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

An interest in Melaleuca cajuputi leaf has been increased due to their benefits especially as potential sources for insects control agents. Cockroaches are one of the rough insects that abundantly found in household areas which can pose various threat to human health and hard to be eliminated. The use of natural insecticides can be an alternative to synthetic insecticides as they are more biodegradable and safer compare to synthetic insecticides which are harmful to human and environment. Therefore, a study was conducted to evaluate the toxicity and repellency of essential oil and extracts from leaves of Melaleuca cajuputi. Common household cockroaches were selected for this experiment which is American cockroach (Periplaneta americana). The essential oil and hexane crude extract from Melaleuca leaves were used against American cockroach. Toxic test in this experiment were subjected to force feeding using 50% concentration at room temperature where the extract or essential oils were mixed with the food. For repellent test, the essential oil and leaves crude extract were tested at three different concentrations which are 0.015g, 0.008g and 0.004g. In the control experiment, the insects were exposed and fed with untreated food and normal tap water. Each test was followed with three replications. Mortality and repellency was recorded within 24 hours with several intervals. The essential oil showed highest mortality values for cockroach (97%) after 24 hours exposure compare to the leaves extract which showed no mortality. Besides, the highest repellency was observed at 0.015g respectively for both crude leaves extract and essential oil. Crude leaves extract was more effective in repellent test after 24 hours exposure at almost all concentration used in this experiment. The percentage repellency of leaves extract and essential oil however exhibited no significant differences with the mortality rate in this study. Therefore, the present study has demonstrated that Melaleuca cajuputi have repellent and toxic effects on Periplaneta americana thus this can be developed further for pest control and management in future.