Genetics, cross‐resistance and synergism of indoxacarb resistance in Helicoverpa armigera (Lepidoptera: Noctuidae)

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Resistance selection of indoxacarb in Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae): cross‐resistance, biochemical mechanisms and associated fitness costs

Cui

Wang

et al. 2018

“…On the other hand, resistant organisms might also be more sensitive to another pesticide due to the cost of resistance . Yet, this has been much less documented . One rare example is the finding that a pyrethroid‐resistant amphipod Hyalella azteca population showed a frequent tendency to be more sensitive to DDT, sodium chloride and copper (II) sulfate .…”

Section: Introductionmentioning

confidence: 99%

Effects of predator cues and pesticide resistance on the toxicity of a (bio)pesticide mixture

Delnat

Janssens

Stoks

2019

BACKGROUND Populations of target species are typically exposed to pesticide mixtures and natural stressors such as predator cues, and are increasingly developing resistance to single pesticides. Nevertheless, we have poor knowledge whether natural stressors and the presence of pesticide resistance shape mixture toxicity. We tested the single and combined effects of the pesticide chlorpyrifos and the biopesticide Bacillus thuringiensis israelensis (Bti) on the survival of the Southern house mosquito (Culex quinquefasciatus, Say) and whether these effects were magnified by synthetic predator cues of Notonecta water bugs and differed between a chlorpyrifos‐resistant (Ace‐1R) and non‐resistant (S‐Lab) strain. RESULTS Single exposure to Bti caused mortality in both strains (S‐Lab ∼27%, Ace‐1R ∼41%) and single exposure to chlorpyrifos caused only mortality in the S‐Lab strain (∼33%), while predator cues did not induce mortality. The chlorpyrifos‐resistant strain was 1.5‐fold more sensitive to Bti, indicating a cost of resistance. The interaction types between chlorpyrifos and Bti (additive), between chlorpyrifos and predator cues (additive), and between Bti and predator cues (synergistic) were consistent in both strains. Despite predator cues making Bti approximately 8% more lethal, they did not change the additive interaction between Bti and chlorpyrifos in their mixture in either strain. CONCLUSION These results indicate that the resistance against chlorpyrifos was not partly lifted when chlorpyrifos exposure was combined with Bti and predator cues. Identifying the interaction type within pesticide mixtures and how this depends on natural stressors is important to select control strategies that give a disadvantage to resistant individuals compared to non‐resistant individuals. © 2019 Society of Chemical Industry

Linkage mapping an indoxacarb resistance locus in Helicoverpa armigera (Lepidoptera: Noctuidae) by genotype‐by‐sequencing

Bird

Woolley

Walsh

et al. 2019

BACKGROUND: A major challenge to sustainable agricultural pest control is the rapid evolution of insecticide resistance. This is caused by mechanisms that reduce insecticide efficacy. Understanding the genetic mechanisms of resistance is essential for DNA-based monitoring of resistance in field populations. One such insecticide is indoxacarb, an important selective control option for Helicoverpa armigera in a range of crops including grain, horticulture and cotton. Recently, a strain of H. armigera (GY7-39) resistant to indoxacarb (198-fold) was isolated from field-collected moth. RESULTS:To identify the indoxacarb resistance locus, GY7-39 was backcrossed for six generations to susceptible strain New GR. In each generation, only resistant males were used to cross back to New GR. Genotype-by-sequencing was carried out on 95 H. armigera samples. In total, 13 203 tags with 8697 unique locations on the H. armigera genome were obtained. The indoxacarb resistance locus in strain GY7-39 was mapped to a 2.6 Mbp region on chromosome 16. In this region, two closely linked loci (IndoR1 and IndoR2) were found to be associated with indoxacarb resistant GY7-39. CONCLUSIONS:We mapped indoxacarb resistance in GY7-39 to two closely linked loci IndoR1 and IndoR2 in a narrowed 2.6 Mbp region of H. armigera chromosome 16. The results provide essential background data for future genetic investigations including fine mapping of the indoxacarb resistance gene and the eventual development of an effective DNA-based diagnostic to support resistance management.