Potential global distribution of Aleurocanthus woglumi considering climate change and irrigation

Heat stress. Heat stress parameters were set to allow persistence at all known distribution locations. While most of the native range in south-east Asia does not get above 35˚C, tempera- tures often exceed 44˚C in the Middle East (including Khuzestan province in Iran where there is a persistent population of A. woglumi) [29,53,54]. We set the heat stress temperature thresh- old (TTHS) to 43˚C and the heat stress accumulation rate (THHS) to 0.01 week-1 (stress accu- mulates moderately quickly). The chosen threshold also accords with observations by Cherry [55] that the lethal temperatures for A. woglumi occurred between 40 and 45˚C. Dry stress. Soil moisture dry stress threshold (SMDS) was fitted by using the lower soil moisture growth threshold (SM0) because dry stress begins at the same soil moisture level at which development stops and adjusting the rate (HDS) to -0.05 week-1 to limit the distribution to tropical and subtropical regions where it has been reported. In the Middle East and India, where there are location records, agriculture is only possible because of irrigation. Wet stress. Wet stress was not used to limit the range of A. woglumi in this study because it favours a humid environment and is not limited by this stress. Aleurocanthus woglumi has been found in Madhya Pradesh, India where annual rainfall is close to 1 372 mm, Oyo State, Nigeria with an annual rainfall over 1 000 mm, Trinidad & Tobago with an annual rainfall exceeding 1 600 mm as well as Para´ and Maranhão States in Brazil with an annual rainfall over

1 065 mm according to CLIMEX meteorological data (period 1981–2010). Growth Index (GI). Temperature Index (TI). The Temperature Index in CLIMEX describes the species’ response to temperature and consists of four parameters: DV0, DV1, DV2 and DV3. DV0 and DV3 are the lower and upper temperature thresholds, respectively, whereas DV1 and DV2 are the lower and upper optimum temperatures, respectively, for popu- lation growth [43]. No development occurs below 13.7˚C [56] and therefore we set the value of DV0 at 14˚C. Laboratory experiments found that the optimal temperature for development is 25±3˚C [42], relative humidity 70–80% [41], and survivorship was greatest at 25.6˚C [56]. The range of optimum temperatures was set to 26˚C and 32˚C for DV1 and DV2, respectively. Aleurocanthus woglumi does not occur in areas where temperatures exceed 43˚C [30]. More- over, Cherry [55] estimated that high temperature exposure at 45˚C for 3 hours resulted in 95% adult mortality. The maximum temperature for development is usually reasonably close to the maximum temperature for survival. This is apparent in physiologically based develop- ment functions, such as models of Stinner et al. [57] and Briere et al. [58]. Aleurocanthus woglumi persists in areas such as the Sindh and Punjab provinces in Pakistan and the Maharas- tra state in India, where average long-term monthly maximum temperatures can exceed 42 ˚C (e.g., Sindh 42.9 ˚C). These lines of evidence make it reasonable to set the maximum value for development (DV3) at 43˚C.

Moisture Index (MI). In CLIMEX the effects of rainfall and humidity are combined into a single soil Moisture Index (MI), using a hydrological model to represent moisture availability [59]. The lower soil moisture limit for development (SM0) was set to 0.1 to indicate the perma- nent wilting point of the insect’s host plants, which corresponds to approximately 10% of the soil moisture level [44]. The lower optimal soil moisture (SM1) was set at 0.3, which indicates soil moisture content is 30% of available capacity, and the upper optimal soil moisture (SM2) was set at 1.2. The upper soil moisture limit for development, SM3, was set to 2. Degree-days per generation (PDD) and model validation. PDD denotes the number of degree-days above DV0 required to complete a single generation. It acts as a limiting condition when a minimum of one generation must be completed each year for the species to persist at a location [44]. Following Dowell and Fitzpatrick [56], the heat sum above a 13.7˚C develop- mental threshold to complete one generation of A. woglumi was 981 ± 10˚C degree-days. Dow- ell and Steinberg [60] reported the sum of degree-day above DV0 for A. woglumi at 985 ± 22, 990 ± 18 and 982 ± 20˚C days, depending on nitrogen fertilizer. We set PDD to 985˚C days. PLOS ONE Potential global distribution of Aleurocanthus woglumi PLOS ONE | https://doi.org/10.1371/journal.pone.0261626 December 20, 2021 6 / 18