title: Immunological mechanisms of synergy between fungus Metarhizium robertsii and bacteria Bacillus thuringiensis ssp. morrisoni on Colorado potato beetle larvae.
abstract: The synergistic effect between the entomopathogenic fungus Metarhizium robertsii and a sublethal dose of the bacterium Bacillus thuringiensis ssp. morrisoni var. tenebrionis was studied in terms of immune defense reactions and detoxification system activity of the Colorado potato beetle, Leptinotarsa decemlineata, fourth instar larvae. Bacterial infection led to more rapid germination of fungal conidia on integuments. We found a significant decrease of cellular immunity parameters, including total hemocyte count and encapsulation response, under the influence of bacteria. Phenoloxidase activity in integuments was increased under bacteriosis, mycosis and combined infection compared to controls. However, phenoloxidase activity in the hemolymph was enhanced under bacteriosis alone, and it was decreased under combined infection. Activation of both nonspecific esterases and glutathione-S-transferases in the hemolymph was shown at the first day of mycosis and third day of bacteriosis. However, inhibition of detoxification enzymes was detected under combined infection. The suppression of cellular immunity and detoxification reactions in Colorado potato beetle larvae with a sublethal dose of bacteria is discussed as a reason for synergy between B. thuringiensis and M. robertsii.
authors.affiliation: Institute of Systematics and Ecology of Animals, Siberian Branch of Russian Academy of Sciences, Novosibirsk 630091, Russia. Electronic address: yarosl@inbox.ru.
authors.forename: Olga N
authors.initials: ON
authors.lastname: Yaroslavtseva
authors.affiliation: Institute of Systematics and Ecology of Animals, Siberian Branch of Russian Academy of Sciences, Novosibirsk 630091, Russia.
authors.forename: Ivan M
authors.initials: IM
authors.lastname: Dubovskiy
authors.affiliation: Institute of Systematics and Ecology of Animals, Siberian Branch of Russian Academy of Sciences, Novosibirsk 630091, Russia.
authors.forename: Viktor P
authors.initials: VP
authors.lastname: Khodyrev
authors.affiliation: Kazakh Research Institute for Plant Protection and Quarantine, Almaty, Kazakhstan.
authors.forename: Bahytzhan A
authors.initials: BA
authors.lastname: Duisembekov
authors.affiliation: Institute of Systematics and Ecology of Animals, Siberian Branch of Russian Academy of Sciences, Novosibirsk 630091, Russia.
authors.forename: Vadim Yu
authors.initials: VY
authors.lastname: Kryukov
authors.affiliation: Institute of Systematics and Ecology of Animals, Siberian Branch of Russian Academy of Sciences, Novosibirsk 630091, Russia.
authors.forename: Viktor V
authors.initials: VV
authors.lastname: Glupov
mesh_terms: D000818:Animals; D001413:Bacillus thuringiensis / Q000502:physiology*; D001517:Coleoptera / Q000201:enzymology / Q000254:growth & development / Q000276:immunology* / Q000382:microbiology*; D006434:Hemocytes / Q000166:cytology; D006458:Hemolymph / Q000737:chemistry; D007113:Immunity, Innate; D019476:Insect Proteins / Q000235:genetics / Q000378:metabolism; D007814:Larva / Q000201:enzymology / Q000254:growth & development / Q000276:immunology / Q000382:microbiology; D052981:Metarhizium / Q000502:physiology*; D014442:Monophenol Monooxygenase / Q000235:genetics / Q000378:metabolism; D010572:Pest Control, Biological
chemical_list: D019476:Insect Proteins; D014442:Monophenol Monooxygenase
keywords: Bt; Encapsulation; Esterases; Glutathione-S-transferase; Insect immunity; Leptinotarsa decemlineata; Metarhizium robertsii; Phenoloxidase