In the search for alternative solutions to crop protection problems, the interest in plants and their chemo-biodiversity as a source of bioactive substances has increased. Plants are capable of synthesizing an overwhelming variety of small organic molecules called secondary metabolites, usually with very complex and unique carbon skeleton structures. These subtances have been used for the benefit of humankind for many years as crop protection agents
Plants release chemical compounds into the environment and when they are used as cover crops, mulch, smother crops, intercrops or green manures, or grown in rotational sequences, can combat insect pests and disease pathogens and improve farm yields. Botanicals include crude or semirefined extracts and isolated or purified compounds from various plants species and commercial products
A characteristic feature of plants and other sessile organisms, which cannot run away in case of danger
and do not have an immune system to combat pathogens, is their capacity to synthesize an enormous
variety of low molecular weight compounds, the socalled secondary metabolites. To date, the number
of described structures exceeds 100,000. This rich diversity results in part from an evolutionary process
driven by selection for acquisition of improved defence against microbial attack or insect/animal predation.
By definition, these compounds are not essential for the growth and development of a plant but rather are
required for the interaction of plants with their environment.
When the role of secondary metabolites in natural interactions between organisms is considered, they are
called infochemicals or semiochemicals, terms commonly used in studies of these substances by chemical ecology. semiochemicals are chemicals emitted by plants, animals, and other organisms that evoke a behavioural or physiological response in individuals of the same or other species. They include pheromones and allelochemicals.
Allelochemicals are semiochemicals produced by individuals of one species that modify the behaviour of
individuals of a different species (i.e., an interspecific effect). They include allomones (emitting species
benefits), kairomones (receptor species benefits) and synomones (both species benefit). Pheromones are
semiochemicals produced by individuals of a species that modify the behaviour of other individuals.
a. Plant secondary metabolites as an alternative in pest management
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