Insect pests of many crops, fruits, ornamental plants and turfgrass are controlled by using chemical pesticides, beneficial insects, beneficial nematodes, and/or integrated pest management programs. Over the last decade, the use of chemical pesticides has started diminishing due their detrimental effects on humans, pets and wild animals, birds and the environment. Most of the growers have started to use beneficial organisms including predatory insects, parasitic insects, entomopathogenic nematodes and disease causing pathogens to manage their insect pest problems.
In both the online and published literature, these beneficial organisms are commonly called as biological control agents, beneficial insects, beneficial nematodes, bio-controls, bio-pesticides etc. When you introduce these commercially available beneficial organisms/natural enemies in the field or greenhouses for the control of devastating insect pests, the method is termed as 'Biological Control of Insect Pests'.
What are Natural Predators?
Predators are the group of vertebrate and/or invertebrate animals that generally kill and feed externally on their host and also complete their entire life cycle outside the host body as opposed to parasites. Vertebrate predators of insect include birds, amphibians, reptiles, fish, mammals whereas invertebrate predators include beneficial insects like dragon flies, damselflies, soldier beetles, ladybird beetles, ground beetles, rove beetles, lacewings and hoverflies. Several species of beneficial mites and spiders are also predators of many species of pest insects and mites. Insect predators are generally used in biological control programs against many small insects like aphids, midgeflies, fungus gnats, thrips, mosquitoes and caterpillars/larvae/grubs of many insects.
What are Beneficial Nematodes?
Beneficial nematodes also called as entomopathogenic nematodes including Steinernema spp. and Heterorhabditis spp. are considered as parasites or pathogens of insects. These nematodes are commercially available and have been used as biological agents in controlling many soil dwelling insect pests of many economically important crops.
The list of commercially available beneficial nematodes include:
- Heterohabditis bacteriophora Nematodes
- Heterorhabditis indica Nematodes
- Steinernema carpocapsae Nematodes
- Steinernema feltiae Nematodes
What are Parasites (Parasitoids)?
The beneficial insects that complete their at least some part of life cycle inside their host insects are called as parasites. Larvae of these parasitic insects are called as parasitods. These parasitoids generally enter the body of insect host from outside or hatch from eggs inside the body of host insects. Then inside the insect body, parasite larvae feed on host’s body content, develop, eventually kill their host and emerge as adult in the environment. These adults are typically free-living but they can feed on other insects as predators and on honeydew, plant nectar or pollen when their prey is not around. Since parasites complete part of their life cycle inside their hosts, they have to adapt with the life cycle, physiology and defense mechanisms of their hosts.
There are several species of parasitic wasps are commercially available to use as beneficial insects to control aphids, eggs of lepidopterous insects, leafminers, Mexican bean beetles, scale insects and whiteflies.
What are disease causing Pathogens?
Pathogens are group of microorganisms including bacteria, fungi, protozoans and viruses can infect and cause diseases to insects. These diseases caused by pathogens generally inhibit the rate of feeding, reproduction, development of insect pests or kill their populations entirely. One of the most popular insect pathogen is a bacterium, Bacillus thuringiensis (Bt) has been widely used against many economically insect pests of both field and greenhouse crops.