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

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.

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

Egg morphology, immature stages, midgut and salivary glands of Podisus distinctus (Heteroptera: Pentatomidae)

A subfamília Asopinae apresenta grande número de espécies predadoras, como Podisus distinctus (Stal) (Heteroptera: Pentatomidae), que se destaca como uma das principais desse gênero. Estes podem ser criados em laboratório e apresentam potencial para o controle biológico de lepidópteros desfolhadores em plantações de eucalipto no Brasil. Esse estudo objetivou descrever o desenvolvimento dos ovos (aspectos de formação e dinâmica pós- deposicional), os estágios imaturos (ovos e ninfas) e a morfologia do intestino médio e das glândulas salivares de P. distinctus. Essa espécie apresentou ovos com forma subglobosa a oval, base mais estreita que o ápice; opérculo circular convexo; altura de 1,09 ± 0,03mm; diâmetro de 0,90 ± 0,04mm; processos aero-micropilares clavados, em fileira circular no pólo anterior do ovo, em número de 16,00 ± 2,00. Os ovos de P. distinctus são semelhantes aos de outras espécies do gênero Podisus, mas aspectos como a cor, forma, número de processos aero-micropilares, tamanho e diâmetro dos mesmos, podem ser utilizados para diferenciá-las. Foram observadas alterações pós-deposicionais nos ovos de P. distinctus após uma hora de postura, como a mudança de orientação dos espinhos e dos processos aero-micropilares. Os estádios de P. distinctus podem ser identificados contrastando características apresentadas entre os mesmos, como o número, arranjo e a disposição das manchas abdominais dorsais e também, avaliando características morfométricas, como o comprimento total, medido na linha mediana do corpo. Parâmetros morfométricos como a largura da cabeça ao nível dos olhos e o comprimento do pronoto, podem ser utilizados em auxílio na identificação dos estádios. O reconhecimento e a diferenciação de espécies de Asopinae são facilitados a partir do terceiro estádio, quando forma e manchas dorso-laterais são características. Entretanto, a coloração não é um caracter confiável. O complexo de glândulas salivares e o intestino médio de P. distinctus são semelhantes aos de outros Asopinae. O sistema salivar de P. distinctus é formado por um par de glândulas salivares principais bilobadas e por um par de glândulas acessórias longas e tubulares. As glândulas acessórias de P. distinctus originam-se na porção terminal do ducto acessório, que sofre um abaulamento. As glândulas salivares principais de P. distinctus possuem o lóbulo anterior esférico, menor que o lóbulo posterior, que apresenta forma de saco alongado e porção proximal dilatada. A parede do intestino médio de P. distinctus é formada por uma camada simples de células colunares, revestida externamente por uma camada muscular bem desenvolvida, organizada em uma túnica externa composta por músculo longitudinal e outra interna, de músculo circular. Podisus distinctus apresentou ainda, um feixe de músculos longitudinais justapostos que segue por toda a extensão do intestino médio.The subfamily Asopinae presents a large number of predatory species, including Podisus distinctus (Stal) (Heteroptera: Pentatomidae) as one of the main species of this genus. These insects can be reared in laboratory and it presents potential for biological control of Lepidoptera defoliators in Brazilian eucalyptus plantations. This study aimed to describe the egg development (postdeposition dynamic), the immature stages (eggs and nymphs) and the midgut and salivary glands morphology of P. distinctus. This species presented eggs with oval to subglobe form, base narrower than the apex; convex circular operculum; 1.09 ± 0,03mm height; 0.90 ± 0.04mm diameter; clavated aeromicropilar processes in a circular row in the egg anterior pole, in number of 16.00 ± 2.00. The eggs of P. distinctus are similar to other species of the genus Podisus, but aspects as color, form, number of aero-micropilar processes, size and diameter can be used to differentiate them. Postdeposition alterations were observed on eggs of P. distinctus after one hour of being laid such as the change on orientation of the spines and aero-micropilar processes. The instars of P. distinctus can be identified based on characteristics presented by them, as number, arrangement and disposition of the abdominal stains and also, morphological characteristics, as total length (measured in the body medium line). Morphometric parameters as the width of the head at the eyes level and the pronotum length can also be used to identify the nymph stadiums. The recognition and differentiation of Asopinae species are easier after the third stadium when form and dorsolateral stains are more distinctive. However, the color is not a reliable character for this. Salivary glands complex and the midgut of P. distinctus are similar to those of other Asopinae species. The salivary system of P. distinctus is formed by a pair of principal bilobades glands and a pair of long and tubular accessory glands. The last one arise from the terminal portion of the accessory duct that suffers a camber. The P. distinctus principal salivary glands presents spherical and smaller anterior lobe than the posterior lobe, which has a prolonged sack form and dilated proximal portion. The P. distinctus midgut wall is formed by a simple layer of columnar cells externally covered by a well developed muscle layer, organized in a tunic composed by overlaid longitudinal and circular muscles. Podisus distinctus also present a bundle of longitudinal muscles along the whole midgut extension.Coordenação de Aperfeiçoamento de Pessoal de Nível Superio

