Diurnal activity patterns in hoverflies (Diptera, Syrphidae)

Abstract. 1. Time-budgets are constructed from censuses of hoverflies. Larger species spend less time in flight.
2. Most species are active under similar conditions of light intensity, but a shade-tolerant (Melanostoma scalare Fabr.) and a sun-loving species (Metasyrphus corollae Fabr.) were identified.
3. Large species become active (i.e. move, by flying or feeding) at lower temperatures than small ones, except M.scalare, which is tolerant to cool temperatures. This means that, M.scalare apart, the order of species appearing during the day is size-dependent, largest first.
4. Previous claims about the diel periodicity of syrphids can be reconciled by considering the importance of individual thermal balance.
5. Tolerance to low temperatures in small hoverflies is associated with feeding on anemophilous pollen; this may indicate a proline-fuelled flight.     

On the role of sinigrin (mustard oil) in a tritrophic context: plant–aphid–aphidophagous hoverfly

1. Plant secondary metabolites can govern prey–predator interactions by altering the diet breadth of predators and sometimes provide an ecological refuge to prey. Brassicaceae plants and their specialist pests can be used as a model system for understanding the role of chemically mediated effects restricting the diet breadth of natural enemies, and consequently the occurrence of enemy‐free space for the specialist pest. 2. The objective of the present study was to test the performance of the generalist predator Episyrphus balteatus De Geer (Diptera: Syrphidae) fed on the specialist herbivore Brevicoryne brassicae L.(Homoptera: Aphididae), reared on two different brassica species: black mustard (Brassica nigra), a wild species with high levels of sinigrin; and canola (Brassica napus), a cultivated species without sinigrin. 3. The preference and performance of the predator and the performance of the prey were measured. Sinigrin was quantified by high‐performance liquid chromatography in both leaf samples and aphids reared on the two host plants. 4. The cabbage aphid performed better on canola than on black mustard. The performance of the predator on this aphid when reared on canola was clearly better than when reared on black mustard. Females had a higher overall preference for cabbage aphids reared on canola than on black mustard. 5. The ability of aphids reared on plants with high glucosinolate content to reduce the performance of their generalist predators indicates that the presence of B. nigra may provide enemy‐free space for the cabbage aphid from its predator, a concept that has useful application in the context of biological control for agricultural systems.     

Habitat requirements of the threatened snake species Hoplocephalus stephensii (Elapidae) in eastern Australia

Abstract Although forested habitats in eastern Australia have attracted significant conservation‐related research, this work has focused strongly on endothermic vertebrates. Threatened reptile taxa have received less attention, but information on their habitat requirements should be central to management planning. The arboreal elapid snake Hoplocephalus stephensii is largely restricted to remnant forests in eastern Australia, and is listed as a threatened species under wildlife legislation. We collated 84 records of the current New South Wales geographical distribution of H. stephensii, and compared attributes of these locations to those of randomly chosen points within the same forests, in adjacent forests, in timber plantations and on freehold land across the geographical range of the taxon. Data on climatic and topographic characteristics of these sites were obtained from Geographic Information Systems databases and entered into a principal components analysis. Unsurprisingly, locations where snakes were recorded differed from the random sites in several respects (e.g. rainfall, elevation, seasonality of precipitation). Within a given forest, H. stephensii was generally found in areas similar to randomly chosen points. Comparison of vegetation communities used with those available within forests provided no evidence for active habitat selection. Comparisons of Geographic Information Systems‐derived data for snake‐collection localities along roads versus those within the forest revealed significant biases, and we warn that such methodological errors could generate spurious conclusions about non‐random habitat use by threatened species. In combination with previous data from radio‐tracking, we conclude that although H. stephensii is highly specialized in its arboreality and dependence upon hollow trees, its broad tolerance with respect to other factors (climatic conditions, vegetation communities, food types, etc.) allows populations to persist so long as large areas of forest with high numbers of hollow‐bearing trees are available. These requirements are similar to those of many other components of the Australian forest fauna. Thus, the findings of this study support the idea that the same kinds of management programmes can effectively conserve a wide range of taxa, if such programmes protect critical habitat components at suitable spatial scales.     

