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

Management of <i>Spodoptera frugiperda</i> J.E. Smith Using Recycled Virus Inoculum from Larvae Treated with Baculovirus under Field Conditions

Fall armyworm (FAW) is a major pest of maize and causes huge losses. Chemical pesticides are the commonly used control strategy among farmers. The efficacy of baculoviruses against FAW has been proven; however, farmers may not be able to afford the products. The use of farmer-produced baculovirus mixtures could provide an opportunity for a nature-based solution for FAW at a low cost. This study evaluated the potential of recycled virus inoculum from FAW larvae treated with a commercial baculovirus (Littovir) for the management of FAW under laboratory and field conditions. In the laboratory, the virus from 25, 50, 75 and 100 FAW larvae caused variable mortality among FAW instars. The highest mortality (45%) among 1st–3rd instars was caused by Littovir followed by recycled virus inoculum from 100 FAW larvae (36%). Under field conditions, even though recycled virus inoculum did not offer adequate protection against FAW damage, the maize yield was comparable to that of commercial insecticide-treated plots and similar to that of control plots. This study has shown the potential use of recycled virus inoculum from infected larvae for the management of FAW. This would offer the farmers a sustainable and affordable option for the management of FAW as it would require the farmers to purchase the commercial baculovirus once and collect larvae from treated plots for repeat applications

Assessing Biopesticides for Managing Fall Armyworm <i>(Spodoptera frugiperda)</i> in Africa

In the last 6 years, the fall armyworm (FAW) has spread to the Middle East, Asia and the Pacific, as well as most nations in Africa. This case focuses on sub-Saharan Africa, where more than 300 million people depend on maize, as a staple crop, and the preferred host plant of FAW. Synthetic pesticides against FAW are not always used safely or effectively. Here we assess work on the current state of knowledge on biopesticides for FAW in Africa, document information gaps, including compatibility with other recommended management practices, and list biopesticides that are a priority for research, development and promotion. The case incorporates two earlier assessments, one from 2018 on the status of biopesticide options against FAW, and one from 2020 that led to recommendations for field trials for eight active ingredients – Bacillus thuringiensis subsp. kurstaki , Beauveria bassiana , Dysphania ambrosioides , ethyl palmitate, eugenol, garlic extract, Metarhizium anisopliae and Steinernema spp. Field trials for some of these pesticides have now been carried out but other trials are still ongoing. The team also recommended bioassays to determine the effectiveness of four active ingredients against FAW – GS-omega/kappa-Hx-tx-Hv1a, canola oil, capsaicin and D-limonene. Information © CAB International 202

Farmers’ knowledge and perceptions on fruit flies and willingness to pay for a fruit fly integrated pest management strategy in Gamo Gofa zone, Ethiopia

Bactrocera dorsalis (Hendel) is one of the most economically important invasive pests affecting horticulture production in sub-Saharan Africa (SSA). Mango is the main host for this species and causes up to 80% yield loss. To mitigate against this pest, an area-wide integrated pest management (IPM) programme is being promoted in SSA, and Ethiopia is next in line for roll-out. The IPM strategy reduces pesticide use and generates significant income. However, implementation of the IPM requires significant time investment for pest identification, scouting, certain infrastructure, creating awareness and training for area-wide adoption. To assess farmers’ knowledge and perceptions of B. dorsalis and their willingness to pay (WTP) for the IPM, 365 households were interviewed in two mango producing districts in Goma Gofa zone in Ethiopia. A logistic regression model was used to analyse responses to a double-bounded contingent valuation survey. The results showed that 47% of the respondents are WTP for the IPM strategy. Average WTP per hectare was estimated at US$ 134, revealing an existing demand for fruit fly IPM. The respondents’ WTP for the strategy was driven by farm and socio-economic characteristics. Enhancing skills of extension agents could foster IPM dissemination and adoption among mango growers in this region

Optimum Flight Height for the Control of Desert Locusts Using Unmanned Aerial Vehicles (UAV)

Desert locust is one of the most destructive migratory pest in the world. Current methods of control rely on conventional chemical insecticides during invasion. Some environmentally friendly biopesticides based on Metarhizium acridum and insect growth regulators have also been deployed in preventive control operations. They have been tested in sprayers mounted on commonly used platforms such as vehicles, aircraft, and human. However, despite being used successfully, these tools present many challenges, hence the need to supplement them with suitable alternatives. The successful use of drones to control pests such as fall armyworm, planthoppers, aphids, among others, makes it an attractive technology that has the potential to improve locust management, especially in inaccessible areas. However, key parameters for the safe and optimal use of drones in desert locust control are not documented. This study established the key parameters for spraying desert locusts with a drone. To test the optimum height for spraying Metarhizium acridum on the locusts, the drone was flown at five different heights: 2.5, 5, 7.5, 10, and 12.5 m. At each height, the drone sprayed the ink mixture on spray cards pinned to the ground to approximate the droplet density and compare it to the standard droplet density recommended for desert locust control. To assess the efficacy of M. acridum and the effectiveness of drones in its application, 50 g of spores were mixed in 1 L of diesel and sprayed on caged live locusts of different stages (3rd and 4th instars, as well as the adults); they were monitored for twenty-one days in a controlled room, and their mortality was determined. Variation in droplet density between the tested heights was significant. A height of 10 m agrees with the recommended standard droplet density within the 45 droplets/cm2 range. Mortality varied among the locusts’ developmental stages within and between heights. Survival probability varied between heights for 3rd instar, 4th instar, and adults. All the developmental stages of the desert locust were susceptible to Novacrid and the recommended target stage is the 3rd instar. Management of desert locusts by the use of drone technology appears promising when the pesticides are applied at an optimum height and standard operating procedures are followed. Further research could explore the gap in the effects of environmental parameters on flight application efficiency

Thermal reaction of single life stages of Ceratitis rosa and Ceratitis quilicii

Integrative taxonomy has resolved the species status of the potentially invasive Ceratitis rosa Karsch into two separate species with distinct ecological requirements: C. rosa "lowland type" and the newly described species Ceratitis quilicii De Meyer, Mwatawala & Virgilio sp. nov. "highland type". Both species are notorious tephritid pests threatening the production of horticultural crops in Africa and beyond. Studies were carried out by constructing thermal reaction norms for cohorts of single life stages of both species at constant and fluctuating temperatures. Non-linear functions were fitted to continuously model species development, mortality, longevity and oviposition to establish phenology models that were stochastically simulated to estimate the life table parameters of each species. For spatial analysis of the pest risk, three generic risk indices were visualized using the advanced Insect Life Cycle Modeling software. The study revealed that the highest fecundity, intrinsic rate of natural increase and net reproductive rate for C. rosa and C. quilicii was at 25 and 30°C, respectively. The resulting model successfully fits the known distribution of C. rosa and C. quilicii in Africa and the two Indian Ocean islands of La Réunion and Mauritius. Globally, the model highlights the substantial invasion risk posed by C. rosa and C. quilicii to cropping regions in the Americas, Australia, India, China, Southeast Asia, Europe, West and Central Africa. However, the proportion of the regions predicted to be climatically suitable for both pests is narrower for C. rosa compared to C. quilicii, suggesting that C. quilicii will be more tolerant to a wider range of climatic conditions than C. rosa. This implies that these pests are of significant concern to biosecurity agencies in the uninvaded regions. Therefore, these findings provide important information to enhance monitoring/surveillance and designing pest management strategies to limit the spread and reduce their impact in the invaded range