ABSTRACT Knowledge about the spatial distribution of fruit flies (Diptera: Tephritidae) and tritrophic interactions (fruit-fruit fly parasitoid) contributes to the monitoring and maintenance of the numerical density at a level lower than economic damage. The purpose of this study was to identify the spatial distribution and associations of fruit flies with their parasitoids and host plants in the municipality of Bom Jesus-PI. The flies were obtained from fruit collection from July 2018 to May 2019. A total of 1,711 individuals were obtained, represented by six species: Anastrepha obliqua (Macquart, 1835), An. fraterculus (Wiedemann, 1830), An. alveata Stone, 1942, An. sororcula Zucchi, 1979, An. zenildae Zucchi, 1979 and Ceratitis capitata (Wiedemann, 1824). Anastrepha obliqua was the species with the widest distribution throughout the ecotone area. Ceratitis capitata is distributed only in the urban perimeter. A tritrophic relationship occurred between four species of parasitoids, Asobara anastrephae (Muesebeck, 1958) or Opius sp. associated with An. obliqua in Spondias mombin or S. tuberosa fruits. Opius sp. has also been associated with An. alveata in Ximenia americana. Pachycrepoideus vindemiae was obtained from C. capitata in Malpighia emarginata, in addition to An. obliqua in Averrhoa carambola. Therefore, fruit flies are associated with native fruit trees (S. tuberosa, S. mombin, S. purpurea, P. acutangulum, Inga laurina, X. americana) and exotic fruits (M. emarginata, A. carambola, P. guajava). Ceratitis capitata was recorded for the first time in the state of Piauí infesting I. laurina (Sw.) Willd. This is the first record of the parasitoid genus Spalangia. in An. obliqua in Piauí and in the semiarid region of Brazil.

RESUMO O solo é um dos compartimentos de água de maior importância em uma bacia hidrográfica. A vegetação depende majoritariamente da água retida pelo solo para atender às suas demandas; e o início do escoamento superficial depende fortemente da umidade inicial do solo. Este estudo teve como objetivo avaliar a permanência da efetividade da água no solo sob condições de vegetação preservada no bioma Caatinga, Semiárido do Nordeste brasileiro. Para isso, foram analisados dados horários de umidade do solo através de sensores TDR obtidos entre os anos de 2003 e 2010 para três associações solo-vegetação presentes na Bacia Experimental de Aiuaba. Os resultados indicam que, durante nove meses ao ano, a água no solo encontra-se abaixo do ponto de murcha permanente para duas associações, cujos solos são Argissolo Vermelho -Amarelo e Luvissolo Hipocrômico. Na terceira associação, cujo solo é raso (Neossolo litólico), a água encontra -se não efetiva durante quatro meses ao ano. Avalia-se que a maior permanência de água neste solo dê-se pela limitação de percolação profunda, induzindo o escoamento sub-superficial; o que não se verifica nos solos mais profundos. Verificou-se in situ que o longo período de umidade abaixo do ponto de murcha permanente não comprometeu a vida das espécies da Caatinga. Após o início de cada período chuvoso, observa -se o crescimento de uma densa massa de vegetação, apesar do longo período sob estresse hídrico.

ABSTRACT Soil is an important water compartment into a watershed scale, mainly due to its role in providing water to plants and to the influence of antecedent moisture on the runoff initiation. The aim of this research is to assess the permanence of water effectiveness in the soil under preserved-vegetation constraints in the Caatinga biome, in the semiarid northeastern Brazil. For this purpose, hourly soil moisture measurements were collected with TDR and analyzed between 2003 and 2010 for three soil-vegetation associations in the Aiuaba Experimental Basin. The results showed that in nine months per year soil moisture was below wilting point for two associations, whose soils are Chromic Luvisol and Haplic Lixisol (Abruptic). In the third association, where the shallow soil Lithic Leptosol prevails, water was found non-effective four months per year. A possible reason for the high water permanence in the shallowest soil is the percolation process, generating sub-surface flow, which barely occurs in the deeper soils. In situ observations indicates that the long period of soil moisture below the wilting point was not enough to avoid the blooming season of the Caatinga vegetation during the rainy periods. Indeed, after the beginning of each rainy season, there is a growth of dense green vegetation, regardless of the long period under water shortage.

O objetivo deste trabalho foi representar a umidade do solo no perfil correspondente à zona das raízes a partir de sensores TDR em uma área preservada do Bioma Caatinga e analisar as equações de ajuste de umidade espacializadas sob diferentes camadas do perfil do solo. Para isso, foram analisadas três classes de solo (Argissolo Vermelho-Amarelo; Luvissolo Hipocrômico; Neossolo Litólico) presentes na Bacia Experimental de Aiuaba, Semiárido do Nordeste do Brasil. Os parâmetros físico-hídricos que representam as faixas limítrofes de retenção da água no solo (capacidade de campo, ponto de murcha permanente e umidade residual) foram coletados em quatro campanhas, em seis pontos e nos perfis correspondentes à profundidade efetiva das raízes totalizando 216 amostras analisadas. Para avaliação dos modelos de regressão utilizaram-se o coeficiente de determinação, a escala de Pearson e o índice de desempenho. Os resultados indicam que os parâmetros analisados são homogêneos para os perfis de solo estudados. O coeficiente de correlação de Pearson indica desempenho moderado para as equações de ajuste. Entretanto, o índice de confiança do modelo de regressão linear foi enquadrado como péssimo para o Argissolo Vermelho-Amarelo, sofrível para o Luvissolo Hipocrômico e mau para o Neossolo Litólico para os dados do mês chuvoso, e péssimo para todas as classes no período seco. Os usos dos modelos de regressão são mais recomendados para os períodos de maior umidade do solo.