Cannibalism in the predator Podisus distinctus (Heteroptera: Pentatomidae): population and behavioral aspects

Predadores Pentatomidae são importantes no controle de pragas agrosilviculturais e Podisus distinctus (Stal) (Heteroptera: Pentatomidae) possui potencial para aplicação no controle biológico de lepidópteros. Entretanto, as altas taxas de canibalismo, observadas nas criações massais da espécie, dificultam a produção de um grande número de indivíduos. As causas do canibalismo em P. distinctus ainda não foram estudadas e apesar dos fatores populacionais, como a densidade, idade e sexo dos indivíduos, serem indicados como os principais motivadores da predação intraespecífica nos insetos, comportamentos complexos como a zoofitofagia, o oportunismo, a recognição de parentesco biológico e o cuidado parental podem alterar as frequências deste hábito. Os objetivos deste trabalho foram testar a influência da densidade populacional, idade e sexo dos indivíduos no canibalismo em P. distinctus; observar comportamentos que afetam o canibalismo nesta espécie; e avaliar o desenvolvimento e as tabelas de vida e fertilidade de P. distinctus alimentado com presa alternativa Tenebrio molitor (Coleoptera: Tenebrionidae) e co-específicos. A densidade populacional estimula o canibalismo em ninfas até, aproximadamente, dez indivíduos por placa, quando passa a haver uma estabilização e posterior decréscimo nos níveis de predação em co-específicos. Adultos apresentam crescimento linear da predação intraespecífica. Ninfas de segundo estádio apresentaram menor predação intra-específica (6,00 ± 3,05%) que as de terceiro (22,00 ± 2,00%), quarto (22,00 ± 3,60%) e quinto (20,00 ± 5,16%) estádio. Ninfas de terceiro ao quinto estádio apresentaram maior predação em co-específicos que adultos. O sexo de P. distinctus afeta a predação intraespecífica, pois fêmeas (16,67 ± 2,05%) canibalizam mais que machos (6,67 ± 1,40%). A alimentação em plantas diminuiu o canibalismo em ninfas. As mortes ocasionadas por ataque diminuíram de 20,00 ± 4,22% para 8,00 ± 3,27% na presença de plantas. O comportamento oportunista beneficia os insetos na manipulação da presa, pois aumenta o sucesso dos ataques e diminui as chances de predação recíproca. O número de ataques bem sucedidos foi maior nos tratamentos com indivíduos amputados (1,50 ± 0,33), menores (0,88 ± 0,40) ou em muda (ecdise) (1,38 ± 0,26) quando comparados ao controle (0,12 ± 0,12). A recognição de parentesco biológico diminuiu a predação entre ninfas irmãs em, aproximadamente, 61,5% e não havia sido descrita anteriormente para predadores Asopinae. Outra observação inédita, descrita neste trabalho, foi o comportamento de P. distinctus de utilizar outras fêmeas como sítio de postura, o que pode diminuir a frequência do canibalismo de ovos e aumentar o fitness dos progenitores. Os resultados do desenvolvimento da fase ninfal, da tabela de vida e fertilidade mostraram que co-específicos são presas de baixa qualidade por não permitirem que ninfas sobrevivam além do terceiro estádio. A alimentação em coespecíficos causou aumento do período ninfal e diminuiu a sobrevivência de ninfas em 40%, reduziu o número de ovos por fêmea, número de ovos por postura, número de ninfas por fêmea e peso de adultos de P. distinctus. Esses predadores apresentaram queda acentuada na sobrevivência de adultos e menores picos de produção de ovos e ninfas quando os indivíduos se alimentam em co-específicos e ainda, este hábito reduziu a taxa líquida de reprodução, a razão infinitesimal e finita de aumento populacional. Fêmeas alimentadas exclusivamente em T. molitor apresentaram maior fertilidade específica (92%), que aquelas com dieta mista de T. molitor e co-específicos (60%). Apesar de P. distinctus não obter benefícios nutricionais na alimentação em coespecíficos a predação intra-específica é importante para P. distinctus e parece atuar no controle da densidade populacional e prevenção da competição por recursos. A manutenção de um número baixo de predadores nas gaiolas de criação pode diminuir as taxas de canibalismo e aumentar a eficiência das criações massais, especialmente, entre as ninfas, que apresentaram comportamento canibal mais acentuado. A adoção de táticas como a estratificação por idade, e o manejo adequado, evitando super povoamento, podem favorecer programas de controle