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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

The effect of some micronutrients on the resistance of highland bentgrass to fall armyworms

Watson, Stephen Lawrence January 2011 (has links)
Digitized by Kansas Correctional Industries
12

Efeitos de proteinas Cry e vip nos parâmetros biológicos de populações de Spodoptera frugiperda (Smith, 1797) e injúrias nas plantas de milho por Lepidópteros / Effect of Cry and vip proteins in the biology of populations of Spodoptera frugiperda (Smith, 1797), and on injuries in maize plants caused by Lepidópteros

Crosariol Netto, Jacob [UNESP] 31 January 2017 (has links)
Submitted by JACOB CROSARIOL NETTO Crosariol Netto (jacob_netto@hotmail.com) on 2017-02-24T21:47:39Z No. of bitstreams: 1 Tese_Jacob_Crosariol_Netto.pdf: 1461716 bytes, checksum: 8e775579f98ce9756ce677febd37324b (MD5) / Approved for entry into archive by LUIZA DE MENEZES ROMANETTO (luizamenezes@reitoria.unesp.br) on 2017-03-06T17:33:34Z (GMT) No. of bitstreams: 1 crosariolnetto_j_dr_jabo.pdf: 1461716 bytes, checksum: 8e775579f98ce9756ce677febd37324b (MD5) / Made available in DSpace on 2017-03-06T17:33:34Z (GMT). No. of bitstreams: 1 crosariolnetto_j_dr_jabo.pdf: 1461716 bytes, checksum: 8e775579f98ce9756ce677febd37324b (MD5) Previous issue date: 2017-01-31 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / The fall armyworm Spodoptera frugiperda is the major pest of corn in tropical and subtropical regions in the American Continent. Among the most used methods to control this pest in Brazil, it highlights the use of genetically modified plants from the insertion of a Bacillus thuringiensis gene that confers to the plant the expression of proteins with insecticidal actions. However, after two or three years these technologies reduce the degree of suppression of larvae, mainly due to the continuous and inadequate use of the technology. The objective of this work was to study in field conditions, the behavior of Bt corn hybrids against lepidopteran attacks as S. frugiperda and Helicoverpa zea in four corn-producing regions of São Paulo State, as well as to study in laboratory conditions the comparative biology of populations of S. frugiperda collected in these regions. Field experiments were carried out during the second corn season in 2014 in the regions of Médio Paranapanema, Centro Norte, Noroeste and Norte of São Paulo State where were used 25 corn cultivars with the expression of different insecticidal proteins. To the comparative biology study, the larvae were collected in the four regions of the state, the larvae were sent to Integrated Pest Management Laboratory of FCAV-Unesp where the experiments were carried out with leaves of corn hybrids of different technologies. The results of field experiments demonstrate that the insecticidal protein VIP3Aa20 presents a high level of suppression on the populations of S. frugiperda and H. zea, in addition, the corn hybrids that express the insecticidal protein Cry1F were the most susceptible against the attack of these two pests. Through the results obtained from the experiments of comparative biology, it was verified that the insecticidal protein VIP3Aa20 provided 100% of mortality of larvae from the four regions. The hybrid with expression of the proteins Cry1A.105 + Cry2Ab2 + Cry1F was the one that provided low viability of S. frugiperda larvae coming from the four regions of the São Paulo State. The hybrid that expresses the insecticidal protein Cry1F provided low levels of suppression as well as low adverse effects in the development of S. frugiperda coming from the four regions of the state, indicating that the populations present in these four regions are resistant to the action of this insecticidal protein. / A lagarta do cartucho Spodoptera frugiperda é a principal praga da cultura do milho nas regiões tropicais e subtropicais do continente americano. Dentre os métodos mais utilizados para o controle desta praga no Brasil, destaca-se o uso de plantas geneticamente modificadas a partir da inserção de um gene da bactéria Bacillus thuringiensis que confere a planta a expressão de proteínas com ações inseticidas. No entanto, durante dois ou três anos estas tecnologias reduziram o grau de supressão às lagartas, principalmente pelo uso continuo e inadequado da tecnologia. O objetivo deste trabalho foi estudar em condições de campo, o comportamento de híbridos de milho Bt frente ao ataque de lepidópteros, como a S. frugiperda e Helicoverpa zea, em quatro regiões produtoras de milho do estado de São Paulo, bem como estudar em condições de laboratório a biologia comparada de populações de S. frugiperda coletadas nestas regiões. Os experimentos de campo foram realizados no período da segunda safra de milho, no ano de 2014, nas regiões do Médio Paranapanema, Centro Norte, Noroeste e Norte do estado de São Paulo, onde foram utilizados 25 cultivares de milho com expressão de diferentes proteínas inseticidas. Para o estudo de biologia comparada foi realizada a coleta de lagartas nas quatro regiões do estado, as lagartas foram enviadas ao laboratório de Manejo Integrado de Pragas da FCAV-Unesp onde foram realizados os experimentos com folhas de híbridos de milho de diferentes tecnologias. Os resultados dos experimentos realizados a campo demonstram que a proteína inseticida VIP3Aa20 apresenta alto nível de supressão sobre as populações de S. frugiperda e Helicoverpa zea, além disso, os híbridos de milho que expressam a proteína inseticida Cry1F foram os mais suscetíveis frente ao ataque destas duas pragas. Através dos resultados obtidos para os experimentos de biologia comparada, constatou-se que a proteína inseticida VIP3Aa20 proporcionou 100% de mortalidade das lagartas oriundas das quatro regiões. O híbrido com expressão das proteínas Cry1A.105 + Cry2Ab2 + Cry1F foi o que proporcionou menor viabilidade de lagartas de S. frugiperda oriundas das quatro regiões do estado. O híbrido que expressa a proteína inseticida Cry1F proporcionou baixos níveis de supressão além de baixos efeitos adversos no desenvolvimento de S. frugiperda oriundas das quatro regiões do estado, indicando que as populações presentes nestas quatro regiões se encontram resistentes a ação desta proteína inseticida.
13

