Insects and Pathogens

The technique does not include toxins or secondary metabolites that are produced from living organisms as these are nonliving. In 2000, biopesticides sales worldwide had a value of US $160 million of which about 90% contained Bacillus thuringiensis (Bt), a Gram positive bac terium found in soil or on plant surfaces. The sales of biopesticides have been increasing rapidly since the 1980s.

This market is mainly driven by consumer require ments for environmental and human health and the increasing problem of pest resistance. Currently, key markets for these products are organic and integrated pest management (IPM) systems and systems with high pest resistance and high value speciality crops.

The first example of a commercially available bio pesticide was in the 1920s, where Encarsia formosa was sold to control greenhouse whitefly. This biopesticide is currently widely available commercially and has been sold in increasing amounts since initiation. This is one of the several examples where an invertebrate species has been used as a biopesticide agent and is largely successful because of the controlled environ ment of a greenhouse. Generally, invertebrates are not considered to be appropriate for the technique as they are too difficult to apply and are generally too mobile for field conditions. The first biopesticide containing a microorganism as the biologically active ingredient was Bt and was used in France in the 1930s; it is a product which has dominated the biopesticide market ever since. From this time, development in the area has been focused on creating a product that is easy to culture, store, and apply, has a fast impact, and is environmentally robust. Initially potential agents were usually tested and found to be effective under the ideal environmental conditions of the laboratory, then applied under field conditions where they often failed. Failures were commonly a result of poor spray coverage, low spore viability, or unfavorable environ mental conditions. The importance of the environment for agent virility was then fully acknowledged and agents were then screened and tested for effectiveness under different climatic conditions. This approach not only assessed compatibility between the agent and the host, but also propagule hardiness and viability under adverse conditions. Efforts were also spent on formu lating a nutrient rich, stable medium in which the propagule could be stored and applied, in an attempt to maximize the agent's efficacy.

Currently, research in the area comprises many dis ciplines including pathology, physiology, genetics, mass culturing, formulation technology, and propagule stabi lization and application; yet there is little collaboration between the disciplines and this hinders the rate of development of the technology. Interest in biopesticide products from agriculture is also generally low due to the fragmented nature of the industry, the lack of interest from agrochemical industries, the availably of 'soft' orthodox pesticides, low grower awareness, and their education about and perception of biopesticides. For the technology to develop further, these things need to change and growers need to change their view of biopesticides from purely a substitute for agro chemicals to a biological organism with environmental requirements.

Was this article helpful?

0 0

Post a comment