Indirect effects of deer on insect pests and soybean plants

• Published in: Agricultural and forest entomology 2021-02, Vol.23 (1), p.41-48
• Main Authors: VanGorder, Abigail E., Mahon, Michael B., Penn, Hannah J., Crist, Thomas O.
• Format: Article
• Language: English
• Subjects: Abundance; Agricultural production; crop damage; crop pests; Crop yield; Damage; Deer; Glycine max; Herbivores; Herbivory; Insects; Leaves; Monoculture; Multivariate statistical analysis; Nutrition; Pests; Planting density; Plants; Soybeans; species interactions; white‐tailed deer
• ISSN: 1461-9555; 1461-9563
• DOI: 10.1111/afe.12401

White‐tailed deer (Odocoileus virginianus Zimmermann) and insect pests negatively affect soybean production; however, little is known about how these herbivores potentially interact to affect soybean yield. Previous studies have shown deer browse on non‐crop plants affects insect density and insect‐mediated leaf damage, which together reduce plant reproductive output. In soybeans, reproductive output is influenced by direct and indirect interactions of different herbivores. Here, we quantified indirect interactions between two groups of herbivores (mammals and insects) and their effects on soybean growth and yield. We examined responses of insect pest communities along a gradient of deer herbivory (29% to 49% browsed stems) in soybean monocultures. Structural equation models showed that deer browse had direct negative effects on soybean plant height and yield. Deer browse indirectly decreased insect‐mediated leaf damage by reducing plant height. Deer browse also indirectly increased pest insect abundance through reductions in plant height. Similarly, deer herbivory had an indirect positive effect on leaf carbon: nitrogen ratios through changes in plant height, thereby decreasing leaf nutrition. These results suggest that pest insect abundance may be greater on soybean plants in areas of higher deer browse, but deer browse may reduce insect herbivory through reduced leaf nutrition. Deer browse indirectly increase insect pest abundance, but indirectly decrease insect leaf damage through changes in soybean plant height and leaf nutritional content. Our results suggest that limiting deer browse in soybean field may reduce the risk of insect pest infestation and prevent direct yield loss from deer.