Background Some insects are harmful to humans, plants and animals, but some of them can also be a source of proteins, fats, vitamins and minerals and be of therapeutic value. The therapeutic potential requires that medicinal insects and their derived products need to be scrutinized. This study highlights the indigenous knowledge related to their use of medicinal insects in peri-urban and urban areas of Burkina Faso. Methods The survey was carried out among 60 traditional healers spread across two phytogeographical zones of Burkina Faso. The questionnaire focused on medicinal insects used by experienced traditional healers. Chi-square tests and principal component analysis were performed to test for significant differences regarding knowledge of how insects in phytogeographically different areas were used therapeutically in connection with different disease categories. Results A total of 19 species of medicinal insects belonging to 6 orders were cited in connection with treatments of at least 78 pathologies and symptoms. Most frequently mentioned was gastroenteritis. Our study showed that 48.78% of the insects and their products were associated with 46 plant species for the treatment of pathologies. In addition, honey, beeswax and nests were the most widely insect products used. Conclusion The current study allows us to identify medicinal insects as well as their products used in the treatment of pathologies and symptoms, suggesting the presence of a considerable diversity of therapeutically important insect species. These insects are used alone and/or with their products but often in association with medicinal plants. The results constitute a useful database for future studies of medicinal insects in central and western parts of Burkina Faso.

The whitefly Bemisia tabaci is a pest of many agricultural and ornamental crops worldwide and particularly in Africa. It is a complex of cryptic species, which is extremely polyphagous with hundreds of host plants identified around the world. Previous surveys in western Africa indicated the presence of two biotypes of the invasive MED species (MED‐Q1 and MED‐Q3) living in sympatry with the African species SSA and ASL. This situation constitutes one of the rare cases of local coexistence of various genetic entities within the B. tabaci complex. In order to study the dynamics of the distribution and abundance of genetic entities within this community and to identify potential factors that could contribute to coexistence, we sampled B. tabaci populations in Burkina Faso in 2015 and 2016 on various plants, and also their parasitoids. All four genetic entities were still recorded, indicating no exclusion of local species by the MED species. While B. tabaci individuals were found on 55 plant species belonging to eighteen (18) families showing the high polyphagy of this pest, some species/biotypes exhibited higher specificity. Two parasitoid species (Eretmocerus mundus and Encarsia vandrieschei) were also recorded with E. mundus being predominant in most localities and on most plants. Our data indicated that whitefly abundance, diversity, and rate of parasitism varied according to areas, plants, and years, but that parasitism rate was globally highly correlated with whitefly abundance suggesting density dependence. Our results also suggest dynamic variation in the local diversity of B. tabaci species/biotypes from 1 year to the other, specifically with MED‐Q1 and ASL species. This work provides relevant information on the nature of plant–B. tabaci‐parasitoid interactions in West Africa and identifies that coexistence might be stabilized by niche differentiation for some genetic entities. However, MED‐Q1 and ASL show extensive niche overlap, which could ultimately lead to competitive exclusion.

Annona senegalensis Pers. is a shrub of tropical countries that, during the fruiting period, harbor many insects. All parts of the plant are used and exploited in traditional medicine, food, and firewood. Our study aimed at evaluating the diversity of insects associated with the different phenological stages of A. senegalensis fruits in two phytogeographic zones of Burkina Faso. Sampling was carried out on flowers, green fruits, ripe fruits, and decayed fruits of A. senegalensis. For the first time, a total of 48 insects species belonging to 6 orders and 23 families were identified. These orders were Orthoptera, Hemiptera, Hymenoptera, Coleoptera, Lepidoptera, and Diptera. Our data indicated that the diversity of insect species varies according to the stages of development of the fruit (P = 0.017) and according to the site (P = 2.2e-16). Among these insects, Curculionidae (Endaeus spp.) predominate on flowers, are known to be pollinators, and Formicidae (Messor galla Mayr, [Hymenoptera: Formicidae], Trichomyrmex abyssinicus Forel, [Hymenoptera: Formicidae], and Crematogaster sp.) and Tettigometridae (Hilda undata Walker, [Hemiptera: Tettigometridae]) are suspected to have mutualistic relationships on green fruits. Potential pests belonging to the Scarabaeidae (Pachnoda spp., Polybaphes spp., and Xeloma Maura Boheman, [Coleoptera: Scarabaeidae]), Drosophilidae (Zaprionus indianus Gupta, [Diptera: Drosophilidae]), and Nitidulidae (Carpophilus nepos Murray, [Coleoptera: Nitidulidae]) are associated with ripe and decayed fruits. The data in this study highlight the diversity in terms of pollinators that ensure the fruit production and Formicidae known to protect A. senegalensis against potential pests. These data provide valuable information in terms of valuation of this plant.

