Revision of the section Anillochlamys Jeannel, 1909 (Coleoptera: Leiodidae: Cholevinae: Leptodirini)

The taxonomy of the Iberian Leptodirini species of the section Anillochlamys Jeannel, 1909 has been revised. The proposed classification is based on the study of the genital structures of both sexes, in particular the internal sac of the aedeagus. According to the different models of internal sacs, the following genera, species and subspecies are identified: genus Anillochlamys Jeannel, 1909: A. aurouxi Español, 1965, A. bueni Jeannel, 1909 (= A. avariae Comas, 1977 n.syn.), A. cullelli Lagar, 1978, A. moroderi Bolívar, 1923 (= A. negrei Comas, 1990 n. syn.), A. subtruncatus Jeannel, 1930 (= A. baguenai Jeannel, 1930) and A. tropicus (Abeille, 1881) (= Adelops hispanicus Ehlers, 1893; A. tropicus var. apicalis Jeannel, 1909); genus Paranillochlamys Zariquiey, 1940: P. catalonicus (Jeannel, 1913), P. urgellesi (Español, 1965) and P. velox Zariquiey, 1940 (= P. velox montadai Lagar, 1963 n. syn.); genus Pseudochlamys Comas, 1977: P. raholai (Zariquiey, 1922) (= Anillochlamys raholai luis-bofilli Zariquiey, 1940 n. syn.); genus Spelaeochlamys Dieck, 1870 (= Typhlochlamys Español, 1975 n.syn.): S.bardisai (Español, 1975) (= Typhlochlamys escolai Comas, 1978 n. syn.), S. ehlersi Dieck, 1870 and S. ehlersi verai Comas, 1977 n. stat.     

Dealing with food shortage: larval dispersal behaviour and survival on non‐prey food of the hoverfly Episyrphus balteatus

1. Predatory larvae often have to face food shortages during their development, and thus the ability to disperse and find new feeding sites is crucial for survival. However, the dispersal capacity of predatory larvae, the host finding cues employed, and their use of alternative food sources are largely unknown. These aspects of the foraging behaviour of the aphidophagous hoverfly (Episyrphus balteatus De Geer) larvae were investigated in the present study. 2. It was shown that these hoverfly larvae do not leave a plant as long as there are aphids available, but that dispersing larvae are able to find other aphid colonies in the field. Dispersing hoverfly larvae accumulated on large aphid colonies, but did not distinguish between different pea aphid race–plant species combinations. Large aphid colonies might be easier to detect because of intensified searching by hoverfly larvae following the encounter of aphid cues like honeydew that accumulate around large colonies. 3. It was further shown that non‐prey food, such as diluted honey or pollen, was insufficient for hoverfly larvae to gain weight, but prolonged the survival of the larvae compared with unfed individuals. As soon as larvae were switched back to an aphid diet, they rapidly gained weight and some pupated after a few days. Although pupation and adult hatching rates were strongly reduced compared with hoverflies continuously fed with aphids, the consumption of non‐prey food most probably increases the probability that hoverfly larvae find an aphid colony and complete their development.     

Contrasting responses in community structure and phenology of migratory and non‐migratory pollinators to urbanization

Aim

Anthropogenic landscape change, such as urbanization, can affect community structure and ecological interactions. Furthermore, changes in ambient temperature and resource availability due to urbanization may affect migratory and non‐migratory species differently. However, the response of migratory species to urbanization is poorly investigated, and knowledge for invertebrates in particular is lacking. Our aim was to investigate whether there was a shift in community structure and phenology of hoverflies in urban landscapes, depending on migratory status.

Location

Switzerland.

Methods

Using a paired design, we compared urban and rural landscapes to investigate the impact of urbanization on the abundance, diversity and phenology of hoverflies. Furthermore, we tested whether migratory and non‐migratory species responded differently to urbanization.

Results

We observed a difference in the response of migratory and non‐migratory hoverfly communities. Although the abundance of hoverflies was higher in the rural ecosystem, driven by a high abundance of migratory species, there was no difference in species richness between the land use types. However, the community structure of non‐migratory species was significantly different between urban and rural ecosystems. The phenology of hoverflies differed between the two ecosystems, with an earlier appearance in the year of migratory species in urban landscapes.

Main conclusions

To our knowledge, this is the first study to investigate the response of migratory insect communities to urbanization. We demonstrated that migratory and non‐migratory hoverflies respond differently to urbanization. This highlights the importance of differentiating between trait and mobility groups to understand community assemblage patterns in anthropogenic landscapes. The differences in phenology supports the growing evidence that urbanization not only affects the phenology of vegetation, but also affects the higher trophic levels. Changes in the phenology and community composition of species as a result of anthropogenic landscape change may have important implications for the maintenance of key ecosystem functions, such as pollination.

