utah prairie dogs.…”

“…Recently, a grain bait treated with the active ingredient imidacloprid (0.025% by vol) and marketed as Kaput 1 (Genesis Laboratories, Wellington, CO) has shown promising results in reducing fleas on black-tailed prairie dogs in the field (Jachowski et al 2011). Imidacloprid is a chloronicotinyl insecticide that impairs insect nerve function by acting as a competitive inhibitor at nicotinic acetylcholine receptors of the nervous system.…”