Ethological aspects of Helicoverpa armigera in the reproductive phase of cotton

Pest behavior studies are important to inform the periods when the pest is more exposed to pesticide. This study aimed to evaluate the movement and feeding of Helicoverpa armigera larvae in the first three instars during the reproductive phase of cotton. First, larval behavior was evaluated with a completely randomized design in a 3 × 5 factorial design with eight replications. The treatments were the instars versus behaviors (crawling, resting, waving, eating and dropping-off). In addition, another 3 × 6 factorial design with eight replications was performed to evaluate the plant region most preferred by the caterpillars. The treatments were the instars versus six parts of the plant (abaxial surface, adaxial surface, on floral bud, internal surface of bract, petiole, and terminal growth). Then, the period of the day when caterpillars are more active was also evaluated by a 3 × 2 factorial essay. The treatments were the instars versus periods of the day. Eating and resting are the most frequent behaviors for all instars. The plant regions preferred by the caterpillars for crawling are on the floral bud and the adaxial face of the leaf. There is no preferred period of the day for eating, resting, waving or dropping-off. Caterpillars (until the third instar) prefer to walk in the morning and other behaviors can occur at any period. Therefore, sprays should preferably occur in the morning, and the insecticide drops/spray should reach the flower buds and the adaxial surface of the leaves to contaminate the larvae.

Molecular identification, characterization, and expression analysis of a serine protease inhibitor gene from cotton bollworm, Helicoverpa armigera (Lepidoptera: Noctuidae) / Identificação molecular, caracterização e análise de expressão de um gene inibidor de serina protease da lagarta Helicoverpa armigera (Lepidoptera: noctuidae) na cultura de algodão

Serine protease inhibitors (serpins), a superfamily of protease inhibitors, are known to be involved in several physiological processes, such as development, metamorphosis, and innate immunity. In our study, a full-length serpin cDNA, designated Haserpin1, was isolated from the cotton bollworm Helicoverpa armigera. The cDNA sequence of Haserpin1 is 1176 nt long, with an open reading frame encoding 391 amino acids; there is one exon and no intron. The predicted molecular weight of Haserpin1 is 43.53 kDa, with an isoelectric point of 4.98. InterProScan was employed for Haserpin1 functional characterization, which revealed that Haserpin1 contains highly conserved signature motifs, including a reactive center loop (RCL) with a hinge region (E341N350), the serpin signature, (F367F375) and a predicted P1P1 cleavage site (L357S358), which are useful for identifying serpins. Transcripts of Haserpin1 were constitutively expressed in the fat body, suggesting that it is the major site for serpin synthesis. During the developmental stages, a fluctuation in the expression level of Haserpin1 was observed, with low expression detected at the 5th-instar larval stage. In contrast, relatively high expression was detected at the prepupal stage, suggesting that Haserpin1 might play a critical role at the H. armigera wandering stage. Although the detailed function of this serpin (Haserpin1) needs to be elucidated, our study provides a perspective for the functional investigation of serine protease inhibitor genes.(AU)

Sabe-se que os inibidores de serina protease (serpinas), uma superfamília de inibidores de protease, estão envolvidos em vários processos fisiológicos, como desenvolvimento, metamorfose e imunidade inata. Neste estudo, um cDNA de serpina de comprimento total, denominado Haserpin1, foi isolado da lagarta Helicoverpa armigera na cultura de algodão. A sequência de ADNc de Haserpin1 tem 1.176 nt de comprimento, com uma grelha de leitura aberta que codifica 391 aminoácidos; existe um éxon, mas nenhum íntron. O peso molecular previsto de Haserpin1 é de 43,53 kDa, com um ponto isoelétrico de 4,98. O InterProScan foi empregado para a caracterização funcional do Haserpin1, que revelou que o Haserpin1 contém motivos de assinatura altamente conservados, incluindo um loop central reativo (RCL) com uma região de dobradiça (E341-N350), a assinatura da serpina (F367-F375) e um local de clivagem previsto de P1-P1' (L357-S358), que são úteis para identificar serpinas. As transcrições de Haserpin1 foram expressas constitutivamente no corpo gordo, sugerindo que é o principal local para a síntese de serpinas. Durante os estágios de desenvolvimento, observou-se uma flutuação no nível de expressão de Haserpin1, com baixa expressão detectada no estágio larval do 5º ínstar. Por outro lado, detectou-se uma expressão relativamente alta no estágio pré-pupal, sugerindo que o Haserpin1 pode desempenhar um papel crítico no estágio errante de H. armigera. Embora a função detalhada dessa serpina (Haserpin1) precise ser elucidada, este estudo fornece uma perspectiva para a investigação funcional dos genes inibidores da serina protease.(AU)

Entomopathogenic nematodes for the control of Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) pupae

