Neotropical Copestylum (Diptera, Syrphidae) breeding in bromeliads (Bromeliaceae) including 22 new species

Twenty-three species of Copestylum (Diptera, Syrphidae) were reared from Bolivia, Costa Rica, Ecuador, Mexico, and Trinidad from 1998 to 2004. Twenty-two were new species. We describe these new species, their breeding sites, and the third stage larva and/or the puparium of all 23 species. Adults had species-specific head shapes and colour patterns, but similarities between 14 of the species enabled two groups and three subgroups to be recognized. Nonetheless, the high level of morphological disparity suggests independent colonizations of bromeliads. Adult colour patterns appear to be predominantly cryptic in function and based on reflectiveness derived from matt to shiny integumental ground colours, combined with overlying areas of variously coloured hairs, dust, and pruinosity. In addition, disruptive spots, bands, and vittae occur on the face, thoracic pleurites, and second tergite. Larvae were saprophagous in either live or dead bromeliads with no overlap between categories. A major factor explaining variation in larval morphology could be access to food. Larvae in live bromeliads are characterized by varying levels of dorso-ventral flattening, and modifications to the mouthparts and prothorax. These features appear to facilitate feeding in the narrow spaces between overlapping bromeliad leaves. Larvae exploiting dead bromeliads are characterized by varying levels of armature to the thorax, and extensions to the anal segment. Armature either consists of arrangements of sclerotized spicules distributed at various places on the thorax or large hooks on the lateral margins. Armoured thoraces facilitate burrowing through decaying tissue, and extended anal segments may reduce exposure during respiration.  © 2007 The Linnean Society of London, Zoological Journal of the Linnean Society , 2007, 150 , 267–317.     

Neotropical Copestylum (Diptera,Syrphidae) breeding in Agavaceae and Cactaceae including seven new species

We studied 42 species of saprophagous, Neotropical Copestylum (Diptera, Syrphidae) reared from decaying Cactaceae and Agavaceae. Thirty‐three species were reared during fieldwork in Bolivia, Costa Rica, Ecuador, Mexico, Peru, and Trinidad from 1998–2007. Nine species came from museum and private collections. Seven were new species. We describe these new species and the third stage larva and/or puparium and breeding sites of 40 species. Not described are two apparent species related to Copestylum apicale (Loew, 1866) reared from Cactaceae. Resolution of their status was beyond the scope of this paper but reference is made to their distinctive larval morphology. Based on early stage characters all reared species can be placed in ten species groups, all but three of which have been recognized previously on the basis of adult characters. A high level of congruence was found between adult and larval characters in terms of these species groups. Eight of the groups appear to be related closely and may represent a monophyletic lineage within Copestylum that has diversified in xeric habitats. Early stage morphology varied within and amongst groups but two trends in functional morphology are recognizable. One trend is towards feeding in watery decay and the other towards feeding in firmer decay. The latter trend is characterized by species that scoop food and use grinding mills in their head skeletons to break it up. They also have armoured thoraces with varying arrangements of sclerotized spicules or stiffened setae for gripping and protection during tunnelling, a short anal segment, and a short posterior breathing tube for protecting the openings. The former trend is characterized by species with opposite and contrasting features. They filter food and have well‐developed pre‐oral setal filters but they lack grinding mills or only have poorly developed grinding mills. They have reduced thoracic armature, elongate anal segments, and posterior breathing tubes which facilitates simultaneous feeding and respiration. Comparison with 23 Copestylum species reared from bromeliads (Bromeliaceae) suggests a common pattern of diversification in that species groups with the largest body sizes are more specialized.     

