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

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 () isolated from 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 with another alkaloid oxymatrine () (isolated from ) and the monoterpene essential oil 1,8-cineole () (isolated from the eucalyptus leaves) were investigated in the laboratory and greenhouse conditions. Moreover, their toxicological properties were also studied. Against when the mass ratio of and was 8/2, good larvicidal activity was obtained; against when the mass ratio of and was 3/7, good acaricidal activity was obtained. Especially when and were combined with , the significant synergistic effects were observed: against the co-toxicity coefficient (CTC) of / (8/2)/ was 213; against the CTC of / (3/7)/ was 252. Moreover, the activity changes over time of two detoxification enzymes, carboxylesterase (CarE) and glutathione -transferase (GST) of treated with / (8/2)/, were observed. In addition, by scanning electron microscope (SEM), the toxicological study suggested that the acaricidal activity of / (3/7)/ may be related to the damage of the cuticle layer crest of .