Helicoverpa armigera (Hübner) is a polyphagous insect of difficult control and maize is an important host crop of this insect. Entomopathogenic nematodes (EPNs) are control agents of soil pests. This study aimed to verify the action of EPNs for the control of H. armigera pupae. Laboratory and greenhouse bioassays were conducted to select the concentration of nematode application and subsequently field test were conducted. It was obtained that Heterorhabditis amazonensis MC01 at the concentration of 400 infective juveniles (IJs) ·pupa-1 caused the highest mortality in a lower concentration, whereas for H. amazonensis JPM4, concentrations of both 200 and 400 IJs ·pupa-1 were similar causing pupae mortality. In the greenhouse, H. amazonensis MC01 caused mortality reached values of 80% after 10 days, at concentrations of 600 and 800 IJs ·pupa-1. The highest mortality caused by Steinernema carpocapsae was observed at eight days after the juvenile application, at a concentration of 600 IJs ·pupa-1, also reaching 80% mortality. In the field test, both forms of application were considered appropriate for H. amazonensis MC01, causing mortality rates of up to 80%.(AU)

Entomopathogenic nematodes for the control of Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) pupae

Helicoverpa armigera (Hübner) is a polyphagous insect of difficult control and maize is an important host crop of this insect. Entomopathogenic nematodes (EPNs) are control agents of soil pests. This study aimed to verify the action of EPNs for the control of H. armigera pupae. Laboratory and greenhouse bioassays were conducted to select the concentration of nematode application and subsequently field test were conducted. It was obtained that Heterorhabditis amazonensis MC01 at the concentration of 400 infective juveniles (IJs) ·pupa-1 caused the highest mortality in a lower concentration, whereas for H. amazonensis JPM4, concentrations of both 200 and 400 IJs ·pupa-1 were similar causing pupae mortality. In the greenhouse, H. amazonensis MC01 caused mortality reached values of 80% after 10 days, at concentrations of 600 and 800 IJs ·pupa-1. The highest mortality caused by Steinernema carpocapsae was observed at eight days after the juvenile application, at a concentration of 600 IJs ·pupa-1, also reaching 80% mortality. In the field test, both forms of application were considered appropriate for H. amazonensis MC01, causing mortality rates of up to 80%.(AU)

Economic survey to support control decision for old world bollworm on processing tomatoes

Helicoverpa armigera (Hübner) regularly requires quick deployment of control practices due to its potential of causing yield loss of processing tomatoes. The monitoring of H. armigera adults using stick traps lured with sex pheromone was correlated to egg densities, larvae, and percentage of damaged fruits, aiming to subsidize control decisions only using the number of males caught in the traps since surveying pest stages or damaged fruits is laborious and costly. Surveys were carried out on 11 tomato fields (ca. 80 to 120 hectares each) for processing during the 2015 and 2016 crop seasons. The survey was initiated at the flowering stage with traps set up along the field borders 100 m distant each. Evaluations of adult male capture in the traps were conducted twice a week for 14 and 10 weeks during the 2015 and 2016 seasons, respectively. Simultaneously, 70 tomato plants were fully inspected for eggs, larvae, and damaged fruits per area using a rate of 10 plants per point of trap setting in each area. Overall capture of male moths correlated to subsequent eggs, larvae, and damaged fruits. Based on the outcome of the regression analysis between male moths captured and percentage of damaged fruits, the control decision is suggested when three to six male moths are captured per trap during one week. The monitoring of adults using pheromone traps help deploy chemical or biological control methods to restrain H. armigera population reaching economic threshold levels.

Economic survey to support control decision for old world bollworm on processing tomatoes

Helicoverpa armigera (Hübner) regularly requires quick deployment of control practices due to its potential of causing yield loss of processing tomatoes. The monitoring of H. armigera adults using stick traps lured with sex pheromone was correlated to egg densities, larvae, and percentage of damaged fruits, aiming to subsidize control decisions only using the number of males caught in the traps since surveying pest stages or damaged fruits is laborious and costly. Surveys were carried out on 11 tomato fields (ca. 80 to 120 hectares each) for processing during the 2015 and 2016 crop seasons. The survey was initiated at the flowering stage with traps set up along the field borders 100 m distant each. Evaluations of adult male capture in the traps were conducted twice a week for 14 and 10 weeks during the 2015 and 2016 seasons, respectively. Simultaneously, 70 tomato plants were fully inspected for eggs, larvae, and damaged fruits per area using a rate of 10 plants per point of trap setting in each area. Overall capture of male moths correlated to subsequent eggs, larvae, and damaged fruits. Based on the outcome of the regression analysis between male moths captured and percentage of damaged fruits, the control decision is suggested when three to six male moths are captured per trap during one week. The monitoring of adults using pheromone traps help deploy chemical or biological control methods to restrain H. armigera population reaching economic threshold levels.(AU)

Oviposition behavior of Helicoverpa armigera in soybean / Comportamento de oviposição de Helicoverpa armigera em soja

The objective of this study was to evaluate the oviposition behavior of Helicoverpa armigera confined in different adult pair density and growth stages of soybean plants, and the resistance of soybean genotypes to H. armigera in the category nonpreference for oviposition. The oviposition behavior of H. armigera was assessed using one, two, and four adult pairs per soybean plant of the cultivar BR-16 at the growth stages: vegetative V8 (eighth unrolled trifoliate leaf), reproductive R2 (full bloom) and reproductive R5.2 (beginning seed). The nonpreference for oviposition was evaluated using eight soybean genotypes and an oviposition preference index was calculated. The number of trichomes in leaflets was quantified for being correlated to H. armigera oviposition. One adult pair and soybean plants stage at pod-set affected and showed the best results oviposition preference on soybean plants. The genotypes M8230-RR and W711-RR presented resistance characteristics, and PI-227687 was preferred for oviposition. The trichome density positively affects the female oviposition behavior.(AU)

