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2 Ulrich W.

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The Hymenoptera of a dry meadow on limestone : species composition, abundance and biomass

Ulrich W.

Polish Journal of Ecology

1999

Vol. 47, no 1

29-47

In 1986 and 1988 the hymenopterous fauna of a semixerophytic meadow on limestone near Gottingen (FRG) was studied using ground-photo-eclectors. A total of 4982 speciments belonging to 475 different species were collected. Extrapolations from double-log functions revealed that there may be as many as 1330 parasitoid species present per year. 455 of the 475 species were parasitoids. 155 of them attack dipterans. 48 lepidopterans, 36 beetles, 23 wasps, 22 plant hoppers and 13 aphids, 47 of the species are egg-parasitoids and parasitoids of miners, ectophytophages count for 44 of the wasp species. The abundance of the wasp fauna was rather high (1120+-53 ind. m^-2 a^-1 (1986) and335 +-42 ind. m^-2 a^-1 (1988). Most abundant were the parasitoids of miners, gall-makers and the eggparasitoids. Compared with the high abundance the biomass was low. In 1986 the wasps weighed a total of 194 +-24 mgDW m^-2 a^-1 and in 1988 only 69+-20 mgDW m^-2 a^-1. The parasitoids of ectophytophagous lepidopter ans and coleopterans counted for more than half of the whole biomass.

The parasitic Hymenoptera in a beech forest on limestone. 1, species composition, species turnover, abundance and biomass

Ulrich W.

Polish Journal of Ecology

1998

Vol. 46, no 3

261-289

Between 1980 and 1987 a beech forest (Fagus sylvatica) on limestone near Gottingen (FRG) was studied using ground-photo-electors. 720 species of Hymenoptera were detected. 669 of the species were parasitoids, 29 phytophagous Tenthredinidae, Cynipidae and Eurytomidae, 9 ants, 4 vespids and 9 nest-building sphecids, megachilids, andrenids and bumble bees. Even after 8 years of sampling a great number of species seems to remain undetected. Estimates of extiction and immigration rates indicate species turnover rates of at least 5 to 10%. The abundance of the parasitic Hymenoptera ranged between 123 +- (1981) and 1078 +- 186 (1984) ind. m^-2 a^-1. The most important groups were the parasitoids of Diptera with 56 +- 15 (1981) to 936 +- 164 (1984) ind. m^-2 a^-1. As judged by the sorting according to parasitoid guild, the parasitoids of gall-makers (23 +- 9 to 880 +- 163 ind. m^-2 a^-1) and the egg-parasitoids (21 +- 17 to 102 +- 33 ind. m^-2 a^-1) reached the highest densities. The biomass of the parasitic wasps ranged between 19 +- 5 (1981) and 170 +- 92 (1987) mg DW m^-2 a^-1 with a mean of 68 mg DW m^-2 a^-1. In comparison with other important insect taxa this is a low value.