scholarly journals Genome evolution in an agricultural pest following adoption of transgenic crops

2020 ◽  
Author(s):  
Megan L. Fritz ◽  
Kelly A. Hamby ◽  
Katherine Taylor ◽  
Alexandra M. DeYonke ◽  
Fred Gould
Keyword(s):  
Helicoverpa Zea ◽  
Agricultural Practices ◽  
Holistic Approach ◽  
Transgenic Crops ◽  
Pest Species ◽  
Whole Genome Analysis ◽  
Genomic Change ◽  
Cry Toxin ◽  
Polygenic Selection ◽  
Broad Understanding

AbstractReplacement of synthetic insecticides with transgenic crops for pest management has been both economically and environmentally beneficial. These benefits have often eroded as pests evolved resistance to the transgenic crops, but a broad understanding of the timing and complexity of the adaptive changes which lead to field-evolved resistance in pest species is lacking. Wild populations of Helicoverpa zea, a major lepidopteran crop pest and the target of transgenic Cry toxin-expressing cotton and corn, have recently evolved widespread, damaging levels of resistance. Here, we quantified patterns of genomic change in wild H. zea collected between 2002 and 2017 when adoption rates of Cry-expressing crops expanded in North America. Using a combination of genomic and genotypic approaches, we identified significant temporal changes in allele frequency throughout the genomes of field-collected H. zea. Many of these changes occurred concurrently with increasingly damaging levels of resistance to Cry toxins between 2012 and 2016, in a pattern consistent with polygenic selection. Surprisingly, none of the eleven previously described Cry resistance genes showed signatures of selection in wild H. zea. Furthermore, we observed evidence of a very strong selective sweep in one region of the H. zea genome, yet this strongest change was not additively associated with Cry resistance. This first, whole genome analysis of field-collected specimens to study evolution of Cry resistance demonstrates the potential and need for a more holistic approach to examining pest adaptation to changing agricultural practices.

scholarly journals Genome evolution in an agricultural pest following adoption of transgenic crops

2021 ◽  
Vol 118 (52) ◽  
pp. e2020853118
Author(s):  
Katherine L. Taylor ◽  
Kelly A. Hamby ◽  
Alexandra M. DeYonke ◽  
Fred Gould ◽  
Megan L. Fritz
Keyword(s):  
Genome Analysis ◽  
Helicoverpa Zea ◽  
Resistance Management ◽  
Holistic Approach ◽  
Transgenic Crops ◽  
Whole Genome ◽  
Whole Genome Analysis ◽  
Genomic Change ◽  
Bt Resistance ◽  
Molecular Signals

Replacing synthetic insecticides with transgenic crops for pest management has been economically and environmentally beneficial, but these benefits erode as pests evolve resistance. It has been proposed that novel genomic approaches could track molecular signals of emerging resistance to aid in resistance management. To test this, we quantified patterns of genomic change in Helicoverpa zea, a major lepidopteran pest and target of transgenic Bacillus thuringiensis (Bt) crops, between 2002 and 2017 as both Bt crop adoption and resistance increased in North America. Genomic scans of wild H. zea were paired with quantitative trait locus (QTL) analyses and showed the genomic architecture of field-evolved Cry1Ab resistance was polygenic, likely arising from standing genetic variation. Resistance to pyramided Cry1A.105 and Cry2Ab2 toxins was controlled by fewer loci. Of the 11 previously described Bt resistance genes, 9 showed no significant change over time or major effects on resistance. We were unable to rule out a contribution of aminopeptidases (apns), as a cluster of apn genes were found within a Cry-associated QTL. Molecular signals of emerging Bt resistance were detectable as early as 2012 in our samples, and we discuss the potential and pitfalls of whole-genome analysis for resistance monitoring based on our findings. This first study of Bt resistance evolution using whole-genome analysis of field-collected specimens demonstrates the need for a more holistic approach to examining rapid adaptation to novel selection pressures in agricultural ecosystems.

scholarly journals Gene-by-environment interactions in agricultural pest management: population effects on diet-Bt interactions in a caterpillar

