Inhibitory effects of oil extract of green Acalypha (Acalypha wilkesiana) on antioxidant and neurotransmitter enzymes in Callosobruchus maculatus

Abstract

Abstract Background Callosobruchus maculatus is an important insect pest of cowpea. The inhibitory effects of oil extract of Acalypha wilkesiana (Muell Arg.) leaves on antioxidant, neurotransmitter, and detoxifying enzyme in adult Callosobruchus maculatus (Fabricius) were evaluated under laboratory condition. The leaves of the plant were collected fresh and air-dried before the oil was extracted from them through cold extraction method while ethanol was used as solvent. Adult C. maculatus were exposed to 0.2, 0.4, 0.6, 0.8, and 1.0 ml of 0.5% concentration of the oil extract and were homogenized separately. The supernatants gotten from them were used as enzyme sources. The activities of SOD, CAT, GPx, AChE, CarEST and GST were observed with photospectrometer. GC-MS analysis was done to evaluate the active compounds present in the oil extract. Results The activities of the enzymes increased at lower dosages of the oil extract (0.2 and 0.4 ml) and reduced drastically at higher dosages of the oil (0.6, 0.8, and 1.0 ml). However, AChE activity was more affected by the oil extract as it was almost inhibited by the oil extract. The GC-MS showed that 114 compounds were present in the oil extract of the plant while acetaldehyde had the highest percentage (46.07%) of the total compounds. Conclusion Based on these findings, the oil extract of A. wilkesiana could be a good biopesticide for the control of adult C. maculatus instead of synthetic chemical insecticides.

Keywords

• Plant extract
• Acalypha wilkesiana
• Callosobruchus maculatus
• Antioxidant
• Detoxification
• Enzymes