Isolation and characterization of polymorphic microsatellite loci in the gudgeon,Gobio gobio (Cyprinidae)

A total of seven polymorphic microsatellite loci from Gobio gobio were isolated and characterized. A preliminary population survey of 82 specimens from four populations, located in a downstream pollution gradient of cadmium and zinc, demonstrated the usefulness of these primers both in population genetic studies in general, as well as in evaluating the effects of anthropogenic pollution on genetic structure. Overall locus polymorphism ranged from two to 13 alleles. Observed heterozygosity per locus ranged from 0.39 to 0.73.     

Effects of ship‐induced waves on littoral benthic invertebrates

1. Ship‐induced waves can affect the physical characteristics of lake and river shorelines, and laboratory studies have shown effects on littoral invertebrates. Here, we explored whether these effects could be observed under field conditions along a natural lake shore affected by wave sequences (trains) produced by boats. 2. Individuals of five invertebrate species (Bithynia tentaculata, Calopteryx splendens, Dikerogammarus villosus, Gammarus roeselii, Laccophilus hyalinus) were exposed to waves with increasing shear stress in five habitats differing in structural complexity. 3. Detachment of invertebrates increased with increasing shear stress and was best modelled using sigmoid response curves. Habitat structural complexity mitigated the effects of shear stress, and detachment rate was influenced more by habitat type than by species. A threshold (90% of the individual invertebrates unaffected) stress level of 0.64 N m^?2 was found for a structurally complex reed habitat, compared to 0.37 N m^?2 for a simple sand habitat. 4. Shear stress associated with wave trains created by recreational boating at a distance of 35 m from the shore and at a speed of 11 km h^?1 resulted in 45% detachment of littoral invertebrates. Decreasing the boat‐to‐shore distance to 20 m increased wave shear stress by 30% and invertebrate detachments up to 75%. 5. Disturbance of littoral habitats and invertebrate assemblages are widespread in inland waters used for recreational and/or commercial navigation. Our findings show that the integrity of littoral zones of navigable surface waters could be much improved by implementing management measures such as physically protecting complex habitats with dense reed belts and tree roots, and reducing boat speeds and increasing their minimum shoreline distance.     

The ectoparasitization of Coleophora alticolella (Lepidoptera) in relation to its aititudinal distribution

Abstract. 1. The parasitization of the larvae of Coleophora alticolella . feeding on Juncus squarrosus , was investigated at a series of altitudes from 15 to 520m above sea-level in northern England during 1977 and 1978.
2. Six species of primary parasitoid and one hyperparasitoid were reared from this host. Five of the primary parasitoids were ectophagous; only two specimens of the endoparasitoid, Gonotypus melanostoma , were reared.
3. All of the parasitoid species were recorded at 15 m but fewer at sites of higher altitude. Only one species, Scambus brevicomis , was recorded above 305 m, and none above 395 m. The hyperparasitoid, Tetrastichus endemus, was present only at 15 m.
4. Percentage parasitization was highest at 15 m; it was reduced from 51% to only 2% between 215 and 305 m in 1978. There was an increase in host density over this altitudinal range.
5. Three species, Scambus brevicomis. Elachertus olivaceus and Euderus viridis , accounted for most of the parasitization, but their relative proportions vaned at different altitudes.
6. The sex-ratios of the parasitoids reared from Coleophora alticolella ranged from 3.2% females for Scambus brevicomis , which is considered to also use larger hosts, to 99.4% females for Elachertus olivaceus , which develops by thelytokous parthenogenesis.
7. Euderus viridis and Scambus brevicomis started to attack the Coleophora alticolella larvae at a later date at 245 m than at 15 m, but attack by Elachertus olivacats was not delayed at the higher site.     

Suppression of Plant-parasitic Nematode Populations in Turfgrass by Application of Entomopathogenic Nematodes

We studied the influence of entomopathogenic nematodes , Steinernema carpocapsae and S. riobravis, on natural populations of plant - parasitic nematodes (PPNs) infesting turfgrass in Georgia and South Carolina . S. riobravis applied at 6 109 infective juveniles (IJs) / acre provided up to 95 - 100% control of the root - knot , Meloidogyne sp ., sting , Belonolaimus longicaudatus, and ring nematode , Criconemella sp ., in Georgia , but S. carpocapsae had no effect . S. riobravis was as effective as the chemical nematicide , Fenamiphos (Nemacur 10G) at 4 weeks after treatment and more effective at 8 weeks after treatment . In South Carolina , both S. riobravis and S. carpocapsae applied at 1 109 IJs / acre provided up to 86 - 100 % control of the root - knot , sting and ring nematodes . Application of 6 109 IJs / acre increased control by only 4 - 14 % over the 1 109 dosage . Possible causes of differences in efficacy of S. carpocapsae at the two sites are discussed . It is concluded that S. riobravis may provide effective , predictable and economical control of PPNs in turfgrass .