Susceptibility of corn to stink bug (\u3ci\u3eDichelops melacanthus\u3c/i\u3e) and its management through seed treatment

We determined the susceptibility of vegetative corn stages to Dichelops melacanthus damage, and how seed treatment can reduce damage and yield loss. Two field trials were carried out. In the first, corn plants were artificially infested with D. melacanthus male/female pairs at rate of 0.5 pair per plant at different vegetative stages and infestation periods lasting 7-28 days (V1-V3, V1-V5, V1-V7, V1-V9, V3-V5, V3-V7, V3-V9, V5-V7, V5-V9, and V7-V9), plus a control without infestation. In the second, corn plants were artificially infested at a rate of one male/female pair per plant at different vegetative stages and infestation periods (V1-V3, V1-V5, V1-V7, V3-V5, V3-V7 and V5-V7) and treated with two pesticide seed coatings: (i) fungicide [carbendazim + thiram (150 g i.a. per L and 350 g i.a. per L)] + insecticide [clothianidin (600 g i.a. per L)] or (ii) only fungicide (carbendazim + thiram), plus three controls without infestation and with only fungicide-treatment (V1-V7, V3-V7 and V5-V7). In both trials, plants were caged during the entire period in order to hold stink bugs in contact with plants and to avoid injury from other arthropods. The most stink bug susceptible corn growth periods were from V1-V5 and from V1-V7. Seed treatment with clothianidin at the rate of 3.5 mL per Kg during the most susceptible infestation periods increased yield gain of 37.8 to 61%. Treatment with clothianidin during V1-V5 and V1-V7 caused 40% to 50% D. melacanthus adult mortality, respectively

Subsidies for management of Leptoglossus zonatus (Dallas) (Hemiptera : Coreidae) as a field pest in corn seed production

