Over the past two centuries, thousands of non-native insects have hitchhiked to the United States in packing material, on living plants, and in passenger luggage. Scientists from two agencies of the United States Department of Agriculture (USDA) and their partners used the history of live plant imports and invasion by a common group of insects to estimate the rate at which new insects arrive and how many new species of insects might still be in store for the forests and agricultural fields of the United States.
The findings suggest that efforts to reduce biological hitchhiking on live plant imports, often referred to as “biosecurity,” are working. However, more than a century of invasion by Hemiptera insects also suggests that increased trade could offset the effects of improved biosecurity. Up to 25% of Hemiptera insect invaders may have yet to be detected in forests and agricultural fields across the country.
The study, “Hidden patterns of insect establishment risk revealed by two centuries of alien species discoveries,” was recently published in the journal Scientists progress. The study’s lead author, Matthew MacLachlan, a research economist with the USDA Economic Research Service, and co-author Andrew Liebhold, a research entomologist with the USDA Forest Service, reviewed records from 1854 to 2012; they found that 930 non-native species of phytophagous insects of the order Hemiptera have invaded the United States. The research team was able to identify the origins of 770 of these species.
“Our work quantifying the risk of establishment posed by imports from distinct regions and how those risks have changed over the accumulation of trade history and time gives policymakers a better picture of the risks of insect infestation per import unit per region,” MacLachlan said. .
Hemiptera are small insects that feed on plants (the order includes true insects, aphids and scale insects), and many of these species cause considerable damage to agricultural and forestry plants. The order Hemiptera includes over 80,000 species of insects, and incidental transport of living plants or plant products is the primary route by which most Hemiptera move between continents.
“Data on historical finds of non-native Hemiptera in the United States have helped us estimate rates of establishment of new species that may occur as a result of plant imports from various parts of the world today,” said said Liebhold.
Co-authors include Takehiko Yamanaka of the Institute of Agricultural Environmental Sciences, NARO (NIAES) in Japan and Michael R. Springborn of the University of California, Davis.
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Material provided by USDA Forest Service – Northern Research Station. Note: Content may be edited for style and length.