Opportunities and constraints facing fish production system in DR Congo

Open Access ArticleThe current aquaculture production systems in the village environment and their constraints and opportunities were studied to understand the reasons for the decrease in the number of fishponds in South Kivu, eastern DR Congo. . Little is known about fish production in South Kivu; thus, this study was carried out in two phases: a survey, a follow-up of the farms over the course of a year and a literature review. Accordingly, 305 aquaculturists from three territories were interviewed from May to November 2019. This breeding is mainly practiced by men (91.6%), adults (45±14 years), married (93.6%), fish farmers with no formal education (36.5%, ) farmers who practice agriculture as their main activity (68.5%, ) and farmers engaged in fish farming as a secondary activity (60.4%). Fish farmers have 13±9 years' experience; and only 39.0 percent of fish farmers received training on good fish farming practices. Membership to groups or associations is low (6.1%). Tilapia sp is the widely cultivated species (82.6%), followed by a combination of Tilapia-Catfish (17.3%). Fish are reared in medium-sized fishponds (358.7±230.4 m2) at unknown age (60.4%), with a reproduction rate of (54.7±37.7 kg) per growth cycle. The main opportunities in aquaculture in South Kivu are water availability (13.5% in Kabare, 31.1% in the Ruzizi plain, and 15.3% in Walungu), the presence of a fish market, and availability of land suitable for aquaculture (27.1% in Kabare, 10.9% in the plain, and 15.3% in Walungu). On the other hand, the main constraints identified are lack of quality fry (75.5% in Kabare) and the high cost of labour (60.9% in the Ruzizi plain and 60.9% in Walungu)

Agrobacterium tumefaciens C58 presence affects Bacillus velezensis 32a ecological fitness in the tomato rhizosphere

International audienceThe persistence of pathogenic Agrobacterium strains as soil-associated saprophytes may cause an inconsistency in the efficacy of the biocontrol inoculants under field condition. The study of the interaction occurring in the rhizosphere between the beneficial and the pathogenic microbes is thus interesting for the development of effective biopesticides for the management of crown gall disease. However, very little is still known about the influence of these complex interactions on the biocontrol determinants of beneficial bacteria, especially Bacillus strains. This study aimed to evaluate the effect of the soil borne pathogen Agrobacterium tumefaciens C58 on root colonization and lipopeptide production by Bacillus velezensis strain 32a during interaction with tomato plants. Results show that the presence of A. tumefaciens C58 positively impacted the root colonization level of the Bacillus strain. However, negative impact on surfactin production was observed in Agrobacterium-treated seedling, compared with control. Further investigation suggests that these modulations are due to a modified tomato root exudate composition during the tripartite interaction. Thus, this work contributes to enhance the knowledge on the impact of interspecies interaction on the ecological fitness of Bacillus cells living in the rhizosphere