O objetivo deste trabalho foi avaliar o comportamento de oviposição de Helicoverpa armigera confinadas em diferentes densidades de casais e estádios fenológicos de plantas de soja, e a resistência de genótipos de soja na categoria não preferência para oviposição para H. armigera. Para o comportamento de oviposição de H. armigera, foram avaliadas as densidades de um, dois e quatro casais por planta, e os estádios fenológicos vegetativo, de florescimento e reprodutivo de plantas de soja do cultivar BR 16. Para o teste de não preferência para oviposição, oito genótipos de soja foram utilizados e um índice de preferência para oviposição foi calculado. A densidade de tricomas nos folíolos foi quantificada para ser correlacionada com a oviposição de H. armigera. A densidade de um casal e plantas de soja em estádio reprodutivo proporcionaram os melhores resultados quanto à preferência para oviposição de H. armigera em soja. Os genótipos M8230 RR e W711 RR apresentaram características de resistência, enquanto o PI 227687 foi o mais preferido para oviposição. A quantidade de tricomas influenciou positivamente no comportamento de oviposição das fêmeas.(AU)

Oviposition behavior of Helicoverpa armigera in soybean / Comportamento de oviposição de Helicoverpa armigera em soja

The objective of this study was to evaluate the oviposition behavior of Helicoverpa armigera confined in different adult pair density and growth stages of soybean plants, and the resistance of soybean genotypes to H. armigera in the category nonpreference for oviposition. The oviposition behavior of H. armigera was assessed using one, two, and four adult pairs per soybean plant of the cultivar BR-16 at the growth stages: vegetative V8 (eighth unrolled trifoliate leaf), reproductive R2 (full bloom) and reproductive R5.2 (beginning seed). The nonpreference for oviposition was evaluated using eight soybean genotypes and an oviposition preference index was calculated. The number of trichomes in leaflets was quantified for being correlated to H. armigera oviposition. One adult pair and soybean plants stage at pod-set affected and showed the best results oviposition preference on soybean plants. The genotypes M8230-RR and W711-RR presented resistance characteristics, and PI-227687 was preferred for oviposition. The trichome density positively affects the female oviposition behavior.(AU)

O objetivo deste trabalho foi avaliar o comportamento de oviposição de Helicoverpa armigera confinadas em diferentes densidades de casais e estádios fenológicos de plantas de soja, e a resistência de genótipos de soja na categoria não preferência para oviposição para H. armigera. Para o comportamento de oviposição de H. armigera, foram avaliadas as densidades de um, dois e quatro casais por planta, e os estádios fenológicos vegetativo, de florescimento e reprodutivo de plantas de soja do cultivar BR 16. Para o teste de não preferência para oviposição, oito genótipos de soja foram utilizados e um índice de preferência para oviposição foi calculado. A densidade de tricomas nos folíolos foi quantificada para ser correlacionada com a oviposição de H. armigera. A densidade de um casal e plantas de soja em estádio reprodutivo proporcionaram os melhores resultados quanto à preferência para oviposição de H. armigera em soja. Os genótipos M8230 RR e W711 RR apresentaram características de resistência, enquanto o PI 227687 foi o mais preferido para oviposição. A quantidade de tricomas influenciou positivamente no comportamento de oviposição das fêmeas.(AU)

Molecular identification, characterization, and expression analysis of a serine protease inhibitor gene from cotton bollworm, Helicoverpa armigera (Lepidoptera: Noctuidae)

Abstract Serine protease inhibitors (serpins), a superfamily of protease inhibitors, are known to be involved in several physiological processes, such as development, metamorphosis, and innate immunity. In our study, a full-length serpin cDNA, designated Haserpin1, was isolated from the cotton bollworm Helicoverpa armigera. The cDNA sequence of Haserpin1 is 1176 nt long, with an open reading frame encoding 391 amino acids; there is one exon and no intron. The predicted molecular weight of Haserpin1 is 43.53 kDa, with an isoelectric point of 4.98. InterProScan was employed for Haserpin1 functional characterization, which revealed that Haserpin1 contains highly conserved signature motifs, including a reactive center loop (RCL) with a hinge region (E341N350), the serpin signature, (F367F375) and a predicted P1P1 cleavage site (L357S358), which are useful for identifying serpins. Transcripts of Haserpin1 were constitutively expressed in the fat body, suggesting that it is the major site for serpin synthesis. During the developmental stages, a fluctuation in the expression level of Haserpin1 was observed, with low expression detected at the 5th-instar larval stage. In contrast, relatively high expression was detected at the prepupal stage, suggesting that Haserpin1 might play a critical role at the H. armigera wandering stage. Although the detailed function of this serpin (Haserpin1) needs to be elucidated, our study provides a perspective for the functional investigation of serine protease inhibitor genes.

