Artificial modification of the chemical composition of orange oil (Citrus sinensis L.) and its effect on larvicidal activity

The use of synthetic pesticide carries along several disadvantages talking about the preservation of the natural homeostasis of the planet, causing the searching of biopesticide, which one presents advantages as well as biodegradability in minimum possible time, the low toxicity in comparison to synthetic pesticides and their variety of structure, which allows slowing down the appearance of resistance. The aim of this work was to evaluate the effect on the larvicidal action when artificially varying the chemical composition of orange oil (Citrus sinensis L.). As results, we found that the analysis of gas chromatography coupled to mass spectrometry showed the presence of terpenoid and sesquiterpenoid compounds in the different samples. The use of electric pulses on samples modified their chemical composition, so that the percentage of limonene went from 72% in the sample that was not subjected to electric treatment to lower percentages, even in sample three the percentage of limonene was <50%. Only three compounds (limonene, linalool and caryophyllene) were found to be common in all samples. Subsequently, the larvicidal action on Drosophila melanogaster larvae was evaluated. Six concentrations of each oil sample were tested (0, 100, 500, 1000, 5000 and 10000 ppm). We found that there was no linear relationship between concentration and lethality. Additionally, in the sample without electrical treatment most of the concentrations tested had lethality higher than 50%, while in sample 7 the results of the lethality were lower than 30%, so that biological tests showed that in samples where the concentration of limonene was lower, the lethality in the larvae decreased.