Distribuição espacial de Aphis gossypii (Glover) (Hemiptera, Aphididae) e Bemisia tabaci (Gennadius) biótipo B (Hemiptera, Aleyrodidae) em algodoeiro Bt e não-Bt

Abstract

ABSTRACT. Spatial distribution of Aphis gossypii (Glover) (Hemiptera, Aphididae) and Bemisia tabaci (Gennadius) biotype B (Hemiptera, Aleyrodidae) on Bt and non-Bt cotton. 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 m 2 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 Adults and Nymphs of Euschistus heros (F.) (Hemiptera: Pentatomidae) on Bt and Non-Bt Soybean

“…Despite the benefits obtained from the Bt cultivar, it is not known exactly how transgenic plants affect the populations of organisms in an agroecosystem (Rodrigues et al, 2010). Understanding the behavior of distribution of non-target pests in transgenic plants makes it necessary to know the shape of the spatial arrangement of this insect in this new technology to determine whether or not to change some characteristics of the sample such as the sample size and sampling units.…”

Spatial distribution of adults and nymphs of stink bug, Edessa meditabunda (Fabricius, 1974) (Hemiptera: Pentatomidae) on soybean Bt and non-Bt

“…According to Rodrigues et al (2010) and Fonseca et al (2013b) report, aggregate behavior of adult insects on cultivation genetically, is modified. However, with respect to non-Bt soybean, adults and nymphs of E. meditabunda set the distribution of aggregate type and even the theoretical frequency distribution.…”

“…This classification is based on the relationship between the variance and mean of the data (Elliott, 1979). However, despite the benefits obtained from the Bt cultivar, exactly how transgenic plants affect the populations of organisms in an agroecosystem is not well known (Rodrigues et al, 2010).…”

Distribuição espacial do pulgão preto em feijão de corda e cálculo do número de amostras

“…A distribuição espacial é a forma de como os indivíduos de uma população se dispersam em seu habitat (RICKLEFS, 2003) e é fundamental para o conhecimento da etologia do inseto, estabelecimento de um plano adequado para otimização das técnicas de amostragem, definição das estratégias de controle, determinação dos danos econômicos e incorporação da dinâmica espacial dentro do modelo populacional (FARIAS; BARBOSA; BUSOLI, 2001;BUSOLI;BARBOSA, 2003;RODRIGUES;SANTOS, 2010).…”