The outcome of assessments of the biodiversity of a taxonomic group often depend on the sampling method. The choice of an adequate method is especially important for biomonitoring purposes. In this study, the effectiveness of two methods of sampling syrphids (Diptera: Syrphidae) is compared: observation plot method vs. line transect, both sampled by sweep netting. Altogether, 18 meadows were selected in three mountain regions in the Austrian and Swiss Alps. We recorded a significantly higher abundance and richness of syrphids using the observation plot method than the line transect method in 2015. Comparing data for one region recorded in 2015 and 2016, similar results were obtained. Syrphid species assemblages were affected by sampling method in both years. More syrphid species and individuals were recorded using the observation plot method, which makes it more suitable for studies aiming at comparing differences in the numbers of adult syrphids in different grassland habitats., Raja I. Hussain, Ronnie Walcher, David Brandl, Arne Arnberger, Johann G. Zaller, Thomas Frank., and Obsahuje bibliografii
When puparia of the onion maggot Delia antiqua were preexposed to 5°C for 5 days starting at different time points after pupariation, a large increase in survival after exposure to -20°C for 5 days was observed only when pre-exposure was initiated at 3-6 days after pupariation. The increase in cold hardiness was not associated with a large increase in the trehalose content of the puparia. The supercooling point of the puparia naturally decreased from -18 to -27°C in the first three days after pupariation, and pre-exposure to 5°C did not have an additional effect. Thus, factors responsible for the enhancement of cold hardiness by acclimation other than trehalose and supercooling point should be sought. The period of responsiveness to cold acclimation coincided with the time soon after head evagination, which corresponds to "pupation" in lepidopteran insects. The puparia appear to be physiologically flexible for a short time after head evagination, and able to adapt their physiology to the contemporary cold environment.
A new genus of parathalassiine-like flies, Eothalassius gen. n., and two new species, Eothalassius platypalpus sp. n. (type species), E. gracilis sp. n., are described from the coasts of Southeast Asia and Papua New Guinea. The phylogenetic relationships of the new genus with other genera assigned to Parathalassiinae and Dolichopodidae are discussed.
Eurytoma robusta Mayr (Chalcidoidea) exploits host galls either as a primary or secondary parasitoid, an entomophytophagous inquiline or occasionally even as a predator. We present data on its ecology and impact on gall densities and population trends of the gall fly Urophora cardui (L.) on Cirsium arvense (L.) Scop. Habitat preference, host gall selection, clutch size, and high incidence of superparasitism causing empty gall cells show that E. robusta, a generalist with a broad host spectrum, is relatively poorly adapted to parasitising U. cardui. The influence of E. robusta on U. cardui in the Belfort-Sundgau region (1970-2004), in the Upper Rhine Valley (1973-2004) and in north-eastern Bavaria (1977-2004), differed considerably. In the forests of the Upper Rhine Valley and the Belfort-Sundgau region, where U. cardui has relatively stable source-sink populations, E. robusta is present but not the dominant mortality factor of the gall fly. In most areas of north-eastern Bavaria U. cardui occurs in fragmented populations and short lived non-equilibrium metapopulations. In these systems E. robusta became more abundant over the last five years, which resulted in a high incidence of superparasitism, an increase in the number of empty gall cells and reduced gall quality. The greatly increased degree of parasitism and an excess of empty cells resulted recently in the collapse of most local populations of U. cardui in the study area south of Bayreuth (north-eastern Bavaria). Together with earlier records the data presented here suggest that in north-eastern Bavaria E. robusta cause fluctuations in the abundance of U. cardui, which have a periodicity of 5-7 years. A remarkable feature of the oligophagous E. robusta is its high fidelity to formerly abundant U. cardui populations, which, with declining host densities, leads to overexploitation, resulting in a high incidence of superparasitism and high larval mortality. The possible influence of the habitat structure on the effect of E. robusta on the population dynamics of U. cardui is discussed. Our data plus that of other authors suggest that, with regard to U. cardui, E. robusta can develop a temporary local host specialisation.
