Avoidance behaviour in laboratory house mice (Musmusculus) and Norway rats (Rattus norvegicus) towards predator odours.

Mus musculus and Rattus sp. are considered pest species because they reach high densities in urban areas, crop fields and food storage and productive systems such as breeding farms and orchards. Their control relies mainly on rodenticide application, but the effectiveness of this application is reduced due to behavioural responses and resistance. Novel methods are based on the use of chemical signals as odours that may be attractants, repellents or may reduce the reproductive success of pest species. The aim of this paper is to study the aversive effect of TMT, cat urine and cat body odour on predator-inexperienced Mus musculus and Rattus norvegicus under laboratory conditions. The experimental apparatus comprised three boxes connected by PVC pipes in a linear arrangement. In lateral boxes, odour sources or distilled water were introduced, while animals were placed in the central box at the beginning of the experiment. Rats showed freezing behaviour, reduced visits in the presence of TMT and cat fur. Mice reduced their visits with cat body and cat urine. This study provides evidence of the usefulness of using fear responses as a way to control rodent pests, which must be adapted to the environment and species to be applied.

Effects of different odours on the reproductive success of Mus musculus as an alternative method of control.

BACKGROUND: The house mouse (Mus musculus) is a cosmopolitan rodent that has become adapted to living in close association with humans and is considered a serious pest because it poses a risk to human health, and causes economic losses due to food and crop consumption and damage to buildings. Its control in livestock farms is achieved mainly through the application of anticoagulant rodenticides, but the effect of these compounds is limited due to the presence of resistant individuals and aversive behaviours. A potential alternative method is the use of chemical signals to reduce rodent reproductive success. In this study, we assessed the effects of odours from an unfamiliar male, 17ß-oestradiol, overcrowding, cat urine and 2,5-dihydro-2,4,5-trimethylthiazoline (TMT) on the reproductive success of laboratory Mus musculus females. RESULTS: According to the generalized linear mixed models, cat urine odour increased the proportion of abortions per female, unfamiliar male odour decreased the mean number of offspring born per female, and TMT had an overall negative effect on mean offspring production at birth and at weaning. The other odours had no significant effects on reproductive success. CONCLUSIONS: TMT seems to be the best candidate for population control because it caused a decrease in the mean number of offspring born and the mean number of live offspring at weaning. TMT also has the advantage of being available in commercial forms. To be useful for rodent management in field conditions, these results should be confirmed using wild house mice females. © 2019 Society of Chemical Industry.