Print PagePlants often experience herbivory on both above and belowground tissues, and damage to either tissue can directly influence the other. While a growing number of studies in above and belowground systems examine the effects of root herbivory on aboveground interactions, the effects of leaf herbivory on root herbivore behavior remain unclear. Understanding these interactions can shed light on how aboveground herbivory may alter the composition of belowground communities. Here we used cucumber plants (Cucumis sativus) to examine how leaf herbivory by the specialist striped cucumber beetle (Acalymma vittatum) affected preference of root feeding larvae by the same herbivore species. We manipulated leaf herbivory using both specialist adult striped cucumber beetles and generalist third instar fall armyworms (Spodoptera frugiperda) in the greenhouse in 2009, and using striped cucumber beetles only in the field in 2010. All experiments allowed larvae to choose between roots of plants with or without damaged leaves.
Results/Conclusions
In the greenhouse, plants with both specialist and generalist herbivore damage had approximately 50% fewer larvae on roots than undamaged plants. A similar pattern was found in the field: plants with damaged leaves recruited marginally significantly fewer larvae to their roots than undamaged plants. Root larval preference for undamaged plants suggest that leaf herbivory in cucumber plants may repel root herbivores through induced chemical responses. However, the lack of substantial differences between specialist and generalist herbivore damage suggests that the effects of leaf herbivory on cucumber roots may not be linked to damage by specific herbivores. Other research has demonstrated that root herbivore damage can negatively affect cucumber plants by reducing growth, production of female flowers and fruit yield. Thus, the current study shows that the costs of leaf damage may be mitigated by deterring belowground damage.