biológico com esses inimigos naturais.Pentatomidae predators are important in pest control in forest systems and Podisus distinctus (Stal) (Heteroptera: Pentatomidae) has potential for application in biological control of Lepidoptera, however, high rates of cannibalism observed in the mass rearing of the predator inhibit the production of a large number individuals. The causes of cannibalism in P. distinctus are still poorly studied. In spite of population factors such as density, age and sex of individuals be appointed as the main motivators of intraspecific predation on insects, complex behaviors such as zoophytophagy, opportunism, kin recognition and parental care may alter the frequency of cannibalism. And besides, the life and fertility tables with different preys and conspecifics may help in understanding the cannibalism and the costs and benefits of this habit. The objectives of this paper were to test the influence of population density, age and sex of individuals in cannibalism in P. distinctus; observe behaviors that affect cannibalism in this specie; and evaluate the development and life and fertility tables of P. distinctus fed with alternative prey Tenebrio molitor (Coleoptera: Tenebrionidae) and conspecifics. Population density raises cannibalism in nymphs until about ten individuals per Petri dish, when going to be a stability and posterior reduction of cannibalism. However, adult P. distinctus showed a linear increase of intraspecific predation. Second instar nymphs showed less intraspecific predation (6.00 ± 3.05%) than third (22.00 ± 2.00%), fourth (22.00 ± 3.60%) and fifth (20.00 ± 5.16%) instar. Nymphs of third to fifth instar showed higher predation on conspecifics than adults. The sex of individuals affected intraspecific predation in P. distinctus and females (16.67 ± 2.05%) cannibalized more than males (6.67 ± 1.40%). Feeding on plants decreased cannibalism on nymphs. The deaths caused by attacks decreased from 20.00 ± 4.22% in absence to 8.00 ± 3.27% in presence of plants, representing a reduction of approximately 60% in mortality. The opportunistic behavior increases the success of the attacks and reduce the chances of reciprocal predation. The number of successful attacks was higher in amputees (1.50 ± 0.33), smaller (0.88 ± 0.40) or in molt (ecdysis) insects (1.38 ± 0.26) compared to control (0.12 ± 0.12), where all individuals were in the same condition. The biological kinship recognition in nymphs decreased predation among sibs, and had not been described previously for Asopinae predators. The deaths caused by attacks decreased from 26.00 ± 4.27% in unrelated nymphs to 10.00 ± 3.33% in sibs, which represents a reduction of approximately 61.5% in mortality. Another inedited observation described in this paper was the behavior of P. distinctus of using conspecifics as sites of oviposition. This habit can decrease the frequency of egg cannibalism and increase the fitness of the parents. The results of the nymphal stage development and life and fertility tables showed that conspecifics are low quality preys. Eating conspecifics not allowed nymphs to survive beyond the third stage. Feeding on conspecifics caused an increase in nymphal development time and decreased nymphs survival by 40%; reduced the number of eggs per female, number of eggs per clutch, number of nymphs per female and adult weight of P. distinctus. This predator showed higher decline in adult survival rate and lower peak production of eggs and nymphs when individuals feed on conspecifics. Besides, this habit has reduced the reproductive and population growth rates. Females fed only on T. molitor showed greater fecundity (92%) than those with mixed diet (60%). Although P. distinctus not get the nutritional benefits of feeding on conspecifics, the cannibalism is important for P. distinctus and acts controlling the population density and preventing resource competition. The maintenance of a low number of predators in the rearing cages can reduce cannibalism rate and increase the mass rearing efficiency, especially among the nymphs, which had a more pronounced cannibalistic behaviour. The use of tactics such as age stratification, and proper management, avoiding overpopulation, can promote the success of biological control programs.Coordenação de Aperfeiçoamento de Pessoal de Nível Superio

