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The use of synthetic chemical rodenticides is the most commonly practiced rodent management method in sub-Saharan Africa which results in health and environmental risks without any significant improvement in terms of reducing rodent pest populations sustainably. In this paper, which is a second part of a diptych, we advocate for better control of the use of synthetic chemical rodenticides in urban and agricultural settings in sub-Saharan Africa, as well as a shift towards more sustainable and environment-friendly rodent management approaches, such as the Ecologically-Based Rodent Management (EBRM), as a realistic alternative to synthetic rodenticides. The EBRM approach relies on a solid knowledge of pest rodent biology, ecology and behavior as well as the use of a pool of rodent management actions implemented through community-based interventions to ensure sustained reduction of rodent pest populations down to economically and sanitary acceptable levels. EBRM is expected not only to ensure reducing the social impacts of pest rodents in cost-beneficial ways, but also the risks of rodents and synthetic rodenticides to human health and the environment.

The use of synthetic chemical rodenticides is the most commonly practiced rodent management method in sub-Saharan Africa which results in health and environmental risks without any significant improvement in terms of reducing rodent pest populations sustainably. In this paper, which is a second part of a diptych, we advocate for better control of the use of synthetic chemical rodenticides in urban and agricultural settings in sub-Saharan Africa, as well as a shift towards more sustainable and environment-friendly rodent management approaches, such as the Ecologically-Based Rodent Management (EBRM), as a realistic alternative to synthetic rodenticides. The EBRM approach relies on a solid knowledge of pest rodent biology, ecology and behavior as well as the use of a pool of rodent management actions implemented through community-based interventions to ensure sustained reduction of rodent pest populations down to economically and sanitary acceptable levels. EBRM is expected not only to ensure reducing the social impacts of pest rodents in cost-beneficial ways, but also the risks of rodents and synthetic rodenticides to human health and the environment.

The effectiveness of the “attract and kill” approach for the management of Bactrocera dorsalis in citrus orchards using autoinoculation strategy was evaluated in three locations in Senegal (Sindia, Sebikhotane and Ndoyene), between 2016 and 2018. Attractant Contaminant Traps (ACT) were treated with 0.3 g of Metarhizium acridum, and methyl eugenol was then deployed at densities of 25, 50 and 100 ACT to infect the flies. Recovery Traps (RT) containing methyl eugenol and a toxicant, Timaye were used to monitor the B. dorsalis population and the contamination rate. Results showed that the rate of contaminated flies increases with the number of ACT, at an average daily rate of contaminated flies of 68.1%, 85.44% and 99.67% at 25, 50, 100 traps, respectively. No contaminated flies were found in the control. The number of flies caught decreased from 21.7, 4.2 and 6.2 flies per day, respectively, for 25, 50, 100 ACTs and control in the first week, to 0.64, 0.71, 0.71 and 99.9 flies per day, respectively, for 25, 50, 100 ACTs and the control. All the flies caught at M. acridum treated sites were contaminated. No significant difference between the incidence of fruit damage in the three ACT densities and the control was found in the first week; however, there was a significant difference over time, from 90.0, 96.7 and 83.3% in the first week, to 30, 50 and 46.7% at the 14th week, respectively, for 25, 50 and 100 ACTs. No significant differences were found in the control. This present study demonstrated the efficacy of autoinoculative systems based-M. acridum for the management of B. dorsalis in citrus orchards in Senegal. This strategy is economical as it uses very little amounts of inoculum with locally made materials.

International audience; The South American tomato pinworm, Tuta absoluta (Meyrick 1917) (Lepidoptera: Gelechiidae), is an invasive pest native to South America. Outside of its native range, it was first detected in Spain in 2006 and then rapidly spread to most tomato-growing regions in Central America, Europe, Africa and Asia where the species has become a major threat to tomato production. To implement appropriate policy and surveillance practices, to limitnew introductions and spread, and inherent economic losses, better knowledge of its invasion pathways is required. To this end, a large sampling of T. absoluta was performedin native and invaded areas including European and for the first time many African countries. Samples were analysed using a mitochondrial marker (mtCOI) and a phylogenetic approach. Despite extensive sampling and sequencing efforts, an overall lack of genetic variation among the tested specimens (140) was observed. This striking finding may result from a combination of factors and phenomena such as extensive gene flow, severe bottlenecks, reproductive system and human activities, and will be discussed in the framework of biological invasion and pest management.

