Reproductive Performance of Glossina palpalis gambiensis (Diptera: Glossinidae) when fed frozen or fresh bovine blood meals

The tsetse and trypanosomoses control by sterile insect technique (SIT), requires mass production of quality tsetse pupae and consequently high-quality blood meal for the fly feeding. The reproductive performances of Glossina palpalis gambiensis (Diptera : Glossinidae), fed frozen or fresh blood meals has been studied. Three diets of slaughtered bovine blood stored at -18 °C for six months (R6), three months (R3) and one month (R1) were used in the present investigation. Fresh blood samples stored at 4°C and renewed every four days were used as control (R0). The defibrinated blood was packaged in batches of 30 x 20 ml vials. For each blood meal, 30-day feeding tests were conducted at the beginning and end of freezing. All blood meal was irradiated using 137 caesium irradiation before being used. The parameters monitored daily were: the number of dead flies (fed and unfed), the number and weight of pupae and the emergence rate. No difference in survival rates was observed for the three regimes (df: 15; Chi-square: 7.53; p > 0.05), on average 32.1% (R0), 32.4% (R6), 37.5% (R3) and 38.2% (R1). However, flies fed with the six-month-old frozen blood were less efficient in pupa production (df: 3; F: 6. p < 0.001) and pupae weight (df: 3, F: 3.24, p < 0.05) compared to the control. The mortality rate was affected by the duration of freezing: 26.7% for R6 and 8% for the other diets (p <0.05). The implications of our results in terms of blood meal management for efficient production of insectary pupae were discussed

Tsetse and trypanosomes relationship in Southwestern part of Burkina Faso

African Animal Trypanosomosis (AAT), transmitted by tsetse flies, are one of the main constraints for the development of livestock farming in Burkina Faso. The objective of this study was to understand the impact of the level of degradation of tsetse habitat on the epidemiology of AAT. Entomological and parasitological surveys were carried out in two different landscape areas: conserved (Folonzo) and fragmented (Moussodougou) in southwestern part of Burkina Faso. The results revealed that the diversity, abundance and infection rate of tsetse flies were related to the conservation status of the habitat. In Folonzo, four species of tsetse were present (84.76% (2870/3386)) versus a single species (15.24%) in Moussodougou. The tsetse infection rate was also higher in Folonzo (21% (133/633)) than in Moussodougou (7.8% (23/294)). In addition, in Folonzo, the tsetse flies were infected with all 3 species of trypanosomes. However, in Moussodougou, G. p. gambiensis (the only species present) was infected primarily with T. congolense (68.44% (13/19)). We suggest that the current fragmentation of tsetse habitats does not reduce the risk of trypanosomiasis, but leads to selection and maintaining the best trypanosome and tsetse (G. p. gambiensis / T. congolense) pair that may affect the epidemiology of AAT

Using self–organizing maps and machine learning models to assess mollusc community structure in relation to physicochemical variables in a West Africa river–estuary system

International audienceThe poor understanding of changes in mollusc ecology along rivers, especially in West Africa, hampers the implementation of management measures. We used a self–organizing map, indicator species analysis, linear discriminant analysis and a random forest model to distinguish mollusc assemblages, to determine the ecological preferences of individual mollusc species and to associate major physicochemical variables with mollusc assemblages and occurrences in the Sô River Basin, Benin. We identified four mollusc assemblages along an upstream–downstream gradient. Dissolved oxygen (DO), biochemical oxygen demand (BOD), salinity, calcium (Ca), total nitrogen (TN), copper (Cu), lead (Pb), nickel (Ni), cadmium (Cd) and mercury (Hg) were the major physicochemical variables responsible for structuring these mollusc assemblages. However, the physicochemical factors responsible for shaping the distribution of individual species varied per species. Upstream sites (assemblage I) showed high DO and low BOD and mineral compounds (i.e., TN, salinity, and Ca), which are primarily responsible for structuring the occurrences of bivalves (Afropisidium pirothi, Etheria elliptica, Sphaerium hartmanni) and the gastropod Lanistes varicus. Sites along the middle reach (assemblage II) were characterised by a high degree of organic pollution but low heavy metal pollution; we detected no specific mollusc indicator species. Downstream sites (assemblage III) displayed high mineral and heavy metal concentrations and a fauna without specific indicator species. Finally, downstream sites associated with brackish water (assemblage IV) displayed important levels of organic and heavy metal pollution. These sites are dominated by diverse gastropods (i.e., Bulinus spp., Gabbiella africana, Indoplanorbis exustus, Pachymelania fusca, Radix natalensis, Stenophysa marmorata and Tympanotonos fuscatus). Our results highlight that mollusc communities in the Sô River Basin are structured by key physicochemical variables related to the river–estuary continuum. Habitats that are progressively more downstream are confronted with increasing anthropogenic stress. Conservation and management plans should focus on downstream habitats