[Show abstract][Hide abstract] ABSTRACT: Feeding habits and the activity of digestive enzymes (total alkaline proteases, α-amylase and lipase) from dace Leuciscus leuciscus, roach Rutilus rutilus, Prussian carp Carassius auratus gibelio, perch Perca fluviatilis and pikeperch Sander lucioperca fry were studied in the Malye Chany Lake–Kargat Estuary (western Siberia, Russia). The diet of fry from all studied species was mainly composed of chironomid larvae and zooplanktonic organisms (i.e. cladocera and copepoda), whereas carnivorous species such as P. fluviatilis and S. lucioperca also preyed on fry from other fishes while detritus and microalgae were also important in the diet of ommivorous species. When comparing diet similarity (Sørensen–Dice index, QS) among fry at different stages of development, both omnivorous and carnivorous species showed a high level of similarity (0·67 < QS < 0·89 and 0·73 < QS < 0·89, respectively). Diet similarity values were in agreement with the overall digestive activity profile analysed by cluster analysis. Diet similarity suggested potential trophic competition when zooplanktonic and benthic prey began to decline towards autumn. The analysis of pancreatic digestive enzymes revealed a correlation among their activities and fry feeding habits with α-amylase:total proteases (A:P) values higher than 1 in omnivorous species and lower (A:P ≤ 1) in carnivorous species.
Journal of Fish Biology 09/2014; · 1.83 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Several aspects of immune response in insects treated with an organophosphate (pirimiphosmethyl) have been assessed. Both humoral (phenoloxidase activity) and cellular (hemocyte count and encapsulation rate) immunity changes have been studied in larvae of the representatives of two insect orders, the Colorado potato beetle Leptinotarsa decemlineata (Coleoptera, Chrysomelidae) and the wax moth Galleria mellonella (Lepidoptera, Pyralidae). A direct contact with sublethal and half-lethal doses of the insecticide results in stimulation of immune reactions: phenoloxidase activity and encapsulation rate are heightened, and hemocyte count increases.
Journal of Evolutionary Biochemistry and Physiology 05/2014; 49(6):592-596. · 0.21 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The immunosuppressive and insecticidal activity of culture of the entomopathogenic fungus Cordyceps militaris on the larvae of the Colorado potato beetle Leptinotarsa decemlineata has been established for the first time. It was found that the peroral effect of the fungal culture resulted in dose�dependent decrease in survival, delayed in development time and molting, decreases in the total hemocyt counts, increased activity of phenoloxidases in the hemolymph, and reduced activity of the enzyme in the cuticle, as well as increased sensitivity of larvae to the fungus Beauveria bassiana at the level of the synergistic effect.
[Show abstract][Hide abstract] ABSTRACT: The mortality rate of Anopheles messeae Fll. and Culex pipiens pipiens L. mosquito larvae infected with entopathogenic fungi Metarhizium brunneum and M. robertsii has been studied in laboratory conditions. It was shown that C. pipiens larvae are more susceptible to a water suspension of fungal conidia treatment while A. messeae larvae are more susceptible to treatment with dry conodia. The mortality of mosquito larvae infected with the most virulent strain and dose of 2 x 10(6) conidia per cm(2) was 87.5-92.5%. Prospects for the use of fungi in the biocontrol of bloodsucking mosquitoes are discussed
Contemporary Problems of Ecology 05/2014; 7(3):334-337. · 0.14 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In this study the cellular and humoral immune reactions of the Greater wax moth Galleria mellonella have been investigated during bacterial infection caused by oral administration of Bacillus thuringiensis. Two different dose strengths were investigated to assess the contribution of immune parameters to induced Bt resistance. Low-dose (sublethal LC15) infection resulted in significantly elevated haemolymph phenoloxidase and lysozyme-like activity, enhanced phagocytic activity of haemocytes, and increased encapsulation responses in infected larvae at 48 and 72 h post infection. Higher doses of Bt (half-lethal LC50) also triggered significantly elevated haemolymph phenoloxidase and lysozyme-like activity, but decreased the coagulation index and activity of phenoloxidase in haemocytes of infected larvae. In both types of infection, the pool of circulating haemocytes became depleted. The importance of cellular and humoral immune reactions in induced insect resistance to intestinal bacterial infection Bt is herein discussed.
Journal of Invertebrate Pathology 04/2014; · 2.67 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A 'dark morph' melanic strain of the greater wax moth, Galleria mellonella, was studied for its atypical, heightened resistance to infection with the entomo-pathogenic fungus, Beauveria bassiana. We show that these insects exhibit multiple intraspecific immunity and physiological traits that distinguish them from a non-melanic, fungus-susceptible morph. The melanic and non-melanic morphs were geographical variants that had evolved different, independent defence strategies. Melanic morphs exhibit a thickened cuticle, higher basal expression of immunity-and stress-management-related genes, higher num-bers of circulating haemocytes, upregulated cuticle phenoloxidase (PO) activity concomitant with conidial invasion, and an enhanced capacity to encap-sulate fungal particles. These insects prioritize specific augmentations to those frontline defences that are most likely to encounter invading pathogens or to sustain damage. Other immune responses that target late-stage infection, such as haemolymph lysozyme and PO activities, do not contribute to fungal toler-ance. The net effect is increased larval survival times, retarded cuticular fungal penetration and a lower propensity to develop haemolymph infections when challenged naturally (topically) and by injection. In the absence of fungal infection, however, the heavy defence investments made by melanic insects result in a lower biomass, decreased longevity and lower fecundity in comparison with their non-melanic counterparts. Although melanism is clearly correlated with increased fungal resistance, the costly mechanisms enabling this protective trait constitute more than just a colour change.
Proceedings of the Royal Society B: Biological Sciences 07/2013; 280(1763). · 5.68 Impact Factor