Resumo Sabe-se que os inibidores de serina protease (serpinas), uma superfamília de inibidores de protease, estão envolvidos em vários processos fisiológicos, como desenvolvimento, metamorfose e imunidade inata. Neste estudo, um cDNA de serpina de comprimento total, denominado Haserpin1, foi isolado da lagarta Helicoverpa armigera na cultura de algodão. A sequência de ADNc de Haserpin1 tem 1.176 nt de comprimento, com uma grelha de leitura aberta que codifica 391 aminoácidos; existe um éxon, mas nenhum íntron. O peso molecular previsto de Haserpin1 é de 43,53 kDa, com um ponto isoelétrico de 4,98. O InterProScan foi empregado para a caracterização funcional do Haserpin1, que revelou que o Haserpin1 contém motivos de assinatura altamente conservados, incluindo um loop central reativo (RCL) com uma região de dobradiça (E341-N350), a assinatura da serpina (F367-F375) e um local de clivagem previsto de P1-P1' (L357-S358), que são úteis para identificar serpinas. As transcrições de Haserpin1 foram expressas constitutivamente no corpo gordo, sugerindo que é o principal local para a síntese de serpinas. Durante os estágios de desenvolvimento, observou-se uma flutuação no nível de expressão de Haserpin1, com baixa expressão detectada no estágio larval do 5º ínstar. Por outro lado, detectou-se uma expressão relativamente alta no estágio pré-pupal, sugerindo que o Haserpin1 pode desempenhar um papel crítico no estágio errante de H. armigera. Embora a função detalhada dessa serpina (Haserpin1) precise ser elucidada, este estudo fornece uma perspectiva para a investigação funcional dos genes inibidores da serina protease.

Inseticidas nas sementes e a entomotoxina cry 1 ac protegem a soja contra a lagarta-do-velho-mundo / Insecticides in seeds and entomotoxin cry 1 ac protect soybeans against the old-world caterpillar

A lagarta Helicoverpa armigera ocorre desde a emergência das plantas até a fase reprodutiva da cultura da soja, podendo causar perdas expressivas. Como praga inicial, podem ser encontradas tanto lagartas neonatas como lagartas mais desenvolvidas, estas últimas provenientes da cultura anterior. O uso de cultivares Bt e de inseticidas em tratamento de sementes são alternativas para manejo da praga no início do desenvolvimento da soja, porém existem dúvidas sobre a eficácia destes métodos de controle. Dessa forma, objetivou-se avaliar o efeito protetivo de inseticidas aplicados às sementes e da proteína Cry 1Ac, em relação ao ataque da lagarta H. armigera, como praga inicial em plantas de soja. Os resultados comprovam que, em condições de laboratório, os inseticidas ciantraniliprole (60 g i.a./100 kg de sementes) e clorantraniliprole (62,5 g i.a./100 kg de sementes) protegem a soja em relação às injúrias das lagartas de H. armigera de 3º-4º instares, em cotilédones e folhas unifolioladas e trifolioladas, aos 5 dias após a emergência das plantas. A proteína Cry 1Ac protege as plantas de soja desse tipo de injúria causado tanto por lagartas de 3º-4º e como 5º-6º instares, aos 5 e 10 dias após a emergência.

The Helicoverpa armigera caterpillar occurs from the emergence of the plants to the reproductive stage of the soybean crop, which can cause significant losses. As an initial pest, both neonate and more developed caterpillars can be found, the latter from the previous crop.The use of Bt cultivars and insecticides in seed treatment are options to pest management at the beginning of soybean development, but there are doubts about the efficacy of these control methods. Thus, the objective was to evaluate the protective effect of insecticides applied to seeds and Cry 1Ac protein, in relation to the attack of the H. armigera caterpillar, as an initial pest in soybean plants. Our results confirm that under laboratory conditions the insecticides cyantraniliprole (60 g ai / 100 kg of seeds) and chlorantraniliprole (62.5 g ai / 100 kg of seeds) protect the soybean against the injuries of H. armigera 3º-4º instars, in cotyledons and unifoliolate and trifoliolate leaves, at 5 days after the emergence of the plants. The protein Cry 1Ac protects the soybean plants from this type of injury caused by both 3rd-4th and 5th-6th instars caterpillars, at 5 and 10 days after emergence.

Inseticidas nas sementes e a entomotoxina cry 1 ac protegem a soja contra a lagarta-do-velho-mundo / Insecticides in seeds and entomotoxin cry 1 ac protect soybeans against the old-world caterpillar

A lagarta Helicoverpa armigera ocorre desde a emergência das plantas até a fase reprodutiva da cultura da soja, podendo causar perdas expressivas. Como praga inicial, podem ser encontradas tanto lagartas neonatas como lagartas mais desenvolvidas, estas últimas provenientes da cultura anterior. O uso de cultivares Bt e de inseticidas em tratamento de sementes são alternativas para manejo da praga no início do desenvolvimento da soja, porém existem dúvidas sobre a eficácia destes métodos de controle. Dessa forma, objetivou-se avaliar o efeito protetivo de inseticidas aplicados às sementes e da proteína Cry 1Ac, em relação ao ataque da lagarta H. armigera, como praga inicial em plantas de soja. Os resultados comprovam que, em condições de laboratório, os inseticidas ciantraniliprole (60 g i.a./100 kg de sementes) e clorantraniliprole (62,5 g i.a./100 kg de sementes) protegem a soja em relação às injúrias das lagartas de H. armigera de 3º-4º instares, em cotilédones e folhas unifolioladas e trifolioladas, aos 5 dias após a emergência das plantas. A proteína Cry 1Ac protege as plantas de soja desse tipo de injúria causado tanto por lagartas de 3º-4º e como 5º-6º instares, aos 5 e 10 dias após a emergência.(AU)

