Potential spatial interaction of the invasive species Harmonia axyridis (pallas) with native and endemic coccinellids

Abstract

Biological invasions represent a serious menace to local species assemblages, mainly due to interspecific relationships such as competition and predation. One important invasive species worldwide is Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae), which has invaded many regions of the world, threatening the native and endemic coccinellid assemblages due to negative interspecific interactions. These interactions have been widely studied at a local scale, but have been less studied at regional scales. Our aim was to estimate and analyse the potential spatial interaction associated with the co-occurrence of H.axyridis with native and endemic species in Chile, considering bioclimatic and land cover variables. First, we created species distribution models (SDM) for H.axyridis, native and endemic coccinellids and six representative coccinellid species using maximum entropy technique. Then, we overlapped each SDM with land cover types to estimate the bioclimatic suitability within each land cover type. Finally, we identified the co-occurrences of organisms according to the SDM and the land cover types, estimating in what land covers H.axyridis and the other coccinellids are more likely to co-occur. Our results show that the suitable area for H.axyridis occurs from 30 degrees to 42 degrees S in Chile, while for native and endemic species this area is greater. The six selected species are mainly concentrated in central Chile, but differ in their potential suitable areas; Adalia angulifera Mulsant and Scymnus bicolor (Germain) have the largest range, and Mimoscymnus macula (Germain) has the most restricted one. The highest level of potential spatial interactions with H.axyridis occurs in central Chile, specifically in croplands and scrublands, and the lowest in primary native forest for all the species. Our results provide a spatially explicit baseline for coccinellid conservation and management of this invasive species.