Assessing common bean genotypes for resistance to Diabrotica speciosa (Coleoptera: Chrysomelidae).

Diabrotica speciosa (Germar) (Coleoptera: Chrysomelidae) is a major pest of common bean (Phaseolus vulgaris L.; Fabales: Fabaceae), and adults can defoliate plants during the whole crop cycle. This study was conducted to evaluate the resistance to D. speciosa in 16 common bean genotypes (14 landraces and 2 cultivars), through three different experiments. In the laboratory, choice and no-choice feeding tests were performed to evaluate the percentage of leaf consumption. In the greenhouse, plant height, numbers of leaves, percentage of injured leaves, percentage of injury per leaf, weight of seeds, and D. speciosa survival were evaluated. Furthermore, trichome density, levels of peroxidase (POD), superoxide dismutase (SOD), and protein content in common bean leaves were assessed. In the laboratory, the genotypes Chumbinho Branco, Dobalde, Manteigado, IPR Tuiuiú, and 90D Mouro were the least consumed by D. speciosa. In the greenhouse, the genotypes Dobalde, Manteigado, and IPR Tuiuiú expressed tolerance to the pest, which was associated with a higher plant height and/or unchanged POD and SOD levels and protein content following insect feeding, and no reduction in seed production. The landrace 90D Mouro exhibited antixenosis and tolerance to D. speciosa, observed as a lower leaf injury, higher trichome density, lower protein contents, higher SOD level and no reduction in seed weight. Overall, we have shown that antixenosis and tolerance can help overcome damages resulting from D. speciosa feeding, with emphasis on four common bean genotypes that may be useful in plant breeding programs aimed at controlling D. speciosa in common bean crops.

Repellency and Reduction of Offspring Emergence Potential of Some Botanical Extracts against Sitophilus zeamais (Coleoptera: Curculionidae) in Stored Maize.

Botanical repellents are, usually, considered safe to control Sitophilus zeamais, the main pest of stored maize, as they do not leave toxic residues in food, in addition to having lower costs than chemical insecticides. The aim of this study was to evaluate the repellency potential and the reduction of emerged offspring of botanical extracts, of Schinus terebinthifolius, Ludwigia sericea, L. tomentosa, L. nervosa, L. longifolia, and use them as botanical insecticides for S. zeamais. For the repellency test, arenas were set up, containing 50 g of maize kernels exposed to aqueous extract, besides a control treatment. At the center of each arena, 100 insects were released. After 48 h, the proportion of insects in the treated grains was determined. To test the effects of the extracts on insect mating and egg-laying, free-choice and no-choice tests were performed. Insects in both tests remained for ten days for mating and egg-laying. After this period, insects were removed to evaluate the offspring emergence. Sixty days after grain infestation, the number of emerged insects was counted. All selected botanical extracts demonstrated repellent action against S. zeamais, even after 48 h of application. The L. nervosa aqueous extract significantly reduced the emergence of S. zeamais.

Entomofauna study of bean genotypes by multivariate analysis / Estudio de la entomofauna de genotipos de frijol por medio de análisis multivariado

RESUMEN En el cultivo del frijol existen diversas especies de insectos que pueden ocasionar perjuicios a la productividad y enemigos naturales que pueden ayudar a regular sus poblaciones. El objetivo del presente estudio fue evaluar la entomofauna asociada a 20 genotipos de frijol y correlacionar la interacción entre los insectos utilizando análisis multivariado. Las especies más abundantes en el sistema estudiado fueron Sternechus subsignatus (Curculionidae: Sternechini), Euschistus heros (Hemiptera: Pentatomidae) y Diabrotica speciosa (Coleoptera: Chrysomelidae). Las tres especies presentaron correlación directa entre sí. El cultivo del frijol en estudio presentó tres especies de chinches consideradas importantes plagas. Las especies Cerotoma arcuata (Coleoptera: Chrysomelidae) y Edessa meditabunda meditabunda (Hemiptera: Pentatomidae) presentaron correlación inversa entre sí.

