Ultrastructure of the spermatozoon of Megaselia scalaris Loew (Diptera:Brachycera:Cyclorrhapha:Phoridea:Phoridae)

When viewed by scanning electron microscopy (SEM), the spermatozoon of the phorid dipteran Megaselia scalaris appears threadlike, lacking distinct head and tail areas. These areas can be observed, however, in appropriately stained material. Measurements of Feulgen-stained material reveal average lengths of the head, tail, and total cell of 18.7, 128.7, and 147.4 μm, respectively. When tested for sulfhydryl and disulfide groups, the head displays only disulfide groups. Transmission electron microscopy (TEM) reveals 12 different regions: three (1–3) in the head, four (9–12) in the tail, and five (4–8) in a short zone of overlap between the head and tail. Most of the cell lies in regions 9 and 11 of the tail and 3 of the head, accounting for, respectively, 37.3%, 45.7%, and 11.2% of the total length. A tubelike acrosome indents the anterior end of the nucleus. The tail originates asymmetrically in relation to the long axis of the cell as a peglike structure associated with the dorsolateral region of the nucleus. No centriole is visible, and the nucleus has a notched appearance in longitudinal sections. Two mitochondrial derivatives and an axoneme displaying a 9+9+2 microtubule configuration and ATPase activity extend throughout most of the tail. In regions 9 and 10, an asymmetrically arranged accessory body is also present. Features having possible taxonomic utility include the asymmetrically arranged accessory body, the size and shape of the acrosome, and the notched appearance of the nucleus. The present report is apparently the first to describe the spermatozoon of a cyclorrhaphous dipteran which is not a member of the Schizophora.     

Surface ultrastructure of third-instar Megaselia scalaris (Diptera: Phoridae)

We describe some ultrastructure of the third-instar Megaselia scalaris (Diptera: Phoridae) using scanning electron microscopy, with the cephalic segment, anterior spiracle and posterior spiracle being emphasized. This study provides the taxonomic information of this larval species, which may be useful to differentiate from other closely-related species.     

蛆症异蚤蝇减数分裂染色体观察

以蛹精巢和卵巢组织为材料,采用空气干燥法制备染色体标本,Giemsa和硝酸银分别染色,对蛆症异蚤蝇Megaselia scalaris减数分裂染色体行为进行研究。结果表明:蛆症异蚤蝇的染色体数目n=3,由2条中着丝粒染色体和1条端着丝粒染色体组成;粗线期,第2条二价体具有较强的嗜银性,可能为性染色体;晚粗线期,第1条二价体的同源染色体之间出现一条细线,类似于联会复合体;终变期,第2条二价体形成环状结构;晚终变期,在3条二价体染色体臂上均产生条带,根据二价体着丝粒处是否成环可以将3条二价体分开。     

An interesting new species of Megaselia from Sulawesi, the ground plan of the Phoridae (Diptera) and phylogenetie implications for the Cyclorrhapha

Megaselia biarticulata sp.n. is described from Sulawesi. Its distinctly two-segmented palp reinforces the view that a two-segmented palp is part of the ground plan of the family. The tibial hair palisades are also postulated as part of the ground plan and serve to link the Phoridae to the Platypezidae. The median furrow on the frons is considered as part of the ground plan. Furthermore it is postulated that it is homologous with the frontal vitta in the Schizophora, and that its invaginated lower end gave rise to the ptilinum. The Empidoidea cannot be ancestral to the Cyclorrhapha and the case for regarding these two taxa as sister groups seems highly tenuous in the light of the inferred ground plan for the Phoridae.     

On the fauna of the Diptera Brachycera of Samarskaya Luka: 1. Brachycera Orthorrhapha; Cyclorrhapha: Aschiza

The presumptive data on results of the investigation of the Diptera Brachycera in the territory of Samarskaya Luka, the largest refuge in eastern European Russia, are given. Based on the published data and on examination of 18 000 specimens, a faunal list for the region is compiled, including 897 species of 395 genera of 62 families. The annotated list of Brachycera Orthorrhapha, Cyclorrhapha: Aschiza includes data on the flight periods, habitats, and number of examined specimens.     

Observations on first and second-instar larvae of Megaselia scalaris (Loew) (Diptera: Phoridae).

