Eversible pleural sacs were recently discovered in ♀♀ of European species of Rhamphomyia Meigen 1822 (Empididae). In live specimens, they are showily orange. SEM photos show a peculiar surface with numerous setae arranged in whorls. It remains unclear whether they are simply decoration or in combination with pheromones to increase female attractivity. Appendages of male Dolichopodinae are digitate and not covered by hairs or setae. They seem to be restricted to the subfamily Dolichopodinae and probably work wogether with pheromones.
Flowering plants manipulate the behaviour of their pollinators in a wide range of ways, includ ing exploiting associative learning by changing the colour of flowers as they age and at the same time withdrawing the nectar reward. This study investigated the adaptive function of the floral colour change from white to purple in Erysimum scoparium (Brouss. ex Willd) Wettst in relation to its main pollinator, Anthophora alluadii (Perez 1895). Both species are endemic to the Canary Islands. Field observations of nectar production and bee behaviour, plus inflorescence and whole plant manipulation experiments at sites in Tenerife in 2003, 2004 and 2006, provided support for three hypotheses. Hypothesis 1: The flower colour change in E scoparium serves as a visual signal, indicating to pollinators that the nectar reward of the flower has changed. Late phase purple flowers provide much less (and more frequently zero) nectar compared to early phase white flowers, and pollinators make fewer visits of shorter duration to purple flowers. Hypothesis 2: Removal of purple flowers from inflorescences reduced the rate of pollinator visitation to white flowers on those inflorescences. Retention of late phase, purple flowers therefore increased the visual attraction of individual inflorescences, and this short-distance (up to tens of centimetres) visual signal directs pollinators to newly opened, rewarding flowers on that inflorescence potentially reducing geitonogamy. Hypothesis 3: Finally, evidence was found that retention of late phase, purple flowers on the plant acted as a long-distance visual signal to pollinators, highlighting the presence of plants over scales of metres to tens of metres. Removal of all purple flowers from individual plants did not result in reduced overall visitation rates to those plants, but it did change the relationship between plant size and bee visitation rate, from a positive correlation to no significant relationship. In relation to experimentally testing the function of the floral colour change, previous studies have obtained contrasting results. This may be because whole flower colour changes have evolved as medium and long range signals, whereas colour change of isolated parts of flowers may more often be a short range signal.
Studies on tiger beetle guilds are promising to shed light on general mechanisms that maintain species diversity in the tropics. Therefore this family was studied across a range of habitat types of Central Amazonia in the vicinity of Manaus (open areas and forests on terra firme as well as in white-, mixed-, and blackwater floodplains). In addition to analysis of regional species distribution (extents of habitat specificity), local spatio-temporal guild structures were investigated in order to infer mechanisms mediating coexistence within guilds. Here the results of extensive field observations on habitats, life cycles, and behaviour are summarised for both larvae and adult beetles of most of the 25 species known to occur in the region. Field work was carried out from 1991-99, of which 2-6 years were spent in each habitat. Additionally, life cycles of species were studied by rearing them in the laboratory. At the regional scale, species richness is related with regional habitat diversity, likely because habitat specificity is strong in most species. At the local scale, spatio-temporal guild structure is determined by different life cycles, diel activity patterns, microhabitat preferences and behaviour. Guild structures vary according to habitat types. Guilds from open floodplain areas show strong niche separation whereas guilds from terra firme forest floors exhibit wide niche overlap, with floodplain forests and open terra firme areas lying in between. Thus, tiger beetle guilds of Central Amazonia seem to be variously structured, which indicates different mechanisms mediating coexistence. Possible relations of guild structure with habitat properties are discussed
First evidence is given for the hitherto unknown survival mode of females [♀♀] of the parasitoid Scambus pomorum (Ratzeburg 1848), which propagates once every spring, on larvae of the apple blossom weevil, Anthonomus pomorum Linnaeus 1758. After mating, the ♂♂ die, and the ♀♀ continue as predators of leafminer larvae, and perhaps other concealed insects, while they remain in a state of reproductive diapause. In captivity, the female parasitoids attack the mines of moths of different families, of agromyzid flies and sawflies, living on various tree species. A similar explicitly predatory life style ora parasitoid wasp has not been reported before. Leafminers as prey are not responsible for the absence of oogenesis before winter, for eggs develop in overwintered ♀♀ on the same food. Single ♀♀ kill, and feed upon, up to two Phyllonorycter blancardella (Fabricius 1781) (Lepidoptera: Gracillariidae) larvae per day at 20°C, both in early summer and autumn. Predation is linearly related to temperature. In captivity, predation by well-fed ♀♀ showed a dip in August. ♀♀ fed this way, overwintered successfully in coniferous trees, like they are known to do in nature. They became active again in late March. ♀♀ are ready to oviposit when the first suitable host stages appear, on the earliest flowering apple varieties, or on pear. One ♀ lays up to 14 eggs per day at 16.5°C, and total egg production may exceed 100 eggs, but about 50 eggs is more usual, and many ♀♀ are even less fecund. Some ♀♀ are still alive, and probably reproducing, when suitable host stages are becoming scarce. Parasitism levels should be determined when approximately 75% of the host weevils have become pupae; dissections of capped blossoms and parasitoid rearings gave similar results. Her extended lifespan makes the female wasp vulnerable to calamities like pesticide applications. Perhaps, more elevated leafminer densities in nearby hedgerows could seduce ♀♀ to leave the apple planting in time.
