Invertebrates are the largest group of animal species, encompassing an enormous array of terrestrial and aquatic wildlife. Characterized by their lack of a spine, they include insects, spiders, worms, mollusks, crustaceans, and corals. These animals often form the basis of food chains and are a critical part of healthy, functioning ecosystems. Insects are the largest and most diverse group of invertebrates, serving as important pollinators, controlling vegetation, helping to decompose plants and animals, and providing food for wildlife. They can also kill and damage trees and, when left unchecked by natural predators, undermine the health of entire forest systems.

Forest Service scientists study and develop tools for managing and protecting native invertebrates as well as controlling invasive and exotic invertebrates. This includes basic research to understand environmental factors that make native invertebrate populations vulnerable to decline, methods to prevent and manage invasive and exotic species, and application of innovative technologies like eDNA to more effectively detect and evaluate populations of native and non-native invertebrates.

The Forest Service invests in research on invertebrates because:

• While bark beetles are native to U.S. forests and play important ecological roles, they can cause extensive tree mortality and produce negative economic and social impacts. Climate change has led to an increase in these damaging effects, and the Forest Service is working to better understand bark beetle ecology and improve forest management.

• The emerald ash borer is the most damaging invasive forest insect pest in North America. It has killed hundreds of millions of ash trees across the U.S. since it was introduced. Forest Service researchers study risk, effects, detection, spread, biology, ecology, control and management of emerald ash borer as well as other invasive forest insects including gypsy moth, hemlock woolly adelgid, and spotted lanternfly.

• About 70 percent of the 300 mussel species native to the U.S. are in danger of extinction due to complex factors, including declines in water quality and competition from invasive mussels and clams. Forest Service researchers investigate the drivers of mussel decline to inform land management decisions that might help sustain these important aquatic species.

• Soil invertebrates such as worms, centipedes, nematodes, insect larvae, and beetles are crucial to soil formation, nutrient cycling, biotic regulation, and promotion of plant growth. Forest Service scientists investigate the role these subterranean invertebrates play in forest health and how invasive species like European earthworms are affecting native populations and forest carbon cycling.

Featured Work

• Invasive Species in Forests and Rangelands of the United States: A Comprehensive Science Synthesis for the United States Forest Sector synthesizes current science on species invading U.S. forests, grasslands, and waterways. This book covers invasive species of all taxonomic groups from insects and pathogens, to plants, vertebrates, and aquatic organisms.

• Impacts of Invasive Species on Forest and Grassland Ecosystem Processes in the United States describes the current understanding of how invasive species directly, and indirectly, affect ecosystem processes.

• Tracing the origin of the crayfish plague pathogen, Aphanomyces astaci, to the Southeastern United States describes the origin of the pathogen Aphanomyces astaci, an emerging infectious pathogen affecting freshwater crayfish worldwide that is responsible for one of the most severe wildlife pandemics ever reported.

• Detection of 4 imperiled western North American freshwater mussel species from environmental DNA with multiplex qPCR assays will aid in the detection, monitoring, management, and conservation of these vulnerable mussel species.