Cyanobacteria cause selective action in arthropods depending on their type of nutrition. This influence is complex, many-sided and diverse in nature. We aim to define the role of different components in cyanobacterial activity in arthropod organisms, and to use pathological histology research to identify the various roles of these different componenets. Using several test objects possessing different ways of feeding (e.g., polyphagous fall webworm and oligophagous Colorado potato beetle), histopathological abnormalities were evaluated in model assays using algological, entomological, and histological methods. Cyanobacterial biocidal action caused general and specific inhibitory effects, including mainly deterrent and toxic components, and induced irreversible changes first of all in the digestive tract and then in other organs. A comparative analysis of cyanobacterial action revealed some differences in histopathological abnormalities of the tested objects, most of all in midgut and fat body. Various morphological structures of defensive systems in polyphagous and oligophagous organisms are affective, but, in most cases, degradation and necrosis of the digestive system are the results of penetration of cyanobacterial biological active and/or toxic compounds. In most observations, we revealed these abnormalities in the fall webworm as very intensive and rapid, more frequently than in the Colorado potato beetle; the destructive effect took place during five – seven days. Degradation of the digestive tract produces irreversible abnormal changes in the excretory system of both tested objects. These processes are a part of the general inhibition of vital rhythms in the arthropod organism. Cyanobacterial biocidal characteristics are more likely to be determined as deterrent than toxic; and hereby the fall webworm is more susceptible to cyanobacterial influence than the Colorado potato beetle.
Keywords: cyanobacteria, arthropods, nutrition, pathological histology, midgut, fat body, biocidal activity
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