Biochemical Screening and Evaluation of Eucalptus camaldulensis Dehnh Leaf N-Hexane Extract on Callosobruchus maculatus Fabricius (Coleoptera: Bruchidae)

Abstract

The phytochemical screening and GC-MS analysis of the leaf of E. camaldulensis were carried out in the laboratory, using standard methods, while the extraction wascarried outwith n-hexane using Soxhlet extractor, and concentrated with vacuum evaporator. The extract was tested on Callosobruchus maculatus to evaluate the effects on mortality, oviposition and adult emergence. The extract of E. camaldulensis leaves was effective in controlling C. maculatus as it caused a significantly high mortality of the weevils. Weevil mortality increased with increased in number of days in which they were exposed to the treatments and extract dosage level. Weevil 100% was achieved by 72 h when treated with 3% and 4% dosage level of the exract. The extracts significantly (P < 0.05) caused reduction in oviposition and adult emergence by the weevils. Oviposition and adult emergence decreased with increased in the dosage level of the extract. Oviposition was totally suppressed when insects were exposed to 4% extract dosage level, while there was no adult emergence on exposure to 3 and 4% extract dosage levels. The results obtained from the phytochemical analysis of E. camaldulensis indicated the presence of alkaloids, flavonoids, saponins, tannins, terpenoids, and phenol indicating the quantitative phytochemical composition of phenol to be highest (76.955 mg/100g), followed by alkaloids (33.025mg/100g), flavonoids (11.74 mg/100g), while saponins has the least value of 9.88mg/100g. The GC-MS analysis revealed arrays of bioactive substances that are responsible for the insecticidal and medicinal properties of E. camaldulensis. The leaf of E. camaldulensis is cheap, biodegradable, ecological friendly and very effective bioinsecticides and therapeutic medicine. Hence, can be used as alternative to the poisonous conventional insecticides and drugs.