Impactos do controle de plantas daninhas e da aplicação de herbicidas em inimigos naturais

Weeds compete for different resources with crops and the management of these plants is necessary so that production losses can be minimized. On the other hand, the diversity of plant species which behave as weeds can positively contribute to the survival of many arthropods and natural enemies. The objective of this review was to systematize the scientific evidence on the impacts of control of weeds and herbicides applied to non-target insects such as predators and parasitoids of pests, which are beneficial for agriculture and present in different agricultural crops. In this sense, consequences of control of weeds on insects present in agroecosystems were reported, as well as the potential risks of widespread use of herbicides on crops. Finally, this review compiles the current state of knowledge on ecological relationships in agricultural systems, focusing sustainable weed management, coupled with an integrated pest management.As plantas daninhas competem por diferentes recursos com as culturas agrícolas, sendo o manejo dessas plantas necessário para que se possa minimizar perdas na produção. Por outro lado, a diversidade de espécies vegetais que se comportam como planta daninha pode contribuir de forma positiva para a sobrevivência de diversos artrópodes e inimigos naturais. O objetivo dessa revisão foi sistematizar as evidências científicas sobre os impactos do controle de plantas daninhas e da aplicação de herbicidas em insetos não alvos, como os predadores e parasitoides de pragas, benéficos para a agricultura, e presentes em diferentes culturas agrícolas. Neste sentido, foram reportadas consequências do controle das plantas daninhas em insetos presentes nos agroecossistemas, bem como, os potenciais riscos do uso generalizado de herbicidas em culturas agrícolas. Por fim, essa revisão compila o estado atual do conhecimento de relações ecológicas em sistemas agrícolas, tendo como foco o manejo sustentável de plantas daninhas, aliado ao manejo integrado de pragas

Natural Occurrence and Ecology of Trichogramma pretiosum (Hymenoptera: Trichogrammatidae) in Cotton Plantations with Insecticides Spraying in Minas Gerais State, Brazil

Pest damage is one of the greatest problems in cotton production in the world. The objective of this study was to assess the natural occurrence, parasitism rate, number of adults ofTrichogramma emerged and coexistence with predators species in cotton plantations with insecticide spraying in Brazil. Parasitoids were collected in two areas of two-hectares each with the Dp 4049 and Delta Opal cotton varieties, using 12.0 x 2.5 cm pieces of white cards with an average of 3.000 Anagasta kuehniella (Zeller) (Lepidoptera: Pyralidae) eggs each. The predation percentage of A. kuehniella eggs in the field and parasitism occurrence was estimated based on the cards with eggs of this prey brought from the field. All parasitoids obtained were identified as Trichogramma pretiosum (Riley) (Hymenoptera: Trichogrammatidae). The predators collected were identified as belonging to the families Chrysopidae (Neuroptera), Coccinelidae (Coleoptera) and Sirphidae (Diptera). The average number of eggs parasitized per cardboard, during the cycle of this culture was 16.34 ± 5.1 in the area with Dp-4049 and 23.38 ± 4.3 in that with Delta opal. The predation average during the cycle of this culture was 42.58 ± 3.8 e 35.58 ± 2.9% in these areas, respectively. It is necessary to preserve and to increase the performance of T. pretiosum in cotton plantations

Quality control of Trichogramma atopovirilia and Trichogramma pretiosum (Hym.: Trichogrammatidae) adults reared under laboratory conditions

The objective of this work was to assess the flight capacity, parasitism and emergence of Trichogramma atopoviriliaand two strains of T. pretiosum (Hymenoptera: Trichogrammatidae) (L1 and L2). The flight capacity of these species was assessed in test units consisting of a plastic PVC cylinder with a rigid transparent plastic circle on the upper part and an extruded polystyrene disk closing its bottom. A tube was placed in each test unit containing a card with 300 Anagasta kuehniella (Lepidoptera: Pyralidae) eggs parasitised by Trichogramma. These cards were assessed to determine the parasitism rate and adult emergence of these natural enemies. T. atopovirilia and T. pretiosum L1 presented adequate flight capacity and parasitism, in addition to high percentages of adults emerged