Tese (doutorado)—Universidade de Brasília, Faculdade de Agronomia e Medicina Veterinária, Programa de Pós-Graduação em Agronomia, 2017.O percevejo Leptoglossus zonatus (Dallas) (Hemiptera: Coreidae) apesar de ser considerado praga secundária do milho grão, pode alcançar o status de praga chave no milho semente. Este trabalho objetivou estudar os fatores relativos à biologia de L. zonatus e as perdas que ele ocasiona, bem como selecionar inseticidas eficientes para o seu controle em milho semente e quais as densidades desta praga que requerem a adoção de medidas para o seu controle. Os estudos relativos à biologia do inseto foram iniciados a partir de posturas com no máximo dois dias de idade. Os ensaios para determinação do período suscetível do milho destinado à produção de sementes foram conduzidos em campo e em casa de vegetação com parcelas contendo quatro plantas envoltas em gaiolas de 0,6 x 0,6 x 2,4 m. Cada parcela foi infestada com 10 casais de L. zonatus que foram mantidos em contato com as plantas por 0-20, 0-40, 0-60, 21-40, 21-60, 41-60 dias e por 0-10, 11-20, 21-30, 31-40 e 41-50 dias, além do tratamento testemunha sem infestação. Ao final de 60 dias, as espigas foram colhidas e as sementes obtidas foram classificadas por amostragem visual, em sementes murchas, com dano no embrião, com dano no endosperma e o total de sementes danificadas. Para a quantificação das perdas que o inseto causa a campo foram avaliadas espigas provenientes de quatro lavouras dos cultivos de primeira e segunda safra, amostrando-se 50 espigas de cada lavoura. As espigas foram classificadas, por amostragem visual, nas mesmas categorias descritas anteriormente. Essas categorias, acrescida de sementes provenientes de campo sem infestação (testemunha), foram empregadas ainda em testes para avaliação da qualidade da semente. Os dados obtidos no ensaio para estabelecimento do período suscetível foram usados para estimativa da variável b da fórmula de nível de dano econômico (NDE). Adicionalmente, foi determinada a CL50 dos inseticidas em ensaios de laboratório e testada a CL50 dobrada em ensaios de campo através da exposição da planta, do inseto e da planta + inseto. Os inseticidas que apresentaram eficiência maior que 75% (λ-cialotrina + tiametoxam, permetrina e metomil) foram empregados no cálculo do NDE nas modalidades de aplicação previstas na bula e para genótipos de baixo, médio e alto potencial genético. O nível de controle foi estabelecido como sendo 20% abaixo do NDE. O percevejo L. zonatus passa por cinco instares, com duração média de 7,0 dias. O maior período de suscetibilidade do milho a L. zonatus, avaliado através dos ensaios com e sem sobreposição de dano, coincide com as fases iniciais de desenvolvimento dos grãos (embonecamento e grão bolha d’água). Houve correlação entre os resultados obtidos através da análise visual e dos testes para avaliação da qualidade fisiológica da semente, com a maior qualidade ocorrendo nas sementes sem dano, e a pior qualidade ocorrendo nas sementes danificadas (murchas, com dano no embrião ou endosperma). Não foram verificadas diferenças significativas entre as porcentagens das diferentes categorias de sementes danificadas por percevejos avaliadas visualmente na primeira ou segunda safra. Entretanto, os valores encontrados, em ambas as safras para porcentagem total de sementes danificadas por percevejos ficaram acima dos níveis exigidos em termos de qualidade da semente (85% de germinação ou 97% de sementes sem apresentar injúria de insetos). O NDE variou de três a oito insetos adultos por 1.000 plantas (0,003 a 0,008 insetos adultos por espiga) e o NC variou de dois a seis adultos por 1.000 plantas (0,002 a 0,006 adultos por espiga). A tomada de decisão é mais frequente quando se emprega a pulverização terrestre em comparação à pulverização aérea e linhagens de médio e alto potencial genético em comparação as de baixo potencial genético.The western leaffooted bug, Leptoglossus zonatus (Dallas) (Hemiptera: Coreidae), despite being considered a secondary pest of corn grains, can reach the status of a primary pest in seed corn. This work sought to study the factors related to the biology of L. zonatus and the losses that it causes, as well as to select efficient insecticides for its control in seed corn and the pest densities that require the adoption control measures. Studies on the biology of the insect utilized egg masses with a maximum of two days of age. The tests to determine the susceptible period of corn for seed production were conducted in the field and in the greenhouse with plots containing four plants surrounded by cages measuring 0.6 x 0.6 x 2.4 m. Each plot was infested with 10 couples of L. zonatus that were maintained in contact with the plants for 0-20, 0-40, 0- 60, 21-40, 21-60, 41-60 days and for 0-10, 11-20, 21-30, 31-40 and 41-50 days, in addition to the control treatment without infestation. At the end of 60 days, the corn ears were harvested and the obtained seeds were classified by visual sampling into categories of wilted seeds, with damage to the embryo, with damage to the endosperm and completely damaged seeds. For the quantification of losses caused by the insect in the field the ears from four fields of the first and second seasons were evaluated, sampling 50 ears of each field. The ears were classified by visual sampling in the same categories as described above. These categories, plus seed from the field without infestation (control), were further used in tests to evaluate the quality of the seed. The data obtained in the test for establishment of the susceptible period were used to estimate the variable b of the economic injury level formula (EIL). In addition, the LC50 of the insecticides was determined in laboratory tests and the LC50 in field trials was tested by exposure of the plant, insect and plant + insect. The insecticides that showed efficacy greater than 75% (λ-cyhalothrin + thiamethoxam, permethrin and methomyl) were used in calculation of the EIL for the application modalities included on the package label and for genotypes of low, medium and high genetic potential. The control level was established as being 20% below the EIL. The western leaffooted bug L. zonatus goes through five instars, with an average duration of 7.0 days. The highest susceptibility period of corn to L. zonatus, evaluated via the assays with and without damage overlapping, coincides with the initial development stages of the grains (silking and blister). There was a correlation between the results obtained through the visual analysis and the tests to evaluate the physiological quality of the seed, with the highest quality occurring in the seeds without damage, and the worst quality occurring in damaged seeds (wilt, damage to the embryo or endosperm). There were no significant differences between the percentages of the different categories of seeds damaged by the western leaffooted bug evaluated visually in the first or second season. However, the values found in both crops for total percentage of seeds damaged by the western leaffooted bugs were above the levels required in terms of seed quality (85% germination or 97% seed without presenting insect injury). The EIL ranged from three to eight adult insects per 1,000 plants (0.003 to 0.008 adult insects per ear) and the ET (Economic Threshold) ranged from two to six adults per 1,000 plants (0.002 to 0.006 adults per ear). Decision making is more frequent when terrestrial spraying is used compared to aerial spraying, and medium and high genetic lineages compared to those with low genetic potential

