title: Effects of temperature on fitness costs in chlorpyrifos-resistant brown planthopper, Nilaparvata lugens (Hemiptera: Delphacidae).
abstract: Insecticide resistance is inevitable if an insecticide is widely used to control insect pests. Fortunately, the resistance-associated fitness costs often give chances to manage resistances. In most cases, the fitness cost in resistant insects is often evaluated under laboratory conditions for insect development, which limits its practical application in pest control in the field. In a laboratory population R9 with 253-fold resistance to chlorpyrifos after nine-generation selection with chlorpyrifos, the relative fitness was only 0.206 under laboratory conditions (25°C, humidity 70%-80% and 16 h light/8 h dark photoperiod), when compared to S9, a susceptible counterpart (resistance ratio = 2.25-fold) from the same origin as R9 but without any selection with insecticides. Temperatures varied the resistance-associated fitness costs, with enhanced costs at high temperatures and reduced costs at low temperatures, such as 0.174 at 32°C and 0.527 at 18°C. The copulation rate and fecundity were two key factors for the reduced costs at low temperatures. Another finding was that R9 individuals needed much more time to recover from heat shock than that of S9, but R9 and S9 individuals were similarly sensitive to cold shock. The low fitness cost at low temperatures would increase the overwintering population, which might further increase risks of rapid development and widespread distribution of chlorpyrifos resistance in Nilaparvata lugens.
authors.affiliation: Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), College of Plant Protection, Nanjing Agricultural University, Nanjing, China.|Rice Technology Research and Development Center, China National Rice Research Institute, Hangzhou, China.
authors.forename: Bao-Jun
authors.initials: BJ
authors.lastname: Yang
authors.affiliation: Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), College of Plant Protection, Nanjing Agricultural University, Nanjing, China.
authors.forename: Mei-Ling
authors.initials: ML
authors.lastname: Liu
authors.affiliation: Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), College of Plant Protection, Nanjing Agricultural University, Nanjing, China.
authors.forename: Yi-Xi
authors.initials: YX
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), College of Plant Protection, Nanjing Agricultural University, Nanjing, China.
authors.forename: Ze-Wen
authors.initials: ZW
authors.lastname: Liu
mesh_terms: D000818:Animals; D004390:Chlorpyrifos; D005260:Female; D056084:Genetic Fitness; D006430:Hemiptera / Q000502:physiology*; D007305:Insecticide Resistance / Q000502:physiology*; D007306:Insecticides; D015993:Life Tables; D008297:Male; D013312:Stress, Physiological; D013696:Temperature
chemical_list: D007306:Insecticides; D004390:Chlorpyrifos
keywords: Nilaparvata lugens; fitness cost; insecticide resistance; temperature