Association of arbuscular mycorrhizal fungi and Crotalaria spectabilis to control the burrowing nematodes (Radopholus similis) in banana

Banana belongs to the most consumed fruit worldwide. Unfortunately, its production is threatened by numerous pests such as nematodes. Under conventional production systems, nematodes are most often controlled by nematicides. These chemicals may have side effects on human health and the environment, requiring the development of alternatives control measures. Among these are the use of beneficial microorganisms such as arbuscular mycorrhizal fungi (AMF) and push-pull plants such as Crotalaria spp. Here we investigated the combination of AMF with C. spectabilis as control measure against nematodes in banana. Three objectives were pursued in this thesis. First, we studied the effects of AMF on nematodes population and root infestation of banana plantlets grown under autotrophic in vitro culture conditions. Secondly, we investigated the impact of AMF and C. spectabilis together on the control of R. similis population in banana. Finally, we explored the impact of roots exudates of AMF-colonized C. spectabilis plantlets on the movement and vitality of R. similis. Whatever the experiment, all the developmental stages of the nematodes were affected in presence of the AMF. The multiplication rates of the nematodes were drastically decreased, while no effects of the nematodes were noticed on the AMF. C. spectabilis also decreased the nematode population in banana roots, although more slightly. Interestingly, the effects on nematodes were even more pronounced when the AMF and C. spectabilis were considered together. Indeed, the concomitant use of AMF and C. spectabilis impacted all the developmental stages of the nematodes and significantly decreased the surface of necrotic roots as compared to both organisms alone. Concerning the mobility, nematodes were more attracted by exudates of C. spectabilis when opposed to banana exudates suggesting the presence of attractant compounds. The vitality of nematodes was affected by the root exudates of C. spectabilis, while they remained m
(AGRO - Sciences agronomiques et ingénierie biologique) -- UCL, 2018