The ultrastructure of the first and second-instar larvae of Megaselia scalaris (Loew) was studied using scanning electron microscopy (SEM). Significant changes in morphological features were observed in the anterior and posterior spiracles, but only minimal changes in the labium and mouthhooks were seen. The ultrastructure of M. scalaris larvae not only provides chronological transformation of their larval instars, but it can also be used to explain their feeding behavior and mode of respiration. In addition, morphological structures useful for specific identification of first or second-instar larvae collected from human corpses may be used in forensic investigations.     

Morphological and other observations on Chonocephalus (Phoridae) and phylogenetic implications for the Cyclorrhapha (Diptera)

Chonocephalus blackithorum sp. nov . is described from Sulawesi. Biological observations on it and five other species are reported. In describing the female it proved necessary to re-evaluate the morphology of the female abdomen both in Chonocephalus and in the Phoridae as a whole. This adds to the growing evidence that the ground-plan of the Phoridae, and hence the Cyclorrhapha, is plesiomorphic with respect to the Empidoidea. The supposed affinity between these two groups is called into question and it is suggested that the Cyclorrhapha could even be an independent lineage from the Nematocera. The case for continuing to regard the Brachycera as monophyletic is also called into question by casting doubt on the rotation of the larval mandibles as a synapomorphy.     

Ultrastructure of the larval salivary glands of Megaselia scalaris Loew (Diptera,Phoridae)

Each of the paired salivary glands of third instar larvae of the humpbacked fly Megaselia scalaris is a bag-like structure with a short neck region from which a single duct emerges. The two ducts form a common duct that empties into the ventral region of the pharynx near the mouthparts. The wall of the glands and ducts consists of a simple squamous epithelium that rests upon a connective tissue layer. Cells in the neck are less flattened than those found elsewhere. The basal surfaces of the cells are infolded most deeply in the neck and the least in the duct. The apical surfaces of the cells possess microvilli except in the duct where the apices of the cells are covered by a complex extracellular layer. This layer displays circularly arranged folds that accommodate a thread-like supportive structure resembling taenidial threads of tracheae. Elaborate junctional complexes are associated with the lateral surfaces of the cells. Elements of these complexes include a zonula adherens, a series of pleated septate desmosomes, and conventional desmosomes. The cytoplasm of the glandular cells is filled with RER and other organelles normally seen in cells that export proteins and mucosubstances. Secretory material found in the lumens of the glands reacts only moderately with the PAS procedure but more strongly with alcian blue and methods that demonstrate proteins. The nuclei of the glandular cells contain single large nucleoli and polytene chromosomes whose banding is rather indistinct. Treatment with EDTA produces detrimental effects on all of the foregoing ultrastructural features of the glands and ducts.     

Diversity in neuroblast number forming mushroom bodies of the higher dipterans (Insecta,Diptera, Brachycera Cyclorrhapha)

Neurogenesis in mushroom bodies is studied in 12 species of the higher dipterans. A significant difference in the number of neuroblasts forming mushroom bodies is found. In the majority of species studied, Kenyon cells are formed by four solitary neuroblasts. Among six calliphorid species, the number of neuroblasts increases up to 10–15 (mean 12.6) in each mushroom body in Calliphora vicina only. In young pupae of Muscina stabulans and M. livida, four polyneuroblastic prolipherative centers occur instead of solitary neuroblasts. These centers disintegrate later into numerous solitary neuroblasts. A hypothesis on the origin of the polyneuroblastic structure of mushroom bodies found in C. vicina and, earlier, in Musca domestica, is proposed.     

Differential effect of Agaricus host species on the population development of Megaselia halterata (Diptera: Phoridae)

Twelve isolates from the genus Agaricus (Fungi, Basidiomycota) were investigated for their ability to support development of the phorid fly, Megaselia halterata (Wood), which is an important pest of the commercial white button mushroom Agaricus bisporus. Combined effects of oviposition of adult female M. halterata and larval development in mushroom compost inoculated with Agaricus mycelium were determined using bioassays. The numbers of M. halterata offspring that developed were affected by the Agaricus isolate used, and there was a significant separation between resistant and susceptible isolates. In a bioassay where the female phorids had a choice of all 12 isolates for oviposition, three isolates produced >200 adults per 100 g compost pot while the remaining nine isolates had <20 adults per pot. Where there was no choice of Agaricus isolate for oviposition, five isolates resulted in >100 adults per 100 g compost pot while the remainder resulted in <4 adults per pot. With the susceptible isolates, there was a positive correlation between increasing concentration of mycelium in the substrate and phorid development until the concentration exceeded 40% after which numbers of emerging phorids declined. Genetic identity of Agaricus isolates was determined using ITS sequencing and phylogenetic methods, which revealed two major cluster groups. Isolates supporting the development of large populations of M. halterata were located in one of these clusters (group I), and were either Agaricus bisporus or other species from the same Agaricus section Duploannulatae. Isolates that did not support the development of M. halterata populations were located in a different cluster (group II) and were more genetically distant from A. bisporus, e.g. Agaricus sections Arvenses, Minores and Xanthodermatei. Species of Agaricus with resistance to M. halterata could have significant potential for the breeding and cultivation of phorid-free mushrooms.     

