Distribuição vertical de Crysodeixis includens (Lepidoptera: Noctuidae) em cultivar transgênica e convencional de algodoeiro / Vertical distribution of Crysodeixis includens (Lepidoptera: Noctuidae) in transgenic and conventional cotton cultivars

RESUMO

O objetivo deste estudo foi avaliar a distribuição intra-planta de lagartas de Crysodeixis includens no cultivar convencional FM 993 e na sua isolinha transgênica FM 975 WS (WideStrike), que expressa as proteínas tóxicas Cry1Ac e Cry1F. O experimento foi realizado com o delineamento em blocos casualizados em esquema de parcelas subdivididas, com seis tratamentos (três terços da planta x duas faces foliares) e 40 repetições. As plantas foram visualmente divididas em três terços (superior, médio e inferior) e nas faces adaxial e abaxial das folhas, registrando-se o número de lagartas. Lagartas de C. includens foram identificadas em maior número no cultivar não-Bt (FM 993), enquanto que, na cultivar transgênica FM 975 WS (WideStrike), foram constatadas apenas as pequenas, em número significativamente menor que na sua isolinha não-Bt (FM 993). As lagartas, independentemente do tamanho e do cultivar, foram mais encontradas na parte inferior e mediana do dossel das plantas e, ainda, na face abaxial das folhas.

ABSTRACT

The aim of this study was to evaluate the intra-plant distribution of Crysodeixis includens in conventional FM 993 and transgenic FM 975 WS (WideStrike), which express the toxic proteins Cry1Ac and Cry1F. The experiment was carried out in a split-plot design arranged under a complete block design with six treatments (three thirds x two plant leaf surface) and 40 repetitions. The plants were visually divided into three thirds (upper, middle and lower) and into adaxial and abaxial leaves, registering the number of caterpillars. C includens caterpillars were found at higher numbers in the non-Bt cultivar (FM 993), while in the transgenic cultivar FM 975 WS (WideStrike) were found only small caterpillars, and significantly fewer compared to their non-Bt isoline (FM 993). Caterpillars, regardless of size and cultivar, were most commonly found at the bottom and middle thirds of the plant canopy and on the abaxial leaf surface.