Neotropical Copestylum Macquart (Diptera: Syrphidae) Breeding in Fruits and Flowers,Including 7 New Species

Ten species of Copestylum (Diptera: Syrphidae) were reared from fruits and flowers in Costa Rica, Ecuador and Trinidad. Seven were new and in this paper, we describe them, their development sites and the third stage larva and/or the puparium of all ten species. One new synonym is proposed, Copestylum pinkusi (Curran) [= Copestylum cinctiventre (Curran)]. Similarities and differences between these new and other Copestylum species, suggest they separate into two groups, referred to as the Vagum and Cinctiventre species groups. Features characterising these groups for both adult and early stages are assessed. Each species was also distinguished using adult and early stage characters. Within the Vagum group, adults were more disparate morphologically than the larval stage; this was reversed in the Cinctiventre group. Adult colour patterns are probably cryptic in function and for disguise. Vagum species have disruptive marks, while the Cinctiventre species have reflective colours. Biologically, the groups are almost distinguished by larval development sites. Vagum species use predominantly fruits and have a larval stage that is relatively generalised in form and habit. Cinctiventre species are confined to developing in flowers and the larva is more specialised. A key to both adult and early stages of all ten species is provided.     

Bacteria associated with four species of Dacus (Diptera: Tephritidae) and their role in the nutrition of the larvae

Summary The bacteria associated with Dacus tryoni (Froggatt), Dacus jarvisi (Tryon), Dacus neohumeralis (Hardy) and Dacus cacuminatus (Hering) were examined. Bacteria were isolated from the surface of freshly-laid eggs, from within surface sterilised pupae, from heads and abdomens of wild and laboratory-maintained flies, and from decomposed fruits in which the wild larvae were feeding. A more diverse flora was associated with D. tryoni and D. jarvisi (15 and 14 species, respectively) than with D. neohumeralis and D. cacuminatus (9 and 6 species, respectively). Most of the bacteria belonged to the family Enterobacteriaceae and while there were similarities of bacterial associations between fly species there was no evidence of a strict symbiotic association of a particular bacterium or bacteria with each species of fly. The larvae of D. jarvisi were unable to develop normally in an artificial medium containing unhydrolysed protein and free of bacteria and on a medium containing casein and Serratia liquefaciens (isolated from the flies and shown to secrete protease) the larvae died. On the same casein medium containing Enterobacter cloacae (isolated from the flies and shown to be protease negative) the larvae developed normally. Larvae of D. tryoni and D. jarvisi were devoid of protease and cellulase activity, but contained some amylase activity. The significance of these results in terms of current hypotheses concerning symbioses between tephritids and bacteria is discussed.     

辽宁食蚜蝇科昆虫名录(双翅目:食蚜蝇科)

本文报道了辽宁省食蚜蝇科昆29属53种的名录和分布。     

Water and carbon storage capacity in Isolatocereus dumortieri (Cactaceae) in an intertropical semiarid zone in Mexico

In the biosphere reserve Barranca de Metztitlán in Mexico, there is an extensive area with a semiarid scrub. The dominant species is the cactus Isolatocereus dumortieri. This is a key species in the ecosystem, because many species of birds, bats and insects are feeding from its nectar, pollen and fruits during the dry season thanks to their capacity to store water and carbon. However, there is no information about their potential to store water and carbon. The purpose of this study was to estimate the ability of I. dumortieri to store water and carbon. Water content per plant was estimated as 537.64 ± 71.59 L during the dry season and 692.24 ± 92.18 L during the wet season. In the same way the carbon stored per cactus was 16.75 kg ± 7.07 corresponding to 1.25 kg C m². The results shows the importance of I. dumortieri in maintaining the ecosystem services of the scrub vegetation.     

