Flutuação populacional, distribuição espacial e plano de amostragem sequencial de Anticarsia gemmatalis (Hübner, 1818) (Lepidoptera: Erebidae) e Chrysodeixis includens (Walker, 1858) (Lepidoptera: Noctuidae) em diferentes cultivares de soja
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2018-04-27
Autores
Santos, Leticia Serpa dos [UNESP]
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Universidade Estadual Paulista (Unesp)
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Dentre as lagartas desfolhadoras mais importantes nos cultivos da soja no Brasil estão a Anticarsia gemmatalis e a Chrysodeixis includens. O objetivo deste trabalho foi determinar a flutuação populacional e a relação com fatores meteorológicos e a distribuição espacial de A. gemmatalis e de C. includens em cultivares de soja com diferentes ciclos de desenvolvimento, visando gerar informações sobre o comportamento dessas lagartas na cultura da soja e elaborar um plano de amostragem sequencial para a cultura da soja. Os experimentos foram conduzidos nos anos agrícolas 2013/14 e 2014/15 na FCAV/UNESP, Jaboticabal, SP. Foram selecionados três campos, e em cada um foi demarcada uma área de 8.000 m2, sendo cada área subdividida em 80 parcelas de 100 m2 (10 m x 10 m). As cultivares de soja utilizadas foram: SYN 1365 RR (precoce), M 7908 RR (média) e BRS Valiosa RR (tardia). As amostragens foram realizadas semanalmente pelo método da batida de pano, em 2 m de linha de plantas, registrando-se o número total de lagartas maiores que 1,5 cm de A. gemmatalis e C. includens. Para o estudo da flutuação populacional das espécies de lagartas da soja os resultados foram submetidos à analise estatística, efetuando-se correlação de Pearson, entre o número de espécies de lagartas e as variáveis meteorológicas, precipitação e temperatura. Para o estudo da dispersão foram utilizados os seguintes índices: razão variância/média, índice de Morisita, coeficiente de Green e o expoente k da distribuição binomial negativa. Para os estudos dos modelos de distribuição espacial foram testados os ajustes das distribuições de Poisson e binomial negativa. O plano de amostragem sequencial foi elaborado para os dados de lagartas maiores que 1,5 cm com base no Teste Sequencial da Razão da Máxima Verossimilhança, e foi utilizado o nível de controle de 40 lagartas maiores que 1,5 cm por pano de batida na cultura da soja. De acordo com os resultados da flutuação populacional, as maiores densidades populacionais de A. gemmatalis e C. includens foram observadas no estádio fenológico R1 da soja. A temperatura influenciou a variação da densidade populacional de C. includens no primeiro ano agrícola e a precipitação influenciou a população de ambas as lagartas nos dois anos agrícolas. A distribuição espacial de lagartas maiores que 1,5 cm foi agregada para todas as cultivares no ano agrícola com baixa incidência de lagartas e aleatória no ano agrícola com alta incidência de lagartas, com melhor ajuste à distribuição binomial negativa. No plano de amostragem sequencial, verificou-se um máximo de dez unidades amostrais para tomada de decisão de controle.
The most frequent leafhopper caterpillars on soybean crops in Brazil are Anticarsia gemmatalis and Chrysodeixis includens. The objective of this work was to study the population fluctuation and spatial distribution of A. gemmatalis and C. includens in soybean cultivars of different maturing cycles in order to help the development of a sequential sampling plan. The experiments were carried out in seasons 2013/14 and 2014/15 at FCAV / UNESP, Jaboticabal, SP. Three fields were selected, and on each one an area of 8.000 m² was marked and divided into 80 splits of 100 m² (10 m x 10 m). The soybean cultivars of different maturing cycles were: SYN 1365 RR (early), M 7908 RR (middle) and BRS Valiosa RR (late). Samples were taken weekly using the ground-shake method, in two m line of plants, where it was recorded the number of caterpillars A. gemmatalis and C. includens higher than 1.5 cm. The figures were plotted to demonstrate the population fluctuation between the mean data of insect pest infestation and the phenological stage of culture, and the influence of meteorological factors analyzed using correlation analysis. Insect dispersion in the area was evaluated using the following indexes: variance/mean ratio, Morisita’s index, Green’s coefficient, and the k exponent of negative binomial distribution. For studies of spatial distribution models of A. gemmatalis and C. includens, adjustments of Poisson distribution and negative binomial distribution were tested. The sequential sampling plan was developed for caterpillars higher than 1.5 cm based on the ratio of the Sequential Test Maximum Likelihood, and it was used the threshold levels of 40 and 20 caterpillars higher than 1.5 cm in soybean. According to the results of population fluctuation, the highest population densities of A. gemmatalis and C. includens were observed at the R1 soybean phenological stage. The temperature influenced the variation of population density of C. includens in the first agricultural year and the precipitation influenced the population of both caterpillars in the two agricultural years. The spatial distribution of caterpillars larger than 1.5 cm was aggregated for all cultivars in the agricultural year with low incidence of caterpillars and random in the agricultural year with high incidence of caterpillars, with better adjustment to the negative binomial distribution.In the sequential sampling plan, the maximum number of sample units expected for control of decision-making is around ten samples.
The most frequent leafhopper caterpillars on soybean crops in Brazil are Anticarsia gemmatalis and Chrysodeixis includens. The objective of this work was to study the population fluctuation and spatial distribution of A. gemmatalis and C. includens in soybean cultivars of different maturing cycles in order to help the development of a sequential sampling plan. The experiments were carried out in seasons 2013/14 and 2014/15 at FCAV / UNESP, Jaboticabal, SP. Three fields were selected, and on each one an area of 8.000 m² was marked and divided into 80 splits of 100 m² (10 m x 10 m). The soybean cultivars of different maturing cycles were: SYN 1365 RR (early), M 7908 RR (middle) and BRS Valiosa RR (late). Samples were taken weekly using the ground-shake method, in two m line of plants, where it was recorded the number of caterpillars A. gemmatalis and C. includens higher than 1.5 cm. The figures were plotted to demonstrate the population fluctuation between the mean data of insect pest infestation and the phenological stage of culture, and the influence of meteorological factors analyzed using correlation analysis. Insect dispersion in the area was evaluated using the following indexes: variance/mean ratio, Morisita’s index, Green’s coefficient, and the k exponent of negative binomial distribution. For studies of spatial distribution models of A. gemmatalis and C. includens, adjustments of Poisson distribution and negative binomial distribution were tested. The sequential sampling plan was developed for caterpillars higher than 1.5 cm based on the ratio of the Sequential Test Maximum Likelihood, and it was used the threshold levels of 40 and 20 caterpillars higher than 1.5 cm in soybean. According to the results of population fluctuation, the highest population densities of A. gemmatalis and C. includens were observed at the R1 soybean phenological stage. The temperature influenced the variation of population density of C. includens in the first agricultural year and the precipitation influenced the population of both caterpillars in the two agricultural years. The spatial distribution of caterpillars larger than 1.5 cm was aggregated for all cultivars in the agricultural year with low incidence of caterpillars and random in the agricultural year with high incidence of caterpillars, with better adjustment to the negative binomial distribution.In the sequential sampling plan, the maximum number of sample units expected for control of decision-making is around ten samples.
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Glycine max, dispersão, lagarta-da-soja, lagarta-falsa-medideira, binomial negativa, dispersion, velvetbean caterpillar, looper caterpillar, negative binomial.