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Inheritance of lambda-cyhalothrin resistance, fitness costs and cross-resistance to other pyrethroids in soybean looper, Chrysodeixis includens (Lepidoptera: Noctuidae)

2020; Elsevier BV; Volume: 131; Linguagem: Inglês

10.1016/j.cropro.2020.105096

1873-6904

Regis Felipe Stacke, Daniela N. Godoy, Stefany A. Halberstadt, Eduarda Spagnol Bronzatto, Tiago Giacomelli, Bruna L. Hettwer, Dionei Schmidt Muraro, Jerson VC Guedes, Oderlei Bernardi,

Insect and Pesticide Research

Soybean looper (SBL), Chrysodeixis includens (Lepidoptera: Noctuidae), is one of the main lepidopteran pests of soybean and cotton crops. In this study, we selected a strain of SBL with resistance to lambda-cyhalothrin and evaluated the inheritance, fitness costs and cross-resistance to deltamethrin and cypermethrin. In inheritance pattern studies, SBL larvae were exposed to technical grade insecticides in topical bioassays. To investigate fitness costs, SBL strains were reared on artificial diet without insecticide and the survival, development and reproductive rates were evaluated. Estimated LD50 values of lambda-cyhalothrin for the susceptible and resistant strains were 0.0015 and 0.11 μg a.i./larva, respectively, indicating a resistance ratio (RR) of 73.3-fold. The LD50 values of heterozygous were 0.016 and 0.017 μg a.i./larva, suggesting an autosomal inheritance of resistance. On lambda-cyhalothrin sprayed-leaves, the resistant strain showed >85% survival. By contrast, heterozygous and susceptible strains had <64 and 8% survival, respectively, indicating an incompletely dominant resistance against the field dose of lambda-cyhalothrin. The resistant strain also showed cross-resistance to deltamethrin (RR = 6.2-fold) and cypermethrin (RR = 22.5-fold). Fitness costs studies showed that resistant insects had 71 and 48% lower survival and reproductive rates, respectively, than the susceptible strain (62.8% survival). The inheritance patterns of lambda-cyhalothrin resistance in SBL was autosomal, incompletely dominant and associated with fitness costs. SBL had low cross-resistance to deltamethrin and cypermethrin, indicating the potential to develop resistance to other pirethroids. Therefore, to preserve the useful life of chemical control against SBL are required the development of multi-tactic resistance management programs along with a reduction in insecticides applied.