Liberação de linhagens de Trichogramma pretiosum para controle biológico de Spodoptera frugiperda na cultura do milho / Liberation of Trichogramma pretiosum strains for biological control of Spodoptera frugiperda in the field corn

Cordeiro, Ederval Silva 27 September 2006 (has links)
Made available in DSpace on 2017-07-10T17:37:06Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-09-27 / The objectives of this work were: to identify lineages of Trichogramma which occur naturally in eggs of Spodoptera frugiperda, in the West of Paran?; to select, under laboratory conditions, about eggs of the alternative host Anagasta kuehniella (Zeller), the lineage with the highest potential of parasitism and to evaluate the efficency of the selected line to control S. frugiperda in field conditions. Collections were realized in commercial, conventional and organic crops in properties in the West of Paran?. The collected lineages in the field were named (E1, E3, L3) and after, identified as T. pretiosum. The biology of the collected lineages in the field and the line (L2) breeded massively under laboratory conditions in Anagasta kuehniella eggs, were realized in temperature of 25?2 ?C; 70 ? 10% R.U. and 14 h. photophase. After the line selection through the analysis of biological parameters, two liberation experiments were performed in field conditions. On experiment 1, 100 thousand parasitoids per hectare were liberated and evaluated weekly, evaluating the plants which sufferd or not, the fall armyworm attack, observing the leaf damages, as scrape and perforation. On experiment 2, 200 thousand parasitoids per hectare were liberated and evaluated weekly, observing the same damages caused by Spodoptera related on the previous experiment. L2 was selected, due to this line large number of parasited eggs and larger number of females presented, when compared to males for later use in the field. In general, the conclusion is that in both experiments (1 and 2), there was significant reduction of the number of the damaged plants by S. frugiperda in treated areas with T. pretiosum / Os objetivos deste trabalho foram: identificar linhagens de Trichogramma que ocorrem naturalmente em ovos de Spodoptera frugiperda, na região Oeste do estado do Paraná; selecionar em laboratório, sobre ovos do hospedeiro alternativo Anagasta kuehniella (Zeller), a linhagem com o maior potencial de parasitismo e avaliar a eficiência a campo da linhagem selecionada no controle de S. frugiperda. Para isso foram realizadas coletas em plantações comerciais, convencionais e orgânicas em propriedades da região Oeste do Paraná. As linhagens coletadas a campo foram denominadas de (E1, E3, L6) e posteriormente identificadas como T. pretiosum. Foi realizada a biologia das linhagens coletadas a campo e também da linhagem (L2) criada massalmente em laboratório em ovos de Anagasta kuehniella em temperatura de 25±2 ºC; 70 ± 10% U.R. e 14 h. de fotofase. Após a seleção da linhagem pela análise dos parâmetros biológicos, foram realizados dois experimentos de liberação em campo. No experimento 1, 100 mil parasitóides por hectare foram liberados e avaliados semanalmente, levando em consideração as plantas que sofreram ou não, o ataque da lagarta-do-cartucho, observando os danos foliares, como raspagem e perfuração. No experimento 2, 200 mil parasitóides por hectare foram liberados e avaliados semanalmente, levando em consideração os mesmos danos causados pela Spodoptera citado no experimento anterior. Foi selecionado a L2, devido esta linhagem apresentar maior número de ovos parasitados e maior quantidade de fêmeas em relação aos machos para posterior uso em campo. No geral, pode se concluir que em ambos os experimentos (1 e 2) houve redução significativa do número de plantas danificadas por S. frugiperda em áreas tratadas com T. pretiosum.
14