The Helicoverpa armigera caterpillar occurs from the emergence of the plants to the reproductive stage of the soybean crop, which can cause significant losses. As an initial pest, both neonate and more developed caterpillars can be found, the latter from the previous crop.The use of Bt cultivars and insecticides in seed treatment are options to pest management at the beginning of soybean development, but there are doubts about the efficacy of these control methods. Thus, the objective was to evaluate the protective effect of insecticides applied to seeds and Cry 1Ac protein, in relation to the attack of the H. armigera caterpillar, as an initial pest in soybean plants. Our results confirm that under laboratory conditions the insecticides cyantraniliprole (60 g ai / 100 kg of seeds) and chlorantraniliprole (62.5 g ai / 100 kg of seeds) protect the soybean against the injuries of H. armigera 3º-4º instars, in cotyledons and unifoliolate and trifoliolate leaves, at 5 days after the emergence of the plants. The protein Cry 1Ac protects the soybean plants from this type of injury caused by both 3rd-4th and 5th-6th instars caterpillars, at 5 and 10 days after emergence.(AU)

Danos da lagarta Helicoverpa armigera (Hübner, 1805) (Lepidoptera: Noctuidae) em plântulas de soja / Damage caused by caterpillar of Helicoverpa armigera (Hübner, 1805) (Lepidoptera: Noctuidae) to soybean seedlings

A soja está sujeita ao ataque da lagarta Helicoverpa armigera durante todo seu ciclo. Quando na fase inicial, pode comprometer o estabelecimento da cultura no campo. Esse estudo teve por objetivo avaliar os danos da lagarta em plântulas de soja, para isso, utilizou-se o delineamento experimental em blocos casualizados com cinco repetições. Os tratamentos foram cinco níveis de infestação: 0, 7, 14, 21 e 28 lagartas m-2. A infestação ocorreu no estádio fenológico cotiledonar (VC) utilizando lagartas de quinto ínstar, e, durante três dias, foram avaliados os danos causados nas hastes, cotilédones e folhas unifolioladas. Já ao final do experimento avaliou-se a altura de plantas, a biomassa e o estande final. Houve danos nas três estruturas vegetativas avaliadas e, em geral, o aumento da população do inseto promoveu aumento no nível de danos, reduzindo o estande, a altura e a biomassa das plântulas de soja. Conclui-se que a lagarta H. armigera causa danos severos às plântulas de soja, o que pode afetar o estabelecimento inicial da cultura.

Soybean plants are susceptible to the attack of Helicoverpa armigera caterpillars throughout their cycle, including during early developmental stages, which can compromise their settling in the field. This study aimed to assess the damage caused by caterpillars to soybean seedlings. A randomized block design with five replicates was used and the treatments consisted of five levels of infestation: 0, 7, 14, 21 and 28 caterpillars/m-2. The infestation occurred in the cotyledon stage (VC), using fifth instar caterpillars. For three days, all damage caused to the stem, cotyledon, and unifoliates was evaluated. By the end of the experiment, seedling height, biomass, and the final stand value were determined. Damage was observed in the three vegetative structures and, in general, increase in insect population promoted higher levels of damage, reducing stand, height, and biomass of seedlings significantly. Thus, H. armigera caterpillars cause severe damage to soybean seedlings, which may affect their early establishment.

Danos da lagarta Helicoverpa armigera (Hübner, 1805) (Lepidoptera: Noctuidae) em plântulas de soja / Damage caused by caterpillar of Helicoverpa armigera (Hübner, 1805) (Lepidoptera: Noctuidae) to soybean seedlings

A soja está sujeita ao ataque da lagarta Helicoverpa armigera durante todo seu ciclo. Quando na fase inicial, pode comprometer o estabelecimento da cultura no campo. Esse estudo teve por objetivo avaliar os danos da lagarta em plântulas de soja, para isso, utilizou-se o delineamento experimental em blocos casualizados com cinco repetições. Os tratamentos foram cinco níveis de infestação: 0, 7, 14, 21 e 28 lagartas m-2. A infestação ocorreu no estádio fenológico cotiledonar (VC) utilizando lagartas de quinto ínstar, e, durante três dias, foram avaliados os danos causados nas hastes, cotilédones e folhas unifolioladas. Já ao final do experimento avaliou-se a altura de plantas, a biomassa e o estande final. Houve danos nas três estruturas vegetativas avaliadas e, em geral, o aumento da população do inseto promoveu aumento no nível de danos, reduzindo o estande, a altura e a biomassa das plântulas de soja. Conclui-se que a lagarta H. armigera causa danos severos às plântulas de soja, o que pode afetar o estabelecimento inicial da cultura.(AU)

Soybean plants are susceptible to the attack of Helicoverpa armigera caterpillars throughout their cycle, including during early developmental stages, which can compromise their settling in the field. This study aimed to assess the damage caused by caterpillars to soybean seedlings. A randomized block design with five replicates was used and the treatments consisted of five levels of infestation: 0, 7, 14, 21 and 28 caterpillars/m-2. The infestation occurred in the cotyledon stage (VC), using fifth instar caterpillars. For three days, all damage caused to the stem, cotyledon, and unifoliates was evaluated. By the end of the experiment, seedling height, biomass, and the final stand value were determined. Damage was observed in the three vegetative structures and, in general, increase in insect population promoted higher levels of damage, reducing stand, height, and biomass of seedlings significantly. Thus, H. armigera caterpillars cause severe damage to soybean seedlings, which may affect their early establishment.(AU)

