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Knowing the dispersal of released insects and estimating the size of field populations are keys to the successful implementation of area‐wide management (AWM) programmes based on the sterile insect technique (SIT), as they determine the release strategy of sterile males. Mark–release–recapture (MRR) is a common method used to estimate field populations and spatiotemporal dynamics. However, the extent to which the pest is attracted to lures is often difficult to identify, thereby biasing extrapolation to movement patterns and population size. We performed MRR experiments on the Oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae), in a fruit‐growing area in Senegal. Methyl eugenol and protein baits were used to trap males and females, respectively. After studying the suitability of marking B. dorsalis with fluorescent pigments at the laboratory, two releases of marked sterile flies were organized in the centre of an organic mango orchard, first in the late mango fruiting stage and second in the fruit setting stage. Traps were placed symmetrically along a 250 and 500 m radius from the release point. A very small fraction of the released individuals was recaptured: 0.45% in the first release and 3.08% in the second. Trapping of both sterile and wild flies was completely anisotropic. Sterile flies were mostly trapped at a relatively short distance (250 m) from the release point, in the first two days. Male trapping using methyl eugenol was highly effective, whereas the response of females to food bait traps was low. The direction of the wind was the main driver of recapture, with flies heading upwind. The results underline the importance of taking the odour plume around the traps into account when estimating populations, and the heterogeneous spread of the wild population in the landscape for the set‐up of the release strategy of sterile insects for SIT‐based AWM. [ABSTRACT FROM AUTHOR]

Host range evolution is a central issue for pest management, particularly for invasive species of agricultural importance. The invasive tomato leaf miner, Tuta absoluta Meyrick (Lepidoptera: Gelechiidae), a key pest of tomato in Europe and recently in sub-Saharan Africa, is a good model organism to better understand underlying processes. We studied oviposition acceptance (proportion of females accepting a given plant as host for laying egg), oviposition preference (number of eggs laid by females on a given host plant) and performance (offspring development estimated as survival from egg to adult) of two T. absoluta populations originating from France (FRA) and Senegal (SEN) on six solanaceous plants (tomato, eggplant, Ethiopian eggplant, potato, sweet pepper and pepper). The ovipositional behavioral pattern differed between the two populations; the SEN population showed higher oviposition acceptance on Ethiopian eggplant and sweet pepper than the FRA population. In addition, SEN population showed higher oviposition preference toward sweet pepper and potato than the FRA population. By contrast, the FRA population showed higher preference toward tomato and eggplant than the SEN population. The two populations of T. absoluta performed best on tomato (the preferred host plant) and showed similar decreasing trend in performance when comparing the two populations on the various other host plants. For both populations, performance on solanaceous plant species was closely related to ovipositional response of females to these plants. The differences observed between the two populations may indicate an ongoing differentiation in the host range of T. absoluta in the two invaded areas, possibly due to the abundance of these alternative host crops in Senegal at a period when tomato crops are scarce. [ABSTRACT FROM AUTHOR]

In Africa, Helicoverpa armigera (Hübner) (Lepidoptera, Noctuidae) is a key pest of cotton and vegetable crops, particularly tomato. Alternatives to insecticides to control this pest are needed such as conservation biological control. However, knowledge on the diversity and ecology of naturally occurring enemies of H. armigera is limited. A two-year field survey was conducted in a set of tomato farmer fields in the main vegetable-growing area in Senegal (Niayes) to assess the spatial and seasonal occurrence of indigenous parasitoids of H. armigera, and to evaluate the effect of insecticide use on biological control efficiency. No parasitoid emerged from H. armigera eggs. Incidence of larval parasitoids was generally moderate (20%) but highly variable (0%-100%) among fields, independently of host abundance, and negatively affected by the number of insecticide applications. Larval parasitism was largely dominated by the larval parasitoid Meteorus laphygmarum Brues (Hymenoptera, Braconidae), but a positive correlation was found between specific richness or Shannon diversity index of the parasitoid community and parasitism rate. This study is a first step toward development of research and extension programs for conservation of natural enemies in the framework of integrated management of the tomato fruitworm in Senegal. [ABSTRACT FROM AUTHOR]

