Exploring the Effectiveness of Chlorophacinone in Managing Urban Rat Infestation: A Laboratory Study on the Norway Rat, Rattus norvegicus, a Common Urban Rat in Malaysia

Background: Rat populations in urban areas must be monitored and controlled, as they can transmit zoonotic diseases and pose a risk to human health. Certain urban rat species may not respond well to some of the rodenticides available on the market. Therefore, this study aimed to assess the efficacy of chlorophacinone in controlling urban rats in a laborato­ry setting. Methods: Chlorophacinone, the primary focus of this study, was compared to a commonly used first-generation antico­agulant rodenticide (FGAR) available in the urban market, namely Coumatetralyl. Rat specimens were trapped in Kuantan, Pahang, and the dominant species was identified as Rattus norvegicus. Results: Overall, chlorophacinone demonstrated nearly complete mortality (95%) within an average of eight days post-feeding, followed by coumatetralyl, which exhibited high mortality (85%) within an average of seven days post-feeding. The rats in the chlorophacinone group consumed significantly lower dosages than those in the coumatetralyl group. This was due to variations in the default concentrations of the active ingredient of both treatments. Nevertheless, rats in the chlorophacinone treatment still experienced a higher mortality rate compared to coumatetralyl, despite consuming a low­er dosage. Conclusion: Consequently, this finding suggests that R. norvegicus is more susceptible to chlorophacinone than cou­matetralyl. This underscores the potential of chlorophacinone as an effective rodenticide for controlling rat infestations in urban areas throughout Malaysia.