Insecticidal and repellent activity of Piper crassinervium essential oil and its pure compounds against imported fire ants (Hymenoptera: Formicidae).

Authors: SHAH, FARHAN - University Of Mississippi; Wang, Mei; ZHAO, JIANPING - University Of Mississippi; LEE, JOSEPH - University Of Mississippi; FARAGO, PAULO VITOR - 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: 11/18/2024
Citation: Shah, F., Wang, M., Zhao, J., Lee, J., Farago, P., Manfron, J., Khan, I.A., Ali, A. 2024. Insecticidal and repellent activity of Piper crassinervium essential oil and its pure compounds against imported fire ants (Hymenoptera: Formicidae).. Molecules. 29:1-12. https://doi.org/10.3390/molecules29225430.
DOI: https://doi.org/10.3390/molecules29225430

Interpretive Summary: The present study on the essential oil (EO) of Piper crassinervium Kunth (Piperaceae) addresses the growing need for effective, eco-friendly alternatives to synthetic insecticides in managing red imported fire ants (Solenopsis invicta) and their hybrids (HIFA), which pose serious ecological and economic threats. The EO demonstrated remarkable repellency, surpassing traditional repellents like DEET at lower concentrations, indicating its potential as a viable natural repellent. Additionally, the isolation of the major components, elemicin and myristicin, provides insights into the specific compounds responsible for the EO's bioactivity. Understanding their individual efficacy contributes to the broader knowledge of plant-based insecticides, which may lead to more targeted and environmentally sustainable pest management strategies. The study's findings regarding toxicity levels (LC50 values) further emphasize the potential of myristicin as a more effective option compared to DEET and highlight the necessity for continued research into natural alternatives. Overall, this investigation not only advances our understanding of P. crassinervium but also underscores the importance of developing natural insect repellents that could have significant applications in integrated pest management and sustainable agriculture. Future evaluations of various formulations may enhance the practical application of these findings in real-world settings, making a substantial contribution to pest management practices.

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.