Climate suitability of biological control agents and their hosts
Classical biological control utilises natural enemies from the plant’s region of origin to control it in the introduced/invasive range. Climate change has the potential to expand an invasive plant’s range into areas that were previously unsuitable. This could result in a climate tolerance mismatch between the invasive plant and the biological control agent. To evaluate this, the potential global distributions of Alternanthera philoxeroides (Amaranthaceae, EPPO A2 List), an emergent aquatic plant, and a specialist natural enemy, Agasicles hygrophila (Coleoptera: Chrysomelidae) were modelled under future climate change scenarios. Occurrence data for A. philoxeroides and A. hygrophila were obtained from the Global Biodiversity Information Facility and other online sources. The climate change scenarios modelled were one low to moderate scenario (SSP2-4.5) and a worst-case scenario (SSP5-8.5). The model showed that in general, the global distribution of A. philoxeroides expanded, especially in central Africa, Eastern Europe, western China and North America. A. hygrophila is also predicted to expand, but to a lesser extent, with some loss of currently suitable areas. The overlapping area between their distributions is projected to increase globally, except in the USA. This suggests that A. hygrophila may be a promising biological control agent for A. philoxeroides in many regions in the future, but portions of the distribution of A. philoxeroides may remain unsuitable particularly at higher latitudes.
Sources
Pulzatto MM, Guilherme dos Santos Ribas L, Murillo R, Florĕncio FM, Vilá M, Thomaz SM (2024) Biocontrol in a warmer world: anticipating the climate suitability of an aggressive invasive plant and its specialist herbivore. Hydrobiologia, https://doi.org/10.1007/s10750-025-05808-2