Eggplant Integrated Pest Management AN ECOLOGICAL GUIDE

_____________________________________________________________________Ecology of insect pests and natural enemies4.11.5 Use of mineral based pesticidesAsh from the remains of cooking fires is often used for general insect control. Itseems that ashes can protect leaves from chewing insects. The ashes must becrushed, then thinly and evenly spread. This can be done by putting them into acoarse textured bag, which is shaken over the crop. Ashes provide more protection inthe dry than in the rainy season. Another practice is to spread ash on nursery bedsand homestead gardens to repel ants, commonly done in Bangladesh. In Nepal, amixture of mustard seed kernels (1 part) and ashes (3 parts) is used against red ants.No research data are available to confirm this practice.When washed off the leaves ashes fertilize the soil very effectively. Wood ash is a known source ofpotash and commonly used for fertilization of soils. Unleached wood ash can contain around 5% potashin the form of potassium carbonate, which is alkaline and helps increase soil pH. Ashes contain smallquantities of nitrogen and phosphorus in addition.Kerosene and fuel oil kill plants as well as insects. They can be useful against insects that congregate.Nests of ants can be dipped. Spent motor oil can be used for this operation; the oil kills ants in seconds.The oil is very flammable. Kerosene and fuel oil should not be used frequently and on large scale as it isdetrimental to the environment.Related exercises from CABI Bioscience/FAO Vegetable IPM Exercise Manual:1.4. Effect of pesticides on spiders and other natural enemies4.11.6 Use of soapSoap, both the soft soap and washing powders and liquid detergents, can kill insects oncontact. Soaps are complex mixtures of fats or oils with alkalis (soda or potash) andmetallic salts. They seem to destroy insect membranes. Small insects such as aphids,die instantly. Soaps and detergents are harmless to animals, birds and people. Theyact as insecticides at concentrations under 1% but at higher concentrations can injureplants! Care should be taken when making soap solutions.Depending on concentration soaps have three distinct and separate uses:1. In low concentrations soaps reduce surface tension so that water-drops spread flatly. This brings anypesticide carried by the drops into close contact with the leaf surface. It also helps to spread thechemical evenly over insects. In this way soaps improve the power of pesticides. In addition theymake mixing easier by aiding the dispersal of other substances, powder or liquid, into the water.2. In concentrations from 0.5 – 0.8% (5 – 8 g per liter) they kill insects. At 0.5% aphids and smallcaterpillars are instantly killed. Large caterpillars and beetles need concentrations of around 0.8%.3. High concentrations (over 1%) damage or kill plants. Some farmers use them as herbicides (weedkillers).Soaps kill only when wet, once dry they lose their insecticide action. This limits their action to insects hitat the time of spraying. Thus solutions made to the right concentration are in effect, specific to the targetinsect, provided the user sprays carefully.For sale: Insecticidal soap!For many years, farmers have known that soap and water kill insects, but because the mixturessometimes damage plants users have to be careful.Research has isolated some of the insecticidal compounds in soap and they are sold as insecticidalsoaps, non-injurious to plants. Such commercial packs are expensive and of little interest to farmers.Solutions of soap and water can be easily and cheaply home-made, taken into account the abovelisted points.64Eggplant Ecological Guide