Pharmacokinetic mechanisms associated with cypermethrin toxicity and synergism in larval and adult Helicoverpa zea (Boddie), Spodoptera frugiperda (J.E. Smith), and Agrotis ipsilon (Hufnagle) (Family noctuidae) /

Usmani, Khawja Amin, January 1998 (has links)
Thesis (Ph. D.)--University of Missouri-Columbia, 1998. / Typescript. Vita. Includes bibliographical references (leaves [224]-254). Also available on the Internet.
15

Pharmacokinetic mechanisms associated with cypermethrin toxicity and synergism in larval and adult Helicoverpa zea (Boddie), Spodoptera frugiperda (J.E. Smith), and Agrotis ipsilon (Hufnagle) (Family noctuidae)

Usmani, Khawja Amin, January 1998 (has links)
Thesis (Ph. D.)--University of Missouri-Columbia, 1998. / Typescript. Vita. Includes bibliographical references (leaves [224]-254). Also available on the Internet.
16

Efeito do silício aplicado no solo e em pulverização foliar na incidência da lagarta do cartucho na cultura do milho

Silva, Anne Caroline Arruda e [UNESP] 07 August 2009 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:28:36Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-08-07Bitstream added on 2014-06-13T18:35:01Z : No. of bitstreams: 1 silva_aca_me_botfca.pdf: 486573 bytes, checksum: 7da2829da43c73fb9381ae790a958b36 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Atualmente diversos estudos têm sido desenvolvidos sobre a utilização dos silicatos na adubação de plantas e embora ainda não conclusivos, seu emprego tem sido intensificado em algumas regiões agrícolas do país. No entanto, como o silício não é considerado um nutriente essencial de plantas, uma das principais justificativas para seu emprego na agricultura tem sido o incremento da resistência a pragas e doenças. Dessa forma, foram instalados dois experimentos seguindo o delineamento experimental de blocos ao acaso para verificar o efeito do silício sobre a lagarta-do-cartucho do milho em condições de campo. O primeiro experimento foi composto por 10 tratamentos e 4 repetições, com parcelas de 10 linhas de 10 m e visou verificar o efeito de uma formulação comercial contendo 25% de óxido de silício (12% de Si solúvel) e 15% de óxido de potássio, desenvolvida para aplicação através da pulverização foliar. Os tratamentos no primeiro experimento consistiram da aplicação da formulação silicatada nas concentrações 2, 4 e 8 mL/L, em pulverização aos 15, aos 15 e 30 e aos 15, 30 e 45 dias após a germinação das plantas. O segundo experimento contou com 7 tratamentos e 4 repetições, com parcelas de 7 linhas de 10 m e visou verificar o efeito de uma formulação comercial constituída por escória de siderurgia, aplicada no sulco de semeadura, nas doses de 400 e 800 kg/ha, na semeadura, só na cobertura, e na semeadura e cobertura. Nos dois experimentos avaliou-se a incidência da lagarta-do-cartucho do milho aos 15, 30, 45 e 60 dias após a germinação e os respectivos danos através de uma escala de notas. Também foram avaliados os parâmetros vegetativos indicadores do desenvolvimento como, altura da planta; número de folhas vivas; data do fechamento do cartucho e data do lançamento do pendão e o número de espigas produzido. Finalmente foi a avaliada... / At present several studies about the use of silicates on plant fertilization have been developed, and although there is nothing conclusive regarding it, their use has been intensified in some Brazilian agricultural regions. However, since silicon is not considered an essential plant nutrient, the main reason for its use in agriculture has been the increase in the plant resistance to pests and diseases. This way, two experiments were carried out to verify the effect of silicon on fall armyworm in field corn. The first experiment used a randomized block design with 10 treatments and 4 replicates and with plots of ten 10 m rows to verify the effect of a commercial formula containing 25% of silicon oxide (12% of soluble Si) and 15% of potassium oxide, developed for foliar application. The treatment on the first experiment consisted of the silicate formula at concentration of 2,4 and 8 mL/L, sprayed at 15 days, at 15 and 30 and at 15, 30 and 45 days after plant germination. The second experiment also used a randomized block design with 7 treatment and 4 replications, and with plots of seven 10m rows, to verify the effect of a commercial formula composed by silicate slag applied in the soil, with dosages of 400 and 800 kg/ha, in the sowing, only in coverage and both. The incidence of fall armyworm was evaluated at 15, 30 45 and 60 days after the germination and its respective damage through a grade scale in both experiments. Vegetation development indicator parameters were also evaluated as: plant height; number of living leaves; date of the flowering; number of corncobs. The production was finally evaluated by weighing the corncobs and grain/plant. The data obtained indicated that silicon did not interfere neither on the plant vegetable development nor in the occurrence of fall armyworm. It did not interfere neither on the damage caused by this pest, nor on the number of and grains produced.
17