ABSTRACT There are several species of insects that can cause damage to productivity and natural enemies that can help to regulate populations in beans cultivation. The objective of the present study was to evaluate the entomofauna associated with 20 bean genotypes and correlate the interaction between insects using multivariate analysis. The most abundant species in the studied system were Sternechus subsignatus Boheman, 1836 (Curculionidae: Sternechini), Euschistus heros (Hemiptera: Pentatomidae), and Diabrotica speciosa (Coleoptera: Chrysomelidae). All three species showed direct correlation with each other. The bean crop under study presented three species of stinkbugs considered important pests. The species Cerotoma arcuata (Coleoptera: Chrysomelidae) and Edessa meditabunda (Hemiptera: Pentatomidae) presented inverse correlation with each other.

Sand Fly Fauna, Spatial Distribution of Lutzomyia longipalpis (Diptera: Psychodidae), and Climate Factors in Dourados, Brazil.

Studies of the geographic distribution of sand flies and the factors associated with their occurrence are necessary to understand the risk of leishmaniasis transmission. The objective of this study was to characterize the sand fly fauna, particularly the spatial distribution of Lutzomyia longipalpis (Lutz & Neiva), and correlate these with climate factors in the Dourados municipality, Brazil. The collection of sand flies was carried out with CDC Light Traps over two periods: at six sites for three consecutive nights each month from August 2012 to July 2013; and at four other sites for two consecutive nights each month from April 2017 to February 2018. We collected 591 sand flies in the first period and 121 in the second period for a total of 712 sand flies; 697 of the total collected were Lu. longipalpis. The minimum and maximum sand fly infestation rate (sites with vector presence) was 11.1% and 83.33% in the first period, and 0% and 50.0% in the second period. No sand flies with Leishmania were identified via PCR. Lu. longipalpis presented an aggregate disposition with excellent adjustment. Rainfall and relative humidity were the abiotic factors that influenced the vector infestation level. The aggregate distribution for this species was predicted by the environmental factors that favor the proliferation of Lu. longipalpis. The results of this study should assist in devising measures to control sand flies in Dourados, Brazil.

Resistance of Cowpea Genotypes to Spodoptera frugiperda (Lepidoptera: Noctuidae) and Its Relationship to Resistance-Related Enzymes.

Spodoptera frugiperda (J.E. Smith) can attack cowpea plants (Vigna unguiculata [L.] Walp.) (Fabales: Fabaceae) in any growth stage but attacks primarily in the first days after plant emergence, when the plants are more sensitive to defoliation. This study was carried out to evaluate the resistance to S. frugiperda in six cowpea genotypes, of which four were cultivars (BRS Tapahium, BRS Tumucumaque, Fradinho, and Miranda), and two were landraces (Juti and Nioaque), in three different experiments. In the first experiment, adult emergence, adult weight, adult longevity, larva to adult period, numbers of injured leaves per plant canopy (upper, middle, and lower), and reduction in plant dry matter were assessed. In the second experiment, the oviposition preference of S. frugiperda for the different cowpea genotypes was evaluated under free-choice conditions. In the third experiment, levels of peroxidase (POD), superoxide dismutase (SOD), and protein content in cowpea leaves were assessed. Insects fed on landrace Juti plants showed low adult emergence, yielded a lower fitness index, and caused less plant dry matter reduction. In addition, plants of landrace Juti were less preferred for oviposition. Overall, Juti plants showed higher resistance levels in all three resistance categories and higher levels of POD and SOD in S. frugiperda injured leaves, in addition to a lower protein content. Juti will be tested in field conditions, followed by molecular characterization. This will provide additional information about its potential as an S. frugiperda resistance source in plant breeding programs.

Antibiosis Levels to Spodoptera frugiperda (Lepidoptera: Noctuidae) in Cowpea Commercial Cultivars and Landrace Varieties.

Spodoptera frugiperda (J.E. Smith) is a major pest of cowpea, (Vigna unguiculata [L] Walp.) (Fabales: Fabaceae), and to date, few tactics are available to control this pest. This study was conducted to evaluate whether cowpea commercial cultivars and landrace varieties express antibiosis to S. frugiperda. The commercial cultivars were developed by the Brazilian Agricultural Research Corporation (Embrapa), and the landrace varieties were obtained from indigenous communities of Mato Grosso do Sul, Brazil. The effects of the cowpea genotypes (commercial cultivars and landrace varieties) were assessed on the development, survival, and reproductive capacity of the insect. Out of six genotypes, the two landraces were the most resistant to the pest. Landrace Juti decreased larval weight and survival, and no larvae reached the pupal phase. Landrace Nioaque adversely affected the larval and pupal weight, the period of development from larva to pupa, adult emergence, and the period of development from larva to adult. The cultivar Fradinho was classified as moderately resistant for reducing the larval and pupal weights, and delaying the period of development from larva to pupa. The cultivar Miranda was susceptible regarding the growth and survival of S. frugiperda, however, females reared on this cultivar laid a lower number of eggs. The resistant genotypes, especially the landrace varieties are promising for future plant breeding programs, with the objective of developing resistant cultivars to S. frugiperda larvae.