     

DOES THE ABUNDANCE OF HOVERFLY (SYRPHIDAE) MIMICS DEPEND ON THE NUMBERS OF THEIR HYMENOPTERAN MODELS?

We tested the prediction that, if hoverflies are Batesian mimics, this may extend to behavioral mimicry such that their numerical abundance at each hour of the day (the daily activity pattern) is related to the numbers of their hymenopteran models. After accounting for site, season, microclimatic responses, and general hoverfly abundance at three sites in northwestern England, the residual numbers of mimics were significantly correlated positively with their models nine times of 17. Sixteen of 17 relationships were positive, itself a highly significant nonrandom pattern. Several eristaline flies showed significant relationships with honeybees even though some of them mimic wasps or bumblebees, perhaps reflecting an ancestral resemblance to honeybees. There was no evidence that good and poor mimics differed in their daily activity pattern relationships with models. However, the common mimics showed significant activity pattern relationships with their models, whereas the rarer mimics did not. We conclude that many hoverflies show behavioral mimicry of their hymenopteran models.     

Is there any evidence that aphid alarm pheromones work as prey and host finding kairomones for natural enemies?

1. The aphid alarm pheromone (E)‐β‐farnesene (EBF) is often considered to be used by natural enemies as a prey/host finding kairomone. However, studies show opposing results, some appear to confirm an attraction of aphid natural enemies by EBF whereas others do not provide any evidence for the kairomone function of EBF. 2. To clarify if aphid natural enemies are attracted by the amounts of EBF naturally emitted by aphids, the existing literature was reviewed about EBF attractiveness to aphid natural enemies with consideration of the amounts of EBF used in the studies. 3. Thirty‐one publications that investigated the ability of EBF, aphid cornicle secretion, and attacked aphids, to attract aphid natural enemies were found. Several studies showed an attraction by EBF, but these used much higher amounts of EBF than usually emitted by aphids during a predator attack. Studies investigating EBF amounts similar to what is emitted by aphids are rare and failed to show attraction. Only two studies document an attraction of natural enemies by attacked aphids. 4. As EBF is emitted in very low amounts, not very stable, and only present after an attack, we suggest that aphid‐derived EBF is not a suitable kairomone for most natural enemy species, especially when they are able to use alternative cues. As EBF, amongst other volatiles, is also emitted by herbivore‐induced plants, we propose that natural enemies might use plant‐derived EBF as a synomone to identify aphid‐infested plants via an altered plant volatile bouquet.     

Geographic variation in plasticity in Eristalis arbustorum

To study the evolution of phenotypic plasticity in the field, six populations of the hoverfly Eristalis arbustorum were sampled along two parallel North-South transects over a maximum daily temperature gradient. Three populations were sampled per transect. Egg batches were collected and the offspring were reared in a split family set up over three different pupal temperature regimes in the laboratory to produce population reaction norms of colour pattern, pupal development time, wing length and thorax length. Wing length and colour pattern were corrected for body size. All four characters showed plasticity in response to rearing temperature and significant differences in height, slope and shape of the reaction norms were found. Only male colour pattern showed variation in reaction norms along the North-South gradient. Most other characters showed variation in reaction norms from West to East. The two populations lying in the middle of the transects were frequendy different from the others. Within the populations, significant genotype-environment interactions were frequently found for wing length and colour pattern, indicating that genetic variation for plasticity was present. The results suggest that the populations may have evolved plastic responses to suit local environmental conditions.     

Systematics and phylogeny of the tribe Paragini (Diptera: Syrphidae) based on molecular and morphological characters

We studied the phylogeny and systematics of the tribe Paragini (Diptera: Syrphidae) using morphological and molecular data. The paper presents separate parsimony analyses of both adult morphological characters and partial DNA sequence data from mitochondrial cytochrome c oxidase I and nuclear ribosomal 28S rRNA gene, as well as a combined analysis of all the data. The data set of morphological characters included some features of the male terminalia (i.e. shape of the ejaculatory apodeme; relative position of elements of the aedeagal complex; shape of surstylar apodeme; shape of the aedeagal apodeme) not previously used in the systematics of the Paragini. The trees obtained from separate parsimony analyses of molecular and morphological data produced almost identical topologies. Four lineages are supported by the combined data set, and we establish two new subgenera, i.e. Serratoparagus Vujić et Radenković subgen. nov., and Afroparagus Vujić et Radenković subgen. nov., and redefine Pandasyopthalmus Stuckenberg, 1954 stat. rev. and Paragus Latreille, 1804, stat. rev. The monophyly of the Pandasyopthalmus clade, including the species fitting neither of the current species groups ( jozanus -group) of Paragini, is established. Diagnoses of all known species groups are presented, including a new arrangement of almost all valid species of Paragini.  © 2008 The Linnean Society of London, Zoological Journal of the Linnean Society , 2008, 152 , 507–536.