Oviposition behaviour and host colony size discrimination in Episyrphus balteatus (Diptera: Syrphidae)

Three bioassays were used to examine the oviposition behaviour of the hoverfly, Episyrphus balteatus (Degeer) in which various stimuli purported to influence host assessment and choice were tested. Episyrphus balteatus failed to exhibit enhanced behavioural responses, in terms of approaches and landings, to artificial leaves with the highest numbers of aphids, suggesting that females are merely responding to the colour of the artificial leaves. A density-dependent oviposition response was reported in a second bioassay using whole bean plants, although there was an asymptotic relationship. Syrphid responses, which were measured by oviposition over a five-day period, were greatest towards those plants with the highest number of aphids. In a final series of trials, gravid female E. balteatus showed a behavioural preference for filter papers treated with the greatest honeydew concentrations (0.26 mg microl(-1) honeydew). More time was spent in the treated areas and syrphids demonstrated more proboscis and ovipositor extensions in these treatments. These bioassays provided an opportunity to isolate some of the individual components of decision-making by female E. balteatus during egg-laying behaviour. A greater understanding of natural enemy behaviour is essential before enhanced control of pest populations in the field can be established.     

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.     

Functional morphology of the mandibles of the larvae of Episyrphus balteatus (De Geer, 1776) (Diptera : Syrphidae)

Aphidophagous syrphid (Diptera : Syrphidae) larvae have no structures for seizing and killing such as prehensile legs and strongly sclerotized external mouthparts enabling them to capture and feed on their prey. Nevertheless they are considered to be efficient predators. In order to understand this paradox in Episyrphus balteatus, 2 complementary approaches were followed. These consisted of, first, a careful analysis of the morphology of mouthparts of the larvae, and second, an investigation of their feeding behaviour. The mouthparts were found to be composed of 2 groups of dental sclerites, corresponding to the 2 inner elements of the cephalopharyngeal skeleton. The exterior elements or triangular sclerites are absent in the first-instar larvae. These elements appeared close to the mouth in the second and the third-instar larvae, were oriented in the opposite direction to the other elements, and were positioned laterally. This structure probably serves to anchor the anterior part of the predator within the prey, thus preventing it from escaping. During the feeding activity, the seizing process occurred immediately after the recognition. The lifting-up behaviour of the first-instar larvae is probably due to the absence of the triangular sclerites. The suction was marked by an active movement of the cephalopharyngeal skeleton and a peristaltic movement of the abdomen. The feeding time was inversely proportional to the larval development.     

Food utilization of aphidophagous hoverfly larvae (Diptera: Syrphidae, Chamaemyiidae) on herbaceous plants in an urban habitat

We examined food utilization in a community of aphidophagous hoverfly larvae (Diptera: Syrphidae and Chamaemyiidae) in open lands in an urban habitat in central Japan for 3 years. The community consisted of 17 hoverfly species feeding on 20 aphid species occurring on 14 species of dominant herbaceous plants. In terms of larval prey preference, the dominant eight species of hoverfly were categorized into three groups: a polyphagous ‘generalist’ group consisting of four species,Episyrphus balteatus, Betasyrphus serarius, Syrphus vitripennis andSphaerophoria sp.; an oligophagous ‘specialist’ group consisting of three species,Metasyrphus hakiensis, Dideoides latus andParagus hemorrhous; andLeucopis puncticornis, which showed a preference for two aphid species on the plantTorilis scabra. The prey aphids of the second group have behavioral or morphological defense mechanisms that are effective for preventing attacks by generalist hoverflies; two prey aphids are aggressive toward generalist predators and the others are protected by ant-attendance. The specialist hoverflies seem to be adapted to overcome these defense mechanisms. The prey ranges overlapped little between the generalist and the specialist groups, while those within the generalist group overlapped greatly.     

Differences in ecomorphology and microhabitat use of four saproxylic larvae (Diptera,Syrphidae) in Scots pine stump rot holes

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Two phoretic black-flies (Diptera: Simuliidae) and their associated mayfly host (Ephemeroptera: Heptageniidae) in Cameroon

Simulium afronuri and S.lumbwanum are recorded living in association with nymphs of Afronurus in the forest zone of West Cameroon. Observations on infestation rates, attachment sites, larval size distribution and dispersion are recorded. Evidence of niche separation between the two simuliid species is discussed.     

