ABSTRACT
The presence of termites in the cocoa plantations and quarries of Côte d'Ivoire poses a threat to the producers of this sector. Producer yields are insufficient to cover the strong market demand. This situation leads to food insecurity for the population. Knowledge of the specific inhibitory molecules of digestive enzymes of termites is necessary to enhance the effectiveness of insecticides to optimize crop production. The present study was aimed to characterize termite cellulases according to the trophic group. Specifically, the influence of chemical agents on the cellulase activities of four humivorous (Cubitermes fungifaber) and xylophagous termites (Nasutitermes latifrons, Microcerotermes fuscotibialisand Amitermes guineensis) collected in Daloa during the October period was investigated.Thus, the cellulase activities were measured by the spectrophotometric method in the absence and in the presence of the concentrations of 1 and 5 mM of various chemical agents. The chemical agents used behaved differently on cellulase activities. Thus, Cu2+, Pb2+and EDTA inhibited the cellulase activity of M. fuscotibialismore than 90% at concentrations of 1 and 5 mM, respectively, indicating the presence of a metalloprotein. On the other hand, that of the other two xylophagous species was slightly inhibited. In addition, the cellulase activity of C. Fungifaber was inhibited at the two respective concentrations by Cu2+at about 70%. In conclusion, Cu2+, pb2+and EDTA can be used in the formulation of some specific insecticides against humivorous and xylophagous termites.
ABSTRACT
The aim of the present study was to evaluate the effects of three feeds formulated for three fish farmingagroecological areas of Côte d’Ivoire on the growth and nutritional quality of Oreochromis niloticus juveniles.Feeds were formulated at 30% crude protein with locally-sourced raw materials available by area. The use ofdifferent ingredients at different levels for feeds formulation made variations in the nutritional compositionsand costs of the three feeds produced. The average male weight of O. niloticus juveniles, 26.89 ± 2.98–27.35± 2.74 g, was stocked at a density of 3 fish/m2 and was hand fed at 5%–3% body weight two times daily, 6days per week during 120 days in the triplicate earthen ponds. At the end of the feeding trial, daily weight gainvalues varied between 1.12 ± 0.08 g/day and 1.21 ± 0.06 g/day and survival rate ranged between 99.44 ± 0.00and 100%. No significant difference (p < 0.05) was observed in the growth performance and feed efficiencyparameters of juveniles O. niloticus feeding. An increase in crude lipid and gross energy was observed in wholebody compositions of O. niloticus feeding with the highest dietary lipid levels. Low-cost locally adapted feedsproduced for O. niloticus juveniles growth were competitive and proffer the opportunity to improve availabilityof local quality feeds in the fish farming areas of Côte d’Ivoire.