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

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

Development of plant based biopesticide for bee diseases and pests

Plant-based biopesticides are being developed for control of bee pests and diseases. Plant extracts are evaluated for effectiveness against selected honeybee pests and safety to non target organisms and the environment. The effective and non-toxic plant extracts are formulated, validated, protected by patent and registered with relevant bodies. Overall, 200,000 packaged pieces of bee pest and disease control products will be produced and provided to beekeepers/farmers in the 5 countries in Africa. Commercialization of the plant-derived bee pest and disease control products will be initiated in partnership with the private sector and rural communities will undertake commercial cultivation and processing of the pest control plants. This project activity is important because synthetic acaricides that have been used in the control of bee pests and diseases have had significant drawbacks that include high toxicity, contamination of honey, wax and pollen, and development of pest and disease resistant strains. It is important that beekeepers have access to new control tactics that do not harm bees or contaminate hive products. Plant-essential oils are now recognised as important alternatives. For instance, thymol, a constituent of the traditionally used plant, thyme (Thymus vulgaris), has increasingly been widely used in management and control of bee pests and diseases particularly in developed countries. Currently, it is the major constituent in a number of commercial products for bee pest and disease control such as Api Life VAR, Thymovar and Apiguard that have been registered in a number of developed countries. The objective of this study is to develop safer and affordable plant-derived biopesticides for control of bee pests and diseases from African biodiversity that have potential for use by rural farmers and beekeepers in Africa when the need arises. In the previous project period, 50 plants were selected for evaluation based on previous research work, literature information, indigenous knowledge and practices, observation and availability. Of particular interest were plants that showed visual signs of resistance to pest damage, attraction to bees and release of volatile compounds. Aerial parts from a total of 22 plants were collected and extracted, and 14 extracts were evaluated for efficacy against Varroa destructor. Two plants, icipe-BH-01 and icipe-BH-02 showed the highest potential for practical application in development of products for bee pest control. In preliminary evaluations, both icipe-BH-01 and icipe-BH-02 were toxic to varroa mites but non-toxic to bees at relatively higher doses. In the current project period, further work was undertaken to confirm the efficacy and safety of the two plant extracts and to formulate, and validate a final product

Manipulating the soil ecosystem using fertilizer for improved management of root-knot nematodes and bacterial wilt in smallholder ‘greenhouse’ tomato production in Kenya

The goal of this project is develop improved and inexpensive strategies for suppressing root-knot nematodes (RKN) and bacterial wilt in smallholder high-tunnel (‘greenhouse’) tomato farming in Kenya. Firstly, we will use previous knowledge to identify three greenhouse tomato farmers within Kirinyaga county in Central Kenya. We will establish the farmers’ practices especially on the use of both organic and inorganic fertilizers. Together with the farmers, we will establish the dynamics of RKNs and bacterial wilt for a period of three months and how this relates to crop productivity. To achieve this, firstly, soil samples will be collected within the greenhouse in areas with poor and healthy plant growth and evaluated in the laboratory. At the same time, the allelochemicals produced by these soil samples will also be screened. Secondly, we will evaluate the impact of fertilizer type and application rates on the RKN and bacterial wilt populations on tomato under a controlled environment. Varying fertilizer applications will give a direct measure of how much supports or suppresses the RKN and bacterial wilt populations. The associated allelochemicals will also be determined. Thirdly, we will elucidate the mechanisms underlying nematode-plant interactions using assay systems developed at icipe coupled with chemical analyses of volatiles by chromatographic techniques. We will compare nematode responses to tomato plants treated with different fertilizer rates with untreated ones as well as with plants inoculated with a bacterial wilt strain. Various treatment combinations will guide us to establish the chemical signals produced by the plant that render it susceptible to pathogen infection. Fourthly, we will test all findings with the farmers and develop a simple inexpensive control method for RKNs and bacterial wilt based on successful fertilizer and tomato variety combinations and chemical mechanisms evaluated. Finally, we will conduct a training workshop to disseminate the results to greenhouse tomato farmers and stakeholders. This project will seamlessly integrate research, outreach, and extension with personnel from the university, national and international agricultural research centers. Growing healthy greenhouse tomato will increase productivity in Kenya and progressively in other African countries which is essential for food security and improved livelihoods. With the institution of this permanent collaborative program on tomato health, longer term consequences will undoubtedly involve further understanding of other plant parasitic nematodes and mechanisms of resistance based on farm practices, and eventually their interactions with potential hosts. In addition, results and methodology from this proposal will be broadly disseminated which will serve as a long-term platform for future training of more postgraduate students in Africa on RKN and bacterial wilt management