Microbial and Physicochemical Properties of Fermented African Locust Bean (Parkia biglobosa) Effluent and its Biocidal Potential on some Selected Insects

Abstract

The study was carried out to determine the microbial and physicochemical identify the bacteria and fungi associated with the fermentation of African Locust Bean (Parkia biglobosa) “Iru” effluent and to assess the biocidal effect of fermented Parkia biglobosa effluent on some selected insects (mosquito, bean and rice weevils). The physicochemical properties of the fermented locust bean effluents were assessed. The results obtained on the effluent physicochemical parameters showed that there were differences between the control effluent and the fermented African locust bean effluent from the laboratory. Specifically, total hardness (614.00 – 194.00 mg/l), total dissolved solids (102.15 – 108.53 mg/l), total solids (125.30 - 131.50mg/l), the total alkalinity (762.50 – 688.75 mg/l) and the total acidity (as CaCO3) (206.70 – 263.40 mg/l). The minerals of the two effluents showed sharp differences in the sodium, potassium, calcium and magnesium composition. Control effluent was higher than the test effluent in sodium (1578.19 mg/l), potassium (4734.19 mg/l) and magnesium (4304.16 mg/l) while the test effluent was only higher in calcium (7259.53 mg/l) compared to that of the control. The microbial types in fermented samples were identified after the fermentation period of 72 hrs. The bacterial profile were Bacillus subtilis, Bacillus cereus, Proteus mirabilis, Staphylococcus aureus, Leuconostoc mesenteroides, Escherchia coli and Enterococcus faecalis. Leuconostoc mesenteroides and Bacillus subtilis had the highest occurrences. The fungi isolates were Fusarium sp., Saccharomyces cerevisiae, Aspergillus fumigatus, Aspergilus niger and Penicillium sp. Evaluation of the effect of fermented African locust bean effluent on bean weevil Callosobruchus maculatus (F.) with respect to insect mortality showed considerable biopesticidal potential on the bean weevil. The results revealed that the fermented locust bean effluent had the highest mortality of six after 20 minutes and the lowest mortality of one after 40 minutes. With further research, fermented African locust bean effluent can be used as biopesticide which would be cheaper, less hazardous to human health and easily accessible to local people to preserve cowpea produce.