The cotton plant, Gossypium hirsutum, hosts various pests that damage different structures. Among these pests, Spodoptera cosmioides (Walker) and Spodoptera eridania (Cramer) (Lepidoptera: Noctuidae) are considered important. The objectives of this study were to characterize and to quantify the potential damage of S. eridania and S. cosmioides feeding on different structures of cotton plants. For this purpose, newly-hatched larvae were reared on the following plant parts: leaf and flower bud; leaf and boll; flower bud or boll; and leaf, flower bud and boll. The survival of S. cosmioides and S. eridania was greater than 80% and 70% for larvae fed on cotton plant parts offered separately or together, respectively. One larva of S. eridania damaged 1.7 flower buds, but did not damage bolls, while one larva of S. cosmioides damaged 5.2 flower buds and 3.0 cotton bolls. Spodoptera eridania and S. cosmioides can be considered species with potential to cause economic damage to cotton plants because they can occur throughout cotton developmental stages causing defoliation and losses of reproductive structures. Therefore, the results validate field observations that these two species of Spodoptera are potential pests for cotton.

In this work, the survey of simuliid species and the study of their spatial distribution in four streams of a small watershed situated in Londrina, Paraná State, were carried out from January to October 2007. Changes in the species composition of the breeding sites were also checked along the sampling months. Seventeen black fly species were found, being Simulium botulibranchium Lutz, Simulium travassosi d'Andretta & d'Andretta, Simulium anamariae Vulcano, Simulium brachycladum Lutz & Pinto and Simulium metallicum s. l. Bellardi new records for Paraná State. The Canonical Correspondence Analysis showed that the environmental variables most correlated to the species distribution among sample sites were water conductivity and those linked to physical dimensions of the breeding sites, like width, depth and water velocity. The matrix of faunistic similarity among collecting dates was negatively correlated to the time interval of sampling matrix for three of the water bodies studied, showing the existence of temporal changes in the species composition. According to Multiple Regression Analysis, temporal abundance variation of Simulium perflavum Roubaud, Simulium inaequale Paterson & Shannon and Simulium lutzianum s. l. Pinto was not linked to air temperature, photoperiod and rainfall, suggesting the influence of other factors, probably those directly associated to specific breeding site conditions. The results indicate that differences in physical and chemical characteristics among water bodies may affect the taxonomic composition of simuliids in this watershed.

Spodoptera eridania (Cramer) é uma praga em expansão nas culturas de algodão e de soja no cerrado, necessitando de estudos de biologia em diferentes hospedeiros. Com o objetivo de conhecer a biologia e o consumo foliar de S. eridania em algodoeiro, soja e corda-de-viola (Ipomoea grandifolia), este inseto foi criado em laboratório (27± 2ºC, UR 60± 10%, fotofase de 14h), a partir de lagartas recém-eclodidas e individualizadas. Foram observados parâmetros relacionados à biologia, ao consumo foliar e à reprodução quando alimentadas nos três hospedeiros. O período de desenvolvimento larval foi menor nos insetos alimentados com algodoeiro e corda-de-viola do que em soja, embora a sobrevivência em soja tenha sido satisfatória (80%). Lagartas alimentadas com folhas de algodoeiro e corda-de-viola tiveram peso médio de pupas semelhante, porém 1,3 e 1,4 vezes maior do que o obtido por pupa macho e fêmea, respectivamente, em folhas de soja. A soja, também influenciou negativamente a sobrevivência de pré-pupa e pupa, contrastando com os valores, acima de 91,8%, nos outros dois hospedeiros. Em geral, a folha de soja foi a menos adequada para S. eridania, causando 6,3% de deformidade em pupas. Variáveis como períodos de pré-oviposição, oviposição, número de posturas/fêmea e o total de ovos/fêmea, não foram afetados pelas dietas. Embora as folhas de algodoeiro tenham sido as menos consumidas, elas proporcionaram um bom desenvolvimento do inseto. Comprovou-se que a planta invasora corda-de-viola é um hospedeiro alternativo adequado para a espécie, possibilitando o seu desenvolvimento e a sua reprodução na ausência de hospedeiros cultivados.

