scholarly journals Decline in Sublethal Effects of Bt Corn on Corn Earworm (Lepidoptera: Noctuidae) Linked to Increasing Levels of Resistance

2020 ◽  
Vol 113 (5) ◽  
pp. 2241-2249 ◽  
Author(s):  
Francis P F Reay-Jones ◽  
Thomas R Bilbo ◽  
Dominic D Reisig
Keyword(s):  
South Carolina ◽  
Sublethal Effects ◽  
Sublethal Effect ◽  
Fold Increase ◽  
Field Trials ◽  
Corn Earworm ◽  
Genetically Engineered ◽  
Pupal Weight ◽  
Bt Corn ◽  
North And South

Abstract As part of an ongoing longitudinal study in North and South Carolina, this study reports the recovery of Helicoverpa zea (Boddie) pupae in field trials with genetically engineered corn, Zea mays L., hybrids that produce insecticidal toxins from Bacillus thuringiensis (Bt) in 2017–2019. In total, 10,400 corn ears were collected, which led to 3,927 H. zea pupae (2,215 in South Carolina and 1,712 in North Carolina). Late-planted corn led to a 3.39-fold increase in recovery of pupae compared to early-planted corn. Bt corn expressing Cry1F + Cry1Ab and Cry1A.105 + Cry2Ab2 had 1.67-fold and 2.51-fold fewer pupae than non-Bt near-isolines, respectively. Only six pupae were recovered from the hybrid expressing Cry1F + Cry1Ab + Vip3Aa20. Averaged across trials, Bt corn expressing either Cry1A.105 + Cry2Ab2 or Cry1F + Cry1Ab significantly reduced pupal weight compared to non-Bt near-isolines in North and South Carolina. Combining our data with a previous study at the same locations (Bilbo et al. 2018), reduction in pupal weight between Bt and non-Bt near-isolines significantly declined from 2014 to 2019 for Cry1Ab + Cry1F in North and South Carolina. This decline in levels of a sublethal effect of Bt corn expressing Cry1Ab + Cry1F on H. zea at both locations is likely correlated with resistance development.

Susceptibility of Corn Earworm (Lepidoptera: Noctuidae) to Cry1A.105 and Cry2Ab2 in North and South Carolina

2019 ◽  
Vol 112 (4) ◽  
pp. 1845-1857 ◽  
Author(s):  
Tom R Bilbo ◽  
Francis P F Reay-Jones ◽  
Dominic D Reisig ◽  
Jeremy K Greene
Keyword(s):  
United States ◽  
South Carolina ◽  
Helicoverpa Zea ◽  
Natural Populations ◽  
The United States ◽  
Corn Earworm ◽  
Pupal Weight ◽  
Bt Corn ◽  
Development Of Resistance ◽  
Bacterium Bacillus

Abstract The corn earworm, Helicoverpa zea (Boddie), is managed in corn and cotton in the United States primarily using transgenic cultivars that produce insecticidal proteins from the bacterium Bacillus thuringiensis (Bt). However, increasing reports of resistance to one or more Bt proteins threaten the continued efficacy of Bt traits. To better understand the development of resistance of H. zea to Bt corn and cotton in the southeastern United States, we monitored for resistance to Cry1A.105 and Cry2Ab2 among 22 field populations of H. zea collected in non-Bt and Bt corn expressing Cry1A.105 + Cry2Ab2 during 2017 and 2018. Colonies were established in the laboratory and progeny were screened in diet-overlay bioassays to purified Cry1A.105 and Cry2Ab2 proteins. Compared with two susceptible laboratory colonies, all 14 field colonies tested with Cry1A.105 were highly resistant, with resistance ratios (RRs) ranging from 13.5 to >4,000. For Cry2Ab2, 19 colonies were tested and RRs ranged from 0.26 to 33.7. Field populations were significantly more susceptible to Cry2Ab2 than Cry1A.105. We documented variability in F0 and F1 pupal weight and developmental rates of natural populations of H. zea, but observed no significant correlation with susceptibility to either Cry1A.105 or Cry2Ab2. Our results expand on the recent reports of H. zea resistance to Cry1A and Cry2A proteins and will aid in the design and deployment of future pyramided crops in the United States.

