910 resultados para entomological warfare


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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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In Brazil, soybean Glycine max (L.) Merril crops are subjected to incidence of several pests, which are mainly insect species. However, the occurrences of other pest species are growing. In this context, outbreaks of phytophagous mites are becoming more frequent. Nevertheless, records of mites in such crop are available only for Maranhao, Mato Grosso, Minas Gerais and Rio Grande do Sul states. Thus, this work gathers all information published about the diversity of mites found in soybean in Brazil, and also new records of mite species made on samplings taken from the central Cerrado area. In the whole, occurrence of 44 species of plant mites in soybean has been recorded in Brazil. Data from prior studies and the results of this work present the tetranychid Mononychellus planki (McGregor) as the mite species most frequently occurring in the Brazilian soybean crops. A large portion of Phytoseiidae species has occurred in crops from Rio Grande do Sul state. In addition, spontaneous soybean has hosted almost half of the phytoseiid species sampled in Cerrado region. High diversity of Tarsonemidae has been found in the cultivated soybean. More studies about soybean mites are needed to clarify the damage potential of phytophagous mites and the biological role of predatory mites in this crop.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Existe uma demanda, na região semiárida produtora de uvas no Submédio São Francisco, por medidas sustentáveis de controle de doenças pós-colheita, uma vez que o modelo atual de revestimento de caixas com polietileno de alta densidade, associado ao metabissulfito de sódio, não tem se mostrado eficiente no controle dos fungos que ocorrem na região. O objetivo desse trabalho foi estudar um controle da podridão por Aspergillus em uvas 'Thompson Seedless' por meio da modificação da atmosfera, pelo envolvimento de caixas de uva em bolsões de poliamida. Comparou-se o bolsão de poliamida (PA) ao de polietileno alta densidade (PEAD), comumente usado na região, combinados ou não com o metabissulfito de sódio (SO2). Frutos provenientes de propriedade comercial, após serem selecionados e desinfestados foram feridos com alfinete entomológico e inoculados com uma suspensão de Aspergillus niger na concentração de 10(6) conídios.mL-¹ e submetidos à câmara úmida por 24 horas. em seguida as caixas de uva foram colocadas em bolsões específicos de acordo com o tratamento e armazenadas em câmara fria à temperatura de 2 ºC e umidade relativa de 75%, durante 40 dias. A partir do 12º dia de armazenagem foram feitas avaliações semanais da incidência da doença e de variáveis físico-químicas: perda de massa, sólidos solúveis totais (SST), pH, acidez titulável (AT), ratio (SST/AT); peroxidase (POD) e medição das concentrações de CO2 e O2 até o 40º dia. O delineamento experimental utilizado foi inteiramente ao acaso em parcelas subdivididas com cinco repetições. O revestimento de caixas de uva em bolsões de poliamida, mesmo sem o uso de metabissulfito de sódio, apresenta-se como uma alternativa viável na manutenção da qualidade pós-colheita de uva Thompson Seddless, bem como na redução de podridão causada por A. Niger. A enzima peroxidase pode ter atuado no processo de manutenção de qualidade da fruta, contribuindo para uma redução dos níveis da doença em uvas.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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We tested the host specificity of several parasitic Pseudacteon scuttle flies in South America with 23 species of ants in 13 genera. None of these ant species attracted Pseudacteon parasites except Solenopsis saevissima (F. Smith) and to a lesser extent Solenopsis geminata (Fab.). This result is encouraging because it indicates that the Pseudacteon flies tested in this study would not pose an ecological danger to other ant genera if these flies were introduced into the United States as classical biological control agents of imported fire ants. This prediction of host specificity will, of course, need to be validated with potential hosts in the United States before these flies can be released.

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Although various biological aspects of Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) have been examined, adult movement and dispersal of this insect pest is not well understood. Release-recapture techniques by using marked insects is a useful approach for dispersal studies; however, the marking technique should not significantly affect insect biology or behavior. Therefore, the effect of different concentrations of oil-soluble dyes (Solvent Blue 35 [C.I. 61554], Sudan Red 7B [C.I. 26050], Sudan Black B [26150], Sudan Orange G [C.I. 11920], and Sudan I 103624 [C.I. 12055]) on development, mortality, and fecundity of S. frugiperda was evaluated. Dyes were added to artificial diet used to feed larvae. Larval and pupal development and mortality, adult longevity, and female fecundity were evaluated. High concentrations (400 and 600 ppm) of all dyes led to longer larval and pupal stages. Adult life span and number of eggs were not affected by the dyes. Sudan Red 7B marked both adults and eggs very well. Solvent Blue 35 marked both adults and eggs, but the blue-marked eggs could not be distinguished from some bluish eggs laid by nonlabeled females. Adults and eggs were not adequately marked by the Sudan Black B, Sudan Orange G, and Sudan I 103624 (a yellow dye).

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We studied the responses of Solenopsis fire ants to Pseudacteon phorid fly attacks in southeastern Brazil. The presence of these phorid parasites triggered a suite of phorid-specific defense responses including reduced foraging, bait guarding, a curled defensive posture, and general colony immobility. The existence of these phorid-specific defenses indicates that Pseudacteon phorids exert substantial evolutionary pressure on South American fire ant populations.

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A total of 9 ant species were sampled from four sites covering 2000 km in the Amazon Basin using banana fruit baits: two sites on the Jurua River, one site on the Xingu River and in a dry forest of eastern Amazon, Paragominas. Camponotus abdominalis was present in all sites, and Camponotus sericeiventris, Camponotus sp. and Crematogaster sp. were present in two sites. All other species were present in only one site. Paragominas had the highest species richness because of a higher number of site restricted species. However, Jaccard faunas similarities among sites were not significantly related with distance between sites. Mosaic diversity showed a relatively simple taxonomic composition. The strong differences of the fauna sampled at banana fruit baits from other reported Neotropical ant faunas suggests that the fauna represents widespread fugitive species in an apparently complex environment.

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Two new genera and two new spec ies of Chrysopini (Neuroptera: Chrysopidae) are described from Brazil. The main characteristics of Cryptochrysa chloros are: a sheath of long setae in the oral cavity; slender forewing; triangular intramedian cell; antennal scape longer than wide; and lines of strong setae ventral to the arcessus. Characteristics of Furcochrysa allata are: large gonocornua; presence of a pseudopenis; arcessus absent; and basal marginal vein of forewing forked.

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Differences between castes and related aspects in Parachartegus fraternus (Gribodo) have been studied in various stages of the colony cycle. Five colonies from three colony development stages (namely, pre-emergence, worker-producing and male-producing) were analyzed. The main results were: irrespective of colony age, castes were always morphologically indistinguishable; non-inseminated ovary-developed females were found in four colonies; because differences of castes were physiological rather than morphological, castes are evidently post-imaginally determined and this is probably taking place according to the colony conditions. These findings support the occurrence of caste totipotency in Parachartergus fraternus.