Toxicity of quinones against two-spotted spider mite and three species of aphids in laboratory and greenhouse conditions |
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Authors: | Yasmin Akhtar Murray B Isman Chi-Hoon Lee Sang-Guei Lee Hoi-Seon Lee |
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Institution: | a Faculty of Land and Food Systems, University of British Columbia, Vancouver, BC, Canada b Department of Bioenvironmental Chemistry, Chonbuk National University, South Korea c Division of Planning and Research, National Institute of Health, South Korea d Applied Entomology Division, National Academy of Agricultural Science, RDA, South Korea |
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Abstract: | Toxicities of the eight quinones were evaluated through leaf dip bioassays conducted against Tetranychus urticae, Myzus persicae, Myzocallis walshii, and Illinoia liriodendri. Based on LC50 values, plumbagin (LC50 = 0.001%) was the most active compound against T. urticae and ubiquinone Q0 (LC50 = 0.005%), plumbagin (LC50 = 0.010%), and dibromothymoquinone (LC50 = 0.012%) were the most active compounds against M. persicae. The most active compounds against M. walshii were juglone (LC50 = 0.011%) and ubiquinone Q0 (LC50 = 0.019%), whereas dibromothymoquinone (LC50 = 0.030%), plumbagin (LC50 = 0.033%) and ubiquinone Q0 (LC50 = 0.058%) were the most toxic to I. liriodendri. Ecotrol (positive control) was the least toxic compound (LC50 = 0.39%) against T. urticae and M. persicae (LC50 = 0.447%). Although the majority of the compounds tested were toxic to all four test species in residual bioassays, there was little overlap among the test species in terms of susceptibility to the compounds and interspecific differences were observed. Regarding structure-activity relationships for quinones, the addition of a hydroxyl group resulted in a significant increase in the toxicity of the 1,4-naphthoquinones, and those possessing a methyl group exhibited the highest levels of activity in T. urticae. The bromine atom at the 2- and 5-positions of the benzoquinone ring is crucial to the toxicity of the compounds against I. liriodendri. Toxicity was greatly affected not only by the number of hydroxyl groups, but also by their positions in the ring in the case of M. walshii. Juglone and plumbagin as residual toxins in the laboratory also reduced the population of two-spotted spider mites compared to EcoTrol™ (positive control) and the negative control in the greenhouse experiment. Some quinones tested may have potential as commercial insecticides and miticides, or alternatively, could serve as lead compounds for the development of more potent crop protection agents. |
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Keywords: | Benzoquinones Illinoia liriodendra Myzocallis walshii Myzus persicae Naphthoquinones Structure-activity relationship T urticae Toxicity |
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