Abstract Soybean varieties with indeterminate growth habit are widely used in the state of Mato Grosso do Sul and are characterized by not having well-defined phenological stages. Due to the importance of bee conservation, studies on the frequency and time of visitation in indeterminate soybean are needed. Samples were collected in a 4-ha plot of soybeans not treated with insecticides. Sampling was carried out at random spots, throughout the flowering period, starting at 08h:00min, during 15 min/hour, successively until 16h:00min. Generalized Linear Models were generated and the Poisson regression model provided the best fit, reflecting the significant differences revealed by the deviance analysis. The association between bees and climatic variables was tested with the Spearman’s correlation. The temporal pattern of bee visitation was independently influenced by flowering period and time of day. However climatic variables did not influence significantly bee visitation rate. In the first days of flowering, bees were more abundant, especially between 10h and 15h. These results have practical implications in the maintenance of this species during soybean management practices, contributing to a balanced coexistence between beekeepers and soybean growers, by avoiding applications of phytosanitary products during the periods of high bee visitation.

Abstract Recently, the Neotropical brown stink bug, Euschistus heros (Pentatomidae: Hemiptera), has been detected in cotton in the Brazilian Cerrado. Several reliable surveys have been conducted on the spatial distribution of stink bugs in soybean; however, few studies have examined the behavior of this insect in cotton in Brazil. Thus, this study examined the spatial distribution of E. heros in cotton using aggregation indices based on the variance-to-mean ratio, Morisita index, exponent k, Poisson and negative binomial distributions. Inverse Distance Weighting interpolation maps were also used to represent insect density. The study was conducted in a 1.1 hectare experimental cotton field in which 64 equally-sized plots were sampled on a weekly basis. Our findings revealed that stink bugs presented an aggregate distribution in 2 sampling weeks based on aggregation indices, and this pattern was best described by a negative binomial distribution. Maps showing the density of pests can be an important tool for sampling pests in crops and control measures in early stages of infestation, when there is an edge effect on the distribution of E. heros, can be an efficient strategy in cotton.

ABSTRACT Application technology factors may be influenced by changes in plant architecture, such as height and leaf area. This study aimed to evaluate which angle of sprayer displacement in the application of pesticides in relation to the direction of cotton sowing, cultivated in the ultra-narrow row, narrow row, and conventional systems, provides the best application quality characteristics in the different thirds of plants. The experiment was installed in a split-plot design with four replications in the 3 × 4 factorial scheme, composed of three cotton cultivation systems and four angles of sprayer displacement in relation to the direction of the sowing rows. The evaluated characteristics were mean volumetric diameter, density and coverage of droplets, number of droplets, and open area in the interrows without leaf. The upper third presented the highest values of mean volumetric diameter, number of droplets, and density and coverage of droplets for all interrow spacing and application angles. The angle of displacement of 30° in relation to the sowing row presented the best results in relation to the number and density of droplets. The spacing of 0.90 m in the interrows increased the number of droplets, droplet density, and coverage in the lower third of plants.

RESUMO Dentre as opções para o controle de lagartas de Alabama argillacea(Hubner, 1818) e Heliothis virescens (Fabricius, 1781) na cultura algodoeira, aplicações de inseticidas e o controle biológico têm sido amplamente usados. O algodão transgênico 'Bt' tem se inserido como uma alternativa extremamente viável, porem não se sabe com exatidão como as plantas transgênicas afetam as populações de organismos que se inter-relacionam em um agroecossistema. Nesse sentido, é importante saber como a disposição espacial de insetos pragas ou benéficos é afetada, pois pode alterar o método de amostragem dessas espécies na cultura, além de sua forma de controle. Este estudo foi conduzido buscando investigar o padrão da distribuição espacial de ovos de A. argillacea e de H. virescens em cultivar DeltaOpalR (convencional) e DP90BR (algodão-Bt)A coleta dos dados ocorreu durante o ano agrícola 2006/2007 em duas áreas de 5.000 m2 localizada na região do distrito de Nova América, município de Caarapó. Em cada área amostral, composta por 100 parcelas de 50 m2, foram realizadas 15 avaliações com contagens dos ovos das pragas em analise, em duas plantas por parcela. Os índices de agregação (razão variância/media, índice de Morisita e Expoente k da Distribuição Binomial Negativa) e o teste de qui-quadrado, com o ajuste dos valores encontrados e esperados as distribuições teóricas de frequência (Poisson, Binomial Negativa e Binomial Positiva), mostraram que em ambas cultivares a distribuição espacial de posturas dessas espécies estão distribuídas de acordo com o modelo de distribuição espacial agregada, ajustando-se ao padrão da distribuição binomial negativa.

