Lethal and sublethal effects of carlina oxide on Tetranychus urticae (Acari: Tetranychidae) and Neoseiulus californicus (Acari: Phytoseiidae)

Abstract

BACKGROUNDTetranychus urticae Koch, is a polyphagous and damaging pest, presenting several resistant populations worldwide. Among new and more environmentally friendly control tools, botanical pesticides represent a valuable alternative to synthetic ones within IPM strategies. Accordingly, we investigated on the lethal and sub‐lethal effects of the polyacetylene carlina oxide isolated from Carlina acaulis (Asteraceae) on T. urticae and on its natural enemy, the predatory mite, Neoseiulus californicus (McGregor).RESULTSCarlina oxide (98.7% pure compound) was used for acaricidal tests on eggs, nymphs, and adult females of T. urticae, (concentrations of 312.5, 625, 1250, 2500 and 5000 μL/L), and eggs and females of N. californicus (1250 and 5000 μL/L on eggs and females, respectively). Behavioral two‐choice tests were also conducted on phytoseiid females. Carlina oxide toxicity was higher on T. urticae females than nymphs (LD50 1145 and 1825 μL/L, respectively), while egg mortality and the mean hatching time were significantly affected by all tested concentrations. A decreasing daily oviposition rate of T. urticae was recorded with concentrations ranging from 625 to 5000 μL/L, while negative effects on the population growth rate were recorded only with the three higher concentrations (1250, 2500 and 5000 μL/L). No toxic effect to N. californicus females was found, but a strong repellent activity lasting for 48 h from applications was registered.CONCLUSIONCarlina oxide reduced longevity and fecundity of T. urticae adults, but not of N. californicus. This selective property allows to propose it as a novel active ingredient of eco‐friendly acaricides for T. urticae management.This article is protected by copyright. All rights reserved.