2020 ◽  
Author(s):  
Carrie Deans ◽  
Gregory Sword ◽  
Spencer Behmer ◽  
Eric Burkness ◽  
Marianne Pusztai-Carey ◽  
...  
Keyword(s):  
Helicoverpa Zea ◽  
Control Strategies ◽  
Laboratory Strain ◽  
Population Level ◽  
Nutrient Content ◽  
Pest Species ◽  
Nutrient Regulation ◽  
Cry Toxin ◽  
And Performance ◽  
The Impact

AbstractGiven that plant nutrient content is both spatially and temporally dynamic (Lenhart et al., 2015; Deans et al., 2016, 2018), insect herbivores are exposed to an incredible amount of nutritional variability. This variability can constrain insects to feeding on sub-optimal resources, but it can also provide an opportunity for insects to regulate their intake of specific nutrients to obtain an optimal balance. Nutrient regulation has implications for pest control strategies in agricultural systems, as the nutritional state of pest species may impact their susceptibility to insecticides. Deans et al. (2017) showed that diet macronutrient balance has significant effects on the susceptibility of Helicoverpa zea larvae to Cry1Ac, an endotoxin expressed in transgenic Bt crops. This was demonstrated using a highly inbred laboratory strain of H. zea, limiting the applicability of these results to field populations that encompass greater genetic diversity. In this study, we assessed the impact of field-relevant macronutrient variability on the efficacy of two Bt endotoxins, Cry1Ab and Cry1Ac, using three field populations collected from different geographic regions. This was done to further understand the impact of nutritional variability on Bt susceptibility and also to determine the relevance of these effects in the field. While we saw limited differences in Cry susceptibility across populations, dietary effects were highly variable. Across populations there were distinct population-level differences in the interactions between Cry concentration and diet, the type of Cry toxin impacted by diet, and the treatment diet that produced optimal survival and performance. These results show that nutrition can have strong impacts on Bt susceptibility but also that these impacts are strongly affected by genetic background in H. zea. To accurately assess Bt susceptibility in the field, including resistance monitoring, bioassay methods should incorporate the appropriate nutritional parameters and be as localized as possible.

Ichneumon promissorius (Erichson) (Hymenoptera: Ichneumonidae): Factors Affecting Fecundity, Oviposition, and Longevity

1995 ◽  
Vol 30 (2) ◽  
pp. 279-286 ◽  
Author(s):  
J. E. Carpenter
Keyword(s):  
Helicoverpa Zea ◽  
Biological Control Agent ◽  
Soil Surface ◽  
The United States ◽  
Control Agent ◽  
Pest Species ◽  
Laboratory Rearing ◽  
Factors Affecting ◽  
Preoviposition Period ◽  
Host Pupa

Ichneumon (=Pterocormus) promissorius (Erichson) (Hymenoptera: Ichneumomidae), a native of Australia, is a pupal parasitoid which searches the soil surface for host pupation sites, burrows into a pupal gallery, and oviposits in the host pupa. Fecundity and rate of oviposition were influenced by the mating status of females, the host from which females developed, and the frequency in which females were exposed to hosts. Virgin females continued laying eggs many days after mated females had stopped. A preoviposition period of 17 d in mated females did not affect the oviposition curve or the number of eggs laid, suggesting that the oogenesis is arrested until female wasps are exposed to host pupae. Female wasps exposed to pupae for 24 h every fifth day lived longer than female wasps continuously exposed to pupae. However, females that were continuously exposed to pupae laid more eggs. Virgin females reared on Spodoptera exigua (Hübner) pupae laid fewer eggs than virgin females reared on Helicoverpa zea (Boddie) pupae. These data will be important in evaluating the potential of I. promissorius as a biological control agent for pest species in the United States and will be useful in developing laboratory rearing procedures for I. promissorius.

