Exploration of Synergistic Pesticidal Activities, Control Effects and Toxicology Study of a Monoterpene Essential Oil with Two Natural Alkaloids

Abstract

With the increasing development of pest resistances, it is not easy to achieve satisfactory control effects by using only one agrochemical. Additionally, although the alkaloid matrine (MT) isolated from Sophora flavescens is now utilized as a botanical pesticide in China, in fact, its pesticidal activities are much lower in magnitude than those of commercially agrochemicals. To improve its pesticidal activities, here, the joint pesticidal effects of MT with another alkaloid oxymatrine (OMT) (isolated from S. flavescens) and the monoterpene essential oil 1,8-cineole (CN) (isolated from the eucalyptus leaves) were investigated in the laboratory and greenhouse conditions. Moreover, their toxicological properties were also studied. Against Plutella xylostella, when the mass ratio of MT and OMT was 8/2, good larvicidal activity was obtained; against Tetranychus urticae, when the mass ratio of MT and OMT was 3/7, good acaricidal activity was obtained. Especially when MT and OMT were combined with CN, the significant synergistic effects were observed: against P. xylostella, the co-toxicity coefficient (CTC) of MT/OMT (8/2)/CN was 213; against T. urticae, the CTC of MT/OMT (3/7)/CN was 252. Moreover, the activity changes over time of two detoxification enzymes, carboxylesterase (CarE) and glutathione S-transferase (GST) of P. xylostella treated with MT/OMT (8/2)/CN, were observed. In addition, by scanning electron microscope (SEM), the toxicological study suggested that the acaricidal activity of MT/OMT (3/7)/CN may be related to the damage of the cuticle layer crest of T. urticae.

Control of two-spotted spider mite, Tetranychus urticae, on strawberry by integrating with cyetpyrafen and Phytoseiulus persimilis

“…In both experiments, the TSSM population decreased rapidly when controlled with recommend concentration of cyetpyrafen (Figs. 2 and 3), suggesting that chemical control had advantages over other methods to some extent (Van Leeuwen et al 2015;Zhang et al 2022;Xu et al 2023). In contrast, it took more than 20 days in both experiments by releasing P. persimilis to achieve the same level of control efficiency as chemical control methods (Figs.…”

“…However, TSSM jeopardizes the physicochemical and nutritional quality of strawberries, significantly reducing their market value (Livinali et al 2014). Traditional control methods mainly involve acaricides, but their excessive use has led to TSSM resistance, highlighting the dire need for alternative, eco-friendly control strategies (Desneux et al 2007;Zhang et al 2022;Hamdi et al 2023;Xu et al 2023;Van Leeuwen et al 2010).…”

Discovery of 3-Formyl-N-(un)Substituted Benzylindole Pyrimidines as an Acaricidal Agent and Their Mechanism of Action

“…These results were the same as those reported previously. 32,40 The data and full pictures of the control effects of I-3 and V-34 against T. cinnabarinus are displayed in Table S2 and Figures S1−S4 (see the Supporting Information).…”

“…The effect of compound V-34 on the feature of the cuticle of T. cinnabarinus was observed by SEM (see the Supporting Information). …”

“…31 The effect of compound V-34 on the feature of the cuticle of T. cinnabarinus was observed by SEM (see the Supporting Information). 32 Transcriptome Analysis. To begin, numerous female adults of T. cinnabarinus were placed on three cowpea leaves in a small Petri dish (9 cm) with a damp sponge, as well.…”