Histopathology and ultrastructure of midgut of Alabama argillacea (Hübner) (Lepidoptera: Noctuidae) fed Bt-cotton.
The interaction of Cry toxins from Bacillus thuringiensis in the midgut of some insect larvae determines their efficacies as insecticides, due to the expression and availability of sites of action of the toxin in the midgut. Researches point out cases of resistance to Cry toxin due to alterations in the binding sites in columnar cell membrane. We analyzed the effects of Cry1Ac toxin expressed by Bt-cotton plants on Alabama argillacea midgut morphophysiology clarifying in levels of morphological and ultrastructural. Larvae in the 4th instar of A. argillacea after 20 min from ingesting Bt-cotton leaves expressing 0.183 ng of Cry1Ac exhibited ultrastructural and morphological modifications in the columnar cells with significant changes in the mitochondrial polymorphism, cytoplasmic vacuolization, microvillus and basal labyrinth. Expressive morphological alterations were also observed in the goblet cells indicating that the columnar cells are not the only target of the Cry1Ac toxin. The regenerative cells did not modify their structures and exhibited decrease in regeneration capacity. In conclusion, the ingestion of 0.183 ± 0.077 ng of Cry1Ac was enough to promote alterations in the columnar and goblet cells, besides reducing significantly the number of regenerative cells, which may have contributed to larval death. Nevertheless, further studies are necessary to determine the true cause of death.
Sousa
Maria Esmeralda C
ME
Departamento de Agronomia, Programa de Pós-Graduacão em Entomologia Agrícola, Universidade Federal Rural de Pernambuco, Av. Dom Manoel de Medeiros s/n, Dois Irmãos, CEP 52171-900 Recife, PE, Brazil.
Santos
Fábio A B
FA
Wanderley-Teixeira
Valéria
V
Teixeira
Alvaro A C
AA
de Siqueira
Herbert Álvaro A
HÁ
Alves
Luiz C
LC
Torres
Jorge B
JB
D000818:Animals; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000008:administration & dosage / Q000494:pharmacology; D016009:Chi-Square Distribution; D004064:Digestive System / Q000378:metabolism* / Q000648:ultrastructure; D004731:Endotoxins / Q000008:administration & dosage / Q000494:pharmacology; D003368:Gossypium / Q000378:metabolism; D006460:Hemolysin Proteins / Q000008:administration & dosage / Q000494:pharmacology; D006651:Histocytochemistry; D007814:Larva / Q000378:metabolism / Q000648:ultrastructure; D007915:Lepidoptera / Q000378:metabolism* / Q000648:ultrastructure; D008854:Microscopy, Electron; D010572:Pest Control, Biological / Q000379:methods*; D030821:Plants, Genetically Modified / Q000378:metabolism / Q000648:ultrastructure
D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D004731:Endotoxins; D006460:Hemolysin Proteins; C030956:insecticidal crystal protein, Bacillus Thuringiensis