Insecticidal and repellent activity of piper crassinervium essential oil and its pure compounds against imported fire ants (hymenoptera: formicidae

Authors: SHAH, FARHAN MAHMOOD - University Of Mississippi; Wang, Mei; ZHAO, JIANPING - University Of Mississippi; LEE, JOSEPH - University Of Mississippi; FARAGO, PAULLO - State University Of Ponta Grossa; MANFRON, JANE - State University Of Ponta Grossa; KHAN, IKHLAS - University Of Mississippi; ALI,, ABBAS - University Of Mississippi

Submitted to: Molecules
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/15/2024
Publication Date: 11/19/2024
Citation: Shah, F., Wang, M., Zhao, J., Lee, J., Manfron, J., Khan, I.A., Ali,, A., Farago, P.V. 2024. Insecticidal and repellent activity of piper crassinervium essential oil and its pure compounds against imported fire ants (hymenoptera: formicidae. Molecules. 29(22), 5430. https://doi.org/10.3390/molecules29225430.
DOI: https://doi.org/10.3390/molecules29225430

Interpretive Summary: Imported fire ants are significant pests, especially in the United States, which are famous for their painful stings. Because of their overly aggressive behavior, increasing populations of fire ants have become a major safety concern and a risk for wildlife, agriculture, forestry, and ecological environments. Synthetic toxic baits and contact insecticides are used to manage the fire ant populations. These applications are repeated to maintain control of fire ant populations. Because of concern of potential environmental contaminations of repeated use of synthetic insecticides, there has been an increasing research interest in non-toxic natural products including secondary plant metabolites. Plant-derived natural products can offer a multitude of novel chemistries that can be effective as repellents and toxicants. Piper crassinervium Kunth belongs to genus Piper in the family Piperaceae. The genus Piper is present in tropical and subtropical regions of Africa, America, and Asia, which are aromatic and contain biologically diverse compounds with insecticidal activity. As a continuity of our ongoing natural product screening program, we evaluated P. crassinervium essential oil (EO) and isolated two major components, elemicin and myristicin, through bioactivity-guided fractionation. In this study, we report the repellency and toxicity of P. crassinervium essential oil and two of its main compounds against imported fire ants. Based on digging inhibition as the criterion, the P. crassinervium EO and its major compounds showed repellency against imported fire ants. Further studies using different formulations of these natural products should be conducted to explore their use potential under natural conditions.

Technical Abstract: Piper crassinervium Kunth (Piperaceae) essential oil (EO) was evaluated for its toxicity and repellency against red imported fire ants (RIFA), Solenopsis invicta Buren and hybrids (HIFA). Through bioactivity-guided fractionation, two major components, elemicin and myristicin, were isolated from the EO. Removal of treated sand in a digging bioassay was used as the criterion for repellency. The EO showed significantly higher repellency at concentrations of 7.8 and 7.8 µg/g against RIFA and HIFA workers, respectively, as compared to DEET (N,N-diethyl-meta-toluamide) or ethanol control. Elemicin exhibited repellency at 3.9 and 7.8 µg/g against RIFA and HIFA workers, respectively, whereas myristicin was active at 7.8 µg/g against both the species. DEET failed at 31.25 µg/g against RIFA and 15.6 µg/g against HIFA. The EO showed LC50 values of 97.9 and 73.7 µg/g against RIFA and HIFA workers, respectively. Myristicin was more toxic against RIFA and HIFA with LC50 values of 54.3 and 35.3 µg/g, respectively. Elemicin showed 20-40% mortality at the highest screening dose of 125 µg/g. Fipronil exhibited the highest toxicity against RIFA and HIFA, with LC50 of 0.43 and 0.51 µg/g, respectively. Different formulations of these natural products should be evaluated to explore their use potential under natural field conditions.