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

Abstract

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.

Horizon scanning: Tools to identify emerging threats to plant health in a changing world

“…Workshops have involved training on the tool itself and capacity building in low‐ and middle‐income countries where limited resources mean that routine horizon scanning, pest risk assessment and prioritization activities present a particular challenge. Workshops were held in Kenya and Ghana in 2018–2019 to establish a list of plant pests that were absent from each of the countries but that posed a potential risk to agriculture and/or the environment should they arrive (Kenis et al., 2022; Mulema et al., 2022). Both workshops involved subject matter experts from research and academia, including risk assessors from the NPPO.…”

“…The pilot programme ran for 8 months in 2022 with the NPPOs in Kenya, Ghana, Burkina Faso and Zambia. A total of 120 pests were monitored, including those identified through the horizon scanning activities carried out in Ghana and Kenya (Kenis et al., 2022; Mulema et al., 2022). Results were disseminated monthly to each NPPO in a newsletter format.…”

Prioritizing nematode species likely to be introduced and threaten agriculture, biodiversity, and forestry in Zambia: A Horizon Scanning Approach

“…The risk scoring system used was based on that described by Roy et al (2019). This scoring system (guidelines) had been modi ed in previous studies by Mulema et al (2022) and Kenis et al (2022). Roy et al (2019) assessed the likelihood of arrival, establishment, spread, and magnitude of potential negative impact on biodiversity and ecosystem services whereas in this assessment, the likelihood of entry (arrival), establishment, and potential magnitude of socioeconomic impact and potential magnitude of impact on biodiversity were assessed.…”

“…However, some IAS arrive into new environments unaided such as the iers or facilitated by natural means such as storms, hurricanes and wind currents (Westphal et al 2008;Desneux et al 2011;Nagoshi et al 2018). In SSA, lack of awareness, facilitated by lack of or limited enforcement of laws, porous borders, and weak border biosecurity have played a signi cant role in the introduction and spread of IAS (Mulema et al 2022) as observed in previous years (Desneux et al 2011;Mahuku et al 2015; Day et al 2017).…”

“…In these studies, candidate IAS for risk assessment were generated through extensive literature searches however, the Horizon Scanning Tool developed by CABI supports identi cation of candidates for risk assessment was used in this study. The tool was also recently utilised in horizon scanning studies conducted in Ghana and Kenya (Mulema et al 2022;Kenis et al 2022). It can be accessible at https://www.cabi.org/HorizonScanningTool or via the CABI Compendium (https://www.cabidigitallibrary.org/cabicompendium ).…”