Histopathology of the larval midgut of Helicoverpa armigera (Hübner) fed on Bacillus thuringiensis crystals and Bt-tomato plants

Abstract

The histopathological effects of the spore-crystal complex of indigenous Bacillus thuringiensis (Bt) isolate, as well as Cry 2Ab gene expressed in transgenic tomato plants on the midgut of 4th instar larva of Helicoverpa armigera (Hu¨bner) (Lepidoptera: Noctuidea) has been investigated using the transmission electron microscope (TEM). Remarkable ultrastructural changes were observed in the columnar and goblet cells of the larval midgut after feeding on either transgenic tomato leaves, or spore-crystal complex of Bt. The effects observed included breakdown of microvilli of epithelial cells, increase in the electron density of the cytoplasm and vacuolation associated with different sizes of lysosomes; interruption of the goblet cells and distorted goblet cavities which lost their cytoplasmic projections; destruction of the mitochondria which lost their cristae; degeneration of the endoplasmic reticulum; collapse of the nucleus associated with rupture of nuclear envelope and clumped chromatin. Feeding the larvae on transgenic Bt-tomato plants caused in addition to the aforementioned changes severe vacuolation and degeneration of the nucleus in both columnar and goblet cells and the nuclear membrane was broken into electron dense ring spheres.ª 2015 Production and hosting by Elsevier B.V. on behalf

Bacillus thuringiensis Vip1 Functions as a Receptor of Vip2 Toxin for Binary Insecticidal Activity against Holotrichia parallela

“…Destruction of the midgut manifested as vacuolization of the cytoplasm and abscission of microvilli. These effects were similar to the vacuolization previously described in Helicoverpa armigera [24,25], and Prays oleae [26] larvae treated with Cry toxins and in Spodoptera littoralis [27] fed Vip3A protoxin. This demonstrated that binary toxins Vip1Ad and Vip2Ag, Cry, and Vip3A toxins had similar histopathological effects in the control of agricultural pests.…”

Current Insights on Vegetative Insecticidal Proteins (Vip) as Next Generation Pest Killers

“…This ultimately leads to abnormal microfilament formation and cell death [15,23]. The insecticidal activity of Vip2Ag and Vip1Ad is characterized by the vacuolization and destruction of BBMVs and microvilli depletion, similar to what has been observed in H. armigera fed on Cry2Ab and Vip3AcAa/Cry1Ac binary toxins [51,52]. In a nutshell, the histopathological effects of Vip1/Vip2 binary toxins are comparable to those of Cry proteins.…”

Proteotranscriptomic analyses of the midgut and Malpighian tubules after a sublethal concentration of Cry1Ab exposure on Spodoptera litura

“…Recently, a study has shown that the midgut of Helicoverpa armigera after Bt infection appears to have an accumulation of ribosomes near the nucleus. 41 This suggests that the ribosome might be a universal target response to Cry1Ab stress. Because the RPs are responsible for protein synthesis in the cell being energetically expensive, 42 and the PPI analysis indicated that the RPs interact with energy metabolism processes (e.g., OXPHOS and metabolism), we speculated that the Cry1Ab sublethal effect on S. litura larvae could disrupt of energy homeostasis, causing the larvae to delay growth and development.…”

“…Furthermore, the proteome of the midgut emphasized the prominent role of ribosome proteins (RPs) under Cry1Ab exposure, and these are also presented in the transcriptome and proteome of the Malpighian tubules. Recently, a study has shown that the midgut of Helicoverpa armigera after Bt infection appears to have an accumulation of ribosomes near the nucleus 41 . This suggests that the ribosome might be a universal target response to Cry1Ab stress.…”