Cropping, soil type and manure application effects on phosphorus export and bioavailability

2004 ◽  
Vol 84 (3) ◽  
pp. 295-305 ◽  
Author(s):  
A. R. Michaud ◽  
M. R. Laverdière
Keyword(s):  
Soil Type ◽  
Chemical Properties ◽  
Agricultural Practices ◽  
Holistic Approach ◽  
Management Control ◽  
Transport Processes ◽  
Rainfall Simulation ◽  
Pig Slurry ◽  
Soil P ◽  
High Level

A simulated rainfall study was conducted on an array of 36 runoff plots (6 m2 each) deployed on three benchmark soil series of the Missisquoi region in southwestern Québec. The split-plot experimental design tested the effects and interactions of pig slurry treatment as main plots (check vs. 59 kg P ha-1) and cropping (tilled vs. hay) as subplots, on runoff volume and concentrations in total suspended sediment (TSS), tot al phosphorus (TP), dissolved reactive soluble P (DRP), particulate P (PP) and bioavailable P (BioP). TP concentration in runoff ranged from a low of 1.17 mg L-1 average on non-amended Bedford hay, to a peak concentration average of 9.55 mg L-1 on manured and tilled Saint-Sébastien plots. Variance analysis indicated significant contributions of treatments in explaining TP concentration in runoff as follows: Soil type effect > Cropping effect > Soil × Cropping interaction > Manure effect. Erosion and sediment transport processes were identified as prime vectors of TP export . Manure effect alone accounted for 35% of overall DRP variability, while soil type alone accounted for 70% of variability in particulate P bioavaibility (BioP/PP). Among practical implications of this study is the importance of assessing PP bioavaibility to adequately predict the adverse impact of runoff on aquatic ecosystems. The high level of interaction among cropping and manure treatment and the site- specific influence of soil physical and chemical properties also calls for a holistic approach to nonpoint P risk assessment and management, that focusses on timely manure P management, control of soil P build-up and agricultural practices minimizing surface runoff. Key words: Phosphorus, P-index, rainfall simulation, runoff, erosion, bioavailability, sediment

scholarly journals Documenting the Welfare and Role of Working Equids in Rural Communities of Portugal and Spain

Animals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 790 ◽  
Author(s):  
Emily Haddy ◽  
Joao B. Rodrigues ◽  
Zoe Raw ◽  
Faith Burden ◽  
Leanne Proops
Keyword(s):  
Rural Communities ◽  
Cultural Context ◽  
Management Practices ◽  
Agricultural Practices ◽  
Holistic Approach ◽  
Traditional Use ◽  
Middle Income ◽  
Transfer Of Information ◽  
The Impact ◽  
Working Equids

Recently, the need for a more holistic approach to welfare assessment has been highlighted. This is particularly pertinent in the case of working equids who provide vital support for human livelihoods, often in low- to middle-income countries, yet suffer from globally low standards of welfare. This study aimed to provide insight into the welfare status and traditional use of working equids in rural Western European communities using the new EARS welfare tool, designed to provide a broad view of the welfare of working equids and the context in which they are found. Other questions on the topics of equid management practices, social transmission of expertise, environmental stressors, and traditions, alongside physical and behavioural welfare assessments were also included to explore the impact of these wide-ranging factors on an understudied population of working equids. The protocol was trialled on 60 working equid owners from communities in Portugal and Spain where, despite the decline in traditional agricultural practices and livestock keeping, donkeys and mules remain working animals. Many owners stated that the help donkeys provided was invaluable, and donkeys were considered to be important for both farming and daily life. However, participants also recognised that the traditional agricultural way of life was dying out, providing insights into the traditional practices, community structure, and beliefs of equid owners. Questions investigating the social networks and social transfer of information within the villages were effective in finding local sources of equid knowledge. Overall, welfare was deemed fair, and the protocol enabled the identification of the most prevalent welfare problems within the communities studied, in this case obesity and the use of harmful practices. The findings suggest that the new protocol was feasible and detail how contextual factors may influence equid welfare. Increasing understanding of the cultural context, social structure, and attitudes within a community, alongside more traditional investigations of working practices and animal management, may, in the future, help to make equid welfare initiatives more effective.

