S u m m a r yOsmia rufa as a polylectic insect is used in the pollination of numerous plants. The usefulness of this insect for plant breeders is considerably limited because of the short flight periods of the insects in the natural environment. In order to break this limitation, the wintering period of the insects in cocoons is elongated. The temperature is maintained at 4°C up to the time of plant blooming. This treatment does shortens the lifetime of the insects which may be the result of oxidative stress. Such results led to the examination of the selected components of antioxidative system. These components are: total antioxidative status, content of glutathione and activity of peroxidase and glutathione S-transferase in O. rufa emerged in spring, according to their biological clock, and emerged in summer -after elongated diapause. It was observed that diapause elongation unprofitably influenced the antioxidative system of a bee. A statistically significant decrease in total antioxidative status, and activity of both antioixidative enzymes -peroxidase and glutathione S-transferase, was noted. The changes in the glutathione level in turn, were insignificant. In our opinion, the lower efficiency of antioxidative systems of the red mason bee emerged in summer, may limit their response ability to endo-and exogenous factors influencing oxidative stress. The results of our study are the first publication concerning an antioxidative system in mason bees.

Bees of the genus Osmia are being used in crop pollination at an increasing rate. However, a short life expectancy of adult individuals limits the feasibility of their use. Cocoons of the red mason bee, Osmia rufa L. (Hymenoptera: Megachilidae), can be stored at 4° C in a postdiapause state, and adult bees can be used for pollination outside their natural flight period. The period of storage in this form has an unfavorable influence on the survival rate, life expectancy, and fertility of the bee. It was suggested that the negative results are connected with exhaustion of energy reserves. To test this hypothesis, the present study examined the contents of protein, carbohydrates, lipids, and the activities of some enzymes, and their degradation in red mason bees that emerged in spring according to their biological clock and in summer after elongated diapause. It was found that postdiapause artificially elongated by 3 months caused significant decreases in body weight, total sugar, glycogen, lipids, and protein content in O. rufa. Glucose level was highest in bees that emerged in the summer, which was coincident with increased activities of maltase and trehalase. The activities of sucrase and cellobiase were not changed, while amylase activity was considerably decreased. The activities of triacylglycerols lipase and C2, C4, C10 carboxylesterases were highest in bees that emerged in July. Low temperatures restrict O. rufa emergence, and during prolonged postdiapause, metabolic processes lead to significant reductions of structural and energetic compounds.

a b s t r a c t osmia rufa is a solitary bee that is used commercially for pollinating crops. The bee enters obligatory diapause as an imago. The activity of proteolytic enzymes during diapause has not been investigated. we studied the proteinase activity on four substrates -casein, haemoglobin, bovine serum albumin (bsa), and gelatine -during diapause (from october to march) and in newly hatched males and females in april. during diapause, greater fluctuations in enzyme activity levels were noted in males than in females, and a significant decrease in male enzyme activity was observed in January and march. male enzymes were most effective in decomposing gelatine; whereas, female enzymes were equally effective in hydrolysing gelatine and bsa. The differences in substrate preferences between male and female enzymes were particularly pronounced in october and in the newly hatched individuals. The levels of gelatinolytic activity likely indicate that a high proportion of proteinases in o. rufa are elastase-like enzymes. They are involved in the digestion and remodelling of proteins with numerous peptide bonds formed by amino acids with short side-chains.

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Lymnaea stagnalis is an intermediate host of many Digenea. The infestation affects host metabolism. The aim of the work was to investigate hemolymph biochemical indicators of L. stagnalis infected with four species of trematodes: Diplostomum pseudospathaceum, Paryphostomum radiatum, Plagiorchis elegans or Opisthioglyphe ranae. The protein profiles and proteinase activity in the hemolymph of sexually mature individuals of Lymnaea stagnalis maintained at 19 • C were tested. As the carbohydrates are main substrates for energetic metabolism of the great pond snail their content and disaccharidase activity were also studied. Hemolymph samples were collected during weeks 3 and 4 of rearing. No significant differences in the total protein content between uninfected individuals and snails infected with the first three trematode species were detected. In the snails infected with O. ranae the quantity of total proteins was near twice higher than in those uninfected. A higher share of 70 kDa proteins in infected than in uninfected snails as well as reduction of the low molecular weight fractions of proteins for snails infected with D. pseudospathaceum and P. radiatum were detected. During week 3, carbohydrate content in the infected snails did not differ from that in the controls while during week 4 it was significantly lower in snails infected with P. elegans or O. ranae. The content of the major soluble carbohydrate in the hemolymphsaccharose -changed in a similar way. No activity of trypsin or pepsin in the hemolymph sample was detected while the activity of chymotrypsin was lower in infected snails vs. controls. On the other hand, saccharase and maltase activities were higher in infected than in uninfected snails. The biochemical hemolymph indicators in naturally infected host-snails show some differences depending on the parasite species but they are not sufficiently species-specific to offer the basis for establishing the model unique for a particular parasitosis. Our results from the field did not always coincide with those from the laboratory.