Predators, Parasites, Pathogens for control of Insect Pests

The beneficial species of insects and other bio-control agents often control insect pests, especially in places where use of broad-spectrum pesticides is avoided. Without these beneficial species the insect pests would multiply so quickly that they would completely damage the crop.

The natural balance between insect pests and their natural enemies is often disrupted by indiscriminate use of chemical pesticides. Although pesticides are needed in some cases they must be used judiciously in order to save these natural bio-control agents.

Predators


Predators often are most important group of biological control agents; each predator will consume many preys during its lifetime. These predators are some times confused with pests. Predators occur in almost all crops. Some, such as, certain Spiders, Ladybird Beetles, Green Lacewing, Dragon Fly, Reduviid Bug and Wasp search the crops for prey such as Red spider mites, Caterpillars etc.

It is important to realize that the presence of insect pests in small numbers which cause no economic damage (i.e. below threshold level) is helpful for they provide food to maintain populations of the beneficial species at levels which can effectively prevent damaging pest outbreaks.

It is extremely costly to mass-rear predators for release in field. There are already many predators in the agriculture field. Predators should be conserved by using broad-spectrum insecticides very sparingly or by applying insecticides which are selectively toxic to pests but not to predators.

Parasites

Parasites are generally more host-specific than predators. However, their effect on a pest population can be extremely important. Parasites should be spared by using insecticides judiciously.

Pathogens

Various microorganisms can infect and kill insect pests. The major groups are fungi, viruses and bacteria. Pathogens causing diseases of pests can be mass-produced at a low cost in liquid or powder form that can be sprayed like an ordinary insecticide.

Bacillus thuringiensis, Trichoderma, Pseudomonas, Beauveria bassiana, Meterrhizium and NPV are approved as Bio-Pesticides by Central Insecticides Board and Registration Committee under Insecticides Act, 1968.