Interactions between syrphid predators and their prey are poorly known. The adaptations of syrphids to aphid defences and the consequences for the evolution of life history traits in these predators especially are mostly unstudied. This is the first of two papers investigating the evolution of prey specialization in aphidophagous hoverflies. The study focuses on two questions: (1) Are differences in the body size of syrphid predators reflected in differences in the size of their prey? (2) Are differences in body size, body mass and development time of the syrphid predators correlated with the defence strategies of their aphid prey (e.g. mobility, toxicity)? Platycheirus clypeatus (Meigen, 1822), Platycheirus fulviventris (Macquart, 1829), Melanostoma mellinum (Linnaeus, 1758), and Melanostoma scalare (Fabricius, 1794), which differ considerably in their prey specialization, but are closely related, were chosen as model species. Life history data for these syrphids came from a laboratory study, and that for the aphids from a literature survey. These syrphid species can be arranged on a gradient of increasing prey specialization, from 32 prey species for the generalist M. mellinum and only 3 for the specialist P. fulviventris. Differences in prey specialization were even more evident when the defence ability of the various species of aphid prey was considered. For instance, the specialization on ant-attended aphids in M. scalare. Larvae exhibited a one or two weeks diapause which made the determination of developmental time imprecise. Body size of the predators was not reflected in that of their aphid prey. The postulated relationship between body size of the predator and the defence strategies of their prey was not supported by our data. A comparison of a wider range of syrphid species from different taxonomic groupings together with a phylogenetic correction procedure might reveal clearer trends. The second part of this paper (Dziock, in prep.) will investigate the correlation between prey specialization and reproductive strategies (i.e. clutch size, egg size and number) and will put the results into a broader framework.
Oviposition behaviour of Delia radicum is not only influenced by host plant duality but also by the duality of the substrate in which the plant grows. Direct behavioural observations showed that the females partition their visits to a host plant (cauliflower) into ovipositional bouts separated by exploration of the host plant surface. Ovipositional bouts were further partitioned into acts of egg deposition separated by exploration of the substrate. While the mean number of ovipositional bouts per visit (2.6), and eggs laid per egg deposition event (1.4) were stable, the mean number of egg deposition events per ovipositional bout significantly varied (from 2.1 to 7.3) with the duality of the substrate and the physiological state of the female (egg load). Ovipositing females adjusted the final number of eggs laid around the plant during the behavioural stage of substrate exploration. Additional experiments using plant surrogates treated with methanolic extract of Brassica leaves mounted in different substrates showed that: (a) the presence of living Brassica, Hordeum or Allium roots in a substrate enhances the number of eggs laid into this substrate, but females do not discriminate between the different plants; (b) females avoid both wet and dry substrates and prefer the substrates with a dry surface and moist particles directly accessible at a depth of about 5 mm; (c) substrates rich in organic matter are preferred to sand; (d) olfactory perception of volatile chemicals from the substrate must at least partially be responsible for the differences in oviposition in various substrates.
Until recently, the Canadian distribution of the blueberry maggot, Rhagoletis mendax Curran (Diptera: Tephritidae), was restricted to Nova Scotia, Prince Edward Island and New Brunswick. The insect was first mentioned in southern Quebec in 1996 and, to date, it has not reached the Lac St-Jean region, where 34% of Canadian blueberry acreage is located. Two questions concerning the northern limit of distribution of the blueberry maggot in Quebec were addressed. First, are wild plants suitable hosts for larval development? We collected the fruit of five wild plants, (e.g. Vaccinium corymbosum, Vaccinium angustifolium, Vaccinium myrtilloides, Gaylussacia baccata, and Aronia melanocarpa) growing in southern Quebec and allowed larvae to complete their development into pupae. Blueberry maggot pupae were recovered from Vaccinium corymbosum, Vaccinium angustifolium, and Gaylussacia baccata, indicating that these plants are suitable for larval development. Second, are harsh winter temperatures a factor limiting the northern distribution of the blueberry maggot? Pupae collected in Quebec and Nova Scotia were put in the soil in the fall and were brought back to the laboratory to determine their supercooling points at different times during winter. The supercooling points of pupae collected in Quebec and Nova Scotia averaged -22.6°C. In natural conditions, air temperatures <-20°C are frequently observed in Quebec in January, February and March. However, due to snow cover, soil temperatures are rarely <-12°C. If -22.6°C constitutes the lower limit for the survival, then winter temperatures are probably not a limiting factor to its northern distribution in Quebec, because blueberry maggot pupae overwinter in the soil., Charles Vincent, Pierre Lemoyne, Sonia Gaul, Kenna Mackenzie., and Obsahuje bibliografii
