Interspecific associations between cycloneda sanguinea and two aphid species (Aphis gossypii and Hyadaphis foeniculi) in Sole-crop and fennel-cotton intercropping systems.

Aphids cause significant damage to crop plants. Studies regarding predator-prey relationships in fennel (Foeniculum vulgare Mill.) and cotton (Gossypium hirsutum L.) crops are important for understanding essential ecological interactions in the context of intercropping and for establishing pest management programs for aphids. This study evaluated the association among Hyadaphis foeniculi (Passerini) (Hemiptera: Aphididae), Aphis gossypii Glover (Hemiptera: Aphididae) and Cycloneda sanguinea (L.) (Coleoptera: Coccinellidae) in cotton with coloured fibres, fennel and cotton intercropped with fennel. Association analysis was used to investigate whether the presence or absence of prey and predator species can indicate possible interactions between aphids and ladybugs. Significant associations among both apterous and alate H. foeniculi and C. sanguinea were observed in both the fennel and fennel-cotton intercropping systems. The similarity analysis showed that the presence of aphids and ladybugs in the same system is significantly dependent on the type of crop. A substantial amount of evidence indicates that the presence of the ladybug C. sanguinea, is associated with apterous or alate A. gossypii and H. foeniculi in fennel-cotton intercropping system. We recommend that future research vising integrated aphid management taking into account these associations for take decisions

Agronomic and biochemical evaluation of cassava clones with roots that have pink pulp.

RESUMO: Os programas de melhoramento genético de mandioca de mesa estão focados no desenvolvimento de variedades biofortificadas que aliem aos caracteres agronômicos a presença de carotenoides nas raízes de reserva. Neste trabalho, objetivou-se avaliar características agronômicas e bioquímicas em clones de mandioca de mesa com polpa rosada. Os nove genótipos foram avaliados por duas safras em delineamento experimental de blocos casualizados com três repetições. Dentre os clones avaliados se destacaram: i) para altura da primeira ramificação (390/08, 345/08 e a testemunha IAC 576-70); ii) para altura da planta (390/08, 345/08 e 378/08); iii) para peso da parte aérea sem a cepa (390/08, 406/08, 378/08 e 341/08); iv) para porcentagem de amido nas raízes (378/08, 413/08, 390/08 e a testemunha IAC 576-70); v) para produtividade de raízes (IAC 576-70 e 341/08, 390/08, 406/08 e 387/08). Na safra 2011/2012, todos os clones cozinharam em até 30 minutos, indicando que todos apresentam boas qualidades culinárias. Com relação ao teor de carotenoides totais nas raízes, os clones que se destacaram foram 406/08 e 341/08. Todos os clones avaliados apresentaram teores de HCN nas raízes de reserva de mandioca, inferiores a 100 mg kg-1. Os clones 341/08 e 406/08 apresentam potencial agronômico e bioquímico para cultivo direto pelos produtores na região do Cerrado do Brasil Central e/ou para a utilização como genitores em programas de melhoramento genético de mandioca de mesa. ABSTRACT: Sweet cassava breeding programs are focused on the development of bio fortified cultivars that combine significant amounts of carotenoids in their reserve roots with desirable agronomic. The objective of this research was to evaluate agronomic and biochemical traits in sweet cassava clones with roots that have pink pulp. The nine genotypes were evaluated in two seasons in a randomized block design with three replications. Among the evaluated clones, the following stood out: i) for the height of the first branch (390/08, 345/08 and the control IAC 576-70); ii) for plant height (390/08, 345/08 e 378/08); iii) for shoot weight without original steam cutting (390/08, 406/08, 378/08 e 341/08); iv) for the percentage of starch in roots (378/08, 413/08, 390/08 and the control IAC 576-70); and v) for the root yield (the control IAC 576-70 and 341/08, 390/08, 406/08 e 387/08). In the 2011/2012 season, all clones cooked within 30 minutes, indicating that they all have good culinary qualities. Regarding the total carotenoid content in the roots, the clones that stood out were 406/08 and 341/08. All clones evaluated had HCN content below 100 mg kg-1. Clones 341/08 and 406/08 have agronomic and biochemical potential for direct cultivation by producers in the Cerrado region of Central Brazil and / or for use as stock in sweet cassava breeding programs.Título em português: Avaliação agronômica e bioquímica de clones de mandioca com polpa rosada

Larval dispersal of Spodoptera frugiperda strains on Bt Cotton: a model for understanding resistance evolution and consequences for its management.

