Survival and Development of Spodoptera frugiperda and Chrysodeixis includens (Lepidoptera: Noctuidae) on Bt Cotton and Implications for Resistance Management Strategies in Brazil

2015 ◽  
Vol 44 (1) ◽  
pp. 186-192 ◽  
Author(s):  
R. J. Sorgatto ◽  
O. Bernardi ◽  
C. Omoto
Keyword(s):  
Spodoptera Frugiperda ◽  
Management Strategies ◽  
Resistance Management ◽  
Bt Cotton ◽  
Survival And Development ◽  
Lepidoptera Noctuidae ◽  
Chrysodeixis Includens

Impact of Bt cotton on the immune system and histology of the midgut of the fall armyworm Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae)

2013 ◽  
Vol 63 (2) ◽  
pp. 185-197 ◽  
Author(s):  
Franklin M. Cunha ◽  
Valéria Wanderley-Teixeira ◽  
Jorge B. Torres ◽  
Álvaro A.C. Teixeira ◽  
Thiago J.S. Alves ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Spodoptera Frugiperda ◽  
Fall Armyworm ◽  
Bt Cotton ◽  
Contributing Factors ◽  
Qualitative And Quantitative ◽  
Cry1ac Toxin ◽  
Cellular Immune ◽  
Natural Tolerance ◽  
Lepidoptera Noctuidae

Despite the efficiency of transgenic plants expressing Bacillus thuringiensis (Bt) toxins as insecticides against several lepidopterans, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) is one species that presents low susceptibility to most Bt crops. This study investigated the effects of the Cry1Ac toxin expressed by Bt cotton in the midgut of S. frugiperda and its effects on the humoral and cellular immune responses. Three hypotheses were proposed and tested with contributing factors for the natural tolerance of S. frugiperda: (i) midgut regenerative cells are activated by the Cry1Ac toxin, and thus renew the epithelial cells damaged by the protein, (ii) Cry1Ac increased production of nitric oxide or phenoloxidase in the hemolymph, and (iii) there are qualitative and quantitative variations in the hemocyte levels of S. frugiperda. Caterpillars were reared using Bt cotton (Acala 90B) and non-Bt isolines (Acala 90), from the first to the fourth instar. The Bt cotton promoted elongation of the epithelial cells in the midgut of S. frugiperda caterpillars. Hence, evidence only supported the hypothesised increase of phenoloxidase (ii) and qualitative and quantitative differences in hemocyte levels (iii) in insects that were fed with Bt and non-Bt cotton. These parameters seem to explain the low susceptibility of S. frugiperda to Cry1Ac toxin and they are a viable set of responses for the evaluation of other xenobiotic factors.

Helicoverpa zea (Lepidoptera: Noctuidae) Preference for Plant Structures, and Their Location, Within Bt Cotton Under Different Nitrogen and Irrigation Regimes

2019 ◽  
Vol 112 (4) ◽  
pp. 1741-1751
Author(s):  
Lewis R Braswell ◽  
Dominic D Reisig ◽  
Clyde E Sorenson ◽  
Guy D Collins
Keyword(s):  
Helicoverpa Zea ◽  
Resistance Management ◽  
Larval Feeding ◽  
Bt Cotton ◽  
Larval Distribution ◽  
Cotton Plants ◽  
Small Plot ◽  
Nitrogen Treatments ◽  
Behavioral Resistance ◽  
Lepidoptera Noctuidae

Abstract Helicoverpa zea Boddie is a common economic pest of cotton (Gossypium hirsutum L.), including transgenic cotton varieties that express Bacillus thuringiensis (Bt). Helicoverpa zea oviposition is similar in Bt and non-Bt cotton, but behavior of H. zea larvae can be different in the presence of Bt, with neonates moving away from terminals faster in single-toxin Bt than non-Bt cotton or avoiding Bt-treated diet in the lab. We quantified H. zea oviposition and larval distribution on structures within cotton plants in small plot experiments of Cry1Ac + Cry1F cotton for 2 yr under different irrigation and nitrogen treatments. More eggs were oviposited on plants receiving nitrogen application during 2016 and on leaves in the top section of irrigated plants during 2017, but other treatment effects on eggs or larvae were minimal. Helicoverpa zea eggs were most common on leaves in the top third of plants at position zero and middle section of cotton plants throughout the season, but some oviposition occurred on fruiting structures as well. First and second instars were more common on squares in the top section of plants during 2016 and bolls in the middle and lower sections during 2017 due to oviposition lower in the canopy during 2017. During both years, third through fifth instars were more common on bolls in the middle and lower section of plants closer to the main stem. These findings have resistance management implications as extended larval feeding on bolls could optimize nutrition, decrease Bt susceptibility, and potentially influence behavioral resistance.

Baseline Response, Monitoring, and Cross-Resistance of Spodoptera frugiperda (Lepidoptera: Noctuidae) to Sodium Channel Blocker Insecticides in Brazil

2021 ◽  
Author(s):  
Ingrid S Kaiser ◽  
Rubens H Kanno ◽  
Anderson Bolzan ◽  
Fernando S A Amaral ◽  
Ewerton C Lira ◽  
...  
Keyword(s):  
Sodium Channel ◽  
Spodoptera Frugiperda ◽  
Channel Blocker ◽  
Resistance Management ◽  
Response Monitoring ◽  
Cross Resistance ◽  
Channel Blockers ◽  
Sodium Channel Blocker ◽  
Baseline Response ◽  
Lepidoptera Noctuidae

Abstract Spodoptera frugiperda (J.E. Smith) is one of the key cross-crop pests in Brazilian agroecosystems. Field-evolved resistance of S. frugiperda to some conventional insecticides and Bt proteins has already been reported. Thus, the use of insecticides with new mode of action such as sodium channel blockers (indoxacarb and metaflumizone) could be an important tool in insecticide resistance management (IRM) programs. To implement a proactive IRM, we conducted baseline response and monitoring to indoxacarb and metaflumizone in 87 field populations of S. frugiperda collected from major maize-growing regions of Brazil from 2017 to 2020, estimated the frequency of resistance alleles to indoxacarb, and evaluated cross-resistance of indoxacarb and metaflumizone to some selected insecticides and Bt proteins. Low variation in susceptibility to indoxacarb (4.6-fold) and metaflumizone (2.6-fold) was detected in populations of S. frugiperda in 2017. The frequency of the resistance allele to indoxacarb was 0.0452 (0.0382–0.0527 CI 95%), by using F2 screen method. The mean survival at diagnostic concentration, based on CL99, varied from 0.2 to 12.2% for indoxacarb and from 0.0 to 12.7% for metaflumizone, confirming high susceptibility of S. frugiperda to these insecticides in Brazil. No cross-resistance was detected between sodium channel blocker insecticides and other insecticides (organophosphate, pyrethroid, benzoylurea, spinosyn, and diamide) and Bt proteins. These findings showed that sodium channel blocker insecticides are important candidates to be exploited in IRM strategies of S. frugiperda in Brazil.

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