Morphology and Postdepositional Dynamics of Eggs of the Predator Podisus distinctus (Stål) (Heteroptera: Pentatomidae: Asopinae)

Sá, Veríssimo Gibran Mendes De, Zanuncio, José Cola, Soares, Marcus Alvarenga, Rosa, Cassiano Sousa, Serrão, José Eduardo (2013): Morphology and Postdepositional Dynamics of Eggs of the Predator Podisus distinctus (Stål) (Heteroptera: Pentatomidae: Asopinae). Zootaxa 3641 (3): 282-288, DOI: http://dx.doi.org/10.11646/zootaxa.3641.3.

Idade do plantio de Eucalyptus urograndis e a ocorrência de insetos pragas

Eucalyptus species are originally from Australia and its plantations is the major forestry activity in Brazil. The Myrtaceae family is widely represented in Brazil, enabling native insects to migrate to Eucalyptus plants. Native herbivorous insects may adapt to the species planted in monoculture with low availability of their natural host plants and natural enemies. Within this context, the differential occurrence pattern of eleven insect pests of Lepidoptera, Coleoptera and Hemiptera orders, from 450 Eucalyptus stands of different ages recorded in 2002 to 2010 in eastern State of Minas Gerais, Brazil was evaluated. Bayesian inference was used for data analyses in hypothesis testing. The probability of occurrence of pest species was estimated using a linear multinomial model, relating their occurrence with the Eucalyptus stand age. Pest occurrence in Eucalyptus stands were linked to plant age, with younger ones being more susceptible to phytophagous insects. That association with chronological plant age may be associated with the resource exploration strategy of each group of pest insects. Thus, Eucalyptus forest management should be adapted to the temporally differential use of the stands by pest species, providing more efficient control strategies.As espécies de Eucalyptus são originárias da Austrália e suas plantações são a principal atividade florestal no Brasil. A família Myrtaceae é amplamente representada no Brasil, permitindo que insetos nativos utilizem as plantas de Eucalyptus. Insetos herbívoros nativos podem se adaptar-se a espécies plantadas em monoculturas quando privados de suas plantas hospedeiras naturais e inimigos naturais. Nesse contexto, o padrão de ocorrência diferencial de 11 espécies de insetos pragas das ordens Lepidoptera, Coleoptera e Hemiptera, de 450 talhões de Eucalyptus de idades variadas, foi avaliado entre 2002 e 2010 no leste do Estado de Minas Gerais foi avaliado. A inferência bayesiana foi usada para análise de dados nos testes de hipóteses. A probabilidade de ocorrência das espécies pragas foi estimada usando um modelo multinomial linear, relacionando sua ocorrência com a idade do talhão de Eucalyptus. A ocorrência das pragas nos talhões de Eucalyptus foi relacionada à idade da planta, observando-se que talhões mais jovens foram mais suscetíveis à insetos fitófagos. Essa associação com períodos cronológicos da planta pode estar associado às estratégias de exploração que cada grupo de insetos praga apresenta. Assim, o manejo de florestas de Eucalyptus deve ser adaptado com base no diferencial das espécies pragas no talhão, gerando estratégias mais eficientes de controle de pragas

