Question

What are the benefits of biological control? What are the negative impacts of chemical control on invasive plant species? Do the benefits of biological control outweigh the negative impacts of chemical control? (Explain)

Answer 1

Biological control refers to the method of controlling pests such as mites, insects, weeds etc with the help of natural predators rather than chemicals or pesticides. For example, ladybird (beetles with red and black markings) helps in controlling the population of aphids, dragonflies are used for controlling the population of mosquitoes. In addition, Bacillus thuringiensis is used as microbial biocontrol agents against butterfly caterpillars.

It is important to know about all the life forms inhabiting the fields such as predators as well as pests, their life cycles, pattern of feedings, habitats they prefer in order to develop appropriate means of biocontrol.

Chemical control on other hand uses chemicals such as pesticides, herbicides, weedicides etc in order to control or manage the pests, weeds, etc in agriculture. These chemicals have many negative effects such as:

• They may kill both harmful and useful life forms indiscriminately.
• Complete eradication of insects or pests may disturb the balance of an ecosysytem and hence decreases the biodiversity.
• Water pollution by biomagnification and accelerated eutrification.
• Decreased quality of soil (acidification of soil, mineral deplition, etc).
• It also decreases the yields of the crops.
• These chemicals have adverse effects on other life forms such as other plants, animals, fish, birds etc.

Biological control with advancement in biotechnology is becoming more specific and efficient such as Bt-cotton etc. Genetic engineering is developing insect and pest resistance crops which decreases the dependence on toxic chemicals. These have no negative impacts on other plants, animals, birds, fishes and even on non-target insects. Hence, it not only decreases the pollution but also aids in conserving the beneficial insects.