Species Richness and Community Composition of Ants and Beetles in Bt and non-Bt Maize Fields.

Insect-resistant genetically modified (GM) plants have been cultivated in several countries on a large scale. These plants express the Cry toxins from the bacterium Bacillus thuringiensis Berliner (Bacillales: Bacillaceae) (Bt), which confers target-pest resistance to plants. Studies on the effects of GM plants on nontarget organisms are important to assess the technology's impact on biodiversity. The objective of this study was to determine whether there are differences in the species richness and composition of ants and ground beetles in Bt maize (four different toxins: Cry1Ab, Cry1F, and Cry1A.105/Cry2Ab2) and conventional isoline (non-Bt) fields, in the first (summer) and second (winter) cropping seasons in 13 localities of Mato Grosso do Sul State, Brazil, over a 2-yr period (2009-2011). The assessment of Coleoptera and Formicidae species was performed using pitfall traps placed in fields throughout the period of vegetative growth and maturation of plants. Data were analyzed using faunistic indices of species richness, ordination by nonmetric multidimensional scaling, and multivariate analysis of variance. No statistically significant difference was found in the species richness of ant and ground beetle communities when comparing sites of Bt with those of non-Bt maize. Overall, Bt technology did not affect the composition of ant and ground beetles; however, municipality and cropping season exerted influence on the beetle composition. Some species were only observed in the first crop, whereas others were only observed in the second crop. This research suggests that Bt maize does not affect ant and ground beetle populations differently from its isoline.

Antibiosis and antixenosis resistance to oviposition by Bemisia tabaci (Gennadius) B biotype (Hemiptera: Aleyrodidae) in soybean genotypes / Antibiose e antixenose para oviposição da Bemisia tabaci (Gennadius) Biótipo B (Hemiptera: Aleyrodidae) em genótipos de soja

This study was aimed at assessing some biological parameters of Bemisia tabaci B biotype at immature stages to examine antibiosis in six soybean genotypes, besides antixenosis resistance to oviposition in choice and non-choice tests, under greenhouse and laboratory conditions. Between April 2016 and August 2016, bioassays were carried out at the Laboratory of Applied Entomology at College of Agricultural Sciences at Federal University of Grande Dourados (UFGD) Dourados (MS), Brazil. The following variables were evaluated: egg incubation period, nymphal and egg-to-adult duration, egg and nymph viability, and egg-to-adult survival on the soybean genotypes 68i70 RSF IPRO, M6210 IPRO, MS 947 IPRO, BMX Potência RR, M6410 IPRO, and ANTA 82 RR. Antixenosis resistance to oviposition by the silverleaf whitefly was found for MS 947 IPRO, while oviposition was highest for ANTA 82 RR, M6210 IPRO, and M6410 IPRO. The genotype MS 947 IPRO adversely affected egg and nymph viability, and egg-to-adult survival rates was the lowest among genotypes (59.75%), suggesting antibiosis resistance to this pest.(AU)

Este trabalho teve por objetivo avaliar a antibiose em seis genótipos de soja da Bemisia tabaci biótipo B mediante alguns parâmetros biológicos das fases imaturas do inseto, assim como analisar a resistência do tipo antixenose para oviposição em testes com e sem chance de escolha, em laboratório e casa de vegetação. Os ensaios foram conduzidos no Laboratório de Entomologia Aplicada da Faculdade de Ciências Agrárias da Universidade Federal da Grande Dourados (UFGD), Dourados (MS), entre os meses de abril e agosto de 2016. As variáveis averiguadas foram: período de incubação dos ovos; período ninfal; duração de ovo a adulto; viabilidade de ovo; viabilidade de ninfa e sobrevivência de ovo a adulto. Os genótipos de soja avaliados foram: 68i70 RSF IPRO, M6210 IPRO, MS 947 IPRO, BMX Potência RR, M6410 IPRO e ANTA 82 RR. O genótipo que apresentou antixenose para oviposição da mosca-branca foi o MS 947 IPRO, e constatou-se que o maior número de postura foi realizado nos genótipos ANTA 82 RR, M6210 IPRO e M6410 IPRO. O genótipo MS 947 IPRO também afetou negativamente a viabilidade de ovos e ninfas, bem como a sobrevivência de ovo a adulto, com as menores porcentagens de sobrevivência (59,75%), indicando possível resistência do tipo antibiose à mosca-branca.(AU)

