Eggplant Integrated Pest Management AN ECOLOGICAL GUIDE

_____________________________________________________________________Ecology of insect pests and natural enemiesPyrethroids are synthetic insecticides based on pyrethrins, but more toxic and longer lasting.They are marketed under various trade names, for example Ambush or Decis. Some pyrethroids areextremely toxic to natural enemies! Pyrethroids are toxic to honey bees and fish. Sunlight does notbreak them down and they stick to leaf surfaces for weeks killing any insect that touches the leaves.This makes them less specific in action and more harmful to the environment than pyrethrin. Inaddition they irritate the human skin.Marigold is often grown in gardens for its attractive flowers. They are cultivatedcommercially for use as cut flowers. In addition, marigold can have a repellant effecton insects and nematodes.In Kenya for example, dried marigold when incorporated into the nursery soil wasfound an effective treatment in terms of overall seedling health.Chili or chillipepper: the ripe fruits and seed contain insecticidal compounds.Dried chili powder is highly irritant and difficult to work with, but good resultscan be obtained on control of aphids, ants, several leaf-cutting insects,whiteflies, and other pest insects in vegetable gardens.Studies in cabbage fields in Kenya showed that chili sprays reduced pestnumbers by 50% in the first week after application but these build up again sofarmers concluded from this experiment that chili needs to be sprayed every 14days for effective control (Loevinsohn, 1998). This probably applies for a periodwith low rainfall, as the solution is easily washed off with rain.Several mixtures of chili with other botanicals such as neem or marigold are known to have insecticidalproperties. Set up a field study to experiment!A chili recipe from the Philippines:Boil 500 g of thinly sliced ripe chili peppers in 3 liters of water for 15-20 minutes. Add 30 g of soapas a sticker. Then add 3 more liters of water, allow to cool down and then filter. Apply once a weekif there is no rain, but 2-3 times per week if it rains (Stoll, 2000).Garlic has been long known for its insecticidal activity. It can also protect cropsagainst a variety of fungal and bacterial diseases. Garlic contains garlic oil andallicine, which have insecticidal and bacterial effect. It can be used as a waterextract, for example in a solution of 0,5 l water with 100 garlic cloves, and a littlesoap. The price of garlic can make this recipe expensive. Garlic solutions shouldbe tested on small plots first! Garlic can also be used as a seed coating, toprevent infection by soil-borne diseases or damage by soil insects. See section3.6.3. In some cultivation practices such as biological production, garlic issometimes used as an intercrop for other crops. Its strong odor may repel insects.See section 3.15.Despite being “natural” and commonly used in some regions, from the characteristicslisted above it is clear that botanicals can be very dangerous to use. Some botanicals may bemore dangerous to the user than chemical pesticides! And in addition they may be very toxicfor natural enemies.Always set up a study first on the effects of botanical pesticides on the ecosystem and onthe economics. Do not just replace chemical insecticides with botanicals. First understandthe ecosystem and how botanicals influence it!63Eggplant Ecological Guide