Citizen science reveals the distribution of the invasive harlequin ladybird (Harmonia axyridis Pallas) in Argentina

Abstract

The harlequin ladybird (Harmonia axyridis) was introduced in numerous countries around the world as a biological control agent but nowadays it is considered as a pest itself. It is a highly invasive species that has negative impacts on native biodiversity, may affect some crops, and causes a nuisance to humans. Despite its relevance worldwide, the invasion by H. axyridis in South America has received little attention. Here we used a citizen science approach to study the distribution of H. axyridis in Argentina where the species was intentionally introduced in 1986. We also informally tested and evaluated the preferences for different methods for reporting records: iNaturalist website, Google form, email, WhatsApp, and Facebook. Most records were reported through WhatsApp and iNaturalist. We found that H. axyridis is widely distributed in Argentina but there are large gaps, particularly in arid regions. The invasion seems to be recent in the south of the country. Citizen science is a valuable tool for mapping invasive alien species in a large country like Argentina, and will help to monitor the continuous expansion of H. axyridis.