COS 288-1 - Shifts in range of the invasive stored product insect pest, Prostephanus truncatus, under climate change

Abstract: The invasive larger grain borer (Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae)) is a Central American native, wood-boring insect that has adapted to infest stored maize and cassava. In the late 1970s, the insect was accidentally introduced to Tanzania, Africa, and has become an invasive and pernicious pest across Africa. Like some other stored product insects, P. truncatus populations are a landscape-scale immigration threat to food facilities, with refugia in forested habitats. Consequently, novel infestations can occur without human-mediated dispersal. Models of this destructive insect's potential distribution and movement may greatly inform management programs; however, previous predictions have not been extrapolated into future climate change scenarios, which will likely alter the suitable infestation zones. Therefore, we 1) projected the potential global distribution of P. truncatus using native and invaded occurrence data and 2) modeled potential changes within the native range.

We used the platform Wallace, which utilizes the maximum entropy (MaxEnt) model, to predict future global distribution based on climate data for 2050 and 2070 with Representative Concentration Pathways (RCP) 2.6 and 8.5. We modeled the Americas and Africa occurrence records separately as the niche overlap differed significantly. Additionally, for North America, we separately incorporated topographical information, including percent forest cover, to map potential temporal and spatial changes in P. truncatus native range on a finer scale. Our projection models identified suitable areas ( >75% likelihood) for P. truncatus along coastal regions of southern North America and Central America, much of the northern South American countries, and a broad band of north/central Africa and southern Eurasia (3% and 25% of landmass between 60°N and 60°S for Africa and Americas data, respectively). In the future, the suitable area of P. truncatus will continue to increase, with high suitability between 15°N to 15°S latitudinal lines in the 2070 RCP 8.5 scenario (14% and 27% of landmass for Africa and Americas data, respectively). The wide distribution of occurrence data in the Americas may have promoted greater global suitability predictions. Additionally, native range shifts into the corn-belt states are likely. As a result, increased monitoring for P. truncatus is warranted as its interception along the southern US border represents a rising biosecurity threat emblematic of the Anthropocene. The results from our study can be used to ameliorate global biosecurity risks through timely surveillance programs and management implementation.