Host Plant Influence on Activity of Bacillus thuringiensisBerliner Against Lepidopterous Pests of Crops

2004 ◽  
Vol 39 (3) ◽  
pp. 311-317 ◽  
Author(s):  
M. Ibrahim Ali ◽  
S. Y. Young ◽  
R. C. McNew
Keyword(s):  
Helicoverpa Zea ◽  
Spodoptera Exigua ◽  
Leaf Tissue ◽  
Pest Species ◽  
Speed Of Kill ◽  
Median Lethal Concentration ◽  
Percent Survival ◽  
Treated Leaf ◽  
The Mean ◽  
Laboratory Bioassays

Mortality of second-instar Helicoverpa zea (Boddie), Spodoptera exigua (Hübner) and Pseudoplusia includens (Walker) fed Bacillus thuringiensis Berliner (Bt), Dipel ES®-sprayed leaves of field grown cotton, soybean and tomato were compared in laboratory bioassays. The median lethal concentration (LC50) for larvae of all species fed Bt-treated leaf tissue was higher for cotton than for soybean or tomato. The LC50 for larvae fed Bt-treated soybean and tomato leaves did not differ significantly for any species of insects. When the mean number of days until death was plotted against percent survival at that rate, the mean number of days until death increased with an increase in percent survival. Survival time of the three insect species exposed to Bt increased most rapidly when fed cotton leaves. Results show that foliarly-applied Bt on field-grown cotton leaves is less effective against larvae of these pest species in terms of mortality and speed of kill.

Economic Injury Levels for Bt-resistant Helicoverpa zea (Lepidoptera: Noctuidae) in Cotton

2021 ◽  
Author(s):  
Alejandro I Del Pozo-Valdivia ◽  
Dominic D Reisig ◽  
Lewis Braswell ◽  
Jeremy K Greene ◽  
Phillip Roberts ◽  
...  
Keyword(s):  
Helicoverpa Zea ◽  
The United States ◽  
Yield Response ◽  
Bt Cotton ◽  
Larval Population ◽  
Cry Toxins ◽  
Economic Thresholds ◽  
Cry Toxin ◽  
Economic Injury ◽  
Larval Number

Abstract Thresholds for Helicoverpa zea (Boddie) in cotton Gossypium hirsutum L. have been understudied since the widespread adoption of Bt cotton in the United States. Our study was possible due to the widespread presence of H. zea populations with Cry-toxin resistance. We initiated progressive spray timing experiments using three Bt cotton brands (Deltapine, Stoneville, and Phytogen) widely planted across the U.S. Cotton Belt expressing pyramided toxins in the Cry1A, Cry2, and Vip3Aa19 families. We timed foliar insecticide treatments based on week of bloom to manipulate H. zea populations in tandem with crop development during 2017 and 2018. We hypothesized that non-Bt cotton, cotton expressing Cry toxins alone, and cotton expressing Cry and Vip3Aa19 toxins would respond differently to H. zea feeding. We calculated economic injury levels to support the development of economic thresholds from significant responses. Pressure from H. zea was high during both years. Squares and bolls damaged by H. zea had the strongest negative yield associations, followed by larval number on squares. There were fewer yield associations with larval number on bolls and with number of H. zea eggs on the plant. Larval population levels were very low on varieties expressing Vip3Aa19. Yield response varied across experiments and varieties, suggesting that it is difficult to pinpoint precise economic injury levels. Nonetheless, our results generally suggest that current economic thresholds for H. zea in cotton are too high. Economic injury levels from comparisons between non-Bt varieties and those expressing only Cry toxins could inform future thresholds once H. zea evolves resistance to Vip3Aa19.

Determinants of Insecticide Resistance Evolution: Comparative Analysis Among Heliothines

2022 ◽  
Vol 67 (1) ◽  
pp. 387-406
Author(s):  
T.K. Walsh ◽  
D.G. Heckel ◽  
Yidong Wu ◽  
S. Downes ◽  
K.H.J. Gordon ◽  
...  
Keyword(s):  
Insecticide Resistance ◽  
Helicoverpa Zea ◽  
Management Practices ◽  
Ecological Factors ◽  
Comparative Approach ◽  
Pest Species ◽  
High Genetic Diversity ◽  
Helicoverpa Assulta ◽  
Genetic Characteristics ◽  
Resistance Evolution

