Rodents have an inherent distrust of new things in their environment, so managing their reaction to bait and bait stations is essential for gaining control.

In Australia we tend not to hear a great deal about the health risks associated with rodent infestations. This is quite a contrast to the headlines often seen in Europe and the US. However, various zoonotic diseases in Australian rodent pests are well documented.

In recent years Streptobacillus moniliformis, Angiostrongylus cantonensis, lymphocytic choriomeningitis virus, leptospirosis, rickettsia and cryptosporidia have all been documented as causes for concern.1 Fortunately, whilst hantavirus antibody-positive rodents have been found across Australia, it has not yet been reported in humans. Yet more than 200 human cases of leptospirosis are reported here each year, mostly in Queensland. The rat lungworm Angiostrongylus cantonensis causes neurological disease in humans and several fatalities have been reported in Australia.

In order to reduce the chances of being exposed to rodent-related diseases, eliminating a rodent infestation as quickly as possible is vital.

A core issue in managing rodent problems quickly is the natural neophobia (fear of new things) displayed by rodents, the strong suspicion of and awareness to change, and the presence of unfamiliar objects, which has been widely reported in rat populations in particular. Neophobic responses will vary between rat populations, though there appear to be predictable conditions that should lead us to consider whether a population will likely present greater issues when we commence a baiting program. Neophobia seems to be a behavioural characteristic that is a long-lasting feature within a population.2

Populations that display the highest levels of neophobia tend to be those in stable environments that are less frequently disturbed and where there is an abundance of food. Reduced varieties of food types in a location also lead to increased levels of neophobia. Thus, the variability of available foods and environmental conditions seems to be most important in predicting the level of neophobia in rats. For example, one study showed how rats can be trapped most easily on land fill refuse areas, where the frequently changing environment makes neophobic behaviour impossible.3 Similarly it has been shown that rats prefer to eat more palatable foods and that baits are more readily accepted by rats with naturally lower neophobic behaviour.

Selecting a rodenticide bait that better manages the neophobic responses exhibited by rodents can greatly improve rodent management programs. Steve Broadbent, regional director for Ensystex, says Muskil baits were specifically developed with this in mind.

“Rodents do not have full colour vision; however, they do respond to short wavelength light rays, such as the light in the UV spectrum. This means they can ‘see’ ultraviolet light which is invisible to humans. Muskil Soft Bait and Muskil Block Bait have been formulated to include a non-toxic, fluorescent red dye that makes the bait reflect light in the UV range. To rodents, the bait essentially ‘glows’ in the dark,” explained Mr Broadbent.

“The reason for incorporating this ‘Fluo-NP technology’ is simple – rodent urine also reflects UV light. To any rodent approaching Muskil bait, it will appear that other rodents have already investigated the bait, found it to be safe, and have urinated on it. This reduces neophobia as any rodents approaching the bait believe it to be safe and suitable to eat. The ‘Fluo-NP technology’ encourages quick acceptance of the bait, then its high palatability encourages further feeding.”

As an added benefit, the Fluo-NP dye is excreted into the rodents’ droppings, which shows where rodents are tracking. The bait also glows bright red under a blacklight torch, making it easy to assess bait wastage and spread.

Muskil is also the only bait in the professional pest control market that contains two active constituents, bromadiolone and difenacoum, and is available as both blocks and as a soft bait in sachets. “These two actives combine together to create a synergistic effect with each dynamically intensifying the effects of the other, to create a more potent solution than either alone, yet at the same time achieving reduced risk to people and pets,” added Mr Broadbent.

This was demonstrated in independent, university-led eld trials that showed Muskil killed rodents faster than other anti-coagulant rodenticides including brodifacoum, and that rodents displayed significantly reduced neophobic responses to the bait leading to quicker uptake and control.

Mr Broadbent added, “Muskil’s high potency allows Muskil Soft Bait to be provided as a 10g bait sachet, with a single sachet sufficient to kill several rats in a single feed. This means pest managers get 900 bait placements from the 9kg pail. Muskil allows for more bait placements than most other rodenticides, making it great value.”

By selecting a bait that addresses the issue of neophobia, pest managers can assure their clients that they are presenting a fast-acting solution to their rodent problem and protecting them against serious health risks.

1 G. R. Singleton, L. Smythe, G. Smith, D. M. Spratt, K. Aplin & A. L. Smith. 2003. Rodent diseases in Southeast Asia and Australia: inventory of recent surveys. In Rats, mice and people: rodent biology and management, Australian Centre for International Agricultural Research.

2 S. Priyambodo & H-J. Pelz. 2003. Studies on the feeding neophobic behaviour in Norway rats (Rattus norvegicus Berkenhout, 1769) from farms in Germany. In Rats, mice and people: rodent biology and management, Australian Centre for International Agricultural Research.

3 R. Boice. 1971. Laboratizing the wild rat (Rattus norvegicus). Behavioural Research Methods and Instruments, 3, 177–182.

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