Larval habitat for the avian malaria vector Culex quinquefasciatus (Diptera: Culicidae) in altered mid‐elevation mesic‐dry forests in Hawai'i

Effective management of avian malaria (Plasmodium relictum) in Hawai'i's endemic honeycreepers (Drepanidinae) requires the identification and subsequent reduction or treatment of larval habitat for the mosquito vector, Culex quinquefasciatus (Diptera: Culicidae). We conducted ground surveys, treehole surveys, and helicopter aerial surveys from 2001–2003 to identify all potential larval mosquito habitat within two 100+ ha mesic‐dry forest study sites in Hawai'i Volcanoes National Park, Hawai'i; ‘Ainahou Ranch and Mauna Loa Strip Road. At ‘Ainahou Ranch, anthropogenic sites (43%) were more likely to contain mosquitoes than naturally occurring (8%) sites. Larvae of Cx. quinquefasciatus were predominately found in anthropogenic sites while Aedes albopictus larvae occurred less frequently in both anthropogenic sites and naturally‐occurring sites. Additionally, moderate‐size (≈20–22,000 liters) anthropogenic potential larval habitat had >50% probability of mosquito presence compared to larger‐ and smaller‐volume habitat (<50%). Less than 20% of trees surveyed at ‘Ainahou Ranch had treeholes and few mosquito larvae were detected. Aerial surveys at ‘Ainahou Ranch detected 56% (95% CI: 42–68%) of the potential larval habitat identified in ground surveys. At Mauna Loa Strip Road, Cx. quinquefasciatus larvae were only found in the rock holes of small intermittent stream drainages that made up 20% (5 of 25) of the total potential larval habitat. The volume of the potential larval habitat did not influence the probability of mosquito occurrence at Mauna Loa Strip Road. Our results suggest that Cx. quinquefasciatus abundance, and subsequently avian malaria, may be controlled by larval habitat reduction in the mesic‐dry landscapes of Hawai'i where anthropogenic sources predominate.     

Circadian entrainment by feeding cycles in house sparrows,Passer domesticus

Summary We studied the potential zeitgeber qualities of periodic food availability on the circadian rhythms of locomotor and feeding activity of house sparrows. The birds were initially held in a LD-cycle of 12:12 h, with food restricted to the light phase. After transfer to constant dim light, the birds remained entrained by the restricted feeding schedule. Following an exposure to food ad libitum conditions, the rhythms could be re-synchronized by the feeding cycle. Shortening of the zeitgeber period to 23.5 h resulted in the loss of entrainment in most birds, whereas a longer zeitgeber period of 25 h re-entrained the rhythms of most birds. Although these results prove that periodic food availability can act as a zeitgeber for the circadian rhythms of house sparrows, several features of our data indicate that restricted feeding is only a weak zeitgeber. The pattern of feeding activity prior to the daily time of food access shown under some experimental conditions suggests that anticipation is due to a positive phase-angle difference of the birds' normal circadian system rather than being caused by a separate pacemaker.     

Seed rain of fleshy and dry propagules in different habitats in the temperate rainforests of Chiloé Island,Chile

In temperate rainforests on Chiloé Island in southern Chile (42°S), most canopy trees bear fleshy, avian‐dispersed propagules, whereas emergent tree species have dry, wind‐borne propagules. In the present study, the following hypothesis was tested: regardless of species, fleshy propagules are deposited in greater numbers in canopy gaps and in forest margins and hence have a more heterogeneous seed shadow than wind‐dispersed propagules. To test this hypothesis, the seed rains of these two types of propagules were compared in the following forest habitats: (i) tree‐fall gaps (edges and centre); (ii) forest margins with adjacent pastures; and (iii) under closed canopy (forest interior). Seed collectors (30‐cm diameter) were placed in two (15 and 100 ha) remnant forest patches (n = 60–100 seed collectors per patch) distributed in the four habitats. Seeds were retrieved monthly from each collector during two reproductive seasons (1996, 1997). In both years, the seed rain was numerically dominated by two species with dry propagules (Laureliopsis philippiana and Nothofagus nitida) and three species with fleshy fruits (Drimys winteri, Amomyrtus luma, and Amomyrtus meli). The seed shadows of the two species with dry, wind‐dispersed seeds differed markedly. Seeds of L. philippiana were deposited predominantly in canopy openings, whereas N. nitida seeds fell almost entirely in the forest interior. The fleshy‐fruited species, Drimys and Amomyrtus spp., had similar seed deposition patterns in the various habitats studied, but the between‐year differences in seed rain were greater in Drimys winteri than in Amomyrtus spp. Although no more than 10% of fleshy‐fruited propagules reached the margins of the patch, approximately 7% of these were carried there by birds. Every year, canopy gaps (pooling data from edges and centres) concentrated approximately 60% of the total seed rain of both propagule types in both forest patches. Forest margins received less than 20% of the total seed rain, which was largely dominated by fleshy‐fruited species. Seed shadows were a species‐specific attribute rather than a trait associated with propagule type and dispersal mode.     

