Fernando Felisberto da Silva

Moscas frugívoras associadas a mirtáceas e laranjeira "Céu" na região do Vale do Rio Caí, Rio Grande do Sul, Brasil

This study aimed at recognizing frugivorous flies species in Myrtaceae: Eugenia uniflora L., Campomanesia xanthocarpa Berg. Psidium cattleianum Sabine, Psidium guajava L. and Acca sellowiana (Berg.) Burret., as well as in Citrus sinensis (L.) Osbeck (Rutaceae), at Vale do Cai region, Rio Grande do Sul. Fruits were collected at the maturation stage of each fruit species between October 2004 and July 2005, and at the laboratory they were placed in pots with sand and were kept at 12h photoperiod, 80 ± 10% RH and 25 ± 1oC. Pupae were individualized and their characteristics were recorded. In Tephritidae only Anastrepha fraterculus (Wied.) was recorded and in Lonchaeidae, Neosilba n. sp. 3, Neosilba zadolicha McAlpine & Steyskal and Neosilba certa (Walker). These last two species were recorded for the first time in Rio Grande do Sul. Only on P. cattleianum all species were recorded. Results show that A. fraterculus is the most frequent fruit-fly species found attacking the studied fruit plants in Vale do Cai region.

Nível de infestação de moscas-das-frutas em faixa de fronteira, no Rio Grande do Sul

Fruit flies are considered the major pests of fruit worldwide. Tefritids and lonchaeids are major pests in this group of insects. However, little information exists regarding the potential for harm of lonchaeids. The aim of this study was to identify the infestation levels of fruit flies in the boundary zone of Rio Grande do Sul with Argentina and Uruguay. The study was conducted in 2011 and 2012 in Itaqui, Quarai, Santana do Livramento and Uruguaiana, RS. Fruits were collected from19 exotic and native plant species, and the infestation levels in pupae/kg of fruit and pupae/fruit were calculated. The highest rate of Ceratitis capitata infestation occurred in nectarine, with 72.01 pupae/kg and 2.51 pupae/fruit. Anastrepha fraterculus showed high levels in cherry, corresponding to 57.57 pupae/kg and 0.23 pupae/fruit. Lonchaeids were represented by Neosilba and Lonchaea, infesting papaya and star fruits, respectively. In the studied municipalities of Rio Grande do Sul, the following species of fruit flies occurred: C. capitata, A. fraterculus, Neosilba zadolicha and Lonchaea sp.

Mortalidade de percevejo-do-colmo do arroz no preparo do solo para cultivo mínimo

The objective of this work was to verify the influence of the management of irrigated rice stubble, during soil tillage, on the reduction of pre-hibernating populations of the rice stem bug (Tibraca limbativentris). The treatments consisted of the following rice stubble managements: one harrow pass; two harrow passes; two harrow passes, with a leveling pass; and a control. In each sampling unit, the number of nymphs and adults of the rice stem bug was determined. In the soil preparation, at least two harrow passes are necessary to reduce the pre-hibernating population of the rice stem bug.

Teor residual de fipronil no solo para o controle de Oryzophagus oryzae em cultivos subsequentes de arroz irrigado

The objective of this work was to evaluate the potential of fipronil (a.i.) residual content in the soil of flooded rice fields, for the control of Oryzophagus oryzae (Coleoptera: Curculionidae) in subsequent rice cultivations. In 2010/2011, plots (25x55 m) were installed with three treatments: 30 g fipronil (a.i.) 100 kg-1 seed; mixture of 1/3 treated seed (30 g fipronil 100 kg-1 seed) with 2/3 untreated seed equivalent to 10 g fipronil (a.i.) 100 kg-1 seed; and a control without insecticide application. The plots were regrown in 2011/2012, 2012/2013, and 2013/2014 without any insecticide application. The following variables were evaluated: number of larvae and adults from standard samples of soil and roots, and grain yield. In 2011/2012 and 2012/2013, the concentrations of fipronil and of its residues in the soil of plots were evaluated by liquid chromatography and mass spectrometry, and the metabolite fipronil-sulfide (≤ 1.1 μg kg-1) was detected. In the three seasons, after the use of seeds treated with 10 and 30 g fipronil, the average larval infestation of O. oryzae was 65.2 and 96.1% lower, and the average of rice grain yield was 16.9 and 25.5% higher than in the control plot, respectively. The residual fipronil content in the soil, mainly of the highest dose, effectively controls the insect.

VALIDAÇÃO DO ARRANJO ESPACIAL DO PERCEVEJO-DO-COLMO EM ARROZ IRRIGADO POR INUNDAÇÃO

In order to spatial arrangement validation of Tibraca limbativentris Stal, 1860 (Hemiptera: Pentatomidae) in flooded rice field located at the “Planalto da Campanha” Region, Rio Grande do Sul (RS), Brazil, was carried out a study in flooded rice fields at Itaqui, Rio Grande do Sul State, Brazil, in the 2009/10, 2010/11 and 2011/12 harvests. Were established georeferenced grids for the samplings, totaling 81 points spaced ~50 m in the 2009/10 harvest and, 693 and 352 points in the 2010/11 and 2011/12 harvests, respectively, both with equidistant points ~10 m. Adults and nymphs samplings were performed on each point of the regular grids. We conducted a descriptive statistical analysis for the adults, nymphs and adults + nymphs variables by calculations the mean, standard deviation and minimum and maximum values and dispersion indices: variance/mean, Morisita index, k index, Green coefficient and Taylor potency. The rice stem bug spatial arrangement has been validated when the dispersion indices showed similar results. The rice stem bug T. limbativentris spatial arrangement in flooded rice is the aggregate type, regardless of the infestation level and life stage of the insect.

Abundância sazonal de percevejo-do-colmo do arroz

The rice stem bug ( Tibraca limbativentris ) population has increased over the last years making it one of the main pests in irrigated rice crops in Planalto da Campanha, Rio Grande do Sul State, Brazil. Favorable factors throughout the year provide conditions for its infestation in crops and subsequent hibernation. This study aimed to determine the variation of rice stem bug population in commercial irrigated rice crop and hibernation sites. Therefore, a population survey of nymphs and adults was carried out. It was concluded that the photoperiod and temperature were the factors that most affected the insect population, leading to a hibernation period of 10 months. Management operations also affected the population reduction.