DISTRIBUCIÓN ESPACIAL DE Vatiga spp. (HEMIPTERA: TINGIDAE) EN EL CULTIVO DE YUCA / Spatial Distribution of Vatiga spp. (Hemiptera: Tingidae) on Cassava Crop

El objetivo de este trabajo fue generar informacion acerca de cuál es el modelo de disposición espacial de Vatiga spp. en el cultivo de la yuca. Se realizaron muestreos en dos áreas comerciales de 2500 m², divididas en 100 parcelas. Se contaron adultos y de ninfas de Vatiga spp. en las hojas basales y medias de la planta. En total, se realizaron doce muestreos quincenalmente, desde febrero hasta abril de 2014, época de mayor incidencia de esta plaga. De forma general, a través de los índices de dispersión (varianza/media, índice de Morisita y exponente K) y las distribuciones de frecuencia, se observa que la distribución espacial de Vatiga spp. es agregada, es decir, el padrón de distribución Binomial Negativa fue el que resultó de mejor ajuste a los datos obtenidos a campo, con el conteo de los individuos.

The aim of this study was to generate information about which is the model of spatial distribution of Vatiga spp. in the cassava culture. Sampling was conducted in two commercial areas of 2,500 m², divided into 100 plots. Adults and nymphs of Vatiga spp. were counted in the basal and medium plant leaves. In all, twelve samples were taken fortnightly from February to April 2014, when occurs the highest incidence of this pest. Based in the indices of dispersion (variance/mean, Morisita index and K exponent) and the frequency distributions, it was observed that the spatial distribution of Vatiga spp. is aggregate, it means that the standard Negative Binomial distribution was the best fit to the field data obtained, with the counting direction of individuals.

Himenópteros parasitoides associados a ninfas de Triozoida limbata na cultura da goiabeira, em Ivinhema, MS, Brasil / Parasitoid Hymenoptera associated with Triozoida limbata nymphs in guava plantation, at Ivinhema, MS, Brazil

O Brasil tem excelentes condições climáticas para a exploração comercial da goiabeira Psidium guajava L. (Myrtaceae); porém, em todo o país, a cultura é atacada por insetos-praga, sendo Triozoida limbata Enderlein, 1918 (Hemiptera: Triozidae) uma das pragas dessa cultura. Como o controle químico dessa praga é muito oneroso e, muitas vezes, indesejável, a utilização de parasitoides é uma excelente alternativa, pois pode atuar eficientemente na regulação das populações dos seus hospedeiros. Assim, este trabalho objetivou identificar as espécies de parasitoides ocorrentes e seus índices de parasitismo natural em T. limbata no cultivo da goiabeira, em Ivinhema, MS. Foram realizadas coletas quinzenais de março a outubro de 2010, sendo coletados dez ramos terminais das plantas com ninfas de T. limbata, por coleta, sempre no início da manhã. Estes ramos tinham suas bases enroladas em algodão hidrófilo, introduzidas em frascos de vidro (5mL) com água e acondicionados em copos transparentes de acrílico justapostos, e assim mantidos até que ocorresse a emergência dos parasitoides adultos. Para identificação, foram calculadas a porcentagem e o índice de parasitismo natural. Do total de 349 espécimes de parasitoides encontrados, 91,11% foi Psyllaephagus trioziphagus Howard, 1885 (Hymenoptera: Encyrtidae), com 20,96% de parasitismo natural, e 8,89% foram representantes do gênero Signiphora, com 2,04% de parasitismo natural.

