Rat and mice infestations are common in places with abundant food. Unsurprisingly, farms and croplands are favourable sites for rodents. Therefore, it is common for farmers to use rodenticides to control rat populations. This post explains the different reasons why farmers need rodenticides to sustain their operations.

Crop yields and income

Farmers need to manage rats on their farms because these pests would feed on their crops and cause yield reductions. They could cause up to 30% in crop loss, causing up to millions in dollars of loss for the industry (Shiels et al., 2014). In Malaysia, the presence of rats in rice fields is detrimental because they would cut down growing stalks and eat developing grains (Wood & Fee, 2003).

Food safety

Moreover, rats are vectors that carry around 45 diseases (University of Massachusetts Amherst, 2014). Their presence could lead to several pollution issues. Firstly, they could contaminate local water supplies that communities depend on for drinking and irrigation. Secondly, they could contaminate farm feed for farm animals. Thirdly, they could contaminate the actual produce. All of these issues are worrying because they would compromise the safety of food, potentially leading to health impacts at local and global scales.

Beyond agriculture

Beyond agriculture, rats are invasive species that threaten the survivability of native flora and fauna (Duron et al., 2017).  On Lord Howe Island in Australia, the introduction of black rats due to a shipwreck in 1918 led to the extinction of 5 bird species and 13 invertebrate species (Slezak, 2016). In 2019, local authorities enacted a 16 million dollars eradication program, which involved dropping 42 tonnes of poisoned cereals from helicopters to wipe out the rat population.  While it was deemed to be a success initially, the island saw the reappearance of 2 adult rats in 2021, 2 years after the mass poisoning event (Kurmelovs, 2021). This example illustrates the difficulties in managing rodents and keeping them at bay.

Despite the global reliance on rodenticides to manage rats, there are many problems associated with the use of this agrochemical. The next few blog posts will detail the history of rodenticides, as well as the specific pollution pathways that rodenticides can take to damage the environment.

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