The development of a baculovirus expression system for the production of Helicoverpa armigera stunt virus capsids for use in the encapsidation of foreign molecules

Mosisili, Kekeletso Mpho Thakane January 2003 (has links)
The capsid protein of Helicoverpa armigera stunt virus (HaSV) a T=4 insect virus was expressed in Spodoptera frugiperda 9 cells using a baculovirus vector. When the insect cells were infected at a high MOl the expressed coat protein assembled into virus-like particles (VLPs) that spontaneously underwent maturation and were morphologically indistinguishable from wild-type HaSV. The VLPs were electron dense when viewed under EM and encapsidated their coat protein mRNA. When Sf9 cells were infected at a low multiplicity of infection (MOl) the expressed capsid protein assembled into procapsids that did not spontaneously undergo maturation. These procapsids underwent autoproteolytic maturation cleavage when they were treated with an acidic buffer. The procapsids were used in the encapsidation of a FITC labelled peptide. The peptide encapsidating VLPs showed an increase in their buoyant density that was not collaborated by an increase in the concentration of the FITC labelled peptide detected when these samples were compared to control samples with similar buoyant densities.
18

THE EFFECTS OF INHIBITING DHURRIN BIOSYNTHESIS IN SORGHUM

Shelby M Gruss (11204016) 29 July 2021 (has links)
<p>Dhurrin is a cyanogenic glucoside (CG), an important compound that can interplay with primary and secondary metabolism in sorghum. Dhurrin metabolism contributes to insect resistance, growth, nitrogen (N) metabolism, drought tolerance, and safety for animal consumption when used as a forage. Through chemical mutagenesis with ethyl methanesulfonate (EMS), a mutation in the gene encoding CYP79A1 (<i>cyp79a1</i>), the first enzyme in the biosynthetic pathway of dhurrin, was discovered that inhibits the production of dhurrin. The acyanogenic phenotype of this mutant could be a major benefit in reducing the risk of hydrogen cyanide (HCN) toxicity within animals; however, understanding the effects of inhibiting dhurrin biosynthesis is important in understanding metabolic tradeoffs that could occur. This dissertation describes research to assess impacts and tradeoffs of the dhurrin-free trait on susceptibility to Fall Armyworm [<i>Spodoptera frugiperda</i> (J.E. Smith)] (FAW) feeding, seedling growth, effects on post-flowering drought tolerance, cold stress and utilization as a forage. Insect susceptibility and seedling growth were examined using near-isogenic lines (NILs) within the greenhouse utilizing non-destructive phenotyping technologies for green plant area and in the field comparing total leaf area and dry weight. Post-flowering drought stress was induced within a greenhouse, growth chamber, and field environments. The <i>cyp79a1 </i>mutation was tested in NILs, a near-isogenic backcross (NIBC) population, and near-isogenic hybrids (NIH), to understand the impacts of the <i>cyp79a1 </i>mutation<i> </i>on the stay-green trait. Palatability as forage was examined by comparing the feeding preference of ruminant animals with multiple conventional hybrids and an experimental hybrid carrying the <i>cyp79a1</i> mutation. This preference was also examined using a set of NILs varying in the <i>cyp79a1 </i>mutation<i>. </i> Safety was assessed in preference trials by testing for HCN release before grazing. To further our understanding of the benefits of sorghum as a forage, the dhurrin-free experimental hybrid was compared to seven conventional hybrids as a dry product. The dry sorghum