scholarly journals Toxicity and Sublethal Effect of Farnesyl Acetate on Diamondback Moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae)

Insects ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 109
Author(s):  
Norazila Yusoff ◽  
Idris Abd Ghani ◽  
Nurul Wahida Othman ◽  
Wan Mohd Aizat ◽  
Maizom Hassan
Keyword(s):  
Plutella Xylostella ◽  
Sublethal Effects ◽  
Diamondback Moth ◽  
Sublethal Effect ◽  
Sublethal Concentration ◽  
Pupal Weight ◽  
Control Group ◽  
Hatching Rate ◽  
Egg Hatching ◽  
Female Ratio

The diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), is the most important pest of cruciferous vegetables worldwide. In this study, we evaluated the properties of selected farnesyl derivative compounds against P. xylostella. The toxicity and sublethal concentration (LC50) of farnesyl acetate, farnesyl acetone, farnesyl bromide, farnesyl chloride, and hexahydrofarnesyl acetone were investigated for 96 h. The leaf-dip bioassays showed that farnesyl acetate had a high level of toxicity against P. xylostella compared to other tested farnesyl derivatives. The LC50 value was 56.41 mg/L on the second-instar larvae of P. xylostella. Then, the sublethal effects of farnesyl acetate on biological parameters of P. xylostella were assessed. Compared to the control group, the sublethal concentration of farnesyl acetate decreased pupation and emergence rates, pupal weight, fecundity, egg hatching rate, female ratio, and oviposition period. Furthermore, the developmental time of P. xylostella was extended after being exposed to farnesyl acetate. Moreover, the application of farnesyl acetate on P. xylostella induced morphogenetic abnormalities in larval–pupal intermediates, adults that emerged with twisted wings, or complete adults that could not emerge from the cocoon. These results suggested that farnesyl acetate was highly effective against P. xylostella. The sublethal concentration of farnesyl acetate could reduce the population of P. xylostella by increasing abnormal pupal and adults, and by delaying its development period.

Evaluation of Insecticide Thresholds in Late-Planted Bt and Non-Bt Corn for Management of Fall Armyworm (Lepidoptera: Noctuidae)

2020 ◽  
Vol 113 (2) ◽  
pp. 814-823
Author(s):  
Tom R Bilbo ◽  
Francis P F Reay-Jones ◽  
Jeremy K Greene
Keyword(s):  
South Carolina ◽  
Helicoverpa Zea ◽  
Management Strategies ◽  
Fall Armyworm ◽  
Field Trials ◽  
Bt Corn ◽  
Significant Protection ◽  
Corn Hybrids ◽  
Field Corn ◽  
Development Of Resistance

Abstract The fall armyworm, Spodoptera frugiperda (J. E. Smith), is a major pest of corn in North and South America. It is managed primarily with transgenic corn-producing insecticidal proteins of Bacillus thuringiensis (Bt), but the development of resistance threatens their durability and necessitates the use of alternative management strategies. We conducted late-planted field trials during 2016 and 2017 in South Carolina using natural infestations. We evaluated the use of Bt and non-Bt corn hybrids in combination with foliar applications of chlorantraniliprole at varying infestation thresholds to protect field corn from infestation and damage and determine effects on grain yield. All Bt hybrids were more effective at reducing fall armyworm infestation rates and leaf injury than multiple insecticide sprays, and no Bt hybrid reached the lowest infestation threshold (20%) to require supplemental insecticide treatments, despite infestations in non-Bt corn reaching >68% in each year. The only Bt and/or insecticide treatment to significantly reduce ear feeding or the proportion of ears injured (mainly by Helicoverpa zea [Boddie]) was the Bt hybrid pyramid producing Vip3A. However, significant protection of yield was detected only in the Bt hybrids producing Cry1A.105 + Cry2Ab2. All Bt traits tested in this study were effective in reducing infestation and feeding damage from fall armyworm, although this did not always result in significant protection of yield. Our results demonstrate the potential and limitations of using chlorantraniliprole with Bt (when resistance is present) and non-Bt corn to manage this pest.

