EPPO Platform
on PRAs

Prioritization of invasive alien species with the potential to threaten agriculture and biodiversity in Kenya through horizon scanning


Mulema J, Day R, Nunda W, Akutse KS, Bruce AY, Gachamba S, Haukeland S, Kahuthia-Gathu R, Kibet S, Koech A, Kosiom T (2022) Prioritization of invasive alien species with the potential to threaten agriculture and biodiversity in Kenya through horizon scanning. Biological Invasions 24, 2933–2949. https://doi.org/10.1007/s10530-022-02824-4 

Invasive alien species (IAS) rank among the most significant drivers of species extinction and ecosystem degradation resulting in significant impacts on socio-economic development. The recent exponential spread of IAS in most of Africa is attributed to poor border biosecurity due to porous borders that have failed to prevent initial introductions. In addition, countries lack adequate information about potential invasions and have limited capacity to reduce the risk of invasions. Horizon scanning is an approach that prioritises the risks of potential IAS through rapid assessments. A group of 28 subject matter experts used an adapted methodology to assess 1700 potential IAS on a 5-point scale for the likelihood of entry and establishment, potential socio-economic impact, and impact on biodiversity. The individual scores were combined to rank the species according to their overall potential risk for the country. Confidence in individual and overall scores was recorded on a 3-point scale. This resulted in a priority list of 120 potential IAS (70 arthropods, 9 nematodes, 15 bacteria, 19 fungi/chromist, 1 viroid, and 6 viruses). Options for risk mitigation such as full pest risk analysis and detection surveys were suggested for prioritised species while species for which no immediate action was suggested, were added to the plant health risk register and a recommendation was made to regularly monitor the change in risk. By prioritising risks, horizon scanning guides resource allocation to interventions that are most likely to reduce risk and is very useful to National Plant Protection Organisations and other relevant stakeholders.


  • Anoplolepis gracilipes
  • Aphelenchoides arachidis
  • Aphelenchoides ritzemabosi
  • Bactrocera zonata
  • Banana bunchy top virus
  • Bemisia tabaci
  • Bruchus pisorum
  • Cacoecimorpha pronubana
  • 'Candidatus Liberibacter solanacearum'
  • 'Candidatus Phytoplasma asteris'
  • Ceratitis quinaria
  • Ceratocystis fimbriata
  • Cucurbit yellow stunting disorder virus
  • Dialeurodes citri
  • Dickeya zeae
  • Ditylenchus africanus
  • Ditylenchus destructor
  • Euwallacea fornicatus sensu lato
  • Faba bean necrotic yellows virus
  • Fusarium circinatum
  • Fusarium oxysporum f. sp. cubense Tropical race 4
  • Globodera tabacum sensu lato
  • Glycaspis brimblecombei
  • Helminthosporium solani
  • Herse cingulata
  • Heterodera cajani
  • Heterodera glycines
  • Heterodera goettingiana
  • Meloidogyne graminicola
  • Monomorium destructor
  • Neoceratitis cyanescens
  • Pectobacterium atrosepticum
  • Pepino mosaic virus
  • Peronospora sparsa
  • Phenacoccus solenopsis
  • Potato spindle tuber viroid
  • Pseudaulacaspis pentagona
  • Pseudococcus viburni
  • Ralstonia solanacearum
  • Rastrococcus invadens
  • Rhynchophorus ferrugineus
  • Spodoptera eridania
  • Squash leaf curl virus
  • Synchytrium endobioticum
  • Thrips palmi
  • Tilletia controversa
  • Trogoderma granarium
  • Urocystis agropyri
  • Xanthomonas citri pv. citri


Type File Size
Pest Risk Analysis Download 633,84kB

PRA Area

  • Kenya