Checklist of the family Syrphidae (Diptera) of Finland

A checklist of the Syrphidae (Diptera) recorded from Finland. Three species of Syrphidae, Platycheirus modestus Ide, 1926, Cheilosia barovskii (Stackelberg, 1930) and Mallota tricolor Loew, 1871, are published as new to the Finnish fauna. Platycheirus modestus is also new to the Palaearctic.     

Cold tolerance of the aphid predator Episyrphus balteatus (DeGeer) (Diptera, Syrphidae)

Abstract. Larvae of the hoverfiy Episyrphus balteatus (DeGeer) are important predators of aphids in the U.K. A large proportion of the U.K. population migrates south to warmer climes at the end of summer, but a small number are thought to overwinter in the U.K., with the mated female being the overwintering morph. The cold tolerance of adult flies was investigated to assess the overwintering potential of E. balteatus in the U.K. The high supercooling point (SCP) of -8.3 ± 0.7°C, and lethal temperature (LTemp₃₀) of -9.1°C for acclimated females suggest that E. balteatus has limited cold hardiness. This was confirmed by experiments where, despite a strong acclimation response in both males and females, there was no long-term survival at 5, 0 or - 5°C. At 5°C, 90% of females had died after 10 days. The weak cold hardiness of adult E. balteatus was corroborated by field experiments which demonstrated a 100% mortality after 10 weeks' exposure to U.K. winter conditions. The ecological significance of this limited cold hardiness is discussed in relation to the overwintering abilities of E. balteatus in the U.K.     

Hover fly fauna (Diptera,Syrphidae) of Karaginskii Island (the Bering Sea)

The hover fly fauna of Karaginskii Island, located in the southwestern part of the Bering Sea near Kamchatka Peninsula, was investigated. A total of 39 species belonging to 22 genera were found on the coastal plain covered with the shrub tundra and meadows of various types. Cheilosia with 7 species was the most diverse genus in the fauna. The chorological structure of the fauna has a typical boreal pattern being dominated by widespread species (77% of the fauna), whereas the fraction of arctoboreal species is distinctly smaller (8%). The subspecies Cheilosia illustrata magnifica, one of the dominants in the hover-fly community (9%), was a single subendemic element of the fauna.     

Hoverfly (Diptera, Syrphidae) fauna of Ary-Mas locality (the Taimyr Biosphere Reserve)

The local fauna of Ary-Mas (the Taimyr Biosphere Reserve) was found to comprise 56 species of hoverflies, representing only two subfamilies: Syrphinae (36 species) and Eristalinae (20 species). Analysis of trophic preferences of adult hover-flies showed that Syrphidae visited plants of 17 species from 10 families. The representatives of Syrphidae preferred Tanacetum bipinnatum (18 species), Ranunculus propinquus, and Tripleurospermum hookeri (12 species each). Three species of hoverflies visited the greatest number of plant species: Melangyna arctica (11), Syrphus ribesii (9), and Parasyrphus dryadis (8).     

Estimating attraction of Syrphidae (Diptera) to flowering plants with interception traps

Syrphidae with predaceous larvae are important predators of aphids and other insects and can be attracted and maintained in agricultural environments by the addition of flowering plants. Malaise interception traps baited with moveable flowering plants are a novel means of surveying for attractive species and can have the advantages of: (1) homogenising experimental site and plant quality, (2) portability, (3) continuous sampling, (4) capacity to simultaneously capture a broad range of insects (including pests) and (5) no requirement for additional sensory cues to be effective. Six of the 10 species of plants tested were relatively attractive (number of syrphids captured in flower-traps/numbers captured in no plant controls). While flower-traps captured more syrphid species than their associated controls, there were no differences between flower-traps and controls in the sizes (head height) or proboscis lengths of the flies collected. There were no significant relationships between relative attractiveness and flower width or depth or with plant height and floral area. Similarly, mean proboscis length of flies taken in flower-baited traps was not correlated with flower width or depth. The absence of the latter relationship may be due to the inability of an interception trap to distinguish between attraction and attraction-then-feeding.