Introduction: Factual information and generalisation

Close examination of an example that stands squarely in the realms of pest management will help to introduce the methodological problems faced in IPM-oriented ecological research on pest or beneficial species. The development of ecological understanding of this nature invariably involves a range of theoretical intricacies.

Table 2.1 is a reproduction of the first page, of five, listing the names of all host plants of Helicoverpa armigera and H. punctigera in Australia (Zalucki et al., 1986). Consider, with regard to host plant use by H. punctigera, what actually represents a fact. Almost invariably respondents regard, as a fact, the observation that H. punctigera may feed on any one of numerous host species. By slight extension, it becomes a fact that H. punctigera is polyphagous. But these are not facts; rather, they are generalisations. Although such generalisations in biology have different facets, they are seldom specified in their entirety. In the example above, they specify pattern (H. punctigera larvae feed on many host plant species) as well as process.