Insecticide Resistance and Resistance Management Fitness Trade-Off Associated With Spinosad Resistance in Frankliniella occidentalis (Thysanoptera: Thripidae) Xiaoyu Li, 1, * Yanran Wan, 1,2, * Guangdi Yuan, 1 Sabir Hussain, 1 Baoyun Xu, 1 Wen Xie, 1 Shaoli Wang, 1 Youjun Zhang, 1 and Qingjun Wu 1,3 1 Department of Plant Protection, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, China (lixiaoyu57@outlook.com; zhibao090102@163.com; yuangd42@163.com; sabirhussainbwp@hotmail.com; xubaoyun@caas.cn; xiewen@caas.cn; wangshaoli@caas.cn; zhangyoujun@caas.cn; wuqingjun@caas.cn), 2 Department of Plant Protection, Hebei Agricultural University, Baoding, P. R. China, and 3 Corresponding author, e-mail: wuqingjun@caas.cn *These authors contributes equally to this work Subject Editor: Raul Narciso Guedes Received 16 January 2017; Editorial decision 2 April 2017 Abstract Frankliniella occidentalis (Pergande) is an economically important pest of agricultural crops. High resistance has been detected in field populations of F. occidentalis against the insecticide spinosad. In this study, we com- pared life history traits, body sizes, and feeding behaviors (recorded via an electrical penetration graph) of spinosad-susceptible (Ivf03) and spinosad-resistant (NIL-R) near-isogenic lines of F. occidentalis. Life table anal- ysis showed that NIL-R had reduced female longevity and reduced fecundity. The relative fitness of NIL-R (0.43) was less than half that of Ivf03. NIL-R individuals were smaller than Ivf03 individuals, both in body length and body width at every stage. The number and duration of feeding activities were significantly reduced in NIL-R, with the exception of total duration of long-ingestion probes. These results suggest that there is a fitness trade- off associated with spinosad resistance in F. occidentalis, and that the development of resistance in this pest species may be reduced by rotating spinosad with other pesticides lacking cross-resistance. Key words: Frankliniella occidentalis, spinosad resistance, fitness cost, feeding behavior, electrical penetration graph Insecticide resistance is a major hurdle in pest management. It is a genetic phenomenon that results from intensive application of insecti- cides. Resistance to insecticides can incur fitness costs to resistant individuals in the absence of insecticide pressures (Gassmann et al. 2009, Afzal and Shad 2016, Belinato and Martins 2016). Fitness costs associated with insecticide resistance have been reported in a variety of insect orders, including the Coleoptera, Diptera, Hemiptera, and Lepidoptera (Kliot and Ghanim 2012). The overexpression or molec- ular alteration of a resistance-conferring gene is thought to reduce fit- ness either as a result of the reallocation of resources that affects physiological and reproductive processes (Roush and McKenzie 1987) or as a result of morphological and behavioral changes (Hardstone et al. 2010, Shikano and Cory 2014). The western flower thrips, Frankliniella occidentalis (Pergande), is an important agricultural pest (Tommasini and Maini 1995, Kirk and Terry 2003). Frankliniella occidentalis feeds on leaves, flower parts, and young fruits, and can also transmit two plant-infecting tospoviruses, Tomato spotted wilt virus (TSWV; Allen and Broadbent 1986) and Impatiens necrotic spot virus (INSV; Daughtery et al. 1997). Although diverse pest management methods exist for F. occidentalis, most growers use insecticides because of their quick results (Reitz 2009, Gao et al. 2012). However, the overuse of insecticides and the pest’s short generation time, poly- phagy, high fecundity, and haplodiploid reproduction has resulted in F. occidentalis developing resistance to a number of insecticides through multiple metabolic detoxification pathways (Bielza 2008, Demirozer et al. 2012, Gao et al. 2012). Spinosad, which is derived from the soil bacterium Saccharopolyspora spinosa (Thompson et al. 1997) and which targets the nicotinic acetylcholine receptors (nAChRs) and also c-aminobuty- ric acid (GABA; Salgado and Sparks 2005), has high insecticidal activity against pests in the orders of Lepidoptera, Diptera, Thysanoptera, Coleoptera, and Orthoptera (Thompson et al. 2000). When first introduced for control of F. occidentalis, spinosad was regarded as the most effective insecticide available (Thompson et al. 2000, Williams et al. 2003) and has since become the primary insecti- cide for F. occidentalis control worldwide. Its widespread use, how- ever, has led to the occurrence of resistance. High levels of resistance to spinosad have been observed in F. occidentalis collected from greenhouses in Spain (Bielza et al. 2007) and Australia (Herron and Jame 2005). In China, F. occidentalis was reported for the first time in 2003 (Zhang et al. 2003). Intermediate to high levels of resistance to spinosad in F. occidentalis were recently detected in Beijing, Yunnan, and Shandong provinces (Li et al. 2016, Wan et al. 2016). V C The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com 1755 Journal of Economic Entomology, 110(4), 2017, 1755–1763 doi: 10.1093/jee/tox122 Advance Access Publication Date: 24 April 2017 Research article Downloaded from https://academic.oup.com/jee/article/110/4/1755/3752366 by guest on 16 July 2022