High dispersal of Lepidoptera larvae between non-Bt and Bt cotton plants can favour the evolution of insect resistance; however, information on host acceptance of neonates in tropical transgenic crops is scarce. Therefore, the purposes of this study were as follows: (i) to investigate the feeding behaviour of susceptible and Cry1F-resistant strains of Spodoptera frugiperda (J.E. Smith) on Bt and non-Bt cotton (Gossypium hirsutum L.) varieties and (ii) to understand the possible effects of cotton field contamination on the dispersal and infestation capacity of S. frugiperda larvae by using an individualbased model. The main results of this paper are as follows: (1) the highest post-feeding larval dispersal of the Cry1F-resistant strain occurred at an exposure time of 18?24 h; (2) via video tracking assays, we found that the least distance moved was by larvae resistant to Cry1F on non-Bt cotton; and (3) the model indicated differences in mobility capacity between Bt and non-Bt cotton. We conclude that resistant neonates exhibit sedentary behaviour. Our report represents the first findings concerning the fitness cost of larval behaviour traits of S. frugiperda associated with Cry1F resistance in Brazilian populations.Publicado online em 23 de novembro de 2017

Population dynamics of Aphis gossypii Glover and Aphis craccivora Koch (Hemiptera: Heteroptera: Aphididae) in sole and intercropping systems of cotton and cowpea.

Population dynamics of aphids have been studied in sole and intercropping systems. These studies have required the use of more precise analytical tools in order to better understand patterns in quantitative data. Mathematical models are among the most important tools to explain the dynamics of insect populations. This study investigated the population dynamics of aphids Aphis gossypii and Aphis craccivora over time, using mathematical models composed of a set of differential equations as a helpful analytical tool to understand the population dynamics of aphids in arrangements of cotton and cowpea. The treatments were sole cotton, sole cowpea, and three arrangements of cotton intercropped with cowpea (t1, t2 and t3). The plants were infested with two aphid species and were evaluated at 7, 14, 28, 35, 42, and 49 days after the infestations. Mathematical models were used to fit the population dynamics of two aphid species. There were good fits for aphid dynamics by mathematical model over time. The highest population peak of both species A. gossypii and A. craccivora was found in the sole crops, and the lowest population peak was found in crop system t2. These results are important for integrated management programs of aphids in cotton and cowpea

Modelo bioeconômico para avaliações ex-ante de investimentos e planejamento forrageiro em sistemas tradicionais de produção de bovinos de corte no cerrado.

A baixa rentabilidade da produção de bovinos de corte em pastagens plantadas com inadequado manejo e a falta de planejamento quanto a investimentos, capital de giro e manejo de forragens, envolve questões cruciais do negócio de propriedades rurais com tal atividade no bioma Cerrado. Para tratar tais questões construiu-se uma modelo matemático de otimização visando maximizar a receita líquida no final do período de planeamento de 8 anos com fluxo de caixa mensal e uma alocação otima de recursos. O modelo conceitualizado, formulado, testado e avaliado, visou a obtenção de uma ferramenta de planejamento forrageiro e análise de investimentos em renovação de pastagens e compra de animais. O modelo representa o comportamento dinâmico de processos bioeconomicos de fazendas de gado de corte localizadas em fronteiras no Cerrado, com opções para criação e engorda. A propriedade projetada, foi avaliada em 2 milhões de reais. Capital de giro inicial foi de R$300.000,00, e três políticas de crédito foram consideradas. A fazenda tem 800 hectares, dos quais 600 são ocupados com Brachiaria brizantha. No modelo, três categorias de pastagens são consideradas, e os animais são divididos em classes, a cada trimestre. Várias estratégias de gestão do rebanho e de investimentos são consideradas. A dinâmica do rebanho depende da disponibilidade de capital, o tempo de pastejo e as taxas de mortalidade de cada classe de animal. Usando macros do Excel, arquivos em formato MPS são gerados para diferentes "solvers". Assim, a ferramenta foi construída e implementada para subsidiar o planejamento de fazendas de bovinos de corte. Um plano bioeconômico foi projetado com uma receita líquida de R$ 253,528.55 no final de oito anos e uma taxa interna de retorno anual de 2,3%