## 3 Results and Discussion
### Comparison of Lipid Compositions between Two Insect Species  
The GC responses for _T. castaneum_ and _R. dominica_ that were identified as compounds from the total GC responses were \(91.93\pm 2.74\%\) and \(82.22\pm 3.06\%\) from the homogenized body and \(93.38\pm 3.93\%\) and \(81.32\pm 2.82\%\) from the cuticular extractions, respectively. Thirty-eight and 39 compounds were obtained from the cuticular and homogenized body extraction of _T. castaneum_, whereas 30 and 26 compounds were identified from the cuticular and homogenized body extraction of _R. dominica_, respectively (Tables 3 and 4). The carbon chain lengths of _T. castaneum_ varied from 25 (pentacosane) to 32 (dotriacontane) carbons, and _R. dominica_ had a range of compounds from 26 (11-methylpentacosane) to 34 (tetratriacontane) carbons. According to the cuticular and homogenized body extractions, n-alkanes and methyl-branched alkanes were the major compounds identified from _R. dominica_ and _T. castaneum_. A previous study by [PERSON], 1978 [27] also reported the same classes of n-alkanes and branched alkanes in _T. castaneum_ in the region of C25-C32. In this study, the two major lipid compounds from _T. castaneum_ cuticular extraction were 11-methylheptacosane (20.71%) and 3-methylheptacosane (12.37%), and the two major lipid compounds from the homogenized body were 1-pentadecene (22.70%) and 11-methylheptacosane (16.50%). The lipid compounds 10-methyldotriacontane (14.0%) and 15-methyltritriacontane (9.93%) were the two major compounds in the cuticular extraction from _R. dominica_, and 13-methyllnonacosane and 13-methylheptacosane had the highest peak areas (20.30% and 18.10%, respectively) in the homogenized body. These results demonstrate that this method could extract and identity specific hydrocarbons from different insect species. This might indicate that the method can be used as a tool for the identification of insect species, which further supports previously reported studies that used cuticular hydrocarbons as chemotaxonomic tools for the identification of insect species [36; 37]. The results from both insect species showed that the majority of hydrocarbon waves were in abundance in the cuticular extraction in comparison to the homogenized body extraction (RT = 31.5 to 39.6 min for _T. castaneum_ and RT = 31.5 to 45.2 min for _R. dominica_, Figures 1 and 2) including the major compounds such as 11-methylheptacosane and 3-methylheptacosane from _T. castaneum_. This is evident from the distribution coefficient between the homogenized body and the cuticular extraction (Tables 3 and 4), where the total peak areas were 29.11% and 24.17%, respectively, for the two major compounds of 11-methylheptacosane and 3-methylheptacosane in the homogenized body as compared to the cuticular extraction, suggesting the fact that these compounds are more in abundance in the cuticular extraction. A similar result for _R. dominica_ was also observed for the two major compounds 10-methyldotriacontane and 15-methyltritriacontane, which showed distribution coefficients of 10.61% and 7.11% in the homogenized extraction compared to the cuticular extraction. However, the fatty acids peak areas were opposite in the GC response. The peak areas of most of fatty acids were higher in the homogenized body extraction in comparison to the cuticular extraction. Linolenic acid showed the highest distribution coefficients of 96.01% and 88.72% for _T. castaneum_ and _R. dominica_, respectively, in the homogenized body extraction. Thus, this research provides a robust tool not only to analyze cuticular and whole body lipids but to also assist in understanding the cuticular lipid compositions in comparison to internal lipid composition. This, in turn, may provide information to deduce the essential roles of lipids in many chemical and biological processes such as protecting insect bodies from dryness and pathogens [1; 2; 38].