Himalayan balsam (Impatiens glandulifera Royle) is an annual plant native to the Western Himalayas which was first introduced in Great Britain at Kew Botanical Gardens in 1839, and has now become one of most invasive plants in the UK.
Himalayan balsam disrupts local ecosystems by outcompeting native species, decreasing invertebrate diversity, and exacerbating soil erosion. The rust fungus Puccinia komarovii var. glanduliferae, a natural pathogen of Himalayan balsam was identified by CABI as a potential biocontrol agent and introduced in some UK sites. Despite promising results, some sites have shown little success in either rust overwintering or infection, raising questions as to the possible role of environmental factors in the survival of the pathogen.
For his independent research project, our MSc student Theo Humbeeck set out to map a potential global distribution of P. komarovii var. glanduliferae using a modelling approach (CLIMEX, MaxEnt) and to identify climatic requirements of the rust fungus P. komarovii var. glanduliferae to inform selection of potential.release sites in the UK.
The study identified dry stress as the most influential climatic driver of the rust fungus distribution which restricts the suitable range to humid continental and maritime climates. Differences in rust survival seen across the UK did not seem to be climatically driven, highlighting a possible higher relative impact from balsam biotype susceptibility, shade levels, or microclimatic variables.
Modelled distributions resulting from this study can serve as a useful tool in strategizing localised rust releases in the UK for the biocontrol of Himalayan balsam.
Modelled distributions resulting from this study can serve as a useful tool in strategizing localised rust releases in the UK for the biocontrol of Himalayan balsam.