Impact of Bt sweet corn on lepidopteran pests in Midwestern Brazil

While the cultivation of conventional Bt corn has been widely adopted in Brazil, the production of Bt sweet corn is still incipient. The main lepidopteran pests found attacking conventional and sweet corn in Brazil are Spodoptera frugiperda (J.E. Smith) and Helicoverpa zea (Boddie). Additionally, a new harmful Lepidoptera species has recently appeared in Brazil, Helicoverpa armigera (Hübner). Since Bt sweet corn in Brazil is as yet cultivated on a limited scale there is no scientific information available about the performance of Bt sweet corn against lepidopterans out in the field. Thus, we conducted two field experiments to evaluate the efficacy of Bt sweet corn (event MON89034), alone and in conjunction with insecticides, against major lepidopteran pests found in midwestern Brazil (in the state of Goias). Both experiments followed a completely randomized block design (2 × 2 factorial) with two levels of sweet corn (Bt or conventional) crossed with two levels of insecticide (insecticide or no insecticide). The experimental treatments were replicated six times in each experiment. The results showed a slower advancing of defoliation caused by S. frugiperda in treatments with Bt corn. Likewise, less severe injury was observed on the corn ears (especially on the kernels) of Bt plants. The number of larvae (S. frugiperda and Helicoverpa spp.) sampled was also lower in the treatments with Bt corn. Overall, the application of insecticide did not increase the protection of Bt sweet corn and there was no significant difference in corn ear size and weight, nor in kernel yield, when comparing Bt and insecticide-sprayed plants.

Impact of Bt sweet corn on lepidopteran pests in Midwestern Brazil

While the cultivation of conventional Bt corn has been widely adopted in Brazil, the production of Bt sweet corn is still incipient. The main lepidopteran pests found attacking conventional and sweet corn in Brazil are Spodoptera frugiperda (J.E. Smith) and Helicoverpa zea (Boddie). Additionally, a new harmful Lepidoptera species has recently appeared in Brazil, Helicoverpa armigera (Hübner). Since Bt sweet corn in Brazil is as yet cultivated on a limited scale there is no scientific information available about the performance of Bt sweet corn against lepidopterans out in the field. Thus, we conducted two field experiments to evaluate the efficacy of Bt sweet corn (event MON89034), alone and in conjunction with insecticides, against major lepidopteran pests found in midwestern Brazil (in the state of Goias). Both experiments followed a completely randomized block design (2 × 2 factorial) with two levels of sweet corn (Bt or conventional) crossed with two levels of insecticide (insecticide or no insecticide). The experimental treatments were replicated six times in each experiment. The results showed a slower advancing of defoliation caused by S. frugiperda in treatments with Bt corn. Likewise, less severe injury was observed on the corn ears (especially on the kernels) of Bt plants. The number of larvae (S. frugiperda and Helicoverpa spp.) sampled was also lower in the treatments with Bt corn. Overall, the application of insecticide did not increase the protection of Bt sweet corn and there was no significant difference in corn ear size and weight, nor in kernel yield, when comparing Bt and insecticide-sprayed plants.(AU)

Consumption and use of soybean by the caterpillar Helicoverpa armigera / Consumo e utilização de soja pela lagarta Helicoverpa armigera

A deep insight into the population dynamics of a pest can be achieved by being acquainted with its nutritional ecology, which further assists in understanding the damage potential and decisions to control mainly in diversified production systems such as those in Brazil. The present r research aimed to evaluate the effect of dietary regimens, comprising combinations of acessible organs of soybean plants, at different stages of development, consumption, and utilization of food by the 4th, 5th, and 6thlarvae instar of Helicoverpa armigera (Hübner) (Lep.: Noctuidae). For this purpose, the vegetative and reproductive organs of soybean were brought together in three feeding regimes, followed by making it available to caterpillars. After evaluations, it was found that under laboratory conditions, the development of H. armigera 4th to 6th instar caterpillars was better when they werepurely fed on leaves than on combinations of vegetative and reproductive parts, such as fresh leaves + old leaves + pods at the beginning of grain development, and old leaves + pods at the beginning of grain development +pods with well-developed grain.(AU)

O conhecimento sobre a ecologia nutricional de uma praga pode auxiliar na compreensão da sua dinâmica populacional, na definição do potencial de danos e nas decisões para controle, principalmente, em sistemas de produção diversificados como os existentes no Brasil. O objetivo desse trabalho foi avaliar o efeito de regimes alimentares, constituídos por combinações de órgãos disponíveis nas plantas de soja, em diferentes estádios de desenvolvimento, no consumo e no aproveitamento do alimento pelas lagartas de 4º, 5º e 6º instares de Helicoverpa armigera (Hübner) (Lep.: Noctuidae). Órgãos vegetativos e reprodutivos da soja foram combinados em três regimes alimentares e fornecidos à lagartas. Os resultados demonstram que, em condições de laboratório, na cultura da soja o desenvolvimento de lagartas do 4º ao 6º instar de H. armigera foi melhor quando se alimentaram com folhas do que com folhas novas + folhas velhas + legumes no início do desenvolvimento do grão e folhas velhas + legumes no início do desenvolvimento do grão + legumes com o grão bem desenvolvido.(AU)

