Repellent and insecticidal activities of secondary metabolites from Praxelis clematidea against Solenopsis invicta (Hymenoptera: Formicidae).

Authors

Jie Yao, Huilu Shi, Shumei Qin, Hao Yang, Xianglin Xu, Haiyu Luo

Published in

Pesticide biochemistry and physiology. Volume 223. Pages 107260. Epub Jul 22, 2026.

Abstract

Praxelis clematidea is a high-risk invasive species with potent insecticidal and repellent properties. This study isolated and identified its bioactive constituents against the red imported fire ant, Solenopsis invicta. Through bioassay-guided fractionation using a digging-based repellency assay, an active oily mixture (I₂-[3]) was obtained, with a minimum repellent effective dose (MRED) of 0.0125 mg/g. Notably, caryophyllene oxide, a major component (22.3%), showed stronger repellency (MRED = 0.00156 mg/g) than DEET (MRED = 0.00625 mg/g). Friedelin (MRED = 0.0625 mg/g), stigmasterol, and 4',5,6,7-tetramethoxyflavone (each MRED = 0.125 mg/g), from moderately active fractions, exhibited only moderate activity. Caryophyllene oxide was selected for further evaluation. In behavioral bioassays, it significantly reduced S. invicta nesting activity for at least 15 days, reduced foraging ants within 1 h, and prolonged food transport time throughout the experiment. Moreover, in field tests, its repellency was comparable to DEET. In addition to its repellent effects, caryophyllene oxide also showed rapid contact toxicity (LT₅₀ = 1.19 h at 0.1 mg/cm²), albeit slightly less potent than DEET (LT₅₀ = 0.558 h). Enzyme assays revealed that caryophyllene oxide exhibited concentration- and time-dependent effects: at low concentrations, acetylcholinesterase (AChE) and carboxylesterase (CarE) showed initial activation followed by inhibition, unlike glutathione S-transferase (GST), which remained consistently activated; at high concentrations, both were rapidly inhibited, with GST inhibition likely due to exceeded detoxification capacity. Overall, these results indicate that P. clematidea contains active compounds against S. invicta, with caryophyllene oxide emerging as a promising dual-action (repellent and contact insecticidal) agent for S. invicta management.

PMID:
42697638
Bibliographic data and abstract were imported from PubMed on 05 Sep 2026.

Read full publication at:
Please sign in to see all details.

Stats

1-terrible, 9-excellent. How would you rate this publication? Sign in in to submit your rating.

Post a comment

You need to be signed in to post comments. You can sign in here.

Comments

There are no comments yet.