Eggplant Integrated Pest Management AN ECOLOGICAL GUIDE

_____________________________________________________________________Ecology of insect pests and natural enemiesPicture from Fliert and BraunETLAgro-ecosystem Analysis (AESA)• cost of control • growth stage• harvest value of crop (estimation) • weather conditions• loss of income due to pests (estimation) • crop development factors (incl. compensation ability)• type and number of insect pests• type and amount of diseases• type and number of natural enemies• type and amount of natural disease control agents• type and amount of weeds• water availability (irrigation, drainage)• soil fertility status• fertilizer applications• activities in the field since last week• other observationsEconomic Threshold Levels may give a very general indication for the number of insects that can betolerated on a crop but they are seldom specific for the situation in your field today. Be very critical tothese threshold levels and monitor your field regularly to check for yourself in your own field whatdecisions need to be taken.4.11.4 Use of botanical pesticidesSome plants have components in the plant sap that are toxic to insects. When extractedfrom plants, these chemicals are called botanicals. Generally botanicals degrade morerapidly than most conventional pesticides, and they are therefore considered relativelyenvironmentally safe and less likely to kill beneficials than insecticides with longerresidual activity. Because they generally degrade within a few days, and sometimeswithin a few hours, botanicals must be applied more often. More frequent application, plus higher costs ofproduction usually makes botanicals more expensive to use than synthetic insecticides. When they canbe produced locally they may be cheaper to use than synthetic insecticides. Toxicity to other organismsis variable, although as a group, they tend to be less toxic than non-botanicals to mammals (with theexception of nicotine).Using botanicals is a normal practice under many traditional agricultural systems. A well-known andwidely used botanical is neem, which can control some insects in vegetables. In Vietnam, vegetablefarmers have utilized several botanical pesticides, including extracts from Derris roots, tobacco leavesand seeds of Milletia, which they claim to be effective. However, in addition to pest insects, some naturalenemies may be killed by botanicals!A few commonly used botanicals will be briefly described below.61Eggplant Ecological Guide