Herbicide application on Genetically Modified Maize influences bee visitation

Brazil is one of the world’s largest producers of maize (Zea mays L.). Cry proteins derived from the bacterium Bacillus thuringiensis (Bt) have been widely used in transgenic maize due to their toxicity and specificity against insects that damage crops. In addition, these plants have been stacked with different herbicide tolerance genes. Non-target insects end up being exposed to Bt proteins and herbicide applications. There is little information on the effects of Bt transgenics and their cultural practices on the behavior of pollinators in genetically modified crops. The aim of this research was to verify the impact of genotypes of genetically modified maize, Herculex®, PowerCore®, and the conventional isohybrid, pulverized or not with herbicides (atrazine, glufosinate-ammonium and nicosulfuron) in bee populations. In order to evaluate the presence of insects, a zig-zag tour was carried out throughout the experimental field, ascertained from visual analysis and direct counting of six plants per plot (the dimensions of the plots were 2.5 x 10 m with five maize lines spaced 0.50 m between rows and 0.36 m between plants) randomly, 18 days after spraying herbicides in the area. Apis mellifera (L.) (Hymenoptera: Apidae), Tetragonisca angustula (L.) (Hymenoptera: Apidae) and Trigona spinipes (F.) (Hymenoptera: Apidae) were the pollinator species identified in the crop. It was observed that the incidence of pollinator insects varied according to cultivars and herbicides tested; however, the PowerCore® genotype experienced more visitation of pollinating bees independently of the herbicide treatments.

Pest potencial of Sitophilus zeamais on Brazil nut under storage conditions

The Brazil nut, fruit of Bertholletia excelsa H.B.K., a native plant of the Amazon region and may be considered one of the main extractivist products of countries like Bolivia, Colombia, Guyana, Venezuela, Peru and Brazil. In Brazil this plant can be found in the states of Acre, Amapá, Amazonas, Mato Grosso, Pará, Rondônia, Roraima and Tocantins. Species of the Coleoptera and Lepidoptera, have been classified as pest potentials of Brazil nut under storage conditions. Sitophilus zeamais (Coleoptera: Curculionidae) is one of the main insect pests attacking grain stores worldwide. This specie may be observed attacking grains in the field and in storage facilities (cross-infestation), presenting a wide variety of hosts. The purpose of this study was to assess the potential of adults of this species feed on Brazil nuts, and also to identify the type of injury as well as the life span of this coleopteran exposed to the meat of the Brazil nut. No feeding injury was observed on the surface of Brazil nuts and the life span of the insects was similar in treatments both with and without this food source in all populations evaluated. Due to the fact that S. zeamais adults do not injure, or feed on the Brazil nut, this beetle is not able to colonize this product and therefore may be considered a non-pest insect for stored Bertholletia excelsa almonds stored

Resistência varietal de morangueiro aos pulgões Cerosipha forbesi (Weed) e Chaetosiphon fragaefolii (Cockerell) (Hemiptera: Aphididae)