Brazil has an excellent climate for commercial use of guava Psidium guajava L. (Myrtaceae). However, guava crops throughout Brazil are severely attacked by the insect Triozoida limbata Enderlein, 1918 (Hemiptera: Triozidae), one of the pest of guava crops. The control of this pest with chemicals is costly and often undesirable, whereas parasitoids are a great alternative because they can efficiently regulate their host populations. This study aimed to identify the parasitoid species in T. limbata occurring in a guava plantation and their rates of parasitism, in Ivinhema, MS, Brazil. Data were collected every two weeks early in the morning from March to October 2010, collecting 10 terminal branches from plants with T. limbata nymphs. The base of the branches were wrapped in cotton wool, placed in 5-mL glass vials with water, packed in transparent acrylic glasses, juxtaposed, and maintained until adult parasitoids emerged. These samples were used to calculate the percentage and index of parasitism. From the 349 parasitoid specimens found, 91.11% were Psyllaephagus trioziphagus Howard, 1885 (Hymenoptera: Encyrtidae) with 20.96% of parasitism, whereas 8.89% were from the genus Signiphora with 2.04% of parasitism.

Análise da entomofauna e flutuação associada a quatro culturas com potencial para produção de biodiesel / Analysis and floating entomofauna associated with four cultures with potential for biodiesel production

As culturas oleaginosas vêm ganhando destaque devido ao seu potencial para a produção de biodiesel, como uma alternativa ao diesel. Portanto, neste trabalho objetivou-se avaliar a entomofauna, por meio de análises faunísticas, associada às seguintes culturas: nabo forrageiro, niger, crambe e girassol, no município de Dourados, estado de Mato Grosso do Sul, tendo em vista que esses cultivares possuem potencial para a produção de biodiesel. Os insetos foram coletados com o método de pano de coleta. As avaliações ocorreram em área experimental agrícola (latitude de 22º 14'S, longitude de 54º 49'W). Foi observado um total de 7.406 espécimes nas quatro culturas, correspondendo a 3.569 espécimes no nabo forrageiro, o qual apresentou uma riqueza de insetos com 18 espécies; 2.275 espécimes no niger, com uma riqueza de 17 espécies; 908 espécimes no crambe com uma riqueza de 18 espécies; e 654 espécimes no girassol com uma riqueza de 18 espécies. Com relação ao estudo da diversidade de espécies medida nas quatro culturas analisadas, o índice de Shannon-Wiener (H') indicou baixa diversidade apenas na cultura do nabo forrageiro, uma vez que o maior valor ocorreu na cultura do girassol (22,935), seguida por crambe (17,487), niger (15,364) e nabo forrageiro (0,5716). A cultura que apresentou o maior índice de equitabilidade foi a do girassol (0,7935), seguida por crambe (0,6047), niger (0,5423) e nabo forrageiro (0,1978), indicando uma semelhança de composição faunística entre girassol, crambe e niger.(AU)

The oilseed crops are gaining prominence due to their potential for the production of biodiesel as an alternative to diesel. Therefore, this study aimed to evaluate the insect fauna through faunal analysis, associated with the following crops: turnip, niger, crambe and sunflower in Dourados, Mato Grosso do Sul State, considering that these cultivars have for the production potential of biodiesel. The insects were collected with sample cloth method. Assessments occurred at the experimental farm (latitude 22° 14'S, longitude 54° 49'W). It was observed a total of 7,406 specimens, representing 3,569 specimens in forage radish in which they are included, 18 species, 2,275 in niger with a wealth of 17 species, 908 in crambe with wealth of 18 species and 654 in sunflower with wealth 18 species. Regarding the study of species diversity measured in four crops analyzed, the Shannon-Wiener diversity indicated low only in the culture of radish, since the highest value occurred in sunflower cultivation (22,935), followed by crambe (17,487), niger (15,364) and turnip (0.5716). The culture that had the highest evenness index was the sunflower (0.7935), followed by crambe (0.6047), niger (0.5423) and turnip (0.1978), indicating a similarity of faunal composition between sunflower, crambe and niger.(AU)

Distribuição espacial de Aphis gossypii (Glover) (Hemiptera, Aphididae) e Bemisia tabaci (Gennadius) biótipo B (Hemiptera, Aleyrodidae) em algodoeiro Bt e não-Bt / Spatial distribution of Aphis gossypii (Glover) (Hemiptera, Aphididae) and Bemisia tabaci (Gennadius) biotype B (Hemiptera, Aleyrodidae) on Bt and non-Bt cotton

