Curcuma longa essential oils:toxicity and repellency against hybrid imported fire ants (Formicidae: Hymenoptera)

Authors: ALI, ABBAS - University Of Mississippi; SHAH, FARHAN - University Of Mississippi; RADWAN, MOHAMED - University Of Mississippi; ELHENDAWY, MOSTAFA - University Of Mississippi; ELSOHLY, MAHMOUD - University Of Mississippi; KHAN, IKHLAS - University Of Mississippi

Submitted to: Journal of Medical Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/8/2023
Publication Date: 11/20/2023
Citation: Ali A, Shah FM, Radwan MM, Elhendawy MA, Elsohly MA, Khan IA. Curcuma longa essential oils: toxicity and repellency against imported fire ants (Formicidae: Hymenoptera). J Med Entomol. 2024 Jan 12;61(1):191-200. doi:https://doi.org/10.1093/jme/tjad151
DOI: https://doi.org/10.1093/jme/tjad151

Interpretive Summary: Mosquitoes are important in global public health because they transmit many diseases. Aedes aegypti (L) and Ae. albopictus (Skuse) are considered primary and secondary vectors of Zika virus. Anopheles spp. transmit malaria and Culex quinquefasciatus Say transmits West Nile virus. Insect repellents are reported to play an important role in reducing these diseases by preventing mosquito bites. Curcuma longa L. belongs to family Zingiberaceae produced in warm wet regions of the world. Commonly known as turmeric, C. longa is commonly used in Indian folk medicines. Turmeric is especially popular because of its attractive culinary, cosmetic and medicinal uses. This is an essential spice used in many dishes for good color and aroma. Turmeric contains odoriferous oils and the rhizomes have been reported to possess biological actives including the toxicity and repellency against Ae. aegypti. The hexane extract of C. longa is reported to be fungicidal against Erysiphe graminis Marchal, Phytophthora infestans (Mont.) de Bary, and Rhizoctonia solani Kühn, whereas ethyl acetate extract was fungicidal against Botrytis cineria, , P. infestans, Puccinia Recondita, and R. solani. In this study, we report the toxicity and repellency of essential oils of C. longa rhizome and leaf essential oils against hybrid imported fire ants.

Technical Abstract: Essential oils of Curcuma longa rhizome and leaf were evaluated for their repellency and toxicity against imported fire ants. The samples of essential oils used in this study were reported to have ar-turmerone constituents of 36.9%, and 24.9 % respectively. Ar-turmerone was the major compound of the rhizome oil (36.9%) and leaf oil (24.9%) essential oils. Series of concentrations were tested, starting from 156 µg/g to the dosages, where sand removal in treatments became similar to the solvent control. Hybrid imported fire ant workers removed significantly less sand from rhizome and leaf essential oil treatments at dosages of 156, 78, 39, 19.5, 9.8, and 4.9 µg/g than the solvent control, whereas the amount of sand removed at 2.4, 1.2 and 0.6 µg/g was similar to solvent control. In DEET treatments, hybrid imported fire ant workers removed significantly less sand at dosages of 156, and 78 µg/g than the solvent control, whereas the removal of sand at 39 µg/g was similar to solvent control. Based on the mean amount of sand removed, essential oils of Curcuma longa rhizome and leaf showed significantly higher repellency than DEET. Rhizome essential oil with LC50 of 151.2 µg/g was more toxic than the leaf essential oil (LC50 = 182.7 µg/g) at 24-h post-treatment. Bifenthrin with LC50 value of 0.018 µg/g was significantly more toxic than these essential oils against hybrid imported fire ants. Both the essential oils tested in this study showed very high repellency and appears to have a potential for field use. Further studies will be conducted to test different formulations of these natural products under field conditions.