Plant-modified trophic interactions

• Plant effects on the strength of trophic interactions among insects are widespread.
• Relevance of detailed laboratory studies demonstrated in field-based studies.
• Field-based studies reveal complexity of multi-species interactions.
• Challenge: link short term studies to multi-generation effects in community context.

Plants can modify the interactions between herbivorous insects and their natural enemies in various ways. Chemical defences from the plants against herbivores may in fact harm the latter's natural enemies, thereby weakening the trophic interaction. On the other hand, volatile chemicals produced by the plant in response to herbivory may attract natural enemies, thereby strengthening the interaction. Recent research shows that effects of plants on insect interactions are not curious phenomena confined to a few specialist species but rather that they are ubiquitous in terrestrial ecosystems and often involve complex interactions among many species. The major challenge now is to study how the commonly reported short-term effects of plants affect long term dynamics of insect interactions in the context of complex natural communities.