Crowd surveillance: estimating citizen science reporting probabilities for insects of biosecurity concern

Abstract

Data streams arising from citizen reporting activities continue to grow, yet the information content within these streams remains unclear, and methods for addressing the inherent reporting biases little developed. Here, we quantify the major influence of physical insect features (colour, size, morphology, pattern) on the propensity of citizens to upload photographic sightings to online portals, and hence to contribute to biosecurity surveillance. After correcting for species availability, we show that physical features and pestiness are major predictors of reporting probability. The more distinctive the visual features, the higher the reporting probabilities-potentially providing useful surveillance should the species be an unwanted exotic. Conversely, the reporting probability for many small, nondescript high priority pest species is unlikely to be sufficient to contribute meaningfully to biosecurity surveillance, unless they are causing major harm. The lack of citizen reporting of recent incursions of small, nondescript exotic pests supports the model. By examining the types of insects of concern, industries or environmental managers can assess to what extent they can rely on citizen reporting for their surveillance needs. The citrus industry, for example, probably cannot rely on passive unstructured citizen data streams for surveillance of the Asian citrus psyllid (Diaphorina citri). In contrast, the forestry industry may consider that citizen detection and reporting of species of the large and colourful insects such as pine sawyers (Monochamus spp.) may be sufficient for their needs. Incorporating citizen surveillance into the general surveillance framework is an area for further research. Key message• The citizen reporting probabilities of insects are dramatically influenced by physical features such as size, colour, pattern and morphology. • We demonstrate how it is possible to correct for the inherent bias in citizen reporting by modelling the effect of physical features and species distribution and abundance using a case-control design. This enables predictions of the surveillance sensitivity of citizen reporting of exotic species of biosecurity interest. • For highly featured and/or large exotic insect pests, citizen reporting may provide adequate surveillance for plant health needs. • Exotic insect species for which citizen reporting is unlikely to be effective can be predicted in advance.

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