Assessment of Trichogramma species (Hymenoptera: Trichogrammatidae) for biological control in cassava (Manihot esculenta Crantz)

Cassava is the sixth most important crop in the world, and it is attacked by many pests, such as Erinnyis ello (L.) (Lepidoptera: Sphingidae). This lepidopteran pest has natural enemies that can efficiently control its population, such as Trichogramma spp. (Hymenoptera: Trichogrammatidae). The objective of this research was to assess the flight capacity, parasitism and emergence of Trichogramma pretiosum, T. marandobai and T. demoraesi and to select the most efficient species among them for biological control programs. 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 portion of the cylinder and an extruded polystyrene disk to close the bottom of the cylinder. A tube was placed in each test unit containing a card with 300 Anagasta kuehniella (Zeller) (Lepidoptera: Pyralidae) eggs that had been parasitised by Trichogramma. These cards were later assessed to determine the parasitism rate and adult emergence of these natural enemies. Trichogramma pretiosum presented the highest flight capacity (68 ± 5%), parasitism (74 ± 2%) and percentage of adults emerged (91 ± 3%) in the laboratory, making this species suitable for mass rearing and release in biological control programs.A mandioca é a sexta cultura mais importante no mundo, sendo atacada por diversas pragas, incluindo Erinnyis ello (Linnaeus) (Lepidoptera: Sphingidae). Este lepidóptero apresenta inimigos naturais que podem controlar de forma eficiente sua população, destacando os parasitoides oófagos Trichogramma spp. (Hymenoptera: Trichogrammatidae). O objetivo deste trabalho foi avaliar Trichogramma pretiosum, T. marandobai e T. demoraesi quanto à sua capacidade de parasitismo, emergência e voo, visando selecionar a espécie mais eficiente para programas de controle biológico. Os parâmetros biológicos foram avaliados em unidades teste, consistindo de um cilindro de PVC com um circulo de plástico rígido e transparente no topo e um disco de poliestireno vedando a parte inferior. Um tubo de ensaio contendo 300 ovos de Anagasta kuehniella (Zeller) (Lepidoptera: Pyralidae) parasitados por Trichogramma foi colocado no interior da unidade. Trichogramma pretiosum apresentou maior capacidade de voo (68 ± 5%) e porcentagens de parasitismo (74 ± 2%) e emergência de adultos (91 ± 3%) em laboratório, sendo indicado para criação e liberação em programas de controle biológico

Assessment of Trichogramma species (Hymenoptera: Trichogrammatidae) for biological control in cassava (Manihot esculenta Crantz)

Cassava is the sixth most important crop in the world, and it is attacked by many pests, such as Erinnyis ello (L.) (Lepidoptera: Sphingidae). This lepidopteran pest has natural enemies that can efficiently control its population, such as Trichogramma spp. (Hymenoptera: Trichogrammatidae). The objective of this research was to assess the flight capacity, parasitism and emergence of Trichogramma pretiosum, T. marandobai and T. demoraesi and to select the most efficient species among them for biological control programs. 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 portion of the cylinder and an extruded polystyrene disk to close the bottom of the cylinder. A tube was placed in each test unit containing a card with 300 Anagasta kuehniella (Zeller) (Lepidoptera: Pyralidae) eggs that had been parasitised by Trichogramma. These cards were later assessed to determine the parasitism rate and adult emergence of these natural enemies. Trichogramma pretiosum presented the highest flight capacity (68 ± 5%), parasitism (74 ± 2%) and percentage of adults emerged (91 ± 3%) in the laboratory, making this species suitable for mass rearing and release in biological control programs