International audience; Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) is among the most devastating pests worldwide of solanaceous plants, particularly of tomato (Solanum lycopersicum L.). Since its recent introduction into sub-Saharan Africa, it has become an additional widespread tomato pest throughout the region. When no control measures are taken, yield losses caused by T. absoluta larvae can reach 100%. Chemical control remains the primary management option despite its many adverse effects and increasing inefficiency due to the species' endophytic habits and ability to develop insecticide resistance. Safer and more effective alternatives are therefore urgently required. Here, we investigated the effectiveness of two bioinsecticides compared to that of a widely used deltamethrin-based synthetic insecticide, in preventing damage caused by T. absoluta larvae to tomato leaves and fruits, thereby affecting tomato yield. A field trial was conducted in 2018 and 2019 in northwestern Senegal using a randomized complete block design. Damage caused by T. absoluta affected approximately 65% of total leaf area and 3-24% of the fruits. Damage to the leaves caused by other insect species or other factors was less significant. At the dose applied, the chemical insecticide did not significantly reduce the surface area of leaflets affected by T. absoluta or other causal agents, the number of T. absoluta mines on the leaflets, or the proportion of fruits damaged. In contrast, the azadirachtin and Bacillus thuringiensis (Bt) formulations rapidly and significantly reduced damage to both leaves and fruits. The proportion of fruits damaged was reduced by a factor two and the total tomato yield was improved, particularly when the Bt formulation was used. In addition to their effectiveness in reducing damage caused by T. absoluta larvae to tomato leaves and fruit, and increasing the yield of marketable fruits, the viability of these organic alternatives was shown. The scope of our results is discussed in the context of T. absoluta control, in particular in integrated pest management programmes for tomato crops.

International audience; The fall armyworm (FAW), Spodoptera frugiperda, a major agricultural insect pest in the Western Hemisphere, currently also poses a significant threat to many cereal crops in Africa. FAW consists of two morphocryptic strains, the corn- and the rice strains, which were thought to display typical genetic, physiological and behavioural features. However, this is not absolutely true, rendering direct identification and distribution of the strains impossible in field. Thus, to investigate 1) the composition and diversity of FAW strains, 2) their distribution at various spatial scales, and 3) the host plants they use, in invaded countries we used the COI barcode fragment, a marker capable of accurately distinguishing the two strains. A total of 125 specimens mainly sampled on maize in Niger and Senegal and to a lesser extent in Guinea, Mali, Togo, Burkina Faso and Cape Verde were analyzed. Sixteen haplotypes were identified among which two occurred very frequently. Phylogenetic analysis delineated two lineages, the rice and corn strains, but no typical geographical and host-plant patterns were found. The FAW-strain haplotypes derived from West African specimens were genetically comparable with those sampled elsewhere in Africa, the Americas and Asia. Considering all sites and plants sampled, the corn strain slightly predominated but on maize, the two strains were statistically comparable. Their distribution is largely sympatric at region, field and even maize plant scales. These findings are compared to populations recorded elsewhere and are discussed in the framework of biological invasions, and the management and ecology of the species.

The fall armyworm, Spodoptera frugiperda, is a serious invasive pest of the family Noctuidae (Lepidoptera) and given its broad host range, has the potential to cause severe yield losses in many economically important crops, especially maize. Native to tropical and subtropical regions of the Americas, the pest was first detected in Africa (Nigeria) in January 2016. Here, we report the first records of this invasive pest in the westernmost part of West Africa (Senegal) where both 'rice' and 'maize' moth strains were identified. The species was unambiguously identified based on morphological traits and molecular analyses. Implications of this new threat to crop production and solutions for sustainable management are discussed.

The invasive tomato leafminer, Tuta absoluta (Meyrick) (Lepidoptera, Gelechiidae) has become a real threat for the continued production of tomatoes across Sub-Saharan Africa since its first detection in Senegal. However, little is known of its geographical expansion, seasonal population dynamics, and damage to crops. A trapping network was deployed in 2014 and 2015 in Senegal to monitor the dynamics of T. absoluta populations at a regional and nationwide scale. A field network was also implemented in the most infested area to get information on the pest incidence during the 2013–2014 cropping season. In 2014, pheromone traps did not detect the presence of T. absoluta moths in remote areas of Eastern Senegal. In 2015, moths were detected in all the fifteen monitored areas deployed throughout the country. Abundance of trapped moths was greatest in 'Niayes', the main tomato-producing area. Unexpectedly, T. absoluta moths were trapped in some areas with few or no tomato crops, including off-season in the 'Vallee du fleuve', hot drylands ('Matam' and 'Kidira') and urban environments ('Dakar'). This suggests high mobility of moth populations and capacity to survive in harsh environments and to persist on alternative host plants. Field monitoring in the main tomato-producing area showed a very low incidence of T. absoluta over the early dry season (0–2% mined leaves), followed by severe outbreaks during the late dry season (up to 60% mined leaves). Results on the invasive pest occurrence will be helpful to decision-makers with a view to develop alternative strategies such as biological control by indigenous natural enemies or collective management strategies based on the temporal or spatial exclusion of host crops. (Resume d'auteur)

Eggs of Heliocheilus albipunctella de Joannis were picked up during ear formation of millet at Bambey in 1988 and were followed up in the laboratory at temperatures 25–30°C and 60–70% r.h. Trichogrammatoidea sp. probably T. armigera parasitized 60.3% of them. During the period in which eggs were collected, percentage of parasitism increased, which certainly means a build-up of parasite populations.