One of the common rodent control methods used in residential environments is application of rodenticides. Rodenticide modes of toxicity vary from neurotoxins to anticoagulants and have differing efficacy. We developed population viability analysis (PVA) models to estimate the effect of efficacy differences on commensal Norway rat (Rattus norvegicus) population reduction and rat infestation days. We evaluated two usage scenarios: 25% brodificoum or bromethalin and 75% first-generation anticoagulants (FGARs, e.g., warfarin), and 75% brodificoum or bromethalin and 25% FGARs. We compiled life history data, infestation rates, and rodenticide efficacy rates for commensal Norway rats from available literature for model inputs into the commercially available RAMAS Metapop v5.0. Populations modeled were small rat populations in single units of a multi-unit residential housing area or city block of houses, and included dispersal between units. We structured PVA models as birth-flow, single-sex, age-class models, and evaluated demographic stochasticity to reflect variability from the influence of small populations. We calibrated the PVA models against available literature, and included immigration from an outside source into the multi-unit metapopulation to reflect literature-based recovery rates following rodenticide application. Modeling predicts that 75% FGARs use increases rat infestation days by 98% when compared to 25% FGARs use. Extrapolated across United States residences reporting rodent infestations, 75% FGARs use produces 14 million more rat infestation days. These results indicate the rodenticide purchasing choices consumers make can affect the level of rat infestations and associated health problems across the United States.

Modeling rodenticide efficacy in controlling Norway rat (<i>Rattus norvegicus</i>) populations

248th National Meeting (2014)

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Modeling rodenticide efficacy in controlling Norway rat (Rattus norvegicus) populations