ISSN:
1570-7458
Keywords:
Bacillus thuringiensis var.
;
biocidal activity
;
midgut epithelium histopathology
;
Culex pipiens
;
Aedes rusticus
;
Anopheles claviger
;
Culiseta morsitans
;
Chironomus annularius
;
Glyptotendipes barbipes
;
Simulium variegatum
;
Odagmia ornata
;
Simocephalus vetulus
;
Simocephalus serrulatus
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Species of Diptera (larval Culicidae, Chironomidae and Simuliidae) and Crustacea (cladoceran adults) that are representative of the fauna of aquatic alpine ecosystems are routinely treated with Bacillus thuringiensis var. israelensis (Bti) for mosquito control. The toxicity of Bti on these organisms was investigated. Bioassays indicated that Bti used at the concentration for operational field application is deleterious to all dipteran species, but not to Cladocera. Histopathological observations reveal that, in all cases, the midgut epithelium is affected by Bti treatment. However, the vulnerability of epithelial cells to the microbial insecticide is different from one cell-type to another, clear cells being more vulnerable than dark cells. Because of the concentration of clear cells within the anterior midgut of dipteran larvae, this region appears to be the first to show symptoms of intoxication through enhancing a natural process of cell turnover. The relative importance of such a vulnerable region in the midgut of dipteran larvae may account for the general efficacy of Bti to these species. Its harmlessness to Cladocera may be correlated to the relative scarcity of clear cells and their patchy distribution along the whole midgut together with important cellular renewal capacity of the epithelium.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1003440012880
Permalink
