Cabbage Integrated Pest Management : An Ecological Guide.

Ecology of Insect Pests and Natural EnemiesIf traps are used in isolation, information from them can be misleading. A low number catch will notindicate the timing of a pest attack, let alone its severity. Similarly, the number of insects caught in onecrop cannot be used to predict the number that will occur in other crops, not even when the crop are inadjacent fields.The most common types of traps used in the field are shortly described below.Pheromone traps: these are traps that contain a sticky plateand a small tube with a chemical solution called a pheromone.Pheromones are chemicals produced by insects that causestrong behavioral reactions in the same species at very smallamounts. They are usually produced by females to attract malesof the same species for mating. Such chemical is called ‘sexpheromone’.The males will fly to the pheromone trap and are trapped onthe sticky plate. Pheromones have been developed for severalvegetable pests including diamondback moth and armyworms(Spodoptera sp.). Pheromones are mainly used for detectingand monitoring pests, to a lesser extent for control of pestpopulations. One of the reasons is the high cost of pheromones.Light traps: Light traps are usually made of a light (can beelectronic, on a battery or on oil-products) switched on during thenight, and either a sticky plate or a jar filled with water or otherliquids. Insects (mainly night-active moths) are attracted to thelight, and are caught on the sticky plate or fall into the water anddie. Various types of traps are used, and they normally serve onlyas supplementary measures to other control methods. In China forexample, light traps are used for trapping and monitoring thepopulations of the cabbage moth, aphids and whitefly in bothgreenhouses and fields. When adult moths are found in the trap,look for egg masses and young larvae in the field. However, naturalenemies may also be attracted to light traps. When large numbersof natural enemies are caught it may be better to remove the traps.Pitfall traps: are plastic or glass jars,half-filled with water and a detergentlike soap, buried into the soil up tothe rim of the jar. These traps are goodfor catching ground-dwelling insectslike ground beetles. Purpose of thesetraps is purely for monitoring as manyground beetles are active during thenight and you may miss them whenmonitoring the field during the day.Pitfall traps may also be used withoutwater and detergent, to catch livinginsects for insect zoos. However, goodclimbers will escape.Cabbage Ecological Guide - 200062