ABSTRACT Among the options to control Alabama argillacea (Hübner, 1818) and Heliothis virescens (Fabricius, 1781) on cotton, insecticide spraying and biological control have been extensively used. The GM'Bt' cotton has been introduced as an extremely viable alternative, but it is yet not known how transgenic plants affect populations of organisms that are interrelated in an agroecosystem. For this reason, it is important to know how the spatial arrangement of pests and beneficial insect are affected, which may call for changes in the methods used for sampling these species. This study was conducted with the goal to investigate the pattern of spatial distribution of eggs of A. argillacea and H. virescens in DeltaOpalTM (non-Bt) and DP90BTMBt cotton cultivars. Data were collected during the agricultural year 2006/2007 in two areas of 5,000 m2, located in in the district of Nova América, Caarapó municipality. In each sampling area, comprising 100 plots of 50 m2, 15 evaluations were performed on two plants per plot. The sampling consisted in counting the eggs. The aggregation index (variance/mean ratio, Morisita index and exponent k of the negative binomial distribution) and chi-square fit of the observed and expected values to the theoretical frequency distribution (Poisson, Binomial and Negative Binomial Positive), showed that in both cultivars, the eggs of these species are distributed according to the aggregate distribution model, fitting the pattern of negative binomial distribution.

El algodón es un cultivo atractivo a una amplia variedad de organismos incluyendo plagas, enemigos naturales de las plagas y los polinizadores. Por lo tanto, el manejo integrado de plagas es necesario para este cultivo ya que el control químico se requiere a menudo para evitar pérdidas de producción. Entre los polinizadores encontrados en algodón, Apis mellifera es uno del más importantes pues puede aumentar la producción de 20 - 30% del algodón. Por otro lado, la selectividad es una característica importante de insecticidas, pues permite disminuir impactos en polinizadores y otros organismos no-blanco. Se examinó la toxicidad de varios insecticidas sobre abejas de Apis mellifera forrajeando en el algodón en condiciones de invernadero, incluyendo Turbine® 500 WG (150 g ha-1) (flonicamid), Actara® 250 WG (200 g ha-1) (thiametoxam), Cartap® 500 SP (1500 g ha-1) (cartap), Talstar® 100 CE (1000 ml ha-1) (bifenthrin) y Match® 50 CE (1000 ml ha-1) (lufenuron). Las aplicaciones de Talstar®, Actara® y Cartap® fueron absolutamente tóxicos. Talstar ® fue el más mortal, mientras que el Match® CE y Turbine® fueron solamente levemente tóxicos para los adultos de la abeja. El tratamiento Match® CE presentó mortalidad similar a la del control; entonces, lo clasificamos como inofensivo para los adultos de A. mellifera.

Cotton is a crop that is attractive to a wide variety of organisms, including pests, natural enemies of the pests and arthropod pollinators. Consequently, integrated pest management is necessary for this crop as chemical control is often required to avoid production losses. Among pollinators found on cotton, Apis mellifera is one of the most important, as it can increase cotton production 20 - 30%. On the other hand, selectivity is an important characteristic of insecticides, as it makes it possible to lessen impacts on pollinators and other non-target organisms. We examined the toxicity of various insecticides for honey bees foraging on cotton in a greenhouse, including Turbine® 500 WG (150 g ha-1) (flonicamid), Actara® 250 WG (200 g ha-1) (thiamethoxam), Cartap® 500 SP (1500 g ha-1) (cartap), Talstar® 100 CE (1000 mL ha-1) (bifenthrin) and Match® 50 CE (1000 mL ha-1) (lufenuron). Applications of Talstar®, Actara® and Cartap® were quite toxic. Talstar® was the most deadly, while Match CE® and Turbine® were only slightly toxic for adult honey bees. The Match CE® treatment mortality was similar to that of the control; thus, we classified it as innocuous for A. mellifera adults.

O pulgão Aphis gossypii Glover é uma das pragas do algodoeiro e suas relações com o hospedeiro são dependentes da quantidade de nitrogênio disponível para a planta. A biologia do A. gossypii, em função do regime de adubação nitrogenada no algodoeiro, foi estudada em condições de casa-de-vegetação, em Dourados, MS. Para isto foi utilizado o delineamento experimental inteiramente casualizado com nove repetições, com os tratamentos arranjados em fatorial (2 x 4 x 2) + 1, com duas fontes de adubo nitrogenado, quatro doses de nitrogênio (50, 100, 150 e 200 kg ha-1), duas épocas de aplicação do nitrogênio em cobertura e um tratamento adicional sem a adição do nitrogênio. Foram avaliadas as durações dos estádios ninfais e da fase ninfal, os períodos pré-reprodutivo, reprodutivo e pós-reprodutivo, a longevidade, o ciclo biológico e a fecundidade dos pulgões. Concluiu-se que apenas as doses de nitrogênio influenciaram a biologia do pulgão-do-algodoeiro, independente da fonte e época de aplicação, favorecendo seu desenvolvimento e fecundidade.

