Potential of gelam (Melaleuca cajuputi) stem as natural insecticide.

Carpenter ant, Camponotus spp. is one of the most common and destructive insect pest in residential area. Synthetic insecticide is used to control the population of carpenter ants. Synthetic insecticides create various problems to the environment and human health causes research to look into alternative strategies. Present study was conducted to determine the potential of Melaleuca cajuputi stem as natural insecticide by evaluating the toxicity and repellency rate. Repellency and toxicity of the plant to carpenter ants were tested by using crude extract extracted using n-hexane, dichloromethane and methanol. Repellency test was conducted using modified WHO by using 20% concentration of crude extract diluted with acetone. Repellency rate was calculated based on the number of ants entered the treated area in the experimental setup. For toxicity test, 10% of each crude extract was prepared by mixing with honey. The toxicity rate was calculated based on the number of ants died after eating the honey mixed with extract. The results for repellency test showed a significantly higher repellency rate in hexane extract with the percentage of 97.30%, followed by dichloromethane extract with percentage of 83.40% and lastly 42.80% repellency for methanol extract. Hexane extract has the highest repellency rate because it might contain essential oil which is a non-polar compound that the smell of the oil repels the ants. The extract smell of dichloromethane and methanol, which was mild to almost no smell, was not strong enough to repel the ants. The result for toxicity test showed a significantly higher toxicity rate in methanol extracts to ants with the percentage of 84.30%, followed by dichloromethane extract with the percentage of 77.70% and hexane with 54.30%. Methanol extract showed higher percentage due to higher content of active ingredients that are toxic to the carpenter ants. In conclusion, Melaleuca cajuputi stem has higher repellency effect compared to toxicity effect.