Potential for the biological control of Lycium ferocissimum in Australia
Lycium ferocissimum (Solanaceae: EPPO Alert List) was recently identified as naturalised in France (2019) where it poses a risk to natural plant communities and associated ecosystem services. The species is native to South Africa and is reported as invasive in Australia and New Zealand. In Australia, it is a designated Weed of National Significance and in Southern Australia, it occurs in coastal and semi-arid inland habitats. Lycium ferocissimum is a major problem in agricultural and natural systems and dense stands can act to exclude native plant species, reduce access to water, harbour pest species (rabbits) and host agricultural pests (e.g. Bactrocera tryoni and B. cockerelli). Australian researchers carried out surveys for potential biological control agents across the plants’ native range and two promising strains (eastern and western Cape) of the rust fungus Puccinia rapipes were identified as potential candidates. Life cycle studies confirmed that the species is macrocyclic and autoecious, producing all five spore stages on L. ferocissimum. Pathogenicity and species susceptibility testing was conducted L. ferocissimum and all of the Lycium species of Eurasian origin (L. barbarum, L. chinense and L. ruthenicum) were susceptible to both isolates of P. rapipes. The Australian native L. australe and three more distantly related species in different genera (Hyoscyamus albus, H. aureus and Solanum aviculare) were resistant to both isolates. The isolate from the Western Cape was more pathogenic on L. ferocissimum from Australia, than the Eastern Cape isolate. The results suggest that P. rapipes may be sufficiently host specific to pursue as a biological control agent for Australia, if regulators are willing to accept damage to the Eurasian goji berries which are grown to a limited extent.
Sources
Ireland KB, Hunter GC, Wood A, Delaisse C, Morin L (2019) Evaluation of the rust fungus Puccinia rapipes for biological control of Lycium ferocissimum (African boxthorn) in Australia: Life cycle, taxonomy and pathogenicity. Fungal Biology 123, 811-823