Impacts of climate change on high priority fruit fly species in Australia

Victoria and Western Australia. Under 1–3 scenarios, suitable habitat is projected to shift inland in Queensland and NSW. However, the amount of habitat projected to be suitable under all six scenarios remains relatively stable from 2030–2070 (S1 File). Beyond 2030, novel conditions are primarily restricted to the north-western regions (S1 File). The major horticultural host for B. bryoniae is Capsicum annuum (chilli) (S1 File). Our model indicates that key growing regions for this crop in Queensland contained suitable habi- tat for B. bryoniae during the baseline period, and this will continue to be the case until at least 2070 (S1 File). Bactrocera frauenfeldi. Climatically suitable habitat for the baseline period is projected to have been mostly confined to Cape York Peninsula and the Wet Tropics, although small areas in northern Western Australia and the Northern Territory from which the species has not been recorded were also classified as suitable (S1 File). The most important variable in the model for B. frauenfeldi was precipitation of the wettest quarter (75.4%) (S1 File). As the century progresses, suitable habitat is projected to expand under all scenarios except CanESM2 (S1 File). This scenario projects a hot, very dry future, leading to loss of suitable habitat in northern Queensland by 2050. However, the extent of suitable habitat for this species is likely to remain small, relative to other species. In addition, the far north-east of Queensland contains novel conditions, decreasing confidence that this area will be suitable as the century

progresses. As with other species, the Wet Tropics is projected to remain suitable and is not a region in which the model is extrapolating. The major crops for B. frauenfeldi are Mangifera indica (mango) and Carcica papaya (paw- paw) (S1 File). Major production regions in north-western Northern Territory may remain suitable for this species until at least 2070, although there is substantial uncertainty across the climate scenarios. In contrast, it is very likely that the Wet Tropics will remain suitable until at least 2070, irrespective of the climate scenario (S1 File). Bactrocera halfordiae. Baseline climatically suitable habitat for B. halfordiae occurred in the Wet Tropics and subtropics, from north Queensland to eastern New South Wales (S1 File). Precipitation of the driest month (66.8%) and annual mean temperature (32.3%) con- tributed most to this model (S1 File). The geographic extent of suitable habitat is projected to vary considerably across the six cli- mate scenarios. As the century progresses, gains in new habitat may exceed losses under some scenarios (e.g. see ACCESS and MIROC5 in S1 File) while losses are projected under the CanESM2 scenario (which projects a hot future, drying across central regions and higher pre- cipitation in the north-east), mostly due to contractions in the south and east. Across the sce- narios there is consensus that lower elevation regions in the south-east will be suitable. Furthermore, MESS maps indicate little model extrapolation for this species (S1 File).

Crops in the Wet Tropics may continue to be at risk from this species, until at least 2070. However, only 1–2 scenarios project horticultural regions in southern Queensland to retain suitable climate (S1 File). Although horticultural regions along the NSW-Victorian border are projected to have been unsuitable for B. halfordiae in the baseline period, these areas may become suitable between 2050–2070 under some scenarios (S1 File). Bactrocera jarvisi. Suitable habitat for this species is projected to have been mostly con- fined to northern Western Australia, the Top End of the Northern Territory, and eastern Aus- tralia from Cape York to NSW during the baseline period (S1 File). Annual mean temperature (38.0%) and precipitation of driest month (37.2%) had the highest contributions to the model for this species (S1 File). There is substantial consensus across the six scenarios that regions currently suitable for B. jarvisi will remain so until at least 2070 (S1 File). In addition, across some models gains are Impacts of climate change on high priority fruit fly species in Australia PLOS ONE | https://doi.org/10.1371/journal.pone.0213820 February 13, 2020 7 / 19