Distribuição espacial de Aphis gossypii (Glover) (Hemiptera, Aphididae) e Bemisia tabaci (Gennadius) biótipo B (Hemiptera, Aleyrodidae) em algodoeiro Bt e não-Bt. O estudo da distribuição espacial de adultos de Bemisia tabaci e de Aphis gossypii nas culturas do algodoeiro Bt e não-Bt é fundamental para a otimização de técnicas de amostragens, além de revelar diferenças de comportamento de espécies não-alvo dessa tecnologia Bt entre as duas cultivares. Nesse sentido, o experimento buscou investigar o padrão da distribuição espacial dessas espécies de insetos no algodoeiro convencional não-Bt e no cultivar Bt. As avaliações ocorreram em dois campos de 5.000 m² cada, nos quais se realizou 14 avaliações com contagem de adultos da mosca-branca e colônias de pulgões. Foram calculados os índices de agregação (razão variância/média, índice de Morisita e Expoente k da Distribuição Binomial Negativa) e realizados os testes ajustes das classes numéricas de indivíduos encontradas e esperadas às distribuições teóricas de freqüência (Poisson, Binomial Negativa e Binomial Positiva). Todas as análises mostraram que, em ambas as cultivares, a distribuição espacial de B. tabaci ajustou-se a distribuição binomial negativa durante todo o período analisado, indicando que a cultivar transgênica não influenciou o padrão de distribuição agregada desse inseto. Já com relação às análises para A. gossypii, os índices de agregação apontaram distribuição agregada nas duas cultivares, mas as distribuições de freqüência permitiram concluir a ocorrência de distribuição agregada apenas no algodoeiro convencional, pois não houve nenhum ajuste para os dados na cultivar Bt. Isso indica que o algodão Bt alterou o padrão normal de dispersão dos pulgões no cultivo.

The study of spatial distribution of the adults of Bemisia tabaci and the colonies of Aphis gossypii on Bt and non-Bt cotton crop is fundamental for improving the sampling techniques and revealing differences in the behavior of non-target species between both cultivars. So, this experiment aimed to investigate the spatial distribution pattern of those species on the conventional non-Bt cotton crop, compared to the Bt cultivar. The samplings took place in two areas of 5.000 m² each, where it was done 14 evaluations counting adults of white-flies and colonies of aphids. The aggregation indexes (variance/mean rate, index of Morisita and Exponent k of the Negative Binomial Distribution) were calculated and accomplished the fitness tests of the individuals' numeric classes found and expected to the theoretical distributions of frequency (Poisson, Negative Binomial and Positive Binomial). Those analyses showed that in both cultivars, the spatial distribution of B. tabaci fitted to negative binomial distribution throughout the study period, indicating that the transgenic cultivar did not influence the pattern of aggregate distribution of this insect. With respect to the analysis for A. gossypii, the aggregation indexes showed aggregated distribution in both cultivars, but the distributions of frequency pointed to the occurrence of aggregate distribution only on conventional cotton, since there was no adjustment to the data on Bt crop. This indicates that Bt cotton has altered the aphids normal pattern of dispersion in the crop.

[Spatial distribution of Aedes albopictus in the southern area of Mato Grosso do Sul State, Brazil]. / Distribuição espacial de Aedes albopictus na região sul do Estado de Mato Grosso do Sul.

OBJECTIVE: To investigate the spatial distribution of Aedes albopictus population to provide input for developing sampling plans and supporting decision making on the control of this vector in field sampling. METHODS: A study was carried out in an urban area that has a vestige of primary vegetation, 20 km away from Dourados, Midwestern Brazil. Ten samplings were conducted between January 28, 2003 and April 9, 2003, using ovitraps which were monitored once a week, and distributed in a fixed sample area with 10 collection points for each sampling 300 m away from each other. Aggregation indexes were calculated and adjusted to the following theoretical frequency distribution: negative binomial, positive binomial and Poisson's. RESULTS: The sample variance was higher than the sampling mean, resulting in mean-variance indexes above the unit (32.066, 29.410, 14.444, 58.840, 56.042, 111.262, 70.140, 50.701, 93.221 and 8.481). Morisita's index was also statistically above the unit in all samplings (6.275, 3.947, 1.484, 3.725, 3.014, 5.450, 3.214, 3.886, 3.954 and 5.810), and K parameter ranged 0 and 8 (0.174, 0.309, 1.867, 0.332, 0.449, 0.203, 0.408, 0.314, 0.306 and 0.200). The Chi-square test for adjustment to the negative binomial distribution, positive binomial distribution, and Poisson's distribution was not statistically significant. CONCLUSIONS: Ae. albopictus population in the studied municipality showed an aggregated standard spatial distribution. This means that when individual vectors are found in a certain site, it is likely that other vectors can be found in the proximities, recommending insecticide spraying for vector control in this site without requiring sampling other sites in this same locality.