Parasitoides associados com Helicoverpa armigera em áreas de refúgio de algodão, no Oeste da Bahia, Brasil

Natural biological control is one of the major causes responsible for reduction of pest population in agricultural ecosystem. However, natural biological control importance is usually minimized by not being estimated. This study reports the occurrence of Campoletis sonorensis (Cameron, 1886) (Hymenoptera: Ichneumonidae), Archytas marmoratus (Townsend, 1915) and Archytas incertus (Macquart, 1851) (Diptera: Tachinidae) associated with Helicoverpa armigera (Hübner, 1809) (Lepidoptera: Noctuidae). The rate of larval parasitism was up to 41% in structured refuge areas of cotton, without chemical control with insecticides. This study strengthens our knowledge relating to parasitoids associated with natural control of H. armigera in the American continent. In addition, it documents the rule that structured refuge areas could play as a source of natural enemies, besides their contribution to production of non-selective populations to Bt technology.(AU)

O controle biológico natural é um dos principais componentes responsáveis pela redução populacional de pragas em agroecossistemas. Entretanto, a importância do controle biológico natural, usualmente, é minimizada devido não ser estimada. Este estudo documenta a ocorrência de Campoletis sonorensis (Cameron, 1886) (Hymenoptera: Ichneumonidae), Archytas marmoratus (Townsend, 1915) e Archytas incertus (Macquart, 1851) (Diptera: Tachinidae) associados a Helicoverpa armigera (Hübner, 1809) (Lepidoptera: Noctuidae). A taxa de parasitismo larval foi superior a 41% em áreas de refúgio estruturado de algodão, sem uso de inseticidas químicos. Este estudo fortalece o conhecimento relacionado com os parasitoides associados ao controle natural de H. armigera no Continente Americano. Adicionalmente, documenta o efeito que áreas de refúgio estruturado podem desempenhar como fonte de inimigos naturais, além da sua contribuição para produzir insetos não expostos à tecnologia Bt.(AU)

Age and density of eggs of Helicoverpa armigera influence on Trichogramma pretiosum parasitism / Influência da idade e densidade de ovos de Helicoverpa armigera no parasitismo deTrichogramma pretiosum

This study evaluated the parasitism of Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae) on eggs of Helicoverpa armigera Hübner (Lepidoptera: Noctuidae) at different ages and densities. The rates of parasitism and emergence, the number of parasitoids emerged per egg and sex ratio of offspring were evaluated in both experiments. Eggs of H. armigera up to 36 hours provided greater parasitism and emergence of adults compared to eggs up to 60 hours old. The number of parasitoids, which emerged per host egg, was greater than one and the sex ratio remained around 80% of females, regardless of the egg development stage. Females of T. pretiosum responded with superior rates of parasitism, emergence and number of parasitoids per egg at the densities of 20 and 25 eggs of H. armigera. These results indicate that T. pretiosum parasite with superior performance in eggs of up to 36h of age and densities of 20 eggs per female day-1 in laboratory conditions. These results will help to establish the intervals between releases of parasitoids, aiming to control this pest, when adjusted with knowledge of the survival of the parasitoids in the field and in pest infestation.(AU)

Este trabalho avaliou o parasitismo de Trichogramma pretiosum Riley (Hymenoptera:Trichogrammatidae) em ovos de Helicoverpa armigera Hübner (Lepidoptera: Noctuidae) em diferentesidades e densidades. As taxas de parasitismo e emergência, número de parasitoides emergidos por ovo erazão sexual dos descendentes foram avaliados em ambos os experimentos. Ovos de H. armigera de até 36horas proporcionaram maior parasitismo e emergência dos adultos em comparação com ovos com até 60horas de idade. O número de parasitoides, que emergiram por ovo hospedeiro, foi superior a 1 e a razãosexual permaneceu em torno de 80% de fêmeas, independentemente do estágio de desenvolvimento doovo. Fêmeas de T. pretiosum responderam com taxas superiores de parasitismo, emergência e número deparasitoides por ovo nas densidades de 20 e 25 ovos de H. armigera. Estes resultados indicam que T.pretiosum parasita com desempenho superior em ovos de até 36h de idade e densidades de 20 ovos porfêmea dia-1 em condições laboratoriais. Estes resultados ajudarão a estabelecer os intervalos entre asliberações de parasitoides, visando o controle desta praga, quando ajustado com o conhecimento dasobrevivência dos parasitoides no campo e na infestação de pragas.(AU)

Molecular identification, characterization, and expression analysis of a serine protease inhibitor gene from cotton bollworm, Helicoverpa armigera (Lepidoptera: Noctuidae)

