Distribuição espacial de Saccharicoccus Sacchari (Cockerell, 1895) e ação de fatores abióticos e bióticos em sua população
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Data
2022-03-25
Autores
Cruz, Maiara Alexandre [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
RESUMO – Saccharicoccus sacchari (Cockerell, 1895) (Hemiptera: Pseudococcidae) é uma espécie amplamente difundida, conhecida principalmente por infestar Saccharum spp. (Poaceae) e outras poucas espécies de gramíneas. No Brasil, foi registrada em estados de Norte a Sul, com relatos informais sobre o aumento do nível de infestação nos canaviais, especialmente em São Paulo. No entanto, é desconhecido como esta espécie se distribui espacialmente nas áreas agrícolas e como fatores bióticos e abióticos interferem em sua população. Neste sentido, objetivou-se determinar a distribuição espacial e estudar a correlação de fatores abióticos (edafoclimáticos), além de inventariar as formigas associadas a S. sacchari em cultivos de cana-de-açúcar convencional e orgânico. O experimento foi conduzido durante dois anos, em dois talhões de cana, convencional e orgânico, com a variedade CTC4, no município de Jardinópolis - SP. Os talhões com um hectare foram subdivididos em 100 parcelas de 10m x 10m. Para o estudo da distribuição espacial, foram utilizados os índices de dispersão: Razão variância/média, Índice de Morisita, Coeficiente de Green e Expoente k da distribuição binomial negativa; e os seguintes modelos de distribuição probabilística: Distribuição de Poisson, Distribuição Binomial Negativa e Positiva. Para os estudos sobre fatores abióticos e o inventário de formigas associadas, as coletas foram realizadas mensalmente, iniciando com duas avaliações de uma touceira por parcela e, posteriormente, com a avaliação no início e no final dos seguintes estádios vegetativos: brotação, perfilhamento e crescimento vegetativo, totalizando duas coletas por estádio e oito ao ano. A cochonilha foi avaliada diretamente sobre as plantas (touceiras/estruturas aéreas), as formigas coletadas quando associadas às colônias do pseudococcídeo. Saccharicoccus sacchari demonstrou ocupar o espaço de forma agregada em canaviais convencional e orgânico. O número de estruturas infestadas pela cochonilha correlacionou-se positivamente com a umidade relativa, precipitação e com valores de zinco, para a área orgânica. Dezoito espécies de formigas foram associadas às colônias do pseudococcídeo. Estudos sobre o padrão espacial e os fatores abióticos e bióticos associados à população de uma espécie são características de considerável significado ecológico; pois, com isto, torna-se possível retratar a distribuição da população ao longo de um determinado período de tempo dentro do ecossistema agrícola.
ABSTRACT – Saccharicoccus sacchari (Cockerell, 1895) (Hemiptera: Pseudococcidae) is a widespread species known mainly for infesting Saccharum spp. (Poaceae), and a few other grasses species. In Brazil, it was registered in states from North to South, with informal reports on the increase in the level of infestation in sugarcane fields, especially in Sao Paulo. However, it is unknown how this species is spatially distributed in agricultural areas and how biotic and abiotic factors interfere in its population. In this sense, the aim was to determine the spatial distribution and to study the correlation of abiotic factors (climate and edaphic), besides to inventorying the ants associated with S. sacchari in conventional and organic sugarcane field. The experiment was carried out for two years in a row, in two sugarcane systems, conventional and organic, with the variety CTC4, in Jardinópolis, SP. The one-hectare plots were subdivided into 100 plots of 10m x 10m. To study the spatial distribution, the following dispersion indices were used: variance/mean ratio, Morisita Index, Green's Coefficient and Exponent k of the negative binomial distribution; and the following probabilistic distribution models: Poisson distribution, Negative and positive Binomial Distribution. For studies on abiotic factors and associated ant inventory, collections were carried out monthly, starting with the evaluation of one clump per plot and later with the evaluation at the beginning and end of the following vegetative stages: budding, tillering and vegetative growth, totaling two collections per stadium and eight per year. Scale insects was evaluated directly on the plants, ants were collected while associated with the mealybug colonies. Saccharicoccus sacchari shown to occupy the space in an aggregated way in conventional and organic sugarcane systems. The number of structures infested by mealybug correlated positively with relative humidity, rainfall and zinc values for the organic area. Eighteen species of ants were associated with scale insect colonies. Studies on the spatial pattern and abiotic and biotic factors associated with the population of a species are characteristics of considerable ecological significance, as this makes it possible to portray the population distribution over a given period of time within the agricultural ecosystem.
ABSTRACT – Saccharicoccus sacchari (Cockerell, 1895) (Hemiptera: Pseudococcidae) is a widespread species known mainly for infesting Saccharum spp. (Poaceae), and a few other grasses species. In Brazil, it was registered in states from North to South, with informal reports on the increase in the level of infestation in sugarcane fields, especially in Sao Paulo. However, it is unknown how this species is spatially distributed in agricultural areas and how biotic and abiotic factors interfere in its population. In this sense, the aim was to determine the spatial distribution and to study the correlation of abiotic factors (climate and edaphic), besides to inventorying the ants associated with S. sacchari in conventional and organic sugarcane field. The experiment was carried out for two years in a row, in two sugarcane systems, conventional and organic, with the variety CTC4, in Jardinópolis, SP. The one-hectare plots were subdivided into 100 plots of 10m x 10m. To study the spatial distribution, the following dispersion indices were used: variance/mean ratio, Morisita Index, Green's Coefficient and Exponent k of the negative binomial distribution; and the following probabilistic distribution models: Poisson distribution, Negative and positive Binomial Distribution. For studies on abiotic factors and associated ant inventory, collections were carried out monthly, starting with the evaluation of one clump per plot and later with the evaluation at the beginning and end of the following vegetative stages: budding, tillering and vegetative growth, totaling two collections per stadium and eight per year. Scale insects was evaluated directly on the plants, ants were collected while associated with the mealybug colonies. Saccharicoccus sacchari shown to occupy the space in an aggregated way in conventional and organic sugarcane systems. The number of structures infested by mealybug correlated positively with relative humidity, rainfall and zinc values for the organic area. Eighteen species of ants were associated with scale insect colonies. Studies on the spatial pattern and abiotic and biotic factors associated with the population of a species are characteristics of considerable ecological significance, as this makes it possible to portray the population distribution over a given period of time within the agricultural ecosystem.
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Palavras-chave
Dispersão, Formicidae, Saccharum, Cana-de-açúcar