Effects of Bacillus thuringiensis kurstaki on Midgut Cells of Thaumetopoea pityocampa (Lepidoptera: Thaumetopoeidae), The Pine Processionary Caterpillar

In this study effects of Bacillus thuringiensis kurstaki (Btk) on midgut cells of Thaumetopoea pityocampa larvae was investigated by electron microscopy. 3 mg/l Btk was given with food. 1 h, 3 h and 6 h after Btk administration no pathological changes in the midgut epitelial cells were observed. 12 h after Btk administration swelling of mitochondria in midgut epitelial cells were observed. Formation of vacuoles in cytoplasm was seen after 24 h. After 48 h decreasing of microvilli of midgut epithelial cell’s and partial dissolving of cytoplasm, dissolving of nucleoplasm and chromatin clumps were observed. 60 h after Btk administration swelling and dissolving of mitochondria in midgut epithelial cells were detected. 96 h after Btk administration a membrane-body and dissolving in the cytoplasm clumps in midgut cells of T. pityocampa larvae were occurred. Present study shows that Btk is effective to T. pityocampa larvae.