Potential of essential plant oils to control insects and microorganisms

Abstract

The repelling or attracting plants substances are mainly from terpenic nature and they appear as molecules with less molecular weight and volatile. Usually, these substances are known as aromatic or essential oils, which amass themselves at all herbal organs. In the herbs, essential oils develop functions related to volatility, acting to attract the pollinating, to protect against pathogens predators, in the missing of water, to rise the temperature and also making ecological functions, especially as a germination inhibitor. These features make the plants which produce these aromatics a powerful source of biocidal agents, being steadily studied in agroecosystems, principally because of the bactericidal, fungicidal, and insecticidal activities. The main components are the monoterpenes, followed by sesquiterpenes, besides aromatic compounds with low molecular weight. The specific function that essential oils turns out on the plant is still unknown; however, it is supposed that the higher plants synthesize terpenoids which are essential to their growth. These substances of secondary metabolism can act as germination inhibitors, protection against predators, pollinator attractors, among others. However, the evaluation of these compounds with general purposes is recent, for example, using it as natural insecticide or herbicide, or to control pathogenic microorganisms of cultured plants, since there are few research papers developed and published in this area. This review tells about the interactions of essential oils of medicinal, wild, and cultured plants with microorganisms and insects.

Key words: essential oils, insects, fungi, bacteria.