Fruit fly surveillance in Togo (West Africa): state of diversity and prevalence of species

The production and marketing of fruits, especially mango, in sub-Saharan Africa are threatened by fruit flies (Diptera: Tephritidae). This baseline study analysed the biodiversity of fruit fly species, in mango orchards, in different ecological zones of Togo. Traps used to monitor the flies in the orchards consisted of dry baits, made from four types of parapheromones specific to the males of different species. Forty species of fruit flies were identified in the mango orchards in Togo. The most common species were Bactrocera dorsalis (Hendel), Ceratitis cosyra (Walker), Ceratitis fasciventris (Bezzi), Ceratitis capitata (Wiedemann), Ceratitis bremii Guérin-Méneville, Dacus bivittatus (Bigot), Dacus humeralis (Bezzi), Dacus punctatifrons Karsch and Zeugodacus cucurbitae (Coquillett). The invasive B. dorsalis and the endogenous species, C. cosyra were dominant in the mango producing areas of Togo because their prevalence were very high (B. dorsalis: 2.1 ≤ flies per trap per day (FTD) ≤ 472.2; C. cosyra: 0.34 ≤ FTD ≤ 97.28). There was no area free from fruit flies in Togo during the study. These results constitute an essential reference in the future evaluation of the effectiveness of any control activities initiated in Togo against fruit flies.

An integrated diagnostic setup for the morphological and molecular identification of the Ceratitis FAR complex (C. anonae, C. fasciventris, C. rosa, C. quilicii, Diptera, Tephritidae)

The Ceratitis FAR complex (Diptera, Tephritidae) includes four economically important frugivorous flies (Ceratitis anonae, Ceratitis fasciventris, Ceratitis quilicii, Ceratitis rosa) whose immature stages and adult females cannot be properly resolved through morphological identification. In order to develop a simplified molecular tool for the identification of two of these species (C. rosa, C. quilicii), we selected a subset of six microsatellite markers out of a panel of 16 loci that were previously developed for the molecular differentiation of the taxa within the complex. These six markers were first tested in silico and then used for the actual genotyping of C. quilicii and C. rosa, resulting in the correct identification of all male reference specimens. Here, we propose an integrated morphological and molecular setup for the identification of the four species of the FAR complex. The decision map relies on preliminary DNA barcoding or morphological identification (when possible) to exclude species not belonging to the complex followed by (a) morphological identification of all adult male specimens and female C. anonae, (b) molecular identification via a panel of 16 microsatellite markers for immature stages, damaged vouchers and samples potentially including adult female C. fasciventris/C. quilicii/C. rosa and (c) molecular identification via a reduced panel of six microsatellite markers for samples including only C. quilicii and C. rosa. This simplified diagnostic setup was profitably implemented in the framework of the ERAfrica fruit fly project and will help correctly identify species within the FAR complex for their early detection and monitoring.

Resolution of three cryptic agricultural pests (Ceratitis fasciventris, C. anonae, C. rosa, Diptera: Tephritidae) using cuticular hydrocarbon profiling

Discrimination of particular species within the species complexes of tephritid fruit flies is a very challenging task. In this fruit-fly family, several complexes of cryptic species have been reported, including the African cryptic species complex (FAR complex). Cuticular hydrocarbons (CHCs) appear to be an excellent tool for chemotaxonomical discrimination of these cryptic species. In the present study, CHC profiles have been used to discriminate among three important agricultural pests from the FAR complex, Ceratitis fasciventris, Ceratitis anonae and Ceratitis rosa. Hexane body surface extracts of mature males and females were analyzed by two-dimensional gas chromatography with mass spectrometric detection and differences in CHC profiles between species and sexes tested through multivariate statistics and compared with species identification by means of microsatellite markers. Quantitative as well as qualitative CHC profile differences between sexes and species are reported. The CHC profiles consisted of a mixture of linear, internally methyl-branched and mono-, di- and tri-unsaturated alkanes. Twelve compounds were pinpointed as potential chemotaxonomical markers. The present study shows that presence or absence of particular CHCs might be used in the chemical diagnosis of the FAR complex. Moreover, our results represent an important first step in the development of a useful chemotaxonomic tool for cryptic species identification of these important agricultural pests.