By BioBichos Ltd agronomist Marcos Gerding

Biological control is an efficient and clean tool for managing agricultural pests, involving the identification, production and liberation of natural enemies in order to reduce the numbers of the pest organism.

The first great success in biological control in Chile was in 1921 with the introduction of the parasitoid, Aphelinus mali (Hymenoptera: Aphelinidae), responsible for the control of the woolly apple aphid (Eriosoma lanigerum). This insect achieved a substantial reduction in pest populations. Recently at the end of the 20th century there was a resurgence in this insect's population, possibly attributed to the application of insecticides to control codling moth.

Until 1983, there were 76 beneficial species that had been introduced to manage pests, and of the 66 of these that were to control insects with parasitoids and predators, three were entomopathogenic, three were phytophagous and one was a nematode pathogen.

All these introductions were made to develop classical biological control programs, meaning they imported beneficial agents, multiplied them in laboratories and liberated them without intervention afterwards. That's how they achieved important successes in controlling pests like the woolly apple aphid, the cottony cushion scale, the black olive scale, the pale green wheat aphid, the green alfalfa aphid, the grain aphid, the Russian wheat aphid, European pine shoot moth, and in weeds such as St John's wort.

Between 1903 and 1983, 55% of the total amount of beneficial insects introduced to the country were positively established, but not all were considered successful in controlling the pests for which they were introduced.

Since that year going forward, the ratio of success to introduction has increased substantially due to an improvement in laboratory breeding techniques, greater knowledge of the biology of each pest, and an improvement in the means of transport that has meant that the conditions of insects are better on arrival than in the past, when shipments were made by sea.

But not all biological control is based on introducing beneficial agents. In Chile there is a great diversity of beneficial species that contain many pest populations to levels that do not affect crop production - ladybirds, hoverflies, tachinid flies, ground beetles, wasps, bedbugs, entomopathogenic fungi and mites, to highlight a few. Many of these species have been in the introduction plans of other countries such as the U.S., Brazil, France, Bolivia, Peru, Argentina, Japan and India.

The most recent achievements of classical biological control involve the introduction of natural enemies to control wheat aphids (1976-1980), the Russian wheat aphid (1987-1990), the European pine shoot moth (1987-1922), the ash whitefly (1995-2000) and the Easter Island domestic fly (1982-1984).

In recent years, interest has increased in the use of biological control for both pests and diseases, which is reflected in an increase in companies dedicated to this area.

So that good perspectives on the use of this system are kept with time, it is important to consider the quality of the biological matter sold, as well as evaluating the establishment of liberated organisms and their control potential.

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