Determination of the chemical and nutritive constituents in oil extracts of whole edible portion of Rhynchophorus phoenicis and Oryctes rhinoceros

Background: Oryctes rhinoceros and Rhynchophorus phoenicis larvae are delicacies eaten by major tribes of the Niger Delta region of Nigeria.

Aim: Insects and their larvae are sources of micronutrients, proteins and biological active compounds. This study is aimed at characterizing the chemical constituents in oils extracted from these larvae.

Methods: The worms were macerated and extracted using 450 mL of n-hexane:dichloromethane (50:50). Extract was concentrated to 1 mL in vacuo and subjected to GC-MS analysis, while elemental analysis was carried out to assess the levels of mineral constituents in whole worms.

Results: GC-MS analyses of extracts were mainly, esters, fatty acids, sterols, ketones, aldehydes, alkanes and alcohols. Spectra showed the presences of 19 and 23 compounds in Rhynchophorus phoenicis and Oryctes Rhinoceros larvae respectively - of which these esters, Methyl hexadecanoate, Methyloctadecan-9,12-dienoate and Methyl stearate were found in both, while major difference is the presence of the tocopherols (Vitamin E) in Rhynchophorus phoenicis only. These compounds were confirmed from the NIST library. Amongst the mineral nutrients, Na content was the highest (207.41 and 216.55 mg/Kg in R. phoenicis and O. Rhinoceros respectively). The order was Na>Fe>Mn>Zn>K>P>Mg>Ca, while Al, Se, Cr and Pb were >0.001 mg/Kg.

Conclusion: Most of the compounds identified are known to exhibit bio-active and curative properties and could also boost the amelioration of different ailments. Therefore, both insect larvae species are likely to have high medicinal and nutraceutical potentials.