Ultrastructural alterations in the midgut of Bacillus sphaericus-treated Culex pipiens (Diptera: Culicidae) larvae

The ultrastructure alterations were described in the midgut of Culex pipiens (Diptera: Culicidae) larvae following Bacillus sphaericus treatment. Two hours post-treatment, the epithelial layer began to have large amount of vacuoles. Explosion in the basement membrane took place 6 h post-treatment. Ten hours post-treatment, the bacterium began to invade the microvilli. At 14 h post-bacterial treatment, epithelial cells were destroyed, microvilli were damaged, and bacteria were present in lumen in large amount. The present study provided the evidence on the main aberrations induced in midgut larvae of Cx. pipiens as a result of ingesting B. sphaericus.