The purpose of this study was to represent the soil moisture in the profile corresponding to the root zone from TDR sensors in a preserved area of the Caatinga biome and analyze the spatialized moisture adjustment equations under different layers of the soil profile. For that, we analyzed three classes of soil (red yellow Ultisol; Hypochromic Luvisol; Udorthent) in the Aiuaba Experimental Watershed, located in the semiarid zone of northeastern Brazil. The hydro-physical parameters representing the soil water retention (field capacity, wilting point and residual moisture) were collected in four campaigns, in six points and in the profiles corresponding to the effective root depth, totaling 216 samples. For the evaluation of the regression models, we used the coefficient of determination, the Pearson correlation and the performance index. The results indicate that the analyzed parameters are homogeneous for the studied soil profiles. The Pearson correlation coefficient indicates a moderate performance for all regression equations. However, the confidence index was determined as very bad for the Red-Yellow Ultisol, passable for the Hypochromic Luvisol and bad for the Udorthent, for the rainy season, and very bad for all classes, for the dry season. Therefore, the use of the regression models is more indicated for periods of higher soil moisture.

A produção de biomassa em uma pastagem pode ser incrementada com o uso de fertilizantes, principalmente os nitrogenados. Diante disso, objetivou-se, com este trabalho, avaliar o fluxo de biomassa do capim-massai, durante o estabelecimento e a rebrotação, em casa de vegetação, sob cinco doses de nitrogênio (0; 150; 300; 450 e 600 mg de N dm-3 de solo), em delineamento inteiramente casualizado, com medidas repetidas no tempo, e cinco repetições. A taxa de alongamento foliar foi incrementada pelas doses de nitrogênio (N) e o crescimento de estabelecimento apresentou maior valor, em relação ao das rebrotações. A taxa de alongamento das hastes não foi influenciada pelas doses de N. O crescimento de estabelecimento apresentou maior valor para esta variável, em relação ao das rebrotações. A taxa de senescência foliar anterior não sofreu influência das doses de N, porém, foi alterada entre os ciclos de crescimento. O número de folhas vivas por perfilho foi superior, para as maiores doses e no estabelecimento, o inverso ocorrendo para o filocrono. A dose aplicada de 600 mg dm-3 de N proporcionou um incremento de 448%, na taxa de produção de forragem, e de 455%, na taxa de acúmulo de forragem, em relação àquelas do manejo sem N. A adubação nitrogenada proporciona respostas positivas nas variáveis do fluxo de biomassa do capim-massai.

The use of fertilizers, especially nitrogen, can increase significantly the biomass production of a pasture. The objective of this study was to evaluate the biomass flow of Massai grass produced in greenhouse during the establishment and regrowth under five nitrogen fertilization levels. The experiment was arranged in a completely randomized split-plot design with five nitrogen levels (0; 150; 300; 450 e 600 mg de N dm-3 of soil) and five replications (plots) .The leaf elongation rate was increased with the nitrogen fertilization levels and the establishment growth presented higher values in relation to the regrowth. The culm elongation rate was not influenced by N levels. The establishment growth presented higher values than regrowth. The leaf senescence rate before the cut was not influenced by the nitrogen fertilization, however it was altered by the growth cycles. The number of living leaves per tiller was superior on plants fertilized with highest N levels and at establishment growth, however an opposite effect was observed to the phylochron. The fertilization level 600 mg de N dm-3 of soil lead to an increase of 448% on herbage growth, and of 455% on herbage accumulation rates in relation to the 0 mg de N dm-3 of soil. The nitrogen fertilization provides positive responses to the biomass flow of Massai grass.

The objective of this study was to evaluate gas exchange in the massai grass during establishment and regrowth cycles in a greenhouse, using five nitrogen (N) fertilization levels. A completely randomized split-plot design of five nitrogen levels (0; 150; 300; 450 and 600 mg N•dm-3 of soil) was employed with the N levels as plots, and the cycles (establishment, regrowth 1 and 2) as subplots, evaluated with five replicates. We evaluated leaf transpiration (E), leaf temperature (TFOL), leaf photosynthesis rate (A), leaf carbon dioxide concentration (Ci), stomatal conductance (gs), photosynthesis/transpiration ratio (A/E), photosynthesis/conductance ratio (A/gs), chlorophyll relative index (CRI), and nitrogen sufficiency index (NSI). Growth cycles influenced all physiological characteristics, except for NSI. N fertilization levels affected TFOL, A, CRI and NSI variables, whereas for gs, E, Ci, A/E and A/gs it did not occur. A increased from 6.38 to 10.33 µmol•m-2.s-1, at levels 0 and 600 mg N•dm-3 of soil, respectively. Gas exchange in the massai grass was favored by nitrogen fertilization, since the cycles amended these characteristics of the grass.

To evaluate biomass components of Massai grass under five doses of N (0, 150, 300, 450 and 600 mg N/dm³ soil) during three cycles of growth (establishment, regrowth 1 and regrowth 2) this study was carried out. The experiment was carried out in a greenhouse, in a completely randomized design with measures repeted over time and five replications. In the three cycles, nitrogen doses had increasing linear effect on green herbage dry matter (GHDM), green leaf dry matter (GLDM), on the tiller population density (TPD) and on forage density. Canopy height and foliage height were the highest ones in establishment of regrowth 2, respectively, and they decreased at the highest doses of nitrogen. Irrigation depth was the greatest at the highest doses and in regrowth 1. Water use efficiency responded positively to the doses, being the regrowth 2 the highest values were obtained at the highest doses of nitrogen. Nitrogen use efficiency by Massai grass is influenced by fertilizantion as well as by the cycles. Nitrogen fertilization has positive effects on the components of Massai grass biomass.