La correspondencia de Valencia : diario de noticias : eco imparcial de la opinión y de la prensa: Año XLII Número 17710 - 1919 Febrero 22

Copia digital. Madrid : Ministerio de Cultura. Subdirección General de Coordinación Bibliotecaria, 200

Susceptibility of corn to stink bug (\u3ci\u3eDichelops melacanthus\u3c/i\u3e) and its management through seed treatment

We determined the susceptibility of vegetative corn stages to Dichelops melacanthus damage, and how seed treatment can reduce damage and yield loss. Two field trials were carried out. In the first, corn plants were artificially infested with D. melacanthus male/female pairs at rate of 0.5 pair per plant at different vegetative stages and infestation periods lasting 7-28 days (V1-V3, V1-V5, V1-V7, V1-V9, V3-V5, V3-V7, V3-V9, V5-V7, V5-V9, and V7-V9), plus a control without infestation. In the second, corn plants were artificially infested at a rate of one male/female pair per plant at different vegetative stages and infestation periods (V1-V3, V1-V5, V1-V7, V3-V5, V3-V7 and V5-V7) and treated with two pesticide seed coatings: (i) fungicide [carbendazim + thiram (150 g i.a. per L and 350 g i.a. per L)] + insecticide [clothianidin (600 g i.a. per L)] or (ii) only fungicide (carbendazim + thiram), plus three controls without infestation and with only fungicide-treatment (V1-V7, V3-V7 and V5-V7). In both trials, plants were caged during the entire period in order to hold stink bugs in contact with plants and to avoid injury from other arthropods. The most stink bug susceptible corn growth periods were from V1-V5 and from V1-V7. Seed treatment with clothianidin at the rate of 3.5 mL per Kg during the most susceptible infestation periods increased yield gain of 37.8 to 61%. Treatment with clothianidin during V1-V5 and V1-V7 caused 40% to 50% D. melacanthus adult mortality, respectively

COMPORTAMENTO DE OVIPOSIÇÃO DE Helicoverpa zea (BODDIE, 1850) (LEPIDOPTERA: NOCTUIDAE) EM MILHO SEMENTE E SIMULAÇÃO DE CONTROLE

Helicoverpa zea (Boddie, 1850) (Lepidoptera: Noctuidae) is a major insect pest in corn seed. In orderto increase efficiency of its control, this research objectified to study the oviposition behavior in the field, aiming tosubsidize the spray of insecticides. The study was conducted in areas of corn seed production in the municipality ofSanto Augusto, Rio Grande do Sul, Brazil. After starting style-stigma emission, monitoring of the H. zea infestationwas performed by verifying the presence of eggs in these structures. Daily, 20 corn ears were sampled at 10 randomizedpoints of two areas. From the oviposition data curve, the most appropriate time to carry out chemical control of H.zea was determined, by simulating spray intervals of 4, 5, 6 and 7 days. In both study areas, at 14 days from the startof emission of styles-stigma, 70% of the corn ears were infested with eggs of H. zea. For the chemical control of H.zea, the best time for the first spray is 4 days after starting emission of styles-stigma, and reapplication after 4 days.In this simulation, 44.5, 48.5 and 7.0% of the corn ears will receive two, one or no spray of insecticide, respectively

Biologia, Seleção e Avaliação de Linhagens de Trichogramma spp. para o Controle da Lagarta-da-Espiga em Milho Semente