In Senegal, damage caused by insect pests is a major obstacle to seasonal stability and an increase in cabbage production. Little is known about the spatial and temporal distribution of cabbage pests, which makes the design of management recommendations to small-scale farmers challenging. The objectives of this study were to: (i) evaluate the status of insect pests observed in cabbage farmers’ fields; (ii) give information on the spatial and temporal distribution of key pests and (iii) assess the effect of temperature, insecticide applications, and host crop abundance on their incidence. A total of 116 cabbage fields were monitored for insect pests and related damage over four crop cycles, from October 2012 to May 2014, in the main vegetable producing area of Senegal (Niayes). The diamondback moth Plutella xylostella (L.) was by far the most important pest present in all the fields and with high levels of incidence (37.1% infested plants), particularly in the latter part of the dry season in the South of Niayes (50% infested plants). The cabbage webworm Hellula undalis (F.) was mainly observed in the early dry season in the south of Niayes, with an incidence of up to 12.5% infested plants. More surprising was the detection of the tomato fruit worm Helicoverpa armigera (Hübner), with damage of up to 9.4% of cabbage heads. The incidence of sucking pests such as whiteflies Bemisia tabaci (Gennadius), or aphids (including Lipaphis pseudobrassicae (Davis, 1914), Myzus persicae (Sulzer) or Brevicoryne brassicae (L.)) was generally low. The incidence of P. xylostella increased significantly with the number of insecticide applications, indicating that control deployed by growers was ineffective. The incidence of H. undalis did not depend on the number of insecticide applications, but significantly increased with host crop abundance and decreased with temperature. This study is a first step towards developing alternative pest management strategies in the framework of sustainable vegetable production systems. [ABSTRACT FROM AUTHOR]

• The boosted sterile insect technique is used to control pests and disease vectors. • Sterile males of Bactrocera dorsalis can disseminate a pathogen to wild population. • An agent-based model simulates the fruit fly dynamics after sterile male releases. • Simulations of boosted SIT strongly reduced wild fly density and infested fruit. • Results encourage field trials to validate the efficacy of boosted SIT. The sterile insect technique (SIT) is a method of biological control of pests and disease vector insects. It includes mass-rearing and release of sterile males of the target species so that wild females mated with sterile males would not produce offspring. An innovative version of this technique, called boosted SIT, relies on the use of sterile males as vectors of biocides to trigger an epizootic in the wild fruit fly population. We built an agent-based model to assess the feasibility of this technique and main modalities of field implementation for the control of the Oriental fruit fly, Bactrocera dorsalis, using the entomopathogenic fungi, Metarizhium anisopliae, as a biocide. The model, called BOOSTIT (BactrOcera dOrsaliS boosTed sIT), simulates the spatio-temporal population dynamics of fruit flies in three different realistic landscape contexts. The releases of infected and uninfected sterile males were simulated and allowed the transmission of the pathogen within the wild fly population as a result of interactions between individuals. A main output was the measurement of losses in mango production. Validation of the model was done by comparing the simulated population dynamics with data from field monitoring (pheromone traps) in three landscapes of the Niayes area in Senegal. The population dynamics of wild flies were then simulated in an intensive cropping and mono-mango cultivar landscape under three scenarios: (1) without the release of sterile males, (2) with the release of non-contaminated sterile males (SIT) and (3) with the release of sterile contaminated males (boosted SIT). The results showed that SIT and boosted SIT strongly reduced the density of wild flies and the amount of infested fruits. Although parameters of the pathogen transfer between individuals need to be studied more deeply, results encourage the implementation of field trials to validate the efficacy of boosted SIT to control fruit flies. [ABSTRACT FROM AUTHOR]

A better understanding of environmental factors driving natural pest regulation is a major challenge for designing sustainable cropping systems. The objective of the present study was to assess the association between vegetation openness in traditional tree-crop agroforestry systems in Senegal, richness and abundance of vertebrates including insectivorous birds and bats, and their contribution to the natural regulation of crop pests. The millet head miner (MHM), Heliocheilus albipunctella (Lepidoptera, Noctuidae), a major constraint to increasing millet crop productivity in sub-Saharan Africa, was selected as a model system. Ten sites separated by at least one km from each other were selected in a 100 km2 study area in the Peanut basin in Senegal. In each site, a pair of millet fields distant from at least 100 m each was selected according to a gradient of vegetation openness within a 100-m radius buffer with sampling plot (5 × 5 m) at the center. Nine insectivorous bird and bat species were recorded in millet fields over the 2017 cropping season and their predator status was confirmed by direct observation or DNA detection in fecal samples. Grain losses were reduced when panicles were accessible to birds and bats, confirming their net contribution to pest regulation. At a local scale, tree diversity and vegetation openness were important predictors of the abundance of insectivorous village weaver birds and grey-headed sparrows, respectively. Some tree species (soapberry trees and neems) indirectly contributed to natural regulation of the MHM likely by providing refuges to insectivorous vertebrates whereas other tree species (baobabs) provided disservices as possible refuges for the MHM moths. Further research is needed to better understand relationships between tree cover, food web interactions and natural pest suppression, so that specific conservation measures such as habitat management can be designed to improve pest control. Image 1 • Vertebrates, including birds and bats, are effective predators of the millet head miner. • They contribute to natural pest control and reduction of millet grain loss. • The abundance of insectivorous birds is enhanced by tree diversity at a local scale. • The contribution of trees for natural pest control is species-dependent. Trees can serve as refuges for pest (eg. baobab/moths) and predators (eg. palm tree/bats or neem/village weavers). [ABSTRACT FROM AUTHOR]

