Comparative Histopathology ofPlodia Interpunctella(Lepidoptera: Pyralidae) andTribolium Castaneum(Coleoptera: Tenebrionidae) As Affected byBacillus ThuringiensisVarietiesIndianaorMorrisoni

Abstract

The present study was initiated to compare the histopathology of two isolates of Bacillus thuringiensis (subsp. indiana and subsp. morrisoni), in the larval tissues of Plodia interpunctella (Hübner) and Tribolium castaneum (Herbst). Most changes were localized in the midgut. Other effects were observed in muscles and tracheoles. In P. interpunctella, larvae were treated with a lethal dose of 500 g of B.t. subsp. indiana/g of grains. Changes appeared in midgut cells 8 h after treatment. At 24 h after treatment, cytoplasmic vacuolization was observed in the basal part of cells. Swollen epithelial cells were accompanied by swelling of the nuclei of columnar and goblet cells. The nuclei of the columnar cells were pycnotic and the membraneous sheaths were completely ruptured. The mitochondria had vacuoles 2 h after treatment followed by complete lysis 24 h after treatment. The circular and longitudinal muscles showed relaxation and disintegration of their fibrils and mitochondria. In T. castaneum, larvae were treated with a lethal dose of 5000 g of B.t. subsp. morrisoni/g of grains. Changes appear in the regenerative cells, where cytoplasmic vacuolization and pycnotic nuclei were observed. The tracheal cells showed relaxation of the taenideal cuticular lining and disintegration of mitochondria and chromatin clumping granules around the nuclear membrane 48 h after treatment. Seventy-two hours after treatment, the tracheal and circular muscle fibers showed complete relaxation. The two varieties of B.t. that were collected from grain dust in Egypt, have potential as control agents for stored-product moths and beetles. The toxic action differs in the two tested insect species.

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

“…Shrinkage of the nucleus and nuclear envelope destruction of nuclear sheath and chromatin clumping with accumulation of ribosomes were observed. These findings coincide with those of Salama and Sharaby [19], Ingle et al [5], Salama et al [21], Pandey et al [14], Griego et al [4], Endo and Nishiitsutsuji-Uwo [3], Percy and Fast [15], Abdel-Razek et al [2], Rashmi and Singh [16] working on other lepidopterous insects. In their investigations, the mitochondria and microvilli showed rapid swelling and the connections between the epithelial cells were loosened by the separation of cell membranes.…”

Toxicity and cytopathology mediated by Bacillus thuringiensis in the midgut of Anticarsia gemmatalis (Lepidoptera: Noctuidae)

“…Columnar and goblet cell alterations and regenerative cell reductions are reported in the midgut of Lepidoptera Plodia interpunctella Hübner (Pyralidae) 26 , Epiphyas postvittana Walker (Tortricidae) 27 , Bombyx mori L. (Bombycidae) 28 and Alabama argillacea Hübner (Noctuidae) 19 when they were exposed to Bt. It is possible that every insecticidal protein affects midgut epithelial cells in a unique way, as there are many potential routes to cause midgut epithelial cell death.…”

Labeling membrane receptors with lectins and evaluation of the midgut histochemistry of Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) populations with different levels of susceptibility to formulated Bt

“…have shown failures in the control of Brazilian insect populations treated with B. thuringiensis . Despite the existence of several publications on interactions between Bt and the midgut of different species of Lepidoptera, only two report the histopathological aspects of T. absoluta after interaction with toxins from Bt , and no study has evaluated alterations in the midgut of T. absoluta after interaction with commercial formulations based on Bt .…”