Poxviral Disease in Red Squirrels Sciurus vulgaris in the UK: Spatial and Temporal Trends of an Emerging Threat

The squirrel poxvirus (SQPV) is the probable mediator of apparent competition between the introduced invading gray squirrel (Sciurus carolinensis) and the red squirrel (Sciurus vulgaris) in the UK, and modeling studies have shown that this viral disease has had a significant impact on the decline of the red squirrel in the UK. However, given our limited understanding of the epidemiology of the disease, and more generally the effects of invasive species on parasite ecology, there is a need to investigate the transmission dynamics and the relative pathogenicity of the virus between species. We aimed to increase our knowledge of these processes through an empirical study in which we: (i) used pathological signs and transmission electron microscopy (TEM) to diagnose SQPV disease in red squirrels found dead during scanning surveillance between 1993 and 2005; (ii) detected antibody to SQPV using an enzyme-linked immunosorbent assay (ELISA) in the same animals; and (iii) mapped cases of the disease, and the gray squirrel distribution, using a geographical information system. We analyzed the distribution of cases of SQPV disease according to woodland type, a measure of squirrel density. SQPV disease occurred only in areas of England also inhabited by seropositive gray squirrels, and as the geographical range of gray squirrels expanded, SQPV disease occurred in these new gray squirrel habitats, supporting a role for the gray squirrel as a reservoir host of the virus. There was a delay between the establishment of invading gray squirrels and cases of the disease in red squirrels which implies gray squirrels must reach a threshold number or density before the virus is transmitted to red squirrels. The spatial and temporal trend in SQPV disease outbreaks suggested that SQPV disease will have a significant effect on Scottish populations of red squirrels within 25 years. The even spread of cases of disease across months suggested a direct rather than vector-borne transmission route is more likely. Eight juvenile and sub-adult free-living red squirrels apparently survived exposure to SQPV by mounting an immune response, the first evidence of immunity to SQPV in free-living red squirrels, which possibly suggests a changing host-parasite relationship and that the use of a vaccine may be an effective management tool to protect remnant red squirrel populations.     

The occurrence of haemosporidian parasites in the Fennoscandian bluethroat ( Luscinia svecica) population

A total of 86 adult bluethroats (Luscinia svecica) from nine different localities, covering the full length of the Fennoscandian mountain range, were screened for blood parasites of the three genera Haemoproteus, Plasmodium and Leucocytozoon using a recently developed polymerase chain reaction method. The overall occurrence of infection was 59.3%. Prevalence of Leucocytozoon spp. (47.7%), Plasmodium spp. (23.3%) and Haemoproteus spp. (1.2%) was detected. Of the infected birds, 15.1% carried mixed infections. Five different mitochondrial DNA-lineages of Leucocytozoon spp., eight lineages of Plasmodium spp. and one lineage of Haemoproteus spp. were found. Due to large sequence divergence these corresponded to at least five different species, but with the possibility of all 14 being independent evolutionary units with the potential of evolving different effects on the host. Of the lineages of Leucocytozoon spp., the most common was found throughout the range. The occurrence of the second most common lineage of Leucocytozoon spp. showed significant variation in prevalence between sites. The data also showed molecular evidence of one lineage of Leucocytozoon sp. existing in more than one species of avian host, thus challenging the use of host taxon as a taxonomic character when distinguishing between different species leucocytozoids.Communicated by F. Bairlein     

Some notes on fig-eating by arboreal mammals in Malaysia

During a study of avian fig-eating at Kuala Lompat, Malaysia, observations were also made of fig-eating by mammals. Four species of primate, seven species of squirrel, and two species of civet consumed figs. Twenty-six species ofFicus were of importance to arboreal mammals. Observations suggest that there were differences in the importance of figs in the diets of sympatric langurs (Presbytis) and congeneric squirrels. Dusky langursPresbytis obscura ate carbohydrate-rich ripe figs despite their ruminant-like digestive system and the danger of bloat.     

The Bionomics ofCoptera Haywardi(Ogloblin) (Hymenoptera: Diapriidae) and Other Pupal Parasitoids of Tephritid Fruit Flies (Diptera)

The endoparasitoidCoptera haywardi(Ogloblin) (Diapriidae) was discovered in Mexico attacking the pupae of the Mexican fruit fly,Anastrepha ludens(Loew). Typically, parasitoids of Diptera Cychlorrhapha pupae develop as ectoparasitoids and are generalists that attack hosts in a number of families. Aspects of the bionomics ofC. haywardiwere compared to those of two chalcidoid ectoparasitoids,Dirhinus himalayanusWestwood andSpalangia geminaBoucek.C. haywardideveloped in three genera of Tephritidae, but not in species of other families. The two species of chalcidoids developed in all the calypterate and acalypterate hosts to which they were exposed. In an olfactometerC. haywardipreferredAnastrepha suspensa(Loew) pupae, while the chalcidoids preferred the pupae ofMusca domestica L.This preference inS. geminawas diminished in insects that had been reared onA. suspensa. C. haywardioviposited in theA. suspensapupae that had been previously parasitized by the braconidDiachasmimorpha longicaudata(Ashmead). However, it completed development only in unparasitized pupae. Mortality of the primary parasitoid due toD. himalayanuswas approximately two-thirds the mortality inflicted on the host fly.S. geminadid not discriminate between parasitized and unparasitized pupae ofA. suspensaand developed in both.C. haywardiappears to have a more restricted host range relative to chalcidoid pupal parasitoids and this may be due to its endoparasitic development.     

