| Popis: |
Plants provide protection (domatia), alternative food (nectar, exudates, pollen) and chemical lures which benefit predatory arthropods and thereby protect plants against herbivorous arthropods. Experimental evidence for these indirect effects is reviewed and hypotheses are provided to explain why plants invest in attracting, feeding and protecting predatory arthropods despite the fact that (1) other organisms not beneficial to the plant may utilize these facilities too, and (2) also competing neighbour-plants may profit from these investments. It is argued that although the plant may benefit under certain conditions, plant-bodyguard interactions do not have a single anticipated outcome. Instead, these interactions may have a range of positive, neutral and negative outcomes, the exact value of which depends on position in space and moment in time. The benefits to the plant investing in indirect defence depend on the availability and responsiveness of predatory arthropods, the abundance and responses of cheaters, the degree to which neighbouring plants profit from these investments, and the extent to which other plants in the environment invest or harbour profitable prey. Possibilities for indirect plant defence to arise from coevolution are discussed. |
