Rats and mice belong to the mammalian order of Rodentia. They occurred about 2 – 4 million years ago and are most closely related to the shrews and moles of the mammalian order Insectivora. As a group, rodents are among the most successful mammals on Earth.
The Economic Significance of Rodents
As pests, rodents compete with us for many different types of resources, damage our buildings and infrastructure, and threaten public heath
Loss and Destruction of Food
It has been repeatedly estimated that between one-fifth and one-third of the world’s food supply never reaches the table due to losses from rodents. In some parts of the world the entire crop grown for human consumption has been lost to rodents during outbreaks. Rodents fecal matter and urine contaminate far more food than the rodent can consume. One rat for example, can consume one once (28 gram ) of food each evening. A colony of 50 rats can consume 3 lbs. of food in one week.
Damage To Buildings And Infrastructure
In general, most of the damage inflicted by rodents to our buildings and items are in form of rodent gnawing and burrowing activities. The very word rodent originates from the French word rodere, meaning “to gnaw”.
Did you know that mice …
- Are fertile every 3-4 days
- Can have a litter every 21 days
- Each litter can be as many as 13
- Mice inflict damage in many ways:
- Damaging electrical wire leading to fire hazard
- Malfunctioning thermostats
- Carries and spreads many diseases
- Ruins the food
Rodents use their powerful front incisor teeth as chisel tools to gnaw on a wide range of items and objects. The rodent’s incisors grow continuously at the rate of up to 0.4 mm per day with the lower incisors growing slightly faster than the uppers. The incisors are harder than iron, and several other “soft” metals and a rat for example, can bite several times per second.
Rats can gnaw through wood, aluminum heeling, sheet rock, soft cement, asphalt, and metals such as lead and copper. Thus, property owners and pest professionals of rat infested ares often observe rat holes drilled into doors, floors, and ceilings. Rats will also gnaw through plastic water pipes and irrigation distribution systems to access the water.
The increased use of sophisticated machinery and high tech equipment, we are vulnerable to the gnawing activity of just a single rodent. In all types of residential, commercial and office buildings rodents are of special concern due to their propensity to gnaw on wires. The ensuing damage to wires, pipes, gas lines, and the like, rodent infestations hold the potential for serious damage to fires and explosions.
Both rat sand mice periodically bite people, especially in areas where rodent populations are high and where rodents live in close proximity to people. Most rat bites occur in the lower socioeconomic areas of cities. Unfortunately, it is babies in cribs, the confined elderly, the homeless who are most vulnerable to foraging rats and mice. Foraging rats that bite sleeping infants or adults most likely are attracted to food residues or odors on the person’s mouth, fingers and hands. Most of the bites are mere punctures on the hands and face, although some were more serious and accompanied by rat bite fever.
Claims and perceptions of “rat attacks” occur when people unknowingly get into the pathway between rat harborage and an established food supply. What is perceived as ” an attacking rat” might simply be fright responses from both the person the rats are wandering close to and the near-sighted rat itself.
Rodents And Human Disease
Despite modern day sanitation efforts and antibiotics, rodents continue to play a significant role in the transmission of a large number of diseases to humans.
History has shown the commensal rodents are responsible for some of the most devastating
disease outbreaks of all time. More than 10 million people have died fro rodent borne diseases during the past century alone. Disease organisms ( pathogens ) can be transmitted directly through rodent’s bite and then carried from the rodent ( i. e., vectored ) by a flea, tick, or mite that bites people, thus transferring the pathogen. Pathogens can also be transmitted via direct contamination of food and/or water via rodent feces and/or urine.
The excrement of house mice and rates contain allergens that can trigger asthma and allergic rhinitis in susceptible individuals. According to studies in which dust samples were collected from bedrooms, kitchens and living rooms , and analyzed for urinary protein that causes asthma, the kitchens were by far the most contaminated areas.
Food Borne Illness
If rodents are present in areas where pathogenic bacteria are present, the potential for dangerous germs to be quickly spread is significant. Rodents move easily and quickly between filthy streets, alleys, sewers, garbage cans and dumpsters, into homes, restaurants, food plants, schools and hospitals. Relative to rodents, two of the more important food borne illness threats are both bacteria, namely Salmonella and Campylobacter. These infections enter the body through the mouth and intestinal track. They are typically spread through contaminated food and water or by contact with vomit or feces.
Natural Enemies Of Rats and Mice
Numerous wild animals will actively hunt and kill rodents. However, I. The majority of urban and rural situations involving commensal rodents, predation by other animals is not likely to keep rodent population in check. I cities and towns, dogs and cats kill the occasional rat and mouse, causing their owners to beam proudly. Unfortunately, cats and dogs are not effective at controlling established rodent population. Technically, should the cat kill the first pregnant mouse the home, and none follow, the pet has prevented a possible infestation.
Most companion dogs and cats are too well fed to be effective predators in a typical urban environment. Actually, companion animals probably contribute to the likelihood of a rodent infestation as both mice and rates are highly attracted to stored pet foods.
Various species of hawks and owls prey heavily on rats and mice but the over all impact , if any at all, the levels of commensal rodents is unknown.
Integrated Pest Management Strategies For Rodents
The concept of IPM is emphasized for both rats and mice. The five steps of rodent IPM include:
Inspection and monitoring
Mechanical and other non-chemical tools
Rodenticides and other chemicals
The most successful rodent control programs begin with thorough inspection. A professional level inspection reveals the extent of infestation, harborages, rodent entry points, and the safest , most appropriate , an cost effective control program for the specific situation.