Made from living organisms or from products derived from them, biopesticides are increasingly expected to supplement or even replace synthetic pesticides. After three years of work, a team lead by the universities of Liege Ghent and Lille, have just succeeded  in increasing scientific knowledge about a very specific “family” of natural molecules: the lipopeptides. The extent of the work is such that the production of these molecules on an industrial scale could very soon be a reality.

As far as the protection of crops is concerned, the future does not belong to synthetic pesticides. While it is certainly true that synthetic pesticides will not disappear from the arsenal of farmers, they are likely to be replaced by more natural products that are capable of killing pathogenic agents such as insects, worms, molds and bacteria which have traditionally been the bane of farmers and these natural products do not have the undesirable side-effects of synthetic pesticides. These side effects can include residual persistence of these pesticides in soils and groundwater, resistance of parasites (requiring increased doses or constant use of new molecules), health problems for users (and eventually consumers). Society is becoming increasingly less prepared to bear the ecological and health costs associated with synthetic pesticides.

The research community has not remained inactive faced with these developments. For several years, teams of researchers have been working on the perfection of pesticides manufactured or derived from living organisms in the hope that they will degrade completely and quickly after they destroy the pathogenic agent in question.  And with some success! Although still on a small scale (2.5% of the world market of pesticides in 2008), the market for biopesticides in Western Europe and North America is increasing by 5 to 8 % every year.

Two prized bacilli

Among the successes recorded to date is the exploitation of the properties of some strains of bacteria that proliferate in the rhizosphere of plants, that is to say, the part of the soil directly in contact with the root.  It is thanks to these strains, notably Bacillus subtilis and Bacillus amyloliquefaciens,  that it is now possible to find biopesticides on the market that can reduce the incidence of these pathogens either by directly inhibiting them or by strengthening the immune system of plants (through the production of “elicitors”).



But there is a drawback: the efficacy of these bacilli may be inconsistent and varies depending on other factors such as the weather, hygrometry, soil composition and the nature of the plants to be protected.  “As Bacillus is a living organism, it has to face numerous environmental factors whose impact remains largely unknown. It is not that the bacteria dies, but all the empirical data shows that it loses its efficacy in certain circumstances. The action mechanisms that explain this loss can be demonstrated by physiological studies, but these are long and complex”, explains Marc Ongena, a research associate at the FNRS and a specialist in biopesticides at Gembloux Agro-Bio Tech (ULg)