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Inheritance and fitness costs of Spodoptera frugiperda (Lepidoptera: Noctuidae) resistance to spinosad in Brazil
Author(s) -
Okuma Daniela M,
Bernardi Daniel,
Horikoshi Renato J,
Bernardi Oderlei,
Silva Aline P,
Omoto Celso
Publication year - 2018
Publication title -
pest management science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.296
H-Index - 125
eISSN - 1526-4998
pISSN - 1526-498X
DOI - 10.1002/ps.4829
Subject(s) - spinosad , noctuidae , biology , pest analysis , spodoptera , lepidoptera genitalia , biopesticide , veterinary medicine , strain (injury) , larva , toxicology , genetics , horticulture , botany , agronomy , pesticide , gene , medicine , recombinant dna , anatomy
BACKGROUND Spodoptera frugiperda is a pest of economically important crops in South America. In Brazil, this species is considered the most destructive pest of maize. Use of spinosyn insecticides in insect resistance management (IRM) has been one strategy to control this pest. In this study, we selected a strain of S. frugiperda resistant to spinosad and evaluated the inheritance and fitness costs of the resistance. RESULTS Estimated LC 50 (concentration required to kill 50% of larvae) values were 0.011 and 9.80 µg cm −2 for the spinosad‐susceptible (Sus) and ‐resistant (Spin‐res) strains, respectively. This represents an 890‐fold resistance ratio. LC 50 values for reciprocal crosses were 0.18 and 0.14 µg cm −2 , indicating that resistance to spinosad is an autosomal incompletely recessive trait. Backcrosses of the F 1 progeny from reciprocal crosses with the parental Spin‐res strain showed a polygenic effect. The estimated minimum number of independent segregations was ∼ 2.45, indicating that resistance to spinosad is associated with multiple genes. In greenhouse assays, third‐instar larvae from the Spin‐res strain showed >92% survival on spinosad‐treated maize. By contrast Sus and reciprocal crosses exhibited 0% and <5% survival, respectively, indicating that resistance is recessive. Life history studies to investigate the fitness cost of resistance revealed a 41% reduction in the rate of survival to adulthood and a 49% lower reproductive rate in the Spin‐res strain compared with the Sus strain. CONCLUSIONS The autosomal, incompletely recessive and polygenic resistance to spinosad in S. frugiperda and the fitness costs associated with this resistance can be exploited in IRM strategies to preserve the lifetime of spinosad for control of S. frugiperda in Brazil. © 2017 Society of Chemical Industry