Pesticides are applied to crops by agricultural aircraft, tractor-mounted crop sprayers, aerial spray by modern aircraft or as seed dressings to control pests. However, successful control by pesticides is not easy; the right formulation must be chosen, the timing is often critical, the method of application is important, adequate coverage and retention on the crop are necessary. The killing of natural enemies of the target Pest Control Colchester should be minimized. This is particularly important in countries where there are natural reservoirs of pests and their enemies in the countryside surrounding plantation crops, and these co-exist in a delicate balance. Often in less-developed countries, the crops are well adapted to the local situation and no pesticides are needed. Where progressive farmers are using fertilizers to grow improved crop varieties, these are often more susceptible to pest damage, but the indiscriminate application of pesticides may be detrimental in the longer term.
The efficacy of chemical pesticides tends to diminish over time. This is because any organism that manages to survive the initial application will pass on its genes to its offspring and a resistant strain will be developed. In this way, some of the most serious pests have developed resistance and are no longer killed by pesticides that used to kill their ancestors. This necessitates higher concentrations of chemicals, more frequent applications and a movement to more expensive formulations.
Pesticides are formulated to kill pests, but many have detrimental effects on non-target species; of particular concern is the damage done to honeybees, solitary bees and other pollinating insects and in this regard, the time of day when the spray is applied can be important. The widely used neonicotinoids have been banned on flowering crops in some countries because of their effects on bees.
Pest control can also be achieved via culling the pest animals generally small- to medium-sized wild or feral mammals or birds that inhabit the ecological niches near farms, pastures, or other human settlements by employing human hunters or trappers to physically track down, kill and remove them from the area. The culled animals, known as vermin, may be targeted because they are deemed harmful to agricultural crops, livestock, or facilities; serve as hosts or vectors that transmit pathogens across species or to humans, or for population control as a means of protecting other vulnerable species and ecosystems.
Pest control via hunting, like all forms of harvest, has imposed an artificial selective pressure on the organisms being targeted. While varmint hunting is potentially selecting for desired behavior and demographic changes, it can also result in unpredicted outcomes such as the targeted animal adapting for faster reproductive cycles.
Forest pests present a significant problem because it is not easy to access the canopy and monitor pest populations. In addition, forestry pests such as bark beetles, kept under control by natural enemies in their native range, may be transported large distances in cut timber to places where they have no natural predators, enabling them to cause extensive economic damage. Pheromone traps have been used to monitor pest populations in the canopy. These release volatile chemicals that attract males. Pheromone traps can detect the arrival of pests or alert foresters to outbreaks. For example, the spruce budworm, a destructive pest of spruce and balsam fir, has been monitored using pheromone traps in Canadian forests for several decades. In some regions, such as New Brunswick, areas of forest are sprayed with pesticides to control the budworm population and prevent the damage caused during outbreaks.