product was tested for the release of HCN and dhurrin content. Lastly, the effects of low temperatures and frost were assessed for their effects on the production of dhurrin in cyanogenic and dhurrin-free sorghum genotypes. </p> <p>Overall, the biosynthesis of dhurrin had a significant effect on the deterrence of FAW and on the growth of sorghum seedlings. Dhurrin-free lines were more susceptible to FAW feeding but also exhibited a significantly higher growth rate. Dhurrin-free lines and hybrids only exhibited a slight increase in susceptibility to post-flowering drought stresses with only one dhurrin-free hybrid discovered to senesce faster than its wild-type NIH. Comparisons of the effects of dhurrin biosynthesis on stay-green in a NIBC population in Tx642 (B35), one of the most important sources of the stay-green trait, did not show any variation in chlorophyll concentration (CC) and normalized difference vegetation index (NDVI). Analyses of the impact of dhurrin on palatability as a forage showed that ewes preferred grazing on the dhurrin-free hybrids and NILs, showing that the ewes were able to detect the presence or absence of dhurrin while feeding. Experiments to assess the safety and stability of dhurrin in dried plant material demonstrated that dhurrin content did not change during drying and HCN was released after rehydration. Furthermore, high levels of HCN were immediately released when rumen fluid was added to dried plant materials containing dhurrin; however, no detectable HCN was released from dhurrin-free genotypes. Finally, sorghum plants exposed to freezing temperatures exhibited an increase in dhurrin content in conventional sorghum hybrids while no detectable dhurrin was noted within <i>cyp79a1 </i>mutants. </p> <p>Taken together, these studies demonstrate pleiotropic effects for the <i>cyp79a1 </i>mutation. Dhurrin-free genotypes were more susceptible to insect herbivory and may be slightly more susceptible to post-flowering drought within the hybrids; however, these genotypes exhibited higher seedling growth rates, feeding preference by ewes, no release of HCN in fresh or dry plant material, and frost did not cause an increase in dhurrin content.</p>
19

Detection And Characterization Of A Volatile Compound As A Response To Fall Armyworm (Spodoptera Frugiperda) Feeding In Maize (Zea Mays)

Smith, Whitney Elizabeth Crow 10 December 2010 (has links)
Maize (Zea mays) is an important agricultural crop frequently targeted by pests that pose a threat to plant development and survival. To deal with this problem, maize generates a wide variety of responses to attack by pests, from activation of woundresponse pathways to the release of volatile compounds. Several maize lines have been developed that show resistance to one common pest, the larvae of the fall armyworm (Spodoptera frugiperda). Analysis of the volatiles released by the resistant and susceptible lines in the presence and absence of the fall armyworm was conducted using SPME coupled to GC/MS. Caryophyllene, a commonly released plant volatile, was identified in the resistant line. In the susceptible line, caryophyllene was detected in smaller quantities or not at all. The results of a preference study demonstrated that fall armyworm larvae show a statistically significant preference for yellow-green whorl tissue from the susceptible over the resistant line.
20

Bases para um programa de manejo da resistência de Spodoptera frugiperda (Lepidoptera: Noctuidae) a chlorfenapyr no Brasil / Bases for resistance management program of Spodoptera frugiperda (Lepidoptera: Noctuidae) to chlorfenapyr in Brazil