The first quantitative assessment of between-colony variation in learning ability within a natural bee population is presented here. Bumblebee (Bombus terrestris audax Harris 1776) colonies were raised in the laboratory, under identical conditions, from wild caught queens. 240 bumblebee workers from 16 colonies were individually tested in an ecologically relevant foraging situation in which they had to distinguish yellow, rewarding artificial flowers from blue, unrewarding ones under laboratory conditions. During the initial stages of the task, 15 colonies showed a very strong, unlearned preference for blue flowers (the other colony showed no strong colour preference). There was significant variation among the colonies tested in learning speed, task saturation performance, and the number of flower choices made prior to first feeding from a rewarding, yellow flower. Such intercolony variation in performance forms the raw material upon which any selection for learning ability might act. Overall, neither age nor size of bees were consistently correlated with learning performance, but older bees learned faster in one of the colonies, an effect that remained significant even after statistical correction for multiple comparisons.
Commercial trade of bumblebees in Europe results in different subspecies of Bombus terrestris being shipped into regions where they are not native. Although previous studies have shown that these subspecies will interbreed, none have assessed mating preference of the different populations. This study examines the mating preferences between two geographically isolated populations of B. terrestris which have unnaturally been brought together through the commercial trade in bumblebees. Under controlled choice conditions, mating between commercially imported B. t. dalmatinus (from South-eastern Europe) and native British B. t. audax was non-random. Commercially imported gynes (unfertilised queens) preferred to mate with males from the same population (71% of matings). In light of the continued escape of imported gynes and males, these results indicate that there is a possibility of establishment of South Eastern European B. t. dalmatinus in Britain, and that hybrids will also occur. The ecological risks of such an establishment are discussed.
The three bumblebee species Bombus terrestris (Linnaeus 1758), Bombus lapidarius (Linnaeus 1758), and Bombus pascuorum (Scopoli 1763) showed consistent differences in their respective levels of flower constancy when foraging on three different pairs of flower species. B. terrestris was always the most flower constant, followed by B. lapidarius, with B. pascuorum the least flower constant species. These interspecific differences in flower constancy were related to foraging performance under field conditions near Würzburg, Germany in 1999 and 2001. B. terrestris was more flower constant, and predominantly outperformed B. lapidarius at collecting nectar in both years. As B. terrestris is also the larger of these species, these data also support the idea that larger bees are more efficient at nectar foraging, i.e. they bring home more nectar per unit time. However B. pascuorum, the least flower constant of the three species tested, was the most efficient of them at collecting nectar, collecting 50% more nectar than B. terrestris per hour. Therefore flower constancy appears to be a relatively poor predictor of species foraging performance, which is likely to be influenced simultaneously by many other factors including worker body size, tongue length, and foraging range.
Bees are highly sensitive to environmental disturbance as they depend on floral resources in both their larval and adult life stages. The aim of this study was to investigate the influence of surrounding habitat quality on variation in body size and corbiculae area of the Neotropical stingless bee, Melipona fasciculata (Hymenoptera: Apidae: Meliponini) in the eastern Brazilian Amazon. We collected a total of 115 bees from managed colonies in an urban area (BEL), and 115 bees from colonies in a preserved area (BRG). We compared bee body sizes of different castes (workers, gynes and drones) between BEL and BGR. We also compared variation in the corbiculae area of worker bees between the two areas. Our results showed that worker body size and males of M. fasciculata did not change between urban and preserved sites. However, gyne body size and worker corbiculae area were larger in individuals collected from BRG compared to those from BEL. We conclude that the differential nutritional statuses of colonies in urban and preserved regions, as a result of inter-regional discrepancies in floral resource availability, influenced adult body size and morphological traits of M. fasciculata, although this effect was not consistent between bee castes.
