Focus on... Biocontrol

Biocontrol is a field that incorporates far more than the introduction of natural enemies to control pests. Classical biological control, as it is known, has been used for centuries, dating back to Chinese citrus growers, who placed nests of predaceous ants (Oncophylla smaradina) in trees for control of leaf-eating insects. Similarly date growers in Yemen used ants from North Africa to control various pests. In more modern times, one of the earliest successes of using natural enemies was with the cottony cushion scale, a pest that was devastating the California citrus industry in the late 1800s.

Biocontrol is now a vital component of integrated pest management and is seen as an effective alternative to chemical pesticides in controlling pests and diseases. Whilst the research and development for biocontrol continues apace the challenge remains at policy level, particularly in developing countries, to have effective legislation in place to ensure that these agents are safe and effective for farmers to use. Predators, parasitoids, plant extracts and pathogens are all used as biocontrol agents against a variety of important pests and diseases and in this edition of New Agriculturist, we focus on recent developments from different regions to provide an example of each these different type of biocontrol agents and their use in the field.

Regulating for safe biocontrol

Over recent years biocontrol has proved to be a promising alternative to chemical pesticides. Agreement on protocols for testing and using biopesticides has, however, initially delayed their rapid development and more widespread use. Yet encouraging progress has been made in Kenya and most recently in Ghana, in achieving legislation for registration of biocontrol agents...

A sweet solution for sugarcane woolly aphid

In the sugarcane fields of Maharashtra and Karnataka in India, a serious outbreak of sugarcane woolly aphid (Ceratovacuna lanigera) in 2002 resulted in up to 30 per cent losses in sugar yields. However, collaborative efforts have proved effective in breeding and releasing large numbers of natural enemies...

Finotin, a promising new biopesticide

A plant protein that has broad biocidal properties against insect pests as well as fungal and bacterial pathogens could be the next best thing in crop disease and pest control. The scientists who have extracted what they have named 'finotin' from seeds of the tropical forage legume Clitoria ternatea think that this could become a cheap and easy pest and disease control option for farmers...

Biocontrol in tea

Tea plants are subject to attack by a large number of insect pests and fungal diseases, also by bacteria, algae and viruses. Natural methods of controlling fungi and insects are being tested in India and Sri Lanka with increasing success. In Sri Lanka, scientists are focussing on antagonistic fungi and bacteria that parasitize pathogenic fungi and destroy the pathogen in one of several ways...

Halting the march of African armyworm

In Tanzania, serious outbreaks of armyworm occur in nine years out of ten, causing up to 90 per cent losses of crops and pasture in bad years. Previously chemical sprays have been used, and have been funded in part by donors, but the recent withdrawal of donor support has led the government to look for a lower cost solution in the form of nuclear polyhedrosis virus, or NPV...