长镰管蚜气味结合蛋白OBP3的cDNA克隆和序列分析及其成虫嗅觉行为反应测定

枫长镰管蚜Drepanosiphum platanoidis是少数几种不分泌E-β-法尼烯(E-β-farnesene,EBF)的蚜虫之一.ApisOBP3是首个被鉴定的特异结合EBF的昆虫气味结合蛋白,来自于豌豆蚜Acyrthosiphum pisum.本研究通过基因克隆技术,在枫长镰管蚜体内获得2个表达ApisOB...     

Sea-level rise and drought interactions accelerate forest decline on the Gulf Coast of Florida, USA

Sea-level rise threatens low-lying coastal ecosystems globally. In Florida, USA, salinity stress due to increased tidal flooding contributes to the dramatic and well documented decline of species-rich coastal forest areas along the Gulf of Mexico. Here, we present the results of a study of coastal forest stand dynamics in thirteen 400 m² plots representing an elevation gradient of 0.58–1.1 m affected by tidal flooding and rising sea levels. We extended previously published data from 1992–2000 to 2005 to quantify the full magnitude of the 1998–2002 La Niña-associated drought. Populations of the dominant tree species, Sabal palmetto (cabbage palm), declined more rapidly during 2000–2005 than predicted from linear regressions based on the 1992–2000 data. Dramatic increases in Juniperus virginiana (Southern red cedar) and S. palmetto mortality during 2000–2005 as compared with 1995–2000 are apparently due to the combined effects of a major drought and ongoing sea-level rise. Additionally, coastal forest stands continued to decline in species richness with increased tidal flooding frequency and decreasing elevation. Stable isotope (H, O) analyses demonstrate that J. virginiana accesses fresher water sources more than S. palmetto . Carbon isotopes reveal increasing δ ¹³C enrichment of S. palmetto and J. virginiana with increased tidal flooding and decreased elevation, demonstrating increasing water stress in both species. Coastal forests with frequent tidal flooding are unable to support species-rich forests or support regeneration of the most salt-tolerant tree species over time. Given that rates of sea-level rise are predicted to increase and periodic droughts are expected to intensify in the future due to global climate change, coastal forest communities are in jeopardy if their inland retreat is restricted.     

Evolution of cave living in Hawaiian Schrankia (Lepidoptera: Noctuidae) with description of a remarkable new cave species

Although temperate cave‐adapted fauna may evolve as a result of climatic change, tropical cave dwellers probably colonize caves through adaptive shifts to exploit new resources. The founding populations may have traits that make colonization of underground spaces even more likely. To investigate the process of cave adaptation and the number of times that flightlessness has evolved in a group of reportedly flightless Hawaiian cave moths, we tested the flight ability of 54 Schrankia individuals from seven caves on two islands. Several caves on one island were sampled because separate caves could have been colonized by underground connections after flightlessness had already evolved. A phylogeny based on approximately 1500 bp of mtDNA and nDNA showed that Schrankia howarthi sp. nov. invaded caves on two islands, Maui and Hawaii. Cave‐adapted adults are not consistently flightless but instead are polymorphic for flight ability. Although the new species appears well suited to underground living, some individuals were found living above ground as well. These individuals, which are capable of flight, suggest that this normally cave‐limited species is able to colonize other, geographically separated caves via above‐ground dispersal. This is the first example of an apparently cave‐adapted species that occurs in caves on two separate Hawaiian islands. A revision of the other Hawaiian Schrankia is presented, revealing that Schrankia simplex, Schrankia oxygramma, Schrankia sarothrura, and Schrankia arrhecta are all junior synonyms of Schrankia altivolans. © 2009 The Linnean Society of London, Zoological Journal of the Linnean Society, 2009, 156 , 114–139.