Date of Award

5-2018

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Animal and Veterinary Sciences

Committee Member

Dr. Peter Skewes, Committee Chair

Committee Member

Dr. William Bridges

Committee Member

Dr. Cady Sartini

Committee Member

Dr. Greg Yarrow

Abstract

Commensal rodents, including the house mouse (Mus musculus L.), pose a substantial risk of damage and disease towards human kind, threatening the infrastructure and food supply on which it depends. The implications of rodent infestations have become more significant as issues of public health and food safety become elevated priorities. Effective control of house mice relies heavily on rodenticides of which, the efficacy is known to be impacted by a variety of factors including palatability, social interaction and the development of behavioral aversions. In this study, analysis of consumption rates, recorded video, and capture-mark-recapture (CMR) data were utilized to investigate changes in house mouse feeding behavior, population demographics, interactions with bait stations, changes in movements, and spatial distribution in response to two sequential temporal rotations from nontoxic bait to a cholecalciferol rodenticide. Compared to nontoxic bait, consumption of cholecalciferol bait fell to 45% within two days of introduction and continued to decline to approximately 2% within seven days. When nontoxic bait was returned, consumption levels rebounded to approximately 25% of original nontoxic levels, while abundance estimates indicated a 62% population reduction. When cholecalciferol bait was returned, consumption trends were similar to the original baiting, resulting in a reduction in abundance to 3% of the original population. Analysis of mouse activity in and around bait station locations suggest that mice visited areas where bait stations were to be placed less frequently (P = 0.0620) before placement than after. The percentage of visits initially entering empty stations was significantly less than all other phases. Mice visited stations significantly less (frequency and duration) and consumed significantly less bait during phases offering cholecalciferol compared to phases offering nontoxic bait. The majority of the time mice spent in observation areas (35 x 95 cm area around the station) was inside a bait station and mice were seldom observed to cohabitate a bait station. When nontoxic bait was returned, mouse activity and consumption rebounded then subsequently declined when nontoxic bait was replaced with cholecalciferol the second time, showing similar trends to the initial placement. Analysis of CMR data revealed that no significant changes were observed in the distance of mouse movements following the initial rodenticide treatment which reduced population abundance by 62%. The location of mouse movements was not significantly impacted by the rodenticide treatment. Juveniles were observed to have significantly greater movements than adults. Typical movements were expansive enough to include multiple bait stations spaced at 2.5 m to 3.5 m intervals. Immigration and emigration were not identified as a significant factor leading to incomplete control after the initial treatment. Demographic analysis of captured individuals and recovered mortality indicated that the cholecalciferol treatment caused greater female mortality, as the male to female ratio increased over twofold from the studies inception to completion.

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