Modeling the distribution of the invasive alien Cycad Aulacaspis scale in Africa under current and future climate scenarios

Abstract

The cycad aulacaspis scale, Aulacaspis yasumatsui Takagi (Hemiptera: Coccoidea: Diaspididae), is native to Southeast Asia but an invasive pest of the gymnosperm order Cycadales in many parts of the world. Aulacaspis yasumatsui was recently reported on the cycad genus Encephalartos in South Africa and is currently categorized as a ‘prohibited terrestrial invertebrate’ in the invasive species legislation, National Environmental Management: Biodiversity Act, 2004 (NEM:BA). Encephalartos is endemic to Africa, and 11 species are listed as critically endangered and four species as endangered. Seeing the limited distribution of A. yasumatsui in South Africa and only one unconfirmed record from the Ivory Coast, understanding the potential distribution range is essential for control and management. Here we model the potential distribution of A. yasumatsui under current and future climate scenarios in Africa, with a focus on South Africa. Future climatic scenarios were simulated using a bioclimatic software, CLIMEX. The model indicates that, under the current climatic scenario, all 17 African countries possessing Encephalartos are susceptible to A. yasumatsui establishment. However, under climatic change, the suitability decreases for large parts of Africa. In South Africa, 93% of the winter rainfall areas, and 90% of the temperate, summer rainfall areas are suitable for A. yasumatsui establishment. In this study, we highlight the urgent need for regulation, management, and research on A. yasumatsui in African countries with native cycads.