A total of 16 fish species have been identified in the Veleka River and its tributaries the Mladezhka River and the Aydere River. Three of the species are included in the Red Data Book of Bulgaria: Anguilla anguilla, Chalcalburnus chalcoides and Rutilus frisii. Mean abundance (N) and mean biomass (B) of fishes were as follows: 3093 ind. ha-1 and 68.19 kg ha-1 in the Veleka River, 1220 ind. ha-1 and 16.73 kg ha-1 in the Mladezhka River, and 1025 ind. ha-1 and 41.18 kg ha in the Aydere River. The values obtained were much lower than the values of N and B of fishes in nine other Bulgarian rivers. The main reasons for the low fish abundance and biomass in the Veleka River and its tributaries were the intensive development of tourist industry in the region and the intensive, practically uncontrolled commercial and sport fishing and poaching.
To understand the factors governing the diversity, abundance and host associations of parasitoids attacking frugivorous drosophilid flies on Iriomote-jima, a subtropical island of Japan, we monitored parasitism on several occasions over the period 2003–2009. Fifteen drosophilid and 12 parasitoid species were recorded. Three species of Drosophila, D. bipectinata, D. albomicans and D. takahashii, bred abundantly in banana baits, though their abundance varied between years and seasons. Frequent parasitoid species were Asobara japonica, A. pleuralis (Braconidae), Leptopilina ryukyuensis and L. pacifica (Figitidae). L. victoriae was recorded only in December 2003. In addition, host acceptance and host suitability of the four most frequently recorded parasitoid species were studied in the laboratory. Most parasitoid and drosophilid species showed species-specific associations with more than one antagonist species, suggesting that they have been subjected to complex coevolutionary interactions. In addition, host range of most of the parasitoid species included one of the three major Drosophila species, suggesting that the abundance of potential hosts is one of the factors determining the evolution of parasitoid host use., Biljan Novkovic ... [et al.]., and Obsahuje seznam literatury