Are galling insects better protected against parasitoids than exposed feeders?: a test using tenthredinid sawflies

ABSTRACT.

• 1 Data mostly from the published literature were used to assess the effect of galling on the number of parasitoid species per host species in the phylogeny of nematine sawflies from free external feeders (colonial and solitary) to leaf gallers and shoot gallers.
• 2 The strongest effects of galling were the total elimination of the species-rich cocoon-attacking guild of parasitoids, and eonymphal parasitoids, from the parasitoid community on shoot gallers, all of which are in the genus Euura.
• 3 All tachinid larval parasitoids were also eliminated by the galling habit.
• 4 The cumulative effects of these exclusions resulted in a decline in mean number of parasitoid species per host species from almost sixteen species on external colonial feeders to 4.0 species on shoot gallers.
• 5 General patterns in per cent parasitism by non-tachinid and tachinid larval parasitoids, eonymphal and cocoon parasitoids, on exposed feeders to shoot gallers, showed declines in non-tachinid attack and elimination of tachinid, eonymphal and cocoon parasitoids. But leaf gallers tended to be attacked more than exposed feeders by non-tachinid larval parasitoids.
• 6 The galling habit had a long-term impact by reducing the number of parasitoid species attacking nematine sawfly gallers and per cent mortality inflicted, so that natural enemies may have been important as a selective factor in the evolution of galling nematine sawflies.

     

The moss mites of the Cheviot (Acari: Oribatei)

A faunal list of oribatid mites collected from the summit of the Cheviot, Northumberland, is given, together with notes on the taxonomy and distribution of several of the species. Special attention is paid to the Arctic-alpine and European-alpine species and the list provides further support for the view that the upland areas of Britain are characterized by a common group of oribatid species. It is suggested that these species may be cold hardy or cold tolerant with relatively high supercooling points, enabling them to survive the winter at these higher altitudes.     

Training in zoo biology,captive breeding,and conservation

Different types of training in zoo biology, captive breeding, and conservation are discussed and the availability of a variety of programs documented. Emphasis is given to the need for more training in general, and especially for less-developed countries where zoos have much potential yet to be realized. The aims, structure, content, and impact of the Jersey Wildlife Preservation Trust's International Training Program are examined.     

Novel heme-binding component in the serum of the channel catfish (Ictalurus punctatus)

The serum of the channel catfish (Ictalurus punctatus) was examined for heme- and hemoglobin-binding proteins. Electrophoretic mobility retardation assays failed to detect a hemoglobin-binding material similar to mammalian haptoglobin; however, a heme-binding component (not previously described) was identified in catfish seru. The heme-binding component was purified by gel filtration chromatography; electrophoretic analyses suggested it to be composed of two polypeptide subunits of molecular masses about 115 and 98 kDa. This composition is inconsistent with hemopexin, the known heme-binding serum protein of mammals. Although it was not fully saturated with heme, the catfish component contained detectable heme in normal sera. When complexed by the binding material, heme was used as an iron source by isolates of the bacterial Gram-negative genusAeromonas; the capacity of other bacteria to use the complex was not tested. The physiological function of the catfish heme-binding serum protein is presently not clear.     

Micropropagation of the rare species Stylidium coroniforme and other Stylidium species

The number of plants in the gazetted rare species Stylidium coroniforme was increased through micropropagation. A method was first developed using the common species S. brunonianum. It was found that for both species, rapid propagation could be obtained by excising shoots from sterile seedlings and inducing shoot proliferation on Murashige and Skoog medium supplemented with 1 M BAP. Rooting was achieved using 1 M IBA and over 100 plants of each species were successfully established in soil. Leaf pieces could also be used to initiate cultures. In media with 20–25 M BAP and 1–5 M IBA, leaf pieces of S. brunonianum, S. piliferum, S. caricifolium and S. crassifolium produced adventitious buds, thus providing another method of micropropagation.     

Analysis of the shape of P vs I curves of a natural phytoplankton assemblage during the year in the mesotrophic Lake Maarsseveen (I), The Netherlands

Production versus light response curves were made of natural phytoplankton assemblages during the year in an incubator at 8 different light intensities ranging from 60 to 1500 Einstein.m^–2.sec^–1. The shape of these curves is analyzed in relation to the sensitivity for photo-inhibition. At the end of the month of April, there is a sudden shift in this sensitivity at higher light intensities. The algal assemblage becomes less sensitive for photo-inhibition. The influence of light-adaptation, temperature, nutrient limitation and species composition is discussed.     

Interference by DDT and cyclodiene types of insecticides with chloroplast-associated reactions

The effects of DDT, some of its analogs, and selected cyclodiene insecticides on isolated spinach (Spinacea oleracea L.) thylakoids were identified, characterized, and compared to responses induced by selected herbicides. Except for endrin, the insecticides inhibited light-induced electron transport, altered chlorophyll fluorescence transients, and competitively displaced [14C]atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine], a known photosystem II inhibitor, from the membranes. The insecticides appeared to act at, or near B, the secondary electron acceptor of photo-system II. Binding of DDT and dieldrin was estimated at 900 and 2200 molecules, respectively, per photosynthetic unit (490 chlorophyll molecules). The insecticides also inhibited valinomycin-induced swelling of the thylakoid membrane. Whereas inhibition of electron transport can be attributed to interaction by the insecticides with a proteinaceous component of the thylakoid membrane, interference with the action of valinomycin may involve interaction with lipoidal constituents of the membrane.     

农业生态系统中新物种引进的初步探讨

在现有的农业生态系统中,引进某些新物种,往往可以使整个系统的功能发生变化。如果新物种引进得当,则可产生良好的效果,系统功能得以改善,效益提高;反之,则会造成人力、物力、财力的损失,削弱系统的功能,甚至可能遗患无穷。因此,对农业生态系统中     

Macrophytes and flood plain water dynamics in the River Danube ecotone research region (Austria)

In the ecotone research region of the Danube in Austria (Man-and-the-Biosphere (MaB)- project 5/21, Austrian Academy of Science) the macrophytes are one of the most important groups of organisms investigated. The species composition and the plant mass in hydrologically dynamic, and in predominantly stagnant sections of a system of lateral branches and sloughs were studied. This study showed that areas protected from frequent disturbance by floods had a greater number of species and higher biomass of aquatic macrophytes. Some species were shown to be evenly distributed throughout the branch system, whereas other species tended to form rare, but large singular patches. A set of new data elaboration techniques enabled us to describe the distribution pattern of the aquatic vegetation in this large branch system of the River Danube.