Distribuição espacial de Aedes albopictus na região sul do Estado de Mato Grosso do Sul / Spatial distribution of Aedes albopictus in the southern area of Mato Grosso do Sul State, Brazil

OBJETIVO: Estudar a distribuição espacial da população de Aedes albopictus, visando fornecer subsídios para construção de planos de amostragem e decisão sobre o controle deste vetor em levantamentos em campo. MÉTODOS: O estudo foi realizado em área urbana próxima de resquícios de vegetação primária, no distrito Picadinha, distante 20 km do município de Dourados, MS. Dez amostragens foram realizadas entre 28/1/2003 e 9/4/2003, utilizando-se armadilhas do tipo ovitrampas e monitoradas semanalmente, distribuídas em uma área amostral fixa com 10 pontos de coleta por amostragem, espaçadas em 300 m. Foram calculados os índices de agregação e ajuste às seguintes distribuições teóricas de freqüência: binomial negativa, binomial positiva e de Poisson. RESULTADOS: A variância amostral foi superior à média nas amostragens, resultando nos índices de razão variância-média sempre acima da unidade (32,066, 29,410, 14,444, 58,840, 56,042, 111,262, 70,140, 50,701, 93,221 e 8,481). O índice de Morisita apresentou valores significativamente acima da unidade em todas as amostragens (6,275, 3,947, 1,484, 3,725, 3,014, 5,450, 3,214, 3,886, 3,954 e 5,810). O parâmetro K resultou em valores entre 0 e 8 (0,174, 0,309, 1,867, 0,332, 0,449, 0,203, 0,408, 0,314, 0,306 e 0,200). Os testes do qui-quadrado de ajuste às distribuições binominal negativa, binomial positiva e de Poisson não foram significativos. CONCLUSÕES: A população de Aedes albopictus da localidade estudada apresentou distribuição espacial padrão agregada. Isso implica que ao encontrar alguns indivíduos do vetor em um determinado local, é provável que outros sejam encontrados nas áreas circunvizinhas, preconizando a aplicação de inseticidas sem a necessidade de amostrar outros pontos dessa localidade.

OBJECTIVE: To investigate the spatial distribution of Aedes albopictus population to provide input for developing sampling plans and supporting decision making on the control of this vector in field sampling. METHODS: A study was carried out in an urban area that has a vestige of primary vegetation, 20 km away from Dourados, Midwestern Brazil. Ten samplings were conducted between January 28, 2003 and April 9, 2003, using ovitraps which were monitored once a week, and distributed in a fixed sample area with 10 collection points for each sampling 300 m away from each other. Aggregation indexes were calculated and adjusted to the following theoretical frequency distribution: negative binomial, positive binomial and Poisson's. RESULTS: The sample variance was higher than the sampling mean, resulting in mean-variance indexes above the unit (32.066, 29.410, 14.444, 58.840, 56.042, 111.262, 70.140, 50.701, 93.221 and 8.481). Morisita's index was also statistically above the unit in all samplings (6.275, 3.947, 1.484, 3.725, 3.014, 5.450, 3.214, 3.886, 3.954 and 5.810), and K parameter ranged 0 and 8 (0.174, 0.309, 1.867, 0.332, 0.449, 0.203, 0.408, 0.314, 0.306 and 0.200). The Chi-square test for adjustment to the negative binomial distribution, positive binomial distribution, and Poisson's distribution was not statistically significant. CONCLUSIONS: Ae. albopictus population in the studied municipality showed an aggregated standard spatial distribution. This means that when individual vectors are found in a certain site, it is likely that other vectors can be found in the proximities, recommending insecticide spraying for vector control in this site without requiring sampling other sites in this same locality.