Spodoptera eridania (Cramer) is a pest under expansion in cotton and soybean fields in the cerrado, and biology studies are needed on different hosts. In order to gain knowledge about the biology and leaf intake of S. eridania on cotton, soybean and morning glory (Ipomoea grandifolia), newly-hatched caterpillars were individualized and reared in the laboratory (27 ± 2ºC, R.H. 60 ± 10%, photophase of 14h). Parameters related to biology, leaf intake and reproduction were observed. The larval development period of caterpillars was shorter when fed on cotton and morning glory leaves than on soybean leaves, even though, the survival on soybean had been satisfactory (80%). Caterpillars fed on cotton and morning glory leaves had similar mean pupal weights, however 1.3 and 1.4 times higher than those obtained for male and female pupae, respectively, on soybean leaves. The soybean also influenced prepupal (37.5%) and pupal survival (68.3%) negatively, in contrast with the values obtained on the two other hosts, which were above 91.8%. In general, the soybean leaves were the least suitable for the development of S. eridania, causing 6.3% of pupal deformities. Variables like the pre-oviposition and oviposition periods, number of egg clutches/female and total number of eggs/female were not affected by the diets. Even though cotton leaves were less consumed, they provided good development to the insect. The morning glory weed was shown a suitable alternate host for the species, allowing its development and reproduction in the absence of cultivated hosts.

O pulgão Aphis gossypii Glover é vetor da Virose Mosaico das Nervuras (V.M.N.), que pode ocasionar na cultura do algodoeiro, produção reduzida ou nula. O objetivo do estudo foi identificar cultivares de algodoeiro resistentes a V.M.N. quando expostas à ação de pulgões. Os experimentos foram conduzidos na fazenda experimental do Instituto Agronômico do Paraná, IAPAR, Londrina, PR, sendo o delineamento estatístico em blocos casualizados. As cultivares comparadas foram: Delta Opal, Deltapine A90, CNPA ITA 90, Coodetec 401, IAC 22, IPR 95, IPR 96 e IPR 94. Para avaliação foram selecionadas 25 plantas observando-se a presença de pulgões e sintomas de V.M.N. Dois experimentos foram realizados nas mesmas condições, sendo que em um deles realizaram-se aplicações de inseticidas, para o controle dos pulgões, quando sua presença foi constatada em 10% das plantas. O outro experimento não recebeu aplicação de inseticidas para controle de pulgões. A presença do vetor foi constatada em plantas de todas as cultivares. Observou-se que, mesmo com menor infestação de pulgões na cultivar CNPA ITA 90, ocorreram elevados índices de V.M.N. com redução de 68% da produção quando comparada com Delta Opal. As cultivares Delta Opal e Coodetec 401 mostraram-se muito resistentes a V.M.N. pela ausência de plantas com sintomas, IAC 22 foi susceptível, enquanto Deltapine A90 e CNPA ITA 90 foram muito susceptíveis. Os inseticidas ofereceram proteção razoável à ação do vetor, mas os dados permitem inferir que em áreas com elevados níveis de infecção de V.M.N., o método de controle mais adequado seria a adoção de cultivares resistentes à enfermidade como Delta Opal e Coodetec 401.

The aphid Aphis gossypii Glover is a vector of Cotton Vein Mosaic Virus (V.M.N.), which can cause reduced or null yields in cotton crops. The objective of this study was to identify cotton cultivars resistant to V.M.N. when exposed to the action of aphids. The experiments were conducted at the experimental farm of the Instituto Agronômico do Paraná, IAPAR, in Londrina, PR, Brazil, in a randomized blocks statistical design. The cultivars compared were: Delta Opal, Deltapine A90, CNPA ITA 90, Coodetec 401, IAC 22, IPR 95, IPR 96, and IPR 94. Twenty-five plants were selected for evaluation; the presence of aphids and V.M.N. symptoms were recorded. Two experiments were conducted under the same conditions; in one of them, insecticides were applied to control aphids when their presence was detected on 10% of the plants. The other experiment received no insecticides for aphid control. The vector was present on the plants from all cultivars. High V.M.N. rates occurred in cultivar CNPA ITA 90 even under lower aphid infestations, with a yield reduction of 68% when compared with Delta Opal. The cultivars Delta Opal and Coodetec 401 proved very resistant to V.M.N. based on the absence of plants with symptoms; IAC 22 was susceptible, while Deltapine A90 and CNPA ITA 90 were very susceptible. The insecticides provided reasonable protection against the action of the vector, but data allowed to infer that in areas with high levels of V.M.N. infection, the most suitable control method would be the adoption of cultivars resistant to the disease, such as Delta Opal and Coodetec 401.