Its like a combination of science fiction and the arms race. Stories about super rats, super bugs and a wide variety of mutant bacteria, vertebrates and invertebrates hit the headlines at least once a week. Whether its in a house in Tunbridge Wells or the House of Commons on the Thames, rats are growing in size and becoming immune to all forms of poison.

Genetically modified crops that have been developed to deter insects are beginning to fail. Their hungry insect predators have developed a resistance to the toxins that have been developed to grow inside a plant.

Add this to ever greater instances of infections in hospitals and other medical centres, and it seems that the super pests are taking over the world.

Evolution And Adaptation

The explanation is that this is not a consequence of science fiction but a lack of common sense. Living organisms have survived on Earth through mass extinctions as well as changing landscapes, oceans and climates because they adapted to the problems that the Earth’s forces threw at them. So surviving and adapting to the infinitely weaker problems thrown at them by humans is easy.

Herbicides, pesticides and insecticides applied to fungus, insects or animal pests eventually run off into water courses after rainfall and cause poisoning and other environmental damage. Proprietary pesticides bought over the counter by the public have become progressively less toxic in order to protect pets, humans, birdlife and garden or agricultural plants.

In addition, local authorities have been cutting back on their pest control services. Householders who spot rats in their garden immediately worry about the costs of hiring private contractors to deal with them. So the rats can live on and multiply.

Waste-Disposal Problems

Less frequent waste disposal and the ubiquity of fast food have provided rats, mice and other pests such as urban foxes with a regular food supply as the waste festers in poorly secured plastic bags or other containers.

Overflowing bins full of waste food are a common sight all over Britain.

But huge rats have even penetrated into well-built apartment blocks in places such as southern Stockholm. This should not be a surprise as many apartment blocks have common waste-disposal chutes that lead to a central point where food is plentiful.

The more food the pests eat, the bigger they grow. Some rats found in southern Ireland had grown to about two feet in length. Even if the rats can be lured into a trap, the animal is so large that it still has to be removed manually.

Mutations

The rats are also mutating and adapting to poisons applied. Weaker specimens may die, but the stronger ones are able to withstand ever more poison as they adapt.

Few animal species are as capable of adapting to a human environment as rats. They can live in cool rooms in food and catering establishments by growing long fur as they live in temperatures close to zero degrees C.

Rats also have no predators aside from humans. Urban development has wiped out many bird species such as hawks, owls and eagles that hunted for rats.

Rural foxes know how to hunt rats but they are moving into urban areas where food is plentiful. They no longer need to hunt rats in order to survive.

This means that eventually rats will be able to develop to a huge size — conceivably to the size of a sheep or even a bull. The capybara is a modern example of this possibility. It is the largest rodent in the world, which is closely related to the guinea pig and more distantly related to the coypu — a rodent first bred for its fur that caused havoc in East Anglia when some escaped into the wild. The coypu was largely eradicated in Britain by the late 1980s.

Genetically Modified Crops

Agricultural crops face more serious problems. Various aphids and mosquitoes, cotton bollworms and silver leaf whiteflies have developed metabolisms that are resistant both to externally applied pesticides and the toxins contained in genetically modified food and fibre crops.

This has left farmers and scientists with a dilemma: do they apply ever stronger pesticides to kill the pests, or will they have to counter the resistance by continuously developing new strains of crops, often in the face of massive public disapproval?

Laboratory experiments conducted on bollworms showed that they exhibit unexpected mutations - sometimes in one gene and sometimes in a completely different gene.

Italian and Australian scientists have discovered a process that incorporates an inhibitor to deactivate an insect’s enzyme metabolism that resists pesticides. This process has been successfully tested in South Africa and Spain.

Every measure to fight the insects will probably be met with a countermeasure when the insect adapts. The future challenge is how to develop crops that can withstand such pests without damaging human health at the same time.