Lantana camara L. is a widespread plant species mostly native to subtropical and tropical regions of the world. In this study, insecticidal and repellent activities of L. camara essential oil were evaluated against Callosobruchus maculatus (Fabricius) (Col: Bruchidae). Analysis of chemical composition by gas chromatography/mass spectrometry (GC/MS) showed high amounts of sesquiterpenes, mainly α-humelene (23.3%) and cis-caryophyllene (16.2%). The results showed that the essential oil of L. camara has strong repellent activity against adults of C. maculatus at all tested concentrations. After 2 and 4 h, 97.4 and 100% repellency was seen at highest concentrations of 0.4 μL cm -2 , respectively. Moreover, the oil was found to be toxic to adults when applied by fumigation. Responses varied with the gender of insect and exposure time. The LC50 values were 282.7 and 187.9 μL L -1 for females and males, respectively. An increase in the exposure time from 3 to 24 h caused increasing in mortality from 23.6 to 100% in males and from 14.1 to 97.1% in females, at highest concentration (1160 μL L -1 ). According to these results, L. camara essential oil may be useful as an alternative for bean protection against C. maculatus.
The essential oil of Callistemon citrinus (Curtis) leaves was extracted by hydro distillation and tested on female and male adults of Callosobruchus macullatus (F.) for insecticidal and repellent effects. GC-MS analysis was used to identify and quantify the volatile composition of the essential oil. Results showed that 1,8-cineole (34.2%) and α-pinene (29.0%) were the major components of the oil. Callistemon citrinus oil was found to be toxic to adult insects when applied by fumigation. Responses varied according to the gender of the insect and exposure time. LC50 values were 12.88 and 84.4 μL. L(-1) for males and females, respectively. An increase in exposure time from 3 to 24 h caused an increase in mortality from 50% to 100% in males and from 15.5% to 85.2% in females, at the highest concentration (500 μL. L(-1)). The essential oil also had a repellent effect against C. macullatus in a filter paper arena test. After 2 and 4 h, 86% and 94%, respectively, repellent effects were demonstrated at the highest concentration of 0.4 μL .cm(-2). These observations suggest that C. citrinus essential oil may be usefully applied to control storage pests.
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