O objetivo deste trabalho foi estudar a biologia de Trichogramma spp. em ovos de Anagasta kuehniella (Zeller) e Helicoverpa zea (Boddie), selecionar e avaliar uma linhagem do parasitóide para o controle de H. zea em milho semente. Para a biologia foram ofertados ovos do hospedeiro alternativo e natural à Trichogramma pretiosum Riley e Trichogramma atopovirilia Oatman & Platner. Para verificação do potencial de parasitismo foram ofertados 40 ovos de cada hospedeiro por fêmea do parasitóide. No estudo em casa de vegetação para determinação do número ideal de parasitóides ofertou-se 60 ovos de H. zea e variou-se o número de parasitóides. No campo avaliou-se o controle de H. zea mediante liberação de 100; 200; 400 e 800 mil parasitóides por hectare, controle químico e tratamento sem liberação e sem inseticida. No estudo de biologia a duração média do período de ovo - adulto e a razão sexual dos parasitóides foram semelhantes nos dois hospedeiros. O número médio de parasitóides gerados por ovo de A. kuehniella e H. zea variou de 1,10 a 1,20 e 2,22 a 2,67, respectivamente. A capacidade de parasitismo de T. pretiosum foi de 93,70 e 82,75 ovos por fêmea de A. kuehniellae H. zea, respectivamente. Em casa de vegetação o percentual de parasitismo de T. pretiosum estabilizou quando liberados 5,33 parasitóides por ovo de H. zea. A campo, a maior eficiência de controle ocorreu quando foram liberados 100 mil parasitóides por hectare em quatro épocas, a partir do início da infestação de H. zea. Biology, Selection and Evaluation of Strains of Trichogramma spp. for Control of Corn Earworm in Corn Seeds Abstract. The objective was to study the biology of Trichogramma spp. in eggs of Anagasta kuehniella (Zeller) and Helicoverpa zea (Boddie), select and evaluate a strain of the parasitoid to control of H. zea in corn seed. In the biology study was offered eggs of the natural and alternative host to Trichogramma pretiosum Riley and Trichogramma atopovirilia Oatman & Platner. To verify the potential of parasitism were offered 40 eggs of both hosts per parasitoid. In greenhouse, a study was conducted to determine the optimal number of parasitoids to be released by egg of H. zea. It was established 60 eggs of H. zea and varied the number of parasitoids. In the field were evaluated of parasitism with the release of 100, 200, 400 and 800 thousand parasitoids per hectare, chemical control and treatment without released and insecticide. In the biology study, the duration of egg – adult period and sex ratio of parasitoids were similar in the two hosts. The number of parasitoids generated per egg of A. kuehniella and H. zea varied from 1.10 to 1.20 and from 2.22 to 2.67, respectively. The capacity of parasitism of T. pretiosum female was 93.70 and 82.75 eggs of A. kuehniella and H. zea, respectively. In greenhouse, the percentage of parasitism of T. pretiosum had established when released 5.33 parasitoids per egg of H. zea. In field, the greater efficiency of control occurred where released 100 thousand parasitoids per hectare in four seasons from the observation of early infestation of H. zea

Economic injury levels and economic thresholds for Leptoglossus zonatus (Dallas) (Hemiptera: Coreidae) infesting seed maize

Não consta volume, número de série e número de páginas.Although Leptoglossus zonatus is considered a secondary pest of maize grown for grain, when grown for seed, this pest can cause significant economic damage. There are no records of management recommendations for this pest. The objectives of this work were to quantify losses caused by L. zonatus to different genotypes used for seed maize production and to estimate the acute toxicity of selected insecticides to L. zonatus using different application technologies. The ultimate goal was to calculate economic injury levels (EILs) and develop economic thresholds (ETs) for L. zonatus infesting seed maize. EILs and ETs varied, respectively, from 3 to 8 and from 2 to 6 adults per 1000 plants, depending on the genotype, insecticide and application technology. Effective control was obtained by using aerial or ground application of λ-cyhalothrin (10.6%) + thiametoxan (14.1%) or permethrin (38.4%) at the rates of 1.48 mL ha-1 and 27.10 mL ha-1, respectively, or ground application of methomyl (21.5%) at the rate of 244.06 mL ha-1. Maize grown for seed is susceptible to L. zonatus damage during reproductive stages, and the pest densities requiring management vary with genotype, insecticide, and application technology. These results contribute significantly to integrated pest management (IPM) for seed maize

Population genomics of fall armyworm by genotyping-by-sequencing: Implications for pest management.

