Soybean cultivars, insect resistant

There are a number of possibilities for using plant secondary chemistry to control herbivory in crop plants. One possibility is to select for insect resistant lines and though it has been done in only a few cases, select for specific allomones. There are, however, some potential problems with this approach. There is a cost for the production of the secondary compounds which may be useful for defense ( ). Insect resistant soybean cultivars produce lower yields of seeds and accumulate nitrogen at a slower rate than insect susceptible varieties in the absence of herbivores 3 ). Conversely, varieties of crop plants selected for high yield are often more susceptible to insects, pathogens, and weeds (35). 

Diseases, nematodes, and insects can cause major yield losses if they are not controlled. In most cases, chemicals are available to help control the problem, but the chemicals and their application can be expensive. Soybean breeders continue to work hard to develop resistant cultivars in areas where specific diseases or nematodes or insects are problems on a regular basis. Space precludes a detailed discussion of management of these pests. Recent summaries of management practices for diseases, nematodes, and insects are found in Grau et al. (2004), Tolin and Lacey (2004), Ni-black et al. (2004), and Boethel et al. (2004). 

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