Contribution of a cadaveric insect from the family Stratyomidae to composting process: Case of enrichment of compost with larvae of the black soldier fly (Hermetia illucens), tested on shallot cultivation

Waste recovery is the most interesting way to overcome public health and environmental problems in a developing country like Cameroon. The general objective of this experiment is to evaluate improvement of the quality of the compost by using black soldier fly larvae (BSFL) during his life cycle. The specific objectives are: (i) study the life cycle of black soldier flies (BSF) as well as the composting process based on various types of waste, (ii) analyze the physicochemical parameters and the activity of microorganisms found inside the compost obtained from the activity of black soldier fly larvae (iii) evaluate the impact of that compost on shallot performance. The results show that the life cycle of BSF has 5 stages (egg, larva, prepupa, nymph and adult) and lasted between 39 to 45 days. These specific flies can produce mature compost during the larval stage which lasted 16 days. This compost has a color that varies from dark brown to black, a texture like forest litter and an odor of humus. The results of the physicochemical characterization of this compost show that it is rich with a C/N ratio of 13 to 15 and a pH varied from 6.8 to 8.0. According to WHO standards, these values characterizing matured compost. Microbiological analysis revealed the abundance of decomposer fungi such as Fusarium spp., Penicillum spp., Alternarium spp., Gram-positive and negative bacteria. The positive reaction to hydrolysis enzymes (amylases, cellulases and proteases) characterizing this type of compost. Compared to the control, the substrate based on these different types of compost has a significant effect on the performance of the shallot. The effect on bulb yield fluctuated from +27% to +124% compared to the control, from +41% to +169% for total fresh biomass. On the other hand, chemical fertilizers have a harmful effect of -64% compared to the control. Furthermore, the comparison between the 5 types of waste indicates that industrial waste shows the best yields on shallots (+124%).