Species richness and seasonal abundance of ectomycorrhizal fungi in plantations of<Emphasis Type="Italic"> Eucalyptus dunnii</Emphasis> and<Emphasis Type="Italic"> Pinus taeda</Emphasis> in southern Brazil

The abundance and diversity of ectomycorrhizal fungi (EMF) was assessed based on the collection of basidiocarps during 12 months comprising the spring of 1995, and the summer, autumn, and winter of 1996, in three stands of young, middle-aged, and rotation age plantations of Pinus taeda and Eucalyptus dunnii, in the state of Santa Catarina, southern Brazil. A total of 3,085 collections yielded 34 presumed EMF taxa in ten genera, including mushroom-like and sequestrate species. Fruiting patterns of EMF differed with host and season, and host specificity was apparent in some. The overall relative importance (RI) and the Shannon diversity index (H) suggested that stands of E. dunnii had a more diverse aboveground EMF community than those of P. taeda. Overall, species of Scleroderma and Laccaria were not only the most abundant but also had the highest biomass values. The results show that a small number of species of abundant biomass and a larger number of species of less-abundant biomass characterize each forest class.     

Epibiota communities of the introduced and indigenous macroalgal relatives<Emphasis Type="Italic"> Sargassum muticum</Emphasis> and<Emphasis Type="Italic"> Halidrys siliquosa</Emphasis> in Limfjorden (Denmark)

Sargassum muticum (Phaeophyceae, Fucales) has recently been introduced to Limfjorden (Denmark) where its closest relative is the indigenous Halidrys siliquosa. Previous studies have demonstrated large quantitative (canopy biomass) and qualitative (canopy persistence) differences in the habitat available to epibiota within the canopies of these two macroalgae. We therefore hypothesised that these algae would support different epibiota communities and tested this by sampling the epibiota of S. muticum and H. siliquosa on seven occasions throughout 1997 by enclosing entire thalli in mesh bags. We found 53 epibiota taxa and, with only one exception, they were all recorded on both host species. Species richness and abundance of epibiota exhibited clear seasonal variation on both host species, although epibiota biomass was seasonally constant on H. siliquosa but not on S. muticum. These patterns were consistent with the different life histories of the host species. There was a weakly negative correlation between thallus size and epibiota biomass for both host species. When taking species-specific seasonal variation in thallus size into consideration, S. muticum and H. siliquosa were found to support significantly different epibiota biomasses. Multivariate analyses showed that epibiota community structure was different, although highly overlapping, between the two species, whereas there was an almost parallel temporal development in epibiota community structure. We conclude that it is unlikely that the introduction of S. muticum to Limfjorden has caused major changes in local epibiota community structure. However, the standing stock of epibiota is likely to have increased.Communicated by H.-D. Franke     

Release in Manitoba,Canada oftownesilitus bicolor [HYM.: Braconidae], an European parasite ofPhyllotreta spp. [Col.: Chrysomelidae]

Townesilitus bicolor (Wesmael), a parasite of some crucifer-infesting species ofPhyllotreta in Europe, was released in Manitoba Canada in 1978–83, in an attempt to reduce populations ofPhyllotreta cruciferae (Goeze) andP. striolata (Fab.). Releases totalled 1936 adults ofT. bicolor and approximately 2639Phyllotreta collected in Manitoba and parasitized in the laboratory. No evidence of establishment was found up to 1985 at either of the 2 release sites. The small numbers of parasite released, and dispersal of the host population twice each year, have reduced the probability of the parasite becoming established and of establishment being detected. Contribution n^o 1248     

Heterostyly in species ofNarcissus (Amaryllidaceae) andHugonia (Linaceae) and other disputed cases

The hypothesis ofHenriques andFernandes that several Iberian species ofNarcissus (Amaryllidaceae) are tristylous is reconsidered. Contrary to the opinion ofBateman and most subsequent authors, we believe that the available evidence indicates that some populations ofN. triandrus andN. fernandesii, at least, are tristylous; other populations ofN. triandrus are distylous.Hugonia cf.penicillanthemum (Linaceae) from new Caledonia is distylous, but it remains possible that other species ofHugonia are tristylous. The disputed occurrence of heterostyly in S. African species ofBauhinia (Leguminosae),Cleome (Capparaceae) andAneilema (Commelinaceae), and inAgelaea (Connaraceae) is discussed.     

Contrasting breeding systems in twoEriotheca (Bombacaceae) species of the Brazilian cerrados

The pollination biology and breeding systems ofEriotheca pubescens andE. gracilipes have been studied. These two species occur as trees in cerrado vegetation, the neotropical savannas of Central Brazil, with partially sympatric distributions. They have similar phenology and floral structure, although the flowers ofE. pubescens are larger. Both species have nectar flowers pollinated by largeAnthophoridae bees but the main pollinators of each species differ in size. The species have markedly different breeding systems: late-acting self-incompatibility inE. gracilipes and apomixis stimulated by pollination inE. pubescens.