In Central Europe, the Asian Artemisia verlotiorum, Lamotte, 1877 (Asteraceae) is becoming increasingly invasive and may in future forced by climate change cause problems in nature conservation and agriculture. To estimate its ecological role as a host plant, its phytophagous arthropod complex was analysed. The analysis is based on field surveys, primarily in the Lake Constance area, as it is an "old" stronghold of the alien herb. A total, of 55 sites were investigated in 2007, of which 26 are lake shore sites and 23 ruderal or segetal sites nearby. Other (ruderal) sites are near Mainz (Germany: Rheinland-Pfalz, 4 sites), Heidelberg (Germany: Baden-Wurttemberg, 1 site) and Locamo (Switzerland, Ticino, 1 site). The sites on Lake Constance were investigated four times a year to capture various phytophagous guilds (e.g. external feeders, leaf miners, stem and rootstock inhabitants). The phytophagous insect complex as studied here encompasses 30 species (12 Homoptera, 6 Lepidoptera, 6 Diptera, 5 Heteroptera and 1 Coleoptera) and is consequently significant pourer than that of the native A. vulgaris (181 sp.). 43.3% of these are polyphagous, 30.0% oligophagous (i.e. restricted to Asteraceae), 6.6% are second degree monophagous (i.e. restricted to the genus Artemisia) and 20.0% were found only on A. vulgaris before (first degree monophagous). More than half the species (55.2%) are sap-suckers, while the rest chew on plant tissue. Epiblema foenella (Torticidae), Phytomyza artemisivora (Agromyzidae) and Ttypeta artemisiae (Trypetidae) are the most abundant chewing species. The stem borer E. foenella in particular can have a noticeable effect on the vitality of the plants. Macrosiphoniella artemisiae, M. oblonga and Pleotrichophorus glandulosus are locally abundant aphid species (Aphididae).
Larvae of Mycodiplosis melampsorae (Diptera: Cecidomyiidae) are reported for the first time in Italy as occurring on the crown of tree spurge (= Euphorbia dendroides), and feeding on the urediniospores of the rust fungus Melampsora gelmii. The identification of the insect was based on the larval morphology. Since only adult individuals of M. melampsorae were already observed in South Tyrol (northern Italy) on goat willow trees (= Salix caprea), this report contributes to increase the knowledge about the ecological preferences and the biology of Mycodiplosis spp. in Italy.
In 1983, about 156.000 Chironomidae in 110 taxa were recorded from two emergence traps (green-houses), one exposed above a sand substratum and another above large moss-covered sand-stones, the clearest substrata difference existing in the Breitenbach (Schlitz, Hesse, Germany). 99 species were recorded from the sand and 85 from the stone trap. Proportions of Prodiamesinae and Chironomini were higher in the sand trap by more than five percent, Tanytarsini relative abundance was almost five percent higher in the stone trap. The ten most abundant species accounted for 83% of specimens in the stone trap but only 63% in the sand trap. 40 species were identified as the basic stock of the chironomid community on the Breitenbach. Species number in the stone trap was 13% smaller than in the sand trap, 24% smaller for total specimen numbers, and biomass was lower by 37%. Similarity between these and some other stream sites and years compared was always below 0.50; high similarity was even observed between the contrasting sediments in the year of investigation. Total production (stone ∼ 1.9 mg m-2 yr-1; sand ∼ 2.7 mg m -2 yr-1) was low and typical for oligotrophic habitats. Thienemann's rule, saying that communities from increasingly monotonous uniform habitats were less diverse than from diverse habitats, was not confirmed. This maybe partly due to a methodological weakness of emergence traps: reduced current speed underneath the sand trap improved the chance for successful emergence from drifting pupae.
The present work intends to show the lack of subspecies status within the cat flea Ctenocephalides felis. Howewer, the conclusion is unsubstantiated because, in an entomological point of view, the work is based on several misinterpretations and the authors fail to read the papers recently published on the subject. Actually, only C f strongylus can be regarded as a geographic form. Inference based on molecular approach relies on misinformation and suffers from the weakness of the data set. The authors should provide more details on sequence variation obtained and substantial revisions in the data analysis need to be achieved.