Effect of jasmonate-induced plant responses on the natural enemies of herbivores
Article first published online: 5 MAR 2002
Journal of Animal Ecology
Volume 71, Issue 1, pages 141–150, January 2002
How to Cite
Thaler, J. S. (2002), Effect of jasmonate-induced plant responses on the natural enemies of herbivores. Journal of Animal Ecology, 71: 141–150. doi: 10.1046/j.0021-8790.2001.00586.x
- Issue published online: 5 MAR 2002
- Article first published online: 5 MAR 2002
- Received 5 March 2001; revision received 10 October 2001
- development time;
- field experiment;
- induced resistance;
- parasitic wasp;
- 1Plant traits can act as defences against herbivores both by reducing herbivore performance directly and by increasing the effectiveness of the natural enemies of herbivores. Natural enemy performance and rate of parasitism can be affected by plant traits and/or changes in herbivore quality.
- 2Jasmonic acid is responsible for the induction of many changes in plant resistance that occur following herbivore attack. This study examines the effects of jasmonate-induced defences on the abundance and performance of natural enemies, as well as the interaction between induced plant responses and parasitism in their ability to kill herbivores.
- 3In a tomato field containing plants induced with jasmonic acid and control plants, the abundance of natural enemies was counted using several census techniques. Induced resistance affected the abundance of natural enemies of herbivores differently. One predator of aphids, syrphid flies, was negatively affected by the decrease in herbivore abundance on induced plants. One parasitoid of caterpillars, Hyposoter exiguae Viereck, was not affected by induced resistance in this study although it was positively affected in a previous study. Two other natural enemies, a parasitoid of aphids and ladybeetle predators, were not affected by induced resistance.
- 4Induced resistance and parasitism both reduced the survivorship of herbivores. In a 2 × 2 factorial design with induced resistance crossed by parasitism, the interaction between the effects of induced resistance and parasitism on herbivore survival was tested. Two trials of this experiment were conducted; one where induced resistance affected both herbivore quantity and quality and one where induced resistance only affected herbivore quality (herbivore density was equalized).
- 5Parasitoids were more effective at killing herbivores feeding on control plants than herbivores on induced plants. This difference was due to a difference in herbivore quality, not herbivore quantity. Herbivores feeding on induced plants have lower mass than herbivores on control plants and this appears to be a major factor reducing the performance of developing parasitic wasps.
- 6Thus, jasmonate-induced responses influence natural enemies species in differing ways, sometimes reducing the density of herbivores and sometimes reducing the quality of herbivores for natural enemies.