The cotton aphid, Aphis gossypii Glove, is one of the pests of cotton crop and its relation with the host seem to depend on the amount of nitrogen available to the plant. The biology of A. gossypii using different cotton nitrogen fertility regimes was studied under greenhouse conditions, in Dourados, MS. A completely randomized design with nine replications in a factorial scheme (2x4x2)+1 was used. Two nitrogen sources (sulphate of ammonium and urea), four doses of nitrogen (50, 100, 150 and 200 kg ha-1), two different times of nitrogen application and one additional treatment without nitrogen were taken as factors. The nymphal phases, the pre-reproductive, reproductive and pos-reproductive periods, longevity, the life cycle and fecundity of the cotton aphid were evaluated. The doses of nitrogen influenced the cotton aphid biology in both sources and times of application, favoring its development and fecundity.

A importância da lagarta-do-cartucho, Spodoptera frugiperda (J.E. Smith), deve-se não somente aos danos causados, mas especialmente à dificuldade de seu controle. É imprescindível o conhecimento dos parâmetros populacionais da praga, como seu padrão de dispersão na cultura, pois, dependendo do arranjo espacial do inseto na área são necessários diferentes métodos de amostragem, variando o número e o tamanho da amostra. Para o presente trabalho foram instalados três campos experimentais em três diferentes áreas. No Campo I foram alocadas 66 parcelas, compostas por sete plantas cada; no Campo II foram demarcadas 55 parcelas, compostas por quatro plantas, e por fim, o Campo III também foi formado por 55 parcelas compostas por seis plantas cada uma. Nas amostragens realizadas avaliou-se a presença ou ausência da praga na planta. De acordo com os dados observados tanto para os índices de dispersão como para os modelos teóricas de distribuições de freqüência, S. frugiperda possui padrão de dispersão espacial definido mais adequadamente pela aleatoriedade, sendo esse modelo de distribuição muito influenciado pelo nível da infestação.

The importance of the fall armyworm, Spodoptera frugiperda (J.E. Smith), is not only due to the damage it can cause, but also to its difficult control. It is essential to know the pest population parameters, such as its standard scattering in the crop, because depending on the space arrangement of the insects in the area, different sampling methods are required. For the present work, three experimental fields were installed in different areas: the first one had 66 plots with seven plants each; the second one had 55 plots with four plants each; and the third field had 55 plots with six plants each. The presence or absence of the pest in the plant was evaluated in the samples. According to the data observed, either to the scattering index or to the theoretical scattering models, S. frugiperda dispersion is scattered at random and strongly depends on the infestation level.

Os experimentos foram conduzidos em culturas comerciais de algodoeiros na região de Dourados no Estado de Mato Grosso do Sul, durante a safra 1996/97. Observaram-se os seguintes aspectos do parasitismo natural em ovos de Alabama argillacea Hübner e Heliothis virescens Fabricius por Trichogramma pretiosum Riley: índice de parasitismo, razão sexual e número de adultos emergidos por ovo. Realizou-se coleta semanal de ovos dos lepidópteros e sua incubação em laboratório. Aos 31 dias após a emergência das plantas (DAE), não se observou parasitismo nos ovos de A. argillacea. Porém, a partir de 58 dias (DAE), acima de 60% dos ovos estavam parasitados por T. pretiosum, atingindo em algumas avaliações quase 100%. Apesar da baixa ocorrência de ovos de H. virescens, esses também apresentaram elevado índice de parasitismo por T. pretiosum. O número de fêmeas emergidas dos ovos parasitados geralmente foi maior do que o de machos. Fêmeas representaram em torno de 60% do total de adultos emergidos na maioria das coletas efetuadas. O número de adultos emergidos por ovo de A. argillacea e H. virescens foi ao redor de dois. Na região de Dourados, portanto, o parasitismo natural em ovos de A. argillacea e H. virescens por T. pretiosum é elevado, mesmo com as freqüentes aplicações de inseticidas.

The experiments were carried out on cotton in the region of Dourados, Mato Grosso do Sul State, in 1996-97. From weekly samples of eggs of Alabama argillacea Hüb. and Heliothis virescens Fab., we determined the level of parasitism, sex ratio and total number of adults of Trichogramma pretiosum Riley emerged from each host egg. The percentage of A. argillacea eggs parasitized by T. pretiosum was null at 31 days after the emergence of the plants (DAE) and increased to more than 60% from the 58th day (DAE)on; sometimes the parasitism reached almost 100%. H. virescens eggs also showed high levels of parasitism by T. pretiosum. The number of adult females emerged from parasitized eggs was always higher than the number of adult males and represented around 60% of the total adults emerged. On the average, around two adult wasps emerged from each egg of A. argillacea or H. virescens. In the region of Dourados, the parasitism by T. pretiosum was high in both A. argillacea and H. virescens eggs, despite the high levels of insecticide use.