Colon Cancer Treatment in Rural North and South Carolina

1999 ◽  
Vol 23 (5) ◽  
pp. 428-434 ◽  
Author(s):  
Sarah E. Tropman ◽  
Theresa Hatzell ◽  
Electra Paskett ◽  
Thomas Ricketts ◽  
M. robert Cooper ◽  
...  
Keyword(s):  
Colon Cancer ◽  
South Carolina ◽  
Cancer Treatment ◽  
North And South

scholarly journals Pest Status and Management of Corn Earworm (Lepidoptera: Noctuidae) in Field Corn in the United States

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Francis P F Reay-Jones
Keyword(s):  
United States ◽  
Selection Pressure ◽  
The United States ◽  
Corn Earworm ◽  
Bt Corn ◽  
Pest Status ◽  
Field Corn ◽  
Type Of Injury ◽  
The Impact ◽  
Economic Pest

Abstract The corn earworm, Helicoverpa zea (Boddie), is a common lepidopteran pest of corn (Zea mays L.) in the United States. This article provides an overview of the life history, ecology, plant injury, and management of H. zea in corn. Leaf injury by H. zea feeding can occur in vegetative stage corn, though this type of injury is rare. The most common type of injury is caused by larval feeding in ears. Because kernel injury is typically limited to the tip of the ear, H. zea is generally not considered an economic pest. The use of transgenic corn hybrids expressing insecticidal Cry proteins from Bacillus thuringiensis (Bt) Berliner can reduce injury from H. zea, though complete control is not achieved with most Bt traits. Resistance has been reported to several Bt toxins. Because H. zea is a major economic pest in cotton (Gossypium hirsutum L.) and because H. zea moths that developed on corn can migrate to cotton, selection pressure on H. zea in Bt corn has major implications for the pest status and injury to Bt cotton. Although the impact of H. zea on yield of field corn is generally negligible, the selection pressure exerted by Bt corn has led to management issues in cotton.

scholarly journals Metabolic Engineering of Non-carotenoid-Producing Yeast Yarrowia lipolytica for the Biosynthesis of Zeaxanthin

2021 ◽  
Vol 12 ◽  
Author(s):  
Yuxiao Xie ◽  
Shulin Chen ◽  
Xiaochao Xiong
Keyword(s):  
Yarrowia Lipolytica ◽  
Fold Increase ◽  
Genetically Engineered ◽  
Cell Factory ◽  
Yeast Nitrogen Base ◽  
Nitrogen Base ◽  
Yeast Extract Peptone Dextrose ◽  
Dry Cell Weight ◽  
A Cell ◽  
Β Carotene

Zeaxanthin is vital to human health; thus, its production has received much attention, and it is also an essential precursor for the biosynthesis of other critical carotenoids such as astaxanthin and crocetin. Yarrowia lipolytica is one of the most intensively studied non-conventional yeasts and has been genetically engineered as a cell factory to produce carotenoids such as lycopene and β-carotene. However, zeaxanthin production by Y. lipolytica has not been well investigated. To fill this gap, β-carotene biosynthesis pathway has been first constructed in this study by the expression of genes, including crtE, crtB, crtI, and carRP. Three crtZ genes encoding β-carotene hydroxylase from different organisms were individually introduced into β-carotene-producing Y. lipolytica to evaluate their performance for producing zeaxanthin. The expression of crtZ from the bacterium Pantoea ananatis (formerly Erwinia uredovora, Eu-crtZ) resulted in the highest zeaxanthin titer and content on the basis of dry cell weight (DCW). After verifying the function of Eu-crtZ for producing zeaxanthin, the high-copy-number integration into the ribosomal DNA of Y. lipolytica led to a 4.02-fold increase in the titer of zeaxanthin and a 721% increase in the content of zeaxanthin. The highest zeaxanthin titer achieved 21.98 ± 1.80 mg/L by the strain grown on a yeast extract peptone dextrose (YPD)–rich medium. In contrast, the highest content of DCW reached 3.20 ± 0.11 mg/g using a synthetic yeast nitrogen base (YNB) medium to culture the cells. Over 18.0 g/L of citric acid was detected in the supernatant of the YPD medium at the end of cultivation. Furthermore, the zeaxanthin-producing strains still accumulated a large amount of lycopene and β-carotene. The results demonstrated the potential of a cell factory for zeaxanthin biosynthesis and opened up an avenue to engineer this host for the overproduction of carotenoids.

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