Sperm divergence in a passerine contact zone: Indication of reinforcement at the gametic level

Postcopulatory sexual selection may promote evolutionary diversification in sperm form, but the contribution of between‐species divergence in sperm morphology to the origin of reproductive isolation and speciation remains little understood. To assess the possible role of sperm diversification in reproductive isolation, we studied sperm morphology in two closely related bird species, the common nightingale (Luscinia megarhynchos) and the thrush nightingale (Luscinia luscinia), that hybridize in a secondary contact zone spanning Central and Eastern Europe. We found: (1) striking divergence between the species in total sperm length, accompanied by a difference in the length of the mitochondrial sperm component; (2) greater divergence between species in sperm morphology in sympatry than in allopatry, with evidence for character displacement in sperm head length detected in L. megarhynchos; (3) interspecific hybrids showing sperm with a length intermediate between the parental species, but no evidence for decreased sperm quality (the proportion of abnormal spermatozoa in ejaculates). Our results demonstrate that divergence in sperm morphology between the two nightingale species does not result in intrinsic postzygotic isolation, but may contribute to postcopulatory prezygotic isolation. This isolation could be strengthened in sympatry by reinforcement.     

Investigation of avian influenza virus in poultry and wild birds due to novel avian-origin influenza A(H10N8) in Nanchang City,China

Multiple reassortment events within poultry and wild birds had resulted in the establishment of another novel avian influenza A(H10N8) virus, and finally resulted in human death in Nanchang, China. However, there was a paucity of information on the prevalence of avian influenza virus in poultry and wild birds in Nanchang area. We investigated avian influenza virus in poultry and wild birds from live poultry markets, poultry countyards, delivery vehicles, and wild-bird habitats in Nanchang. We analyzed 1036 samples from wild birds and domestic poultry collected from December 2013 to February 2014. Original biological samples were tested for the presence of avian influenza virus using specific primer and probe sets of H5, H7, H9, H10 and N8 subtypes by real-time RT-PCR. In our analysis, the majority (97.98%) of positive samples were from live poultry markets. Among the poultry samples from chickens and ducks, AIV prevalence was 26.05 and 30.81%, respectively. Mixed infection of different HA subtypes was very common. Additionally, H10 subtypes coexistence with N8 was the most prevalent agent during the emergence of H10N8. This event illustrated a long-term surveillance was so helpful for pandemic preparedness and response.     

No species is an island: testing the effects of biotic interactions on models of avian niche occupation

Traditionally, the niche of a species is described as a hypothetical 3D space, constituted by well‐known biotic interactions (e.g. predation, competition, trophic relationships, resource–consumer interactions, etc.) and various abiotic environmental factors. Species distribution models (SDMs), also called “niche models” and often used to predict wildlife distribution at landscape scale, are typically constructed using abiotic factors with biotic interactions generally been ignored. Here, we compared the goodness of fit of SDMs for red‐backed shrike Lanius collurio in farmlands of Western Poland, using both the classical approach (modeled only on environmental variables) and the approach which included also other potentially associated bird species. The potential associations among species were derived from the relevant ecological literature and by a correlation matrix of occurrences. Our findings highlight the importance of including heterospecific interactions in improving our understanding of niche occupation for bird species. We suggest that suite of measures currently used to quantify realized species niches could be improved by also considering the occurrence of certain associated species. Then, an hypothetical “species 1” can use the occurrence of a successfully established individual of “species 2” as indicator or “trace” of the location of available suitable habitat to breed. We hypothesize this kind of biotic interaction as the “heterospecific trace effect” (HTE): an interaction based on the availability and use of “public information” provided by individuals from different species. Finally, we discuss about the incomes of biotic interactions for enhancing the predictive capacities on species distribution models.     

禽致病性大肠埃希菌强毒力岛（HPI）全岛缺失株的构建

目的构建大肠埃希菌强毒力岛（HPI）全岛缺失突变株,为进一步评价大肠埃希菌HPI的功能打下基础。方法根据已知大肠埃希菌HPI基因序列设计PCR敲除引物,引物5′端有50 bp的拟敲除基因的同源臂,3′端为扩增引物,以pKD3为模板,扩增两侧含FRT位点的氯霉素抗性基因,利用pKD46的λ重组系统替换E.coli ZL基因组上的毒力岛全岛基因,再利用表达Flp重组酶的质粒pCP20,可将FRT位点之间的氯霉素抗性基因删除,用鉴定引物进行鉴定并测序。结果构建的全岛缺失株与预期一致。结论成功构建了禽致病性大肠埃希菌强毒力岛（HPI）全岛缺失突变株。     

华东地区家鸭中N1亚型禽流感病毒NA基因的遗传进化分析

为了解华东地区家鸭内禽流感病毒的遗传进化情况,对2002~2006年分离自华东地区家鸭的3种主要N1亚型的禽流感病毒:2株H1N1、10株H3N1和14株H5N1,共26株病毒的NA基因进行了遗传进化分析。结果表明,华东地区家鸭中的N1亚型的禽流感病毒正处于不断进化状态中。14株H5N1禽流感病毒均在NA的茎部缺失20个氨基酸(49~68位),而其他N1亚型的禽流感病毒的NA都未见发生此缺失。H3N1病毒可能与H1N1病毒发生了NA基因的重排,但是目前还没有直接证据表明华东地区家鸭中H5N1禽流感参与了基因重排。