Kanno, Rubens Hideo 05 February 2019 (has links)
As principais táticas de controle de Spodoptera frugiperda (Lepidoptera: Noctuidae) têm sido o uso de inseticidas e cultivos Bt no Brasil. Devido à intensa pressão de seleção, a evolução da resistência de S. frugiperda aos principais inseticidas de diferentes grupos químicos e a proteínas Bt já foram documentados no Brasil. Sendo assim, estudos para preservar a vida útil de inseticidas com novos mecanismos de ação como a de chlorfenapyr (desacoplador da fosforilação oxidativa mediante a disrupção do gradiente de prótons) são fundamentais em programas de Manejo da Resistência de Insetos (MRI). Para a implementação de programas proativos de manejo da resistência de S. frugiperda a chlorfenapyr, foram conduzidos estudos para caracterizar e monitorar a suscetibilidade de populações de campo de S. frugiperda a chlorfenapyr, estimar a frequência do alelo da resistência a chlorfenapyr pelo método de F2 screen e avaliar a resistência cruzada entre chlorfenapyr e outros inseticidas e proteínas Bt. O método de bioensaio utilizado foi o de tratamento superficial da dieta. Os dados das linhas-básicas de suscetibilidade das populações de campo a chlorfenapyr demonstraram uma variação da CL50 de 13,87 a 25,07 &#181;g/mL. A concentração diagnóstica de 56 &#181;g/mL foi estimada mediante análise conjunta dos dados de linha-básica de suscetibilidade baseada na CL99. A suscetibilidade foi monitorada a partir de populações de campo de S. frugiperda coletadas nas principais regiões produtoras de milho no Brasil entre 2016 e 2018. A taxa de sobrevivência na concentração diagnóstica variou de 0 a 8,4%. Pelo método de F2 screen a frequência alélica estimada nas safras para a 2ª safra 2016 e a 1ª safra 2017 foi de 0,0008 e a frequência para a entressafra 2016-2017 foi de 0,0012. Não foi verificada resistência cruzada entre chlorfenapyr e os inseticidas: lambda-cyhalothrin, chlorpyrifos, lufenuron, teflubenzuron, spinosad e chlorantraniliprole e as proteínas Bt: Cry1F, Cry1A.105/Cry2Ab2, Cry1A.105/Cry2Ab2/Cry1F e Vip3Aa20 expressas em milho geneticamente modificado. Os resultados demonstraram uma alta suscetibilidade das populações de campo a chlorfenapyr, uma baixa frequência do alelo da resistência e ausência de resistência cruzada aos principais inseticidas e proteínas Bt. Portanto, o inseticida chlorfenapyr pode ser utilizado como uma ferramenta em programas de MRI em S. frugiperda no Brasil. / Chemical control and Bt crops are the major control tactics to control Spodoptera frugiperda (Lepidoptera: Noctuidae) in Brazil. Due to intense selection pressure, the evolution of S. frugiperda resistance to major insecticides from different chemical groups and to Bt proteins has already been documented in Brazil. Therefore, studies to preserve the lifetime of insecticides with new mode of action such as chlorfenapyr (uncouplers of oxidative phosphorylation via disruption of the proton gradient) are important in Insect Resistance Management (IRM) programs. For implementing a proactive resistance management program of S. frugiperda to chlorfenapyr, studies were conducted to characterize and monitor the susceptibility of field populations of S. frugiperda to chlorfenapyr, to estimate the frequency of resistance alleles to chlorfenapyr using F2 screen method and to evaluate the cross-resistance patterns of chlorfenapyr and other insecticides and Bt proteins. Diet overlay bioassays was used to characterize the baseline susceptibility data of field population of S. frugiperda to chlorfenapyr. The LC50 ranged from 13.87 a 25.07 &#181;g/mL. A diagnostic concentration of 56 &#181;g/mL was estimated from the joint analysis of the baseline susceptibility data, based on LC99. Susceptibility was monitored from field populations of S. frugiperda collected from major corn growing regions in Brazil from 2016 to 2018. The survival rate at the diagnostic concentration ranged from 0 to 8.4%. Using the F2 screen method, the estimated allele frequency for the 2nd crop season 2016 and 1st crop season 2017 was 0.0008 and the frequency for the offseason 2016-2017 was 0.0012. No cross-resistance was verified between chlorfenapyr and the insecticides: lambda-cyhalothrin, chlorpyrifos, lufenuron, teflubenzuron, spinosad and chlorantraniliprole and to Bt proteins: Cry1F, Cry1A.105/Cry2Ab2, Cry1A.105/Cry2Ab2/Cry1F and Vip3Aa20 expressed in genetically modified maize. The results demonstrated a high susceptibility of field populations of S. frugiperda to chlorfenapyr, a low resistance allele frequency and lack of cross-resistance to major insecticides and Bt proteins. Therefore, chlorfenapyr can be used as an important tool in IRM programs of S. frugiperda in Brazil.

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