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Lethal and Sublethal Effects of Carlina Oxide and Acmella oleracea Extract Enriched in N-Alkylamides on Aculops lycopersici (Acari: Eriophyidae) and Its Predator Typhlodromus exhilaratus (Acari: Phytoseiidae) in Laboratory Tests
by
, , , , , , , , , , , , and
Thomas Giordano
1,
Giuliano Cerasa
1,
Ilaria Marotta
1,
Mauro Conte
1,
Ernesto Ragusa
1,
Simona Tortorici
2,
Gabriella Lo Verde
1,
Filippo Maggi
3
,
Riccardo Petrelli
3
,
Marta Ferrati
3,
Eleonora Spinozzi
3
,
Luigi Botta
4
,
Roberto Rizzo
2
and
Haralabos Tsolakis
1,* 1
Department of Agricultural, Food and Forest Sciences, University of Palermo, Viale delle Scienze, Bldg. 5, 90128 Palermo, Italy
2
CREA-Research Centre for Plant Protection and Certification, Viale Michelangelo, 1542, 90145 Palermo, Italy
3
Chemistry Interdisciplinary Project (ChIP) Research Center, School of Pharmacy, University of Camerino, Via Madonna delle carceri, 62032 Camerino, Italy
4
Department of Engineering, Viale delle Scienze Ed. 8, 90128 Palermo, Italy
*
Author to whom correspondence should be addressed.
Insects 2025, 16(9), 879; https://doi.org/10.3390/insects16090879 (registering DOI)
Submission received: 29 July 2025
/
Revised: 19 August 2025
/
Accepted: 20 August 2025
/
Published: 24 August 2025
(This article belongs to the Special Issue Advances in the Bio-Ecology and Control of Plant-Damaging Acari)
Simple Summary
The tomato russet mite (Aculops lycopersici) is a major pest of tomato crops worldwide. Current control methods rely on synthetic acaricides, which raise concerns due to resistance development and environmental impact. This study evaluated the acaricidal activity of two plant-derived products in laboratory tests: carlina oxide, the main compound of Carlina acaulis, and an extract enriched in N-alkylamides from Acmella oleracea. Both products showed high toxicity against eriophyids, with complete mortality observed at the highest concentrations tested. Carlina oxide was slightly more toxic and faster-acting, while the N-alkylamides extract also achieved full mortality within 72 h. Side effects on the predatory mite Typhlodromus exhilaratus revealed moderate toxicity for carlina oxide, particularly on eggs, whereas the N-alkylamides extract had limited impact, suggesting greater selectivity. These findings represent the first report of acaricidal activity of these specific compounds against A. lycopersici and indicate their potential as natural alternatives to synthetic pesticides. While this is promising for integrated pest management, further studies are needed to optimize formulations, assess field efficacy, and better understand the mode of action and safety profile of these substances.
Abstract
The tomato russet mite, Aculops lycopersici, is considered one of the most important crop pests globally. The main control strategy is based on synthetic acaricides; however, they create resistant strains and ecological risks. In this context, biopesticides could be a viable and sustainable alternative for eriophyid control. In the present study, the toxic effects of a N-alkylamides-enriched extract obtained from Acmella oleracea and of carlina oxide, the main bioactive component of Carlina acaulis, on A. lycopersici were evaluated, as well as their side effects on the phytoseiid Typhlodromus exhilaratus Ragusa under laboratory conditions. Six concentrations were tested for each product against A. lycopersici adults (0, 320, 640, 1280, 2500, and 5000 μL L−1), and the median concentration (1280 μL L−1) was evaluated against eggs and females of the phytoseiid T. exhilaratus. Both the N-alkylamides-enriched extract and carlina oxide showed total lethal effects (100% of mortality) towards A. lycopersici at the two highest concentrations. Moderate-to-high mortality was also recorded with the lower concentrations: from 42.22 to 97.78%. Probit analysis identified LC50 values of 205.32 μL L−1 for carlina oxide and 253.79 μL L−1 for the N-alkylamides-enriched extract, respectively. Carlina oxide showed a moderate ovicidal effect on T. exhilaratus eggs (50.00% hatching rate) on T. exhilaratus, and caused 39.13% mortality on females, whereas the N-alkylamides-enriched extract was less toxic, with a hatching rate of 88.00% and a mortality rate of 18.75% on females. In conclusion, carlina oxide and the N-alkylamides-enriched extract showed high toxicity on A. lycopersici, with a reduced effect on phytoseiid. These results highlight the potential of these products as sustainable means for the management of tomato russet mite.
