Cabbage Integrated Pest Management : An Ecological Guide.

Major Cabbage Insect PestsDiadegma semiclausum is mass-produced in rearing facilities in the highland areas of many countries inSoutheast Asia. See box below for an example.Diadegma semiclausum in the PhilippinesFarmers in the mountain province Cordilleras applied insecticides for DBM control 24 to 32 timesduring the dry season and 18 times during the wet season. DBM had become resistant to manypesticides and farmers were resorting to highly toxic compounds. When the National IPM Programwas implemented and the parasitoid Diadegma semiclausum was introduced, many of the farmersreduced their pesticide application to only 2 times, for control of other pests. Diadegma is beingreleased into cabbage fields at regular intervals. It can survive by transferring to neighboring fields aslong as farmers do not spray chemical insecticides.It should be noted that farmer training is an essential element in the success of Diadegma.(FAO-ICP Progress report ‘96 – ’99)· Diadegma insulareThe parasitoid Diadegma insulare is better adapted to warmer conditions andmay play a major role in controlling DBM in areas that are too warm for D.semiclausum. Diadegma insulare from Florida (USA) was recently introducedin the Philippines for DBM control under lowland conditions. Currently, parasitoidrearing methods are being studied and small scale experiments under nethouseconditions are being done.· Cotesia plutellaeThe parasitoid Cotesia plutellae is also better adapter to warmerclimates than Diadegma semiclausum. Cotesia plutellae is massproducedin countries like the Philippines for field releases anddemonstrations in farmers’ fields. Cocoons are used for field release(FAO-ICP Progress report ‘96 – ’99).However, Cotesia plutellae is found a less effective parasitoid thanDiadegma semiclausum because it performs well at high DBMdensities, but not so well when DBM populations are low. Therefore,introduction of Diadegma insulare for the lowlands is being considered by Vietnam and Philippines(pers.comm. Mr.J.W.Ketelaar, Vietnam, 2000).· Diadromus collarisA parasitoid that was introduced into Vietnam is Diadromus collaris. This little wasp parasitizes thepupae of DBM. Diadromus was released in cabbage fields in highland areas of Dalat, Vietnam in 1998.Monitoring and ecological studies were conducted by Farmer Field Schools and farmer study groups(FAO-ICP Progress report ‘96 – ’99). However, Diadromus collaris has not established yet (Ooi, 1999).Diadromus collaris is established in highland areas in Malaysia (Cameron Highlands).77 Cabbage Ecological Guide - 2000