Better knowledge of food webs and related ecological processes is fundamental to understanding the functional role of biodiversity in ecosystems. This is particularly true for pest regulation by natural enemies in agroecosystems. However, it is generally difficult to decipher the impact of predators, as they often leave no direct evidence of their activity. Metabarcoding via high-throughput sequencing (HTS) offers new opportunities for unraveling trophic linkages between generalist predators and their prey, and ultimately identifying key ecological drivers of natural pest regulation. Here, this approach proved effective in deciphering the diet composition of key predatory arthropods (nine species.; 27 prey taxa), insectivorous birds (one species, 13 prey taxa) and bats (one species; 103 prey taxa) sampled in a millet-based agroecosystem in Senegal. Such information makes it possible to identify the diet breadth and preferences of predators (e.g., mainly moths for bats), to design a qualitative trophic network, and to identify patterns of intraguild predation across arthropod predators, insectivorous vertebrates and parasitoids. Appropriateness and limitations of the proposed molecular-based approach for assessing the diet of crop pest predators and trophic linkages are discussed. [ABSTRACT FROM AUTHOR]

• Sugar provisioning to weaver ants decreased their association with scale insects. • Sugar provisioning to weaver ants decreased the abundance of their nests. • Sugar provisioning to weaver ants decreased their aggressivity. The use of predatory arthropods in biological pest control in agriculture can generate resistance by farmers when these beneficials become noxious for them or their crops. The African weaver ant, Oecophylla longinoda (Hymenoptera: Formicidae), an effective biocontrol agent of pests, particularly Bactrocera dorsalis fruit flies in mango orchards in West Africa, is a good example of such inconveniences. We here explored whether manipulating their behavior by providing sugar feeders on trees would (i) alter their mutualistic relationships with scale insects, thereby reducing the incidence of this pest, (ii) decrease nest abundance often considered by farmers to reduce foliage development, and (iii) reduce their aggressiveness. To that end, a field monitoring was launched in an organic mango orchard in Senegal wherein three treatments were compared: (1) mango trees with ants and sugar feeder, (2) mango trees with ants but no sugar feeder, and (3) mango trees with neither ants nor sugar feeder. The population dynamics of scale insects and weaver ants as well as their behavior were monitored over two years. Sugar provisioning significantly reduced scale insect infestations, nest abundance, and ant aggressiveness over time. Such manipulation of ant behavior through sugar supplementation should help breaking down obstacles that hamper their wide-scale use for the biological control of fruit flies in mango orchards. [ABSTRACT FROM AUTHOR]

• Strong full-plant watering and insecticide sprays were unfavorable for Nesidiocoris tenuis. • Ceratotheca sesamoides and Physalis micrantha were natural host plants of N. tenuis in Senegal. • Sesamum radiatum supported good N. tenuis development and reproduction without alternative food. • Olfactometry showed that N. tenuis would not abandon tomato crops for S. radiatum. Conservation biological control is a promising approach to natural pest control in both open field and protected crops. In sub-Saharan Africa, tomato crops are commonly damaged by several arthropod pests but can also host the predatory mirid bug, Nesidiocoris tenuis. Unfortunately, farmers do not currently take full advantage of this zoophytophagous and generalist biocontrol agent. We conducted field investigations in the Niayes area of Senegal, combined with laboratory experiments, to determine how to enhance natural regulation services provided by this natural enemy. We found that strong full-plant watering and insecticidal sprays, both conventionally applied in the Niayes area, had a detrimental effect on N. tenuis. We identified Sesamum radiatum (false or black sesame) as a promising insectarium plant that could also serve as a leaf vegetable and medicinal plant. This plant supports good N. tenuis development and reproduction, even without alternative food sources. Y-tube olfactometry indicated no attraction to odors of Sesamum radiatum , suggesting that N. tenuis would not abandon tomato plants for this insectarium plants when present in tomato fields. Our results suggest potential approaches to improve conservation of N. tenuis for biological control of Tuta absoluta and other tomato pests in Africa. [ABSTRACT FROM AUTHOR]