Shadow surveys: How non-target identifications and citizen outreach enhance exotic pest detection

Abstract

At least 70 exotic invertebrate pests have been newly detected in Washington State since 1990, based on records from the Washington State Department of Agriculture (WSDA) or other published accounts. Most of those species are apparently established. Pests were fi rst detected in multiple ways, including formal surveys by regulatory agencies, accidental captures in formal surveys, and complaints or questions by average citizens. We assigned the 70 detections to four broad categories to better understand how exotic pest detections are made. Twenty species (28%) were detected as "targets" in a pest or commodity-focused survey performed by a regulatory agency. Fourteen species (20%) were fi rst detected as non-targets, or "by-catch" in surveys for other taxa. Twenty-fi ve species (36%) were fi rst found by private citizens, and the remaining 11 (16%) were detected by non-regulatory biologists. Th ese numbers are evidence of the value of non-target identifi cations and an educated and engaged public to exotic pest detection. Th e relative cost-to-benefi t ratio of identifying most species collected in pest surveys and of eliciting and supporting engagement by private citizens is low, and both strategies can be important tools for protecting domestic natural and economic resources.