It is increasingly clear that pest species vary widely in their propensities to develop insecticide resistance. This review uses a comparative approach to analyze the key pest management practices and ecological and biochemical or genetic characteristics of the target that contribute to this variation. We focus on six heliothine species, three of which, Helicoverpa armigera, Heliothis virescens, and Helicoverpa zea, have developed resistances to many pesticide classes. The three others, Helicoverpa punctigera, Helicoverpa assulta, and Helicoverpa gelotopoeon, also significant pests, have developed resistance to very few pesticide classes. We find that host range and movement between alternate hosts are key ecological traits that influence effective selection intensities for resistance. Operational issues are also critical; area-wide, cross-pesticide management practices that account for these ecological factors are key to reducing selection intensity. Without such management, treatment using broad-spectrum chemicals serves to multiply the effects of host plant preference, preadaptive detoxification ability, and high genetic diversity to create a pesticide treadmill for the three high-propensity species.Without rigorous ongoing management, such a treadmill could still develop for newer, more selective chemistries and insecticidal transgenic crops.

scholarly journals High Genetic Variability for Resistance toBacillus thuringiensis Toxins in a Single Population of Diamondback Moth

2001 ◽  
Vol 67 (11) ◽  
pp. 5043-5048 ◽  
Author(s):  
Joel González-Cabrera ◽  
Salvador Herrero ◽  
Juan Ferré
Keyword(s):  
Diamondback Moth ◽  
Transgenic Crops ◽  
The Philippines ◽  
Cross Resistance ◽  
High Dose ◽  
Selection Line ◽  
Cry Toxins ◽  
Development Of Resistance ◽  
Refuge Strategy ◽  
Cry Toxin

ABSTRACT The long-term benefit of insecticidal products based on Cry toxins, either in sprays or as transgenic crops, is threatened by the development of resistance by target pests. The models used to predict evolution of resistance to Cry toxins most often are monogenic models in which two alleles are used. Moreover, the high-dose/refuge strategy recommended for implementation with transgenic crops relies on the assumption that the resistance allele is recessive. Using selection experiments, we demonstrated the occurrence in a laboratory colony of diamondback moth of two different genes (either allelic or nonallelic) that confer resistance to Cry1Ab. At the concentration tested, resistance was dominant in one selection line and partially recessive in the other. Resistant insects from the two selection lines also differed in their cross-resistance patterns. The diamondback moth colony was derived from a field population from the Philippines, which originally showed a different resistance phenotype. This is the first time that an insect population has been directly shown to carry more than one gene conferring resistance to the same Cry toxin.

scholarly journals Influence of suspended and off-bottom mussel culture on the sea bottom and benthic habitats: a review1This review is part of a virtual symposium on current topics in aquaculture of marine fish and shellfish.

2011 ◽  
Vol 89 (7) ◽  
pp. 622-646 ◽  
Author(s):  
Christopher W. McKindsey ◽  
Philippe Archambault ◽  
Myriam D. Callier ◽  
Frédéric Olivier
Keyword(s):  
Benthic Communities ◽  
Holistic Approach ◽  
Physical Structure ◽  
Pest Species ◽  
Redox Potentials ◽  
Benthic Respiration ◽  
Sea Bottom ◽  
Mussel Culture ◽  
Culture Effects ◽  
Fish And Shellfish

Aquaculture is the fastest growing sector of the food industry, raising concerns about the influence of this activity on the environment. We take a holistic approach to review off-bottom and suspended mussel culture effects on the benthic environment and benthic communities. Both longline and “bouchot” mussel culture add much physical structure (infrastructure and mussels) to the environment, altering hydrosedimentary processes by modifying currents and increasing sedimentation locally, and providing habitat for many benthic organisms. Biodeposition from mussels and these organisms increases benthic organic loading and linked biogeochemical processes to influence O2, pH, redox potentials, dissolved sulphides, and other sediment parameters, benthic respiration and nutrient fluxes, and benthic infaunal communities. Mussel culture may also influence seagrasses and algae, although this has not been well-studied. Far-field effects on the benthos may occur through a number of mechanisms, including aggregation of epibenthic macrofauna in culture sites, alteration of plankton communities, and the enhancement of exotic and indigenous pest species owing to the addition of physical structure to the environment. Quantitative relationships between farming level and benthic influences are lacking, making predictions of effects difficult.

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