Resumo. A identificação de picos populacionais de pragas e a seleção de genótipos resistentes ajudam a definir o momento do controle e reduzir a aplicação de inseticidas. O objetivo deste estudo foi avaliar aresistência varietal de seis cultivares de morangueiro (Aromas, Campinas, Dover, Festival, Oso Grande e Toyonoka) ao ataque de Cerosipha forbesi (Weed)e Chaetosiphon fragaefolii (Cockerell) (Hemiptera: Aphididae). A presença dos pulgões nas plantas foi avaliada semanalmente por contagem direta em três folíolos por planta, durante cinco meses (Fevereiro a Junho de 2012). Março apresentou a maior densidade de ambas espécies de pulgões, com redução populacional nos meses próximos ao inverno. As cultivares Campinas, Toyonoka e Dover tiveram maior incidência de C. forbesi, e Campinas e Toyonoka foram também mais atacadas por C. fragaefolii. As cultivares Festival, Aromas e Oso Grande apresentaram menores infestações de ambas as espécies, tendo potencial para serem utilizadas em programas de melhoramento visando à resistência ao ataque de C. forbesi e C. fragaefolii. Varietal resistance of strawberry to aphids Cerosipha forbesi (Weed) and Chaetosiphon fragaefolii (Cockerell) (Hemiptera: Aphididae) Abstract. The identification of peak populations of pests and the selection of resistant genotypes help to define the timing of control and to reduce the frequency of insecticide application. The objective of this study was to evaluate varietal resistance of six strawberry cultivars (Aromas, Campinas, Dover, Oso Grande and Toyonoka) to the attack of Cerosipha forbesi (Weed) and Chaetosiphon fragaefolii (Cockerell) (Hemiptera: Aphididae). Attack of the aphids was evaluated on a weekly basis by direct counting in three leaflets per plant for five months (February to June 2012). March presented higher densities of both aphids species, with population reductions in months closer to the winter. The cultivars Campinas, Toyonoka, and Dover had higher incidence of C. forbesi, and Campinas and Toyonoka were also more attacked by C. fragaefolii. The cultivars Festival, Aromas, and Oso Grande presented lower infestation of both aphids species, and hold potential to be used in breeding programs aiming resistance to attack of C. forbesi and C. fragaefolli

Impactos toxicológicos de herbicidas recomendados para a cultura do milho em ninfas do predador Podisus nigrispinus (Hemiptera: Pentatomidae)

A presença de plantas daninhas na cultura do milho (Zea mays L.) pode ocasionar altas perdas na produção. O controle químico das plantas daninhas é o mais utilizado nesta cultura, mas pode afetar negativamente os inimigos naturais presentes nas lavouras. O objetivo do trabalho foi avaliar a toxicidade de herbicidas registrados para a cultura do milho a ninfas do predador Podisus nigrispinus Dallas, 1851 (Hemiptera: Pentatomidae). Avaliou-se o efeito de atrazine, nicosulfuron, mesotrione, paraquat e o controle à base de água destilada, sobre três estádios imaturos do inseto (terceiro, quarto e quinto), em doses equivalentes à metade, ao dobro, a quatro e dez vezes à recomendada para a cultura do milho. Os herbicidas foram aplicados sobre potes plásticos de 500 mL contendo, cinco ninfas de cada estádio do inseto, constituindo a unidade amostral, com seis repetições. Após 96 horas foi realizada a contagem dos sobreviventes. Para todos os estádios de P. nigrispinus o aumento das doses dos herbicidas ocasionou decréscimo na taxa de sobrevivência. Esta foi menor para os insetos expostos ao atrazine e paraquat. O mesotrione foi o menos tóxico e o nicosulfuron apresentou toxicidade mediana. Conclui-se que as ninfas do terceiro ao quinto estádio do inimigo natural P. nigrispinus são mais suscetíveis aos herbicidas atrazine e paraquat. Além disso, mesotrione e nicosulfuron podem ser utilizados na cultura do milho, visando preservar a população deste predador.Weeds presence in corn crop (Zea mays L.) may cause high losses in production. Chemical control of these plants is the most used, but may adversely affect natural enemies present in crops. Therefore, the objective of this study was to evaluate herbicides toxicity s registered for corn crop to nymphs of Podisus nigrispinus Dallas, 1851 (Heteroptera: Pentatomidae) predator. It was evaluated the effect of atrazine, nicosulfuron, mesotrione, paraquat and its control based on distilled water over three immature stages of insects (third, fourth and fifth) in doses equivalent to half, to twice, four and ten times the recommended one for corn crop. Herbicides were applied over plastic pots of 500 mL each, containing five nymphs in each stage of the insect, constituting the experimental plot, with six replications. After 96 hours was performed the counting of survivors individuals. For all stages of P. nigrispinus increasing herbicides doses caused a decrease in survival rate. This one was inferior for insects exposed to atrazine and paraquat herbicides. Mesotrione herbicide was the least toxic and nicosulfuron showed median toxicity. It was concluded that nymphs from third to fifth stage of P. nigrispinus natural enemy are more susceptible to atrazine and paraquat herbicides. Moreover, mesotrione and nicosulfuron may be used for controlling weeds in corn crop when the objective is to preserve the population of this predator

