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Effects of rearing density on larval growth and activity of digestive enzymes in Lymantria dispar L. (Lepidoptera: Lymantriidae)

100%

Lazarevic J., Peric-Mataruga V., Vlahovic M., Mrdakovic M., Cvetanovic D.

Folia Biologica

2004

vol. 52

issue 1-2

105-112

Density dependent responses of 4th, 5th and 6th instar gypsy moth larvae were studied at the level of larval mass, midgut loading and activities of three digestive enzymes (alpha-amylase, trypsin and leucine aminopeptidase). High density significantly reduced larval mass while midgut loading (expressed as relative midgut mass) did not change except in the 5th instar where it was increased at high density. Specific amylase and leucine aminopeptidase activities were not affected by crowding. Specific trypsin activity was on average higher in crowded than in isolated larvae. High density also affected the correlations between midgut protein content and activities of two proteolytic enzymes suggesting differences in regulatory mechanisms of insect digestion. The importance of these changes for survival under stressful conditions is discussed.

Density, biomass, and distribution of benthic invertebrates in the mid-lake zone of the coastal Lake Gardno

88%

Dobrowolski Z.

The mean density (4.2 ? 103 ind. m-2) and mean biomass (10.8 g wet weight m-2) of the mid-lake zoobenthos in the mixo-oligohaline Lake Gardno were consistent with the respective ranges typical of freshwater, polymictic, and strongly poly-trophic lakes of northern Poland. The major components of the Lake Gardno macrozoobenthos were tubificid oligochaetes and chironomid larvae, the latter dominating in terms of abundance and biomass. Neomysis integer (Leach) was the sole and numerically scant marine invertebrate in the Gardno mid-lake macro-zoobenthos. Biodiversity, taxonomic composition, dominance structure as well as densities and biomass of the macrozoobenthos studied showed considerable spatial variation. The lake-river contact zone exhibited the presence of the ecotone effect. Dynamics of the abundance and biomass of the benthic invertebrates inhabiting that zone were markedly different from those found in other mid-lake habitats of the Gardno.

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1 Vlahovic M.

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Effects of rearing density on larval growth and activity of digestive enzymes in Lymantria dispar L. (Lepidoptera: Lymantriidae)

Density, biomass, and distribution of benthic invertebrates in the mid-lake zone of the coastal Lake Gardno