Abstract
Essential oil (EO) was extracted from Callistemon citrinus leaves by hydro-distillation. The extracted oil was analysed by GC and Mass Spectroscopy. Analysis report showed that the major constituent of the essential oil was eucalyptol (40.44%). The EO of C. citrinus exhibited 100% fumigation toxicity (adult mortality) against adult and 95.8% larvicidal activity against Tribolium castaneum at 160 μL/L (12 hrs) and 320 μL/L (48 hrs), respectively. The effective concentration of 37.05 μL/L (adult) and 144.31 μL/L (larva) at 24 and 48 hrs respectively. A 100% repellent activity was observed at 20 μl for adult beetles and 93.3% for larvae of T. castaneum at 20 μl after 24 h. Exposure to C. citrinus EO significantly reduced beetle fecundity, ovicidal activity, egg hatching, larvae survival, and emergence of adult. The effect of EO on detoxification enzymes of T. castaneum adults was examined. Results indicated that the activity of detoxification enzymes drastically varied when compared with control. This EO had toxicant effects on all stages of the life of T. castaneum. Hence it may be used as fumigant instead of the use of using synthetic chemical fumigants.
