The specificity of plant use by aphids is related to symbiont diversity of some aphid models. Aphis craccivora Koch (Hemiptera: Aphididae, Aphidini) is a well‐known aphid that feeds on species of Fabaceae, but has also been recorded recently on Amaranthus species (Amaranthaceae) in Gabon (Africa). Aphis craccivora strains used in this study were originally collected from crop Vigna unguiculata L. Walp. (Fabaceae) from Togba in Benin (Africa) and Amaranthus hybridus L. from Libreville in Gabon, for a comparative study of symbionts. Saliva composition, potentially including bacterial proteins, also contributes to the phytotoxic effect of aphid attacks. Both, endosymbiont bacteria and saliva protein diversity should be targeted to investigate the feeding behavior of aphids and to explain plant–aphid interactions. Bacteria‐targeted PCR was conducted on six symbionts in A. craccivora. The obligate symbiont Buchnera aphidicola Munson et al. (Enterobacteriaceae) was identified in all aphids collected. In comparison, the facultative symbiont Serratia symbiotica Moran et al. (Enterobacteriaceae) was only found in A. craccivora from Gabon, whereas Rickettsia sp. (Rickettsiaceae) was only found in aphids from Benin. Using nano‐LC‐MS/MS (liquid chromatography‐tandem mass spectrometry), some proteins were only found in solid or soluble saliva, whereas others originated from S. symbiotica. Two of the identified proteins are involved in plant–pathogen interactions: calmodulin and elongation factor Tu. This information on endosymbionts and related salivary proteomes from A. craccivora in Gabon helps improve our understanding of aphid–plant interactions.

In response to a predator attack, many Aphidinae species release an alarm pheromone, which induces dispersal behavior in other individuals within the colony. The major component of this pheromone is the sesquiterpene (E)-β-farnesene (Eβf), but variations occur between aphid species. In the present work, we collected, identified, and quantified the alarm pheromone of Aphis craccivora Koch (Hemiptera: Aphididae), before quantifying the escape behavior induced in the neighboring individuals. We compared the semiochemistry and associated behavior of alarm signaling with two other aphid species: Myzus persicae (Sulzer) (Hemiptera: Aphididae) and Aphis fabae Scopoli (Hemiptera: Aphididae). Eβf was the only volatile found for each species. M. persicae produces a higher quantity of Eβf (8.39 ± 1.19 ng per individual) than A. craccivora (6.02 ± 0.82 ng per individual) and A. fabae (2.04 ± 0.33 ng per individual). Following exposure to natural doses of synthetic Eβf (50 ng and 500 ng), A. craccivora respond more strongly than the two other Aphidinae species with 78% of the individuals initiated alarm behavior for 500 ng of Eβf.

Résumé -Au Gabon, le rôle du maraîchage périurbain est essentiel à l'approvisionnement des villes en légumes frais, notamment à Libreville et Owendo. Lors d'une enquête menée dans trois périmètres maraîchers, un état des lieux a été réalisé sur les caractéristiques socio-économiques, la diversité des plantes cultivées et les pesticides utilisés. Les superficies exploitées vont de 0,08 ha à 0,4 ha par maraîcher selon les sites. Les exploitants interrogés sont à 51 % originaires du Gabon alors que 40 % sont originaires du Burkina Faso. Les espèces les plus cultivées tout au long de l'année sont l'amarante (Amaranthus hybridus L.), la laitue (Lactuca sativa L.), l'oseille de guinée (Hibiscus sabdariffa L.), la morelle noire (Solanum nigrum L.). Les ravageurs les plus importants sont les Aphididae et quelques coléoptères. Les produits phytopharmaceutiques les plus utilisés sont des insecticides neurotoxiques conventionnels. Une meilleure maîtrise du suivi des cultures, une vulgarisation en protection des cultures y compris sur l'emploi des pesticides ainsi que la possibilité de développer des systèmes de micro-crédits aux petits producteurs permettraient d'augmenter la production légumière périurbaine et sa qualité sanitaire, ainsi que d'accroître l'autonomie alimentaire locale.Mot clés : légumes / maraîchage / Afrique centrale / ravageur / pesticide Abstract -Peri-urban market gardening in Libreville and Owendo (Gabon): farmers' practices and sustainability. In Gabon, peri-urban gardening is an opportunity to provide vegetables to the main cities, such as Libreville and Owendo. Following a survey conducted in three market gardening areas, an inventory was conducted on the socio-economic characteristics, the diversity of crops, and pesticide uses. The cropped areas range from 0.08 ha to 0.4 ha per farmer, according to the site. National operators represent 51%, while people from Burkina Faso manage 40% of vegetable production. The most cultivated species throughout the year are amaranth (Amaranthus hybridus L.), lettuce (Lactuca sativa L.), Guinea sorrel (Hibiscus sabdariffa L.) and black nightshade (Solanum nigrum L.). The most important pests are Aphididae and some beetles. The most commonly used plant protection products are insecticides, mainly conventional neurotoxic. Best crop monitoring, pest control including pesticide application reduction, and the possibility to offer microcredit systems to small producers would help increasing peri-urban healthy vegetable production and increase local food autonomy.

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As part of the classification of Membracidae from Gabon and Equatorial Guinea, a new species group of the genus Hamma Buckton, 1905 is proposed, and three new species are described: Hamma nigrum sp. nov., Hamma spinellii sp. nov. and Hamma caneparii sp. nov. An updated checklist and key to the genus Hamma are provided.

Banana Bunchy Top disease is the most devastating viral disease that can attack bananas. Its presence prevents the development of bananas and leads to a decrease in production. It is caused by Banana Bunchy Top Virus (BBTV), the vector agent of which is the aphid aphid Pentalonia nigronervosa. The disease is present in the agroecological zone of the coastal sedimentary basin of Gabon, where the prevalence of the disease is reaching worrying proportions. This study focused on the assessment of varietal resistance of Musa spp. the most common in greater Libreville. The diversity of local banana cultivars can be an asset in the search for varieties resistant to BBTV. The results of this study show that not all cultivars have the same sensitivity. Indeed, dessert cultivars are more susceptible than plantain cultivars. Fougamou and Gros-Michel are the most widely cultivated dessert cultivars in greater Libreville, and are very sensitive to BBTV. Alone, these two cultivars failed to germinate after inoculation of pure ground material from a plant infested with BBTV at the highest stage of the disease. While the plantain cultivars, Obel, ZokEkone and Elate, are much more resistant.

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The genus Myrmecobrenthus Kleine, 1920 is revised and a key for the species of this genus is provided. Myrmecobrenthus susinii sp. nov. is described from Gabon, and compared with the closely related M. ater Damoiseau, 1961 and M. wasmanni Kleine, 1920, from which it mainly differs in the shape of the male head and rostrum. Myrmecobrentus wasmanni is recorded for the first time from Gabon.