Cabbage Integrated Pest Management : An Ecological Guide.

Ecology of Insect Pests and Natural Enemies6. Many adult parasitoids and predators also benefit from the protection provided by refuges such ashedgerows and cover crops. Other shelters may be provided for natural enemies to survive. Anexample is given in the box below.Manipulation of Natural Enemies in rice straw bundlesSome of the predators present in rice fields are alsopresent in vegetables. Spiders and other predatorsseek refuge in rice straw bundles at the time of riceharvest. If these straw bundles or tents are placed inrice fields when the crop is harvested and naturalenemies are allowed to colonize them, the bundlesmay be moved to vegetable plots where predatorscould colonize vegetables more quickly. Thus,conservation/augmentation of natural enemiesthrough manipulation of straw bundles could be usefulin reducing the impact of vegetable insect pests.Related exercises from CABI Bioscience/FAO manual:4.9. and 4.10. Importance of flowers as food source to adult parasites.4.10 Purchase and Release of Natural EnemiesIn several countries in Asia, commercial or non-commercial insectaries rearand market a variety of natural enemies including several species of parasitoids,predaceous mites, lady beetles, lacewings, praying mantis, and pathogenssuch as NPV (virus), and Trichoderma. Availability of (commercially) availablenatural enemies in a country also depends on the regulations of this countryregarding registration (Regulatory Affairs).Numerous examples from Asia exist on the use of reared natural enemies for release in the field. Someof those include the release and establishment of the parasitoid Diadegma semiclausum for control ofdiamondback moth in highland cabbage in various Asian countries. Other examples are the introductionof the parasitoid wasp Diadromus for diamondback moth control in Vietnam. Introduction of naturalenemies is often a long process that includes training in parasitoid rearing, establishing an efficientrearing facility, setting up (field) experiments and farmer training (Ooi, Dalat report, 1999).Success with such releases requires appropriate timing (the host must be present or the natural enemywill die or leave the area) and release of the correct number of natural enemies per unit area (releaserate). In many cases, release rates vary depending on crop type and target host density.This guide does not make specific recommendations about the purchase or release of the (commercially)available natural enemies, but it does provide information about the biology and behavior of somecommercially reared species that are important for cabbage pest insect control. This information couldbe helpful in making decisions regarding their use. See chapter 6. In addition, addresses of institutionsproviding or marketing natural enemies in Asia can be found in manuals such as “The BiopesticideManual” (BCPC, 1998) and on several sites on the Internet, for example that of the US department ofAgriculture, at www25 and www29 (see reference list).Cabbage Ecological Guide - 200060