Willmott, Amy L.Cloyd, Raymond A.Zhu, Kun Yan2013-04-122013-04-122013-04-12http://hdl.handle.net/2097/15499Citation: Willmott, Amy L., Raymond A. Cloyd, and Kun Yan Zhu. 2013. “Efficacy of Pesticide Mixtures Against the Western Flower Thrips (Thysanoptera: Thripidae) Under Laboratory and Greenhouse Conditions.” Journal of Economic Entomology 106 (1): 247–56. https://doi.org/10.1603/EC12264.Western flower thrips, Frankliniella occidentalis Pergande is a commonly encountered and economically important insect pest of greenhouses. Greenhouse producers typically apply pesticides as mixtures to mitigate western flower thrips populations; however, there is limited information available on the compatibility and efficacy of commonly used pesticide mixtures. This study assessed nine binary and three tertiary pesticide mixtures used in greenhouses which included pesticides containing abamectin, acephate, azadirachtin, bifenazate, bifenthrin, fenpropathrin, imidacloprid, novaluron, pymetrozine, and spinosad. Compatibility was determined for the binary pesticide mixtures using jar tests. In addition, the binary mixtures were applied to nine horticultural plant species to determine phytotoxicity based on visual appearance assessed 7 d after treatment. Bean-dip bioassays were performed in a laboratory using green bean (Phaseolus vulgaris L.) to determine LC50 values for each individual pesticide and the mixtures to establish whether the mixtures were synergistic, antagonistic, or there was no effect. The mortality of western flower thrips was assessed after 24 h, and LC[suscript 50] values were calculated. Furthermore, semifield bioassays were performed in greenhouses for binary and tertiary mixtures to evaluate the efficacy (based on percent mortality) of the pesticide mixtures against western flower thrips. Results indicated that all binary mixtures were visibly compatible, and not phytotoxic to any of the plant species evaluated. Combination index calculations based on laboratory results indicated most of the binary mixtures were synergistic; however, the mixture containing spinosad + bifenazate appeared to be antagonistic against western flower thrips. The semifield bioassays demonstrated significantly reduced efficacy associated with mixtures containing azadirachtin, however, all binary mixtures provided ≍80% western flower thrips mortality.en-USPermission to archive granted by the Entomological Society of America, April 1, 2013. This article is the copyright property of the Entomological Society of America and may not be used for any commercial or other private purpose without specific written permission of the Entomological Society of America.© 2013 Entomological Society of America This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/), which permits non-commercial reuse, distribution, and reproduction in any medium, provided the original work is properly cited. For commercial re-use, please contact journals.permissions@oup.com.BioassaysSynergismAntagonismHorticulturePest managementText