Dengue vector control strategies are mostly based on chemicals use against Aedes aegypti populations. The current study aimed at investigating the insecticidal effects of essential oils (EOs) obtained from five plant species, Cymbopogon citrates (D. C.) Stapf. (Poaceae), Cymbopogon nardus (Linn.) Rendle (Poaceae), Eucalyptus camaldulensis Linn. (Myrtaceae), Lippia multiflora Moldenke (Verbenaceae), and Ocimum americanum Linn. Lamiaceae, and combinations of Cymbopogon nardus and Ocimum americanum on Ae. aegypti populations from Bobo-Dioulasso. For this purpose, adults of the susceptible and field strains of Ae. aegypti were tested in WHO tubes with EO alone and binary combinations of O. americanum (OA) and C. nardus (CN; scored from C1 to C9). The extraction of the essential oils was done by hydrodistillation, and their components were determined by GC/MS. Among the 5 EOs tested, L. multiflora essential oil was the most efficient, with KDT50 values below 60 min on all Ae. aegypti strains tested, and also with a rate of mortality up to 100 and 85% for Bora Bora and Bobo-Dioulasso strains, respectively. This efficacy may be due to its major compounds which are with major compounds as β-caryophyllene, p-cymene, thymol acetate, and 1.8 cineol. Interestingly, on all strains, C8 combination showed a synergistic effect, while C2 showed an additive effect. These combinations exhibit a rate of mortality varying from 80 to 100%. Their toxicity would be due to the major compounds and the putative combined effects of some major and minor compounds. More importanly, L. multiflora EO and combinations of C. nardus and O. americanum EO, may be used as alternatives against pyrethroid resistant of Ae. aegypti.

Microbial symbionts are widespread in insects and some of them have been associated with adaptive changes. Primary symbionts (P-symbionts) have a nutritional role that allows their hosts to feed on unbalanced diets (plant sap, wood, blood). Most of them have undergone genome reduction, but their genomes still retain genes involved in pathways that are necessary to synthesize the nutrients that their hosts need. However, in some P-symbionts, essential pathways are incomplete and secondary symbionts (S-symbionts) are required to complete parts of their degenerated functions. The P-symbiont of the phloem sap-feeder Bemisia tabaci, Candidatus Portiera aleyrodidarium, lacks genes involved in the synthesis of vitamins, cofactors, and also of some essential amino-acids. Seven S-symbionts have been detected in the B. tabaci species complex. Phenotypic and genomic analyses have revealed various effects, from reproductive manipulation to fitness benefits, notably some of them have complementary metabolic capabilities to Candidatus Portiera aleyrodidarium, suggesting that their presence may be obligatory. In order to get the full picture of the symbiotic community of this pest, we investigated, through metabarcoding approaches, the symbiont content of individuals from Burkina Faso, a West African country where B. tabaci induces severe crop damage. While no new putative B. tabaci S-symbiont was identified, Candidatus Hemipteriphilus asiaticus, a symbiont only described in B. tabaci populations from Asia, was detected for the first time on this continent. Phylogenetic analyses however reveal that it is a different strain than the reference found in Asia. Specific diagnostic PCRs showed a high prevalence of these S-symbionts and especially of Candidatus Hemipteriphilus asiaticus in different genetic groups. These results suggest that Candidatus Hemipteriphilus asiaticus may affect the biology of B. tabaci and provide fitness advantage in some B. tabaci populations.