Acaricides of natural origin, personal experiences and review of literature (1990-2001)

Acari are responsible for millions of dollars worth of damages each year as a result of infestations in animals, plants and man. They affect our health directly and prosperity as animal and plant parasites, vectors of disease, and producers of allergens. The indiscriminate use of pesticides has destroyed many of their natural enemies of hitherto harmless species and quickly induced resistance in many parasites. At present, the control of acarid parasitic diseases in agriculture, human and veterinary medicine is mainly based on the use of drugs; for this reason the lack of effective drugs often prevents the control of some parasitic diseases, making them more serious and important. The use of commercial drugs involves many problems; besides the drug-resistance shown by the most important parasites, the environmental damage and the toxicity of many synthetic drugs, represent the main problems that strongly limit their use. In addition, drug residues in plant and animal food products are important reasons for further economic losses for farmers and must be regarded as potentially hazardous to man and environment. Plant-derived compounds are generally more easily degradable and could show a smaller negative environmental impact with respect to synthetic drugs. For these reasons, the evaluation of the antiacarid activity of plant extracts is increasingly being investigated in order to obtain new leads, as demonstrated by recent studies that have evaluated and confirmed the effectiveness of many plant compounds on bacteria, fungi, protozoa, helmints and arthropods. This review will be limited to the class Arachnida, sub-class Acaridi, particularly to their control in agriculture, veterinary and human medicine with natural methods