Abstract Serine protease inhibitors (serpins), a superfamily of protease inhibitors, are known to be involved in several physiological processes, such as development, metamorphosis, and innate immunity. In our study, a full-length serpin cDNA, designated Haserpin1, was isolated from the cotton bollworm Helicoverpa armigera. The cDNA sequence of Haserpin1 is 1176 nt long, with an open reading frame encoding 391 amino acids; there is one exon and no intron. The predicted molecular weight of Haserpin1 is 43.53 kDa, with an isoelectric point of 4.98. InterProScan was employed for Haserpin1 functional characterization, which revealed that Haserpin1 contains highly conserved signature motifs, including a reactive center loop (RCL) with a hinge region (E341N350), the serpin signature, (F367F375) and a predicted P1P1 cleavage site (L357S358), which are useful for identifying serpins. Transcripts of Haserpin1 were constitutively expressed in the fat body, suggesting that it is the major site for serpin synthesis. During the developmental stages, a fluctuation in the expression level of Haserpin1 was observed, with low expression detected at the 5th-instar larval stage. In contrast, relatively high expression was detected at the prepupal stage, suggesting that Haserpin1 might play a critical role at the H. armigera wandering stage. Although the detailed function of this serpin (Haserpin1) needs to be elucidated, our study provides a perspective for the functional investigation of serine protease inhibitor genes.

Resumo Sabe-se que os inibidores de serina protease (serpinas), uma superfamília de inibidores de protease, estão envolvidos em vários processos fisiológicos, como desenvolvimento, metamorfose e imunidade inata. Neste estudo, um cDNA de serpina de comprimento total, denominado Haserpin1, foi isolado da lagarta Helicoverpa armigera na cultura de algodão. A sequência de ADNc de Haserpin1 tem 1.176 nt de comprimento, com uma grelha de leitura aberta que codifica 391 aminoácidos; existe um éxon, mas nenhum íntron. O peso molecular previsto de Haserpin1 é de 43,53 kDa, com um ponto isoelétrico de 4,98. O InterProScan foi empregado para a caracterização funcional do Haserpin1, que revelou que o Haserpin1 contém motivos de assinatura altamente conservados, incluindo um loop central reativo (RCL) com uma região de dobradiça (E341-N350), a assinatura da serpina (F367-F375) e um local de clivagem previsto de P1-P1' (L357-S358), que são úteis para identificar serpinas. As transcrições de Haserpin1 foram expressas constitutivamente no corpo gordo, sugerindo que é o principal local para a síntese de serpinas. Durante os estágios de desenvolvimento, observou-se uma flutuação no nível de expressão de Haserpin1, com baixa expressão detectada no estágio larval do 5º ínstar. Por outro lado, detectou-se uma expressão relativamente alta no estágio pré-pupal, sugerindo que o Haserpin1 pode desempenhar um papel crítico no estágio errante de H. armigera. Embora a função detalhada dessa serpina (Haserpin1) precise ser elucidada, este estudo fornece uma perspectiva para a investigação funcional dos genes inibidores da serina protease.

Biological parameters of three Trichogramma pretiosum strains (Riley, 1879) (Hymenoptera: Trichogrammatidae) on eggs Helicoverpa armigera (Hübner, 1805) (Lepidoptera: Noctuidae) / Parâmetros biológicos de três linhagens de Trichogramma pretiosum (Riley, 1879)(Hymenoptera: Trichogrammatidae) sobre ovos de Helicoverpa armigera (Hübner, 1805) (Lepidoptera: Noctuidae)

This project has an objective to study the biological parameters of Trichogramma pretiosum on eggs of H. armigera. The three strains of T. pretiosum were evaluated: TM, TMC and TLEM, from different places. The experimental establishing was completely randomizing with twenty repeats per treatment, being used by a female parasitoid by repetition and later on they were offered 20 H. armigera eggs. The experiment was kept on BOD cameras to 25 ± 2 C, UR 60 ± 10% and photo phase of 14 hours. Evaluating the following biological parameters: parasitism percentage, emergency percentage, number of adults emerged per egg, sex ratio, viability, and longevity and cycle duration. The parasitism percentage, viability and number of individuals per egg were higher for TM and TMC. The TMC strain presented a larger sex ratio proportion, not being different statistically from the TM stream. The longevity of the strain TM was different regarding the others. There was no variation regarding the cycle duration. Therefore, according with the evaluated biologic parameters, it is concluded that Trichogramma pretiosum strain TM obtained a better egg development of H. armigera on laboratory conditions.(AU)

Este trabalho teve como objetivo estudar os parâmetros biológicos de Trichogramma pretiosum em ovos de H. armigera. As três linhagens de T. pretiosum avaliadas foram: TM, TMC e TLEM, oriundas de diferentes localidades. O delineamento experimental foi inteiramente casualizado com vinte repetições por tratamento, sendo utilizada uma fêmea do parasitoide por repetição e posteriormente foram oferecidos 20 ovos de H. armigera. O experimento foi mantido em câmaras BOD a 25 ± 2° C, UR 60 ± 10% e fotofase de 14 horas. Avaliou-se os seguintes parâmetros biológicos: porcentagem de parasitismo, porcentagem de emergência, número de adultos emergidos por ovo, razão sexual, viabilidade, longevidade e duração do ciclo. A porcentagem de parasitismo e viabilidade e número de indivíduos por ovo foram superiores para as linhagens TM e TMC. A linhagem TMC apresentou a maior proporção para razão sexual, não diferindo estatisticamente da linhagem TM. A longevidade da linhagem TM se destacou em relação às demais. Não houve variação com relação a duração do ciclo. Assim de acordo com os parâmetros biológicos avaliados, conclui-se que Trichogramma pretiosum linhagem TM obteve o melhor desenvolvimento nos ovos de H. armigera em condições de laboratório.(AU)