The fall armyworm (FAW), Spodoptera frugiperda, is a significant pest of many crops in the world and it is native to the Americas, where the species has shown the ability to rapidly evolve resistance to insecticides and transgenic plants. Despite the importance of this species, there is a gap in the knowledge regarding the genetic structure of FAW in South America. Here, we examined the genetic diversity of FAW populations across a wide agricultural area of Brazil and Argentina using a Genotyping-by-Sequencing (GBS) approach. We also characterized samples by their host strain based on mitochondrial and Z-linked genetic markers. The GBS methodology enabled us to discover 3309 SNPs, including neutral and outlier markers. Data showed significant genetic structure between Brazil and Argentina populations, and also among the Argentinian ecoregions. Populations inside Brazil showed little genetic differentiation indicating high gene flow among locations and confirming that structure is related to the presence of corn and rice strains. Outlier analysis indicated 456 loci putatively under selection, including genes possibly related to resistance evolution. This study provides clarification of the population genetic structure of FAW in South America and highlights the importance of genomic research to understand the risks of spread of resistance genes

Efeito de dietas artificiais para a alimentação de adultos de Bonagota cranaodes (Meyrick) (Lepidoptera: Tortricidae), em laboratório Effect of artificial diets for the adults of Bonagota cranaodes feeding (Meyrick) (Lepidoptera: Tortricidae), in laboratory

Adultos de Bonagota cranaodes (Meyrick) (Lepidoptera: Tortricidae) submetidos a tratamentos com água, solução de mel a 10%, solução de mel a 10% + 25% de cerveja e sem alimento foram mantidos em gaiolas de PVC transparente para avaliar a fecundidade, longevidade e viabilidade de ovos em laboratório a 25&plusmn;1&deg;C e 70&plusmn;10% de UR. Maior longevidade de fêmeas e machos e número de ovos/fêmea foram obtidos nos substratos compostos de mel a 10% (17,75 dias, 17,35 dias e 14,07 ovos/postura) e mel a 10% + 25% de cerveja (18,25 dias, 18,20 dias e 12,71 ovos/postura). A viabilidade dos ovos e a duração do período embrionário foram semelhantes em todos os tratamentos. O substrato alimentar mel a 10% + 25% de cerveja, apresentou efeitos semelhantes ao substrato composto de apenas mel a 10% sobre a longevidade, fertilidade e viabilidade dos ovos. Entretanto, devido ao menor custo, a dieta a base de mel apresenta melhor potencial de utilização para manutenção da criação do inseto em laboratório.<br>Adults of Bonagota cranaodes (Meyrick) (Lepidoptera: Tortricidae) were maintained in cages of transparent PVC without food, with water, and fed with honey solution at 10% and with honey solution at 10% + 25% of beer only with water and without feeding to evaluate their fecundity, longevity and viability of eggs in growth to (25&plusmn;1&deg;C and 70&plusmn;10% of RU). The longevity of females and males was longer and number of eggs/female were obtained in the mean substratum composed of honey at 10% (17,75 days, 17,35 days and 14,07 eggs/posture) and honey at 10% + 25% of beer (18,25 days, 18,20 days and 12,71 eggs/posture). The viability of the eggs and the duration of the embryonic period was similar in all the treatments. The mean with honey at 10% + 25% of beer, presented effects similar to the mean composed with honey at 10% regarding to the longevity, fertility and viability of eggs of B. cranaodes. However, due to the lower cost, the diet based only in honey represents the best choice in laboratory for maintenance rearing of this insect

Detection of outlier SNPs under positive selection using Pcadapt, FstHet, and FLK.

The Venn diagrams shows the number of outlier SNPs associated to (A) FAW host strains and (B) populations. (TIF)</p