The mitochondrial genome of Mesomelena mesomelaena (Loew, 1848) is the first to be sequenced in the flesh fly subfamily Miltogramminae (Diptera: Sarcophagidae). The 14,559 bp mitogenome contains 37 typical metazoan mitochondrial genes: 13 protein-coding genes, two ribosomal RNA genes and 22 transfer RNA genes, with the same locations as in the insect ground plan. All the protein-coding genes have the start codon ATN, except for cox1 (TCG). Eight protein-coding genes have the stop codon TAA, while the remaining five have the stop codon T (cox1, cox2, nad5, and nad4) or TAG (cytb). Synonymous and non-synonymous substitution rates (Ks and Ka) for each protein-coding gene indicate that these genes evolved primarily under negative (or purifying) selection (Ka < Ks). Phylogeny of Sarcophagidae is proposed based on all the sarcophagid mitogenomes in GenBank, and the subfamily topology is reconstructed as (Sarcophaginae (Paramacronychiinae, Miltogramminae))., Liping Yan, Ming Zhang, Yunyun Gao, Thomas Pape, Dong Zhang., and Obsahuje bibliografii
Nutrition is one of the most important environmental factors that influence the development and growth in Drosophila. The food composition strongly affects their reproduction, welfare and survival, so it is necessary for flies to search for a mixture of macronutrients that maximizes their fitness. We have five D. melanogaster strains, which were reared for 13 years on five different substrates: standard cornmeal-agar-sugar-yeast medium and four substrates modified by adding tomato, banana, carrot and apple. This study was aimed at determining how such long-term rearing of flies on substrates with different protein content affects fitness traits (dynamics of eclosion, developmental time and egg-to-adult survival). Further, we determined how transferring flies reared on fruit/vegetable substrates to a standard laboratory diet affected their fitness. Results indicate that strains reared on the diet with the lowest content of protein and the highest C/N ratio had the slowest eclosion and developmental time, and lowest egg-to-adult survival (apple diet). The flies reared on the diet with the highest protein content and the lowest C/N ratio had the highest survival (tomato diet). Flies reared on the carrot diet, which is quite similar in protein content and C/N ratio to the standard cornmeal diet, had the fastest development. Transferring flies to the standard cornmeal diet accelerate eclosion and developmental time, but did not affect survival., Jelena Trajković, Vukica Vujić, Dragana Miličić, Gordana Gojgić-Cvijović, Sofija Pavković-Lučić, Tatjana Savić., and Obsahuje bibliografii
The genetic structure and phenotypic diversity of two populations of Cheilosia aff. longula (Diptera: Syrphidae) in Lapland, Finland, were examined using DNA sequencing, protein electrophoresis, and geometric morphometrics. The morphological identification of the species were verified using partial sequences of mitochondrial cytochrome c oxidase subunit I (COI mtDNA), and the nuclear ribosomal internal transcribed region 2 (ITS2 rDNA), and comparing the corresponding sequences of Cheilosia aff. longula and the closely related C. longula. Two and three haplotypes of the genes COI mtDNA and ITS2 rDNA were identified in the two populations. Analysis of 12 isozyme loci showed an extremely low genetic variability in the populations originating from Utsjoki and Kevo. Discriminant analysis combined with canonical variate analysis revealed inter-population divergence in wing shape. Variation among genetically diverse individuals, both within- and among studied populations was studied, and directional (DA) and fluctuating asymmetry (FA) estimated using landmarks in the framework of geometric morphometrics. It is likely that the documented DA and FA asymmetry in both wing shape and size reflects the developmental instability of the individuals studied. By using Procrustes ANOVA the locations of particular landmarks responsible for the variation in shape were determined. The decomposition of the components of variance accorded to each landmark showed that the landmarks differed in the percentage of variation they accounted for (DA, FA and variation among individuals). In the discussion the implications of the reduced genetic diversity and asymmetry in wing traits for conservation is considered.