Cabbage Integrated Pest Management : An Ecological Guide.

Major Natural Enemies of Cabbage Insect Pests6.1 PredatorsPredators are animals that kill and eat other animals. They can be verylarge animals like lions that kill and eat deers, cats that eat mice, orspiders that eat moths.Predators usually hunt or set traps to get their prey. They can kill orconsume many prey and are generally larger than their prey. They areoften generalists rather than specialists and can attack immature andadult prey. When there is not enough prey around they may even eateach other!Predators of insect pests can be divided into groups such as beetles, true bugs, lacewings, predatoryflies, predatory mites and others like spiders and praying mantids.Predators are especially important natural enemies because they can often survive when there are noinsect pests around. They can switch to other food sources like crop visitors or neutrals, insects that livein the field but do not attack cabbage plants. They may even eat each other in times of low foodavailability or move to the borders of the field to find prey. Predators are therefore often the first cropdefenders against pests. Predators follow the insect population by laying more eggs when there is moreprey available. When no predators are around, pests that arrive in the field can easily increase theirpopulation.In this section, a number of predators that are important for cabbage pest insect control are described.6.1.1 Lady Beetles - CoccinellidaeAlso called ladybugs, ladybird beetles or coccinellid beetles. There are manydifferent species of lady beetles. However, not all lady beetles are predators.Some, like Epilachna sp., are herbivores, particularly on solanaceous crops.Check feeding habits in insect zoo studies (section 4.4)!Primary prey: aphids, mites, whiteflies, small insects, insect eggs.Predatory stages: both adults and larvae.Description and life cycleAdult lady beetles are small, round to oval inshape. The typical species present in manyvegetables has black markings on red, orange oryellow forewings. Different species of ladybeetles have a different color or different markings.Both larvae and adults of lady beetles arepredators: they eat aphids, small caterpillars,mites and insect eggs. Many lady beetles prefera diet of aphids but may switch to other preywhen there are not enough aphids. The larvaehave a very different appearance from the adults.They are dark and look a bit like an alligator with3 pairs of legs. There are usually 4 larval instars.Lady beetles can consume many prey on a dayand can also travel around quite far (larvae maytravel up to 12 m) in search of prey.Life cycle of the lady beetle(from : Hoffmann et al, 1993)Cabbage Ecological Guide - 2000110