Can the diet of the prey Tenebrio molitor (Coleoptera: Tenebrionidae) affect the development of the predator Podisus nigrispinus (Heteroptera: Pentatomidae)?

Inimigos naturais s?o importantes para o controle de pragas em culturas agr?colas e forestais. A cria??o de insetos predadores em biof?bricas deve ser de baixo custo para serem utilizados em programas de Manejo Integrado de Pragas (MIP). O objetivo deste trabalho foi avaliar o desenvolvimento de Podisus nigrispinus Dallas, 1851 (Heteroptera: Pentatomidae), alimentado com larvas de Tenebrio molitor Linnaeus, 1758 (Coleoptera: Tenebrionidae), criadas com as seguintes dietas: farelo de trigo, ra??o triturada ou peletizada para aves poedeiras e fub? de milho. Foram obtidos os par?metros de desenvolvimento e reprodu??o necess?rios para calcular a tabela de vida do predador. Os par?metros da tabela de vida revelaram crescimento populacional em todos os tratamentos. No entanto, a taxa l?quida de reprodu??o (Ro) de P. nigrispinus foi menor quando alimentados com larvas de T. molitor criadas com fub? de milho, mostrando ser a alimenta??o menos adequada para esse predador. Por proporcionar maior n?mero total de ovos, o farelo de trigo constituiu a melhor dieta para P. nigrispinus. Estudos sobre dietas de presas alternativas s?o importantes, pois podem favorecer a nutri??o de inimigos naturais e, consequentemente, melhorar o desempenho das cria??es massais em laborat?rio.Funda??o de Amparo ? Pesquisa do Estado de Minas Gerais (FAPEMIG)Empresa de Pesquisa Agropecu?ria de Minas Gerais (EPAMIG)Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico (CNPq)Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES)Natural enemies are important for controlling pests in agricultural and forestry culture. The reproductions of predatory insects in biofactories should have low cost to be used in Integrated Pest Management Program (IPM). The objective of this study was to evaluate the development of Podisus nigrispinus Dallas, 1851 (Heteroptera: Pentatomidae) fed with Tenebrio molitor Linnaeus, 1758 (Coleoptera: Tenebrionidae). The larvae of T. molitor were created with the following diets: wheat bran, shredded or pelleted poultry feed layers and corn meal. Parameters for the development and reproduction of the P. nigrispinus were obtained. Parameters of the life table show population growth in all treatments. However, the net rate of reproduction (Ro) of P. nigrispinus was lower when they were fed with larvae of T. molitor created with corn meal, which proved to be the least adequate food for this predator. By providing a larger total number of eggs, wheat bran was the best diet for P. nigrispinus. Studies on alternative prey diets are important as they may favor the nutrition of natural enemies and, consequently, improve the performance in laboratory rearing

Educomunicação e diversidade: múltiplas abordagens

Esta coletânea de capítulos intitulada “Educomunicação e Diversidade: múltiplas abordagens” reúne estudos apresentados no VI Encontro Brasileiro de Educomunicação e III EducomSul, realizado em Porto Alegre em 2015. Nessa obra, percebe-se que as dimensões interculturais, transversais e cidadãs suscitadas pela educomunicação vêm contribuindo para o aumento de intervenções comunicacionais diversas, em termos de linguagens e de conteúdos, em práticas educativas formais e não formais. Denotando a diversidade como uma área em expansão na educomunicação