Indoor planting schemes in public places sometimes resort to the use of soaps and detergents against insect pests because these chemicals are short lived and non toxic. They leave minimal residues and no unpleasent odors. These products work by penetrating the fatty acids of the cuticle, dissolving and disrupting cell membranes and causing death of the insect by dehydration. They can also interfere with the insect’s natural production of growth hormones during metamorphosis and they can block the spiracles thus impeding respiration. Not all soaps and detergents are effective because only certain long-chain fatty acids have these insecticidal properties.
Products work by direct contact with insects and will have only minimal action as dried residues on plant surfaces. Trials need to be conducted to decide what products to apply in what concentrations. Some dish-washing products at 0.4 - 3% have been found effective against red spider mites, aphids, psyllids and thrips. The products tend to be very effective against the nymphal stage of aphids. Populations of Citrus mite (Panonychus citrii) and the thrip Heliothrips haemorrhoidalis have also been reduced. In experiments a 1 - 2% acqeous solution using products such as Palmolive®, Dove® and Tide® the numbers of Bemisia tabaci aphids were significantly reduced. Some plants, more especially those with hairy leaves may be more susceptible to pytotoxity using these soaps and detergents. Clearly, these products have not been approved for use as insecticides. For further information: Fax 001 2173334777, E-mail: rcloyd@uiuc.edu www.ofa.org |
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