Pest Management Science (2020) 76, 2674-2680

Ewerton C. Lira, Anderson Bolzan, Antonio R.B. Nascimento, Fernando S.A. Amaral, Rubens H. Kanno, Ingrid S. Kaiser and Celso Omoto (2020)
Resistance of Spodoptera frugiperda (Lepidoptera: Noctuidae) to spinetoram: inheritance and cross-resistance to spinosad
Pest Management Science 76 (8), 2674-2680
Abstract:
BACKGROUND
The use of spinosyn insecticides is one of the major control strategies of the fall armyworm, Spodoptera frugiperda (J. E. Smith) in Brazil. In this study, we selected a spinetoram-resistant strain from a field-population of S. frugiperda to characterize the inheritance of the resistance and cross-resistance relationship between spinosyn insecticides.
RESULTS
The values of LC₅₀ (95% CI) obtained from concentration–response bioassays were 0.63 (0.55–0.73) μg spinetoram mL^-1 for the susceptible strain (SUS), and 1170.96 (1041.61–1323.89) μg spinetoram mL^-1 for the strain resistant to spinetoram (SPT-R). These values resulted in a resistance ratio of 1844-fold. The SPT-R strain showed cross-resistance with spinosad (resistance ratio = 1196-fold). The reciprocal crosses showed LC₅₀ values of 3.91 (2.97–5.84) and 5.37 (4.52–6.52) μg spinetoram mL^-1, suggesting that the resistance of S. frugiperda to spinetoram is autosomal and incompletely recessive. The backcrosses of the F₁ progeny with the SPT-R strain suggest a resistance with polygenic effect. Estimates of the effective number of loci with equal contributions to the resistance effect were from 1.18 to 1.76, suggesting that resistance to spinetoram is associated with a few genes.
CONCLUSION
The inheritance pattern of resistance of S. frugiperda to spinetoram was characterized as autosomal, incompletely recessive and polygenic. Cross-resistance between spinosyns was confirmed in S. frugiperda. The importance of this information for implementing insect resistance management strategies is discussed in this paper.
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Link to article at publishers website
Database assignments for author(s): Celso Omoto

Research topic(s) for pests/diseases/weeds:
pesticide resistance of pest

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Spodoptera frugiperda