Control of the mushroom pests Lycoriella auripila (Diptera: Sciaridae) and Megaselia halterata (Diptera: Phoridae) by Steinernema feltiae (Nematoda: Steinernematidae) in field experiments

The nematode Steinernema feltiae (Nematoda: Steinemematidae) was tested for its ability to control two main mushroom pests i.e. the sciarid Lycoriella auripila (Diptera: Sciaridae) and the phorid Megaselia halterata (Diptera: Phoridae) in growing-rooms filled with spawned compost. A clear difference between female and male sciarid control was observed. A nematode application 1 day after casing preceded by an application 1 day before casing on the compost caused an almost complete control (97%) of the F1-generation of female sciarids. The F2-generation of females was similarly controlled (95%) by an application 7 days after casing. A dosage of 1 × 10⁶nematodes m^-2was found to be equally effective as higher dosages. Diflubenzuron remained active throughout entire the cropping period with high sciarid mortality rates varying from 72% to 99%. Phorid control was variable and seemed to depend on the presence of sciarids. In one occasion the control rate of F2-generation phorid larvae was 75% and was possibly caused by the presence of new infective juvenile nematodes recycled in F2-generation sciarid larvae. Diflubenzuron did not significantly reduce phorid numbers.     

New records of Megaselia (Diptera: Phoridae) reared from fungus sporophores in Japan,including five new species

Megaselia donaldsonae Disney sp. nov., M. flava (Fallén), M. gotoi Disney, M. kanekoi Disney, M. margaretae Disney sp. nov., M. nakayamai Disney sp. nov., M. salteri Disney sp. nov. and M. stepheni Disney sp. nov. were reared from sporophores of fungi.     

First record of Megaselia scalaris (Loew) (Diptera: Phoridae) infesting laboratory colonies of Triatoma brasiliensis Neiva (Hemiptera: Reduviidae)

Megaselia scalaris (Loew) is a cosmopolitan and synanthropic scuttle fly, eclectic in its feeding habits and acts as detritivore, parasite, facultative parasite, and parasitoid. Here we report for the first time M. scalaris infesting laboratory colonies of Triatoma brasiliensis Neiva, the most important Chagas disease vector in semiarid areas of Brazil. M. scalaris larvae were found feeding inside bugs; pupae were found in the esophagus and intestinal regions of T. brasiliensis through dissection. Other relevant information about this finding is also described in this note, including some preventive measures to avoid laboratory colonies infestations.     

Estimation of population profiles of two strains of the fly Megaselia scalaris (Diptera: Phoridae) by bootstrap simulation

Based on experimental population profiles of strains of the fly Megaselia scalaris (Phoridae), the minimal number of sample profiles was determined that should be repeated by bootstrap simulation process in order to obtain a confident estimation of the mean population profile and present estimations of the standard error as a precise measure of the simulations made. The original data are from experimental populations founded with SR and R4 strains, with three replicates, which were kept for 33 weeks by serial transfer technique in a constant temperature room (25 +/- 1.0 degrees C). The variable used was population size and the model adopted for each profile was a stationary stochastic process. By these simulations, the three experimental population profiles were enlarged so as to determine minimum sample size. After sample size was determined, bootstrap simulations were made in order to calculate confidence intervals and to compare the mean population profiles of these two strains. The results show that with a minimum sample size of 50, stabilization of means begins.     

Scuttle flies (Diptera: Phoridae) from Ardabil province in Iran,with description of a new species of Megaselia Rondani

our named species of scuttle flies were collected from Ardabil province-Iran, during 2013–2014. A new species of the genus Megaselia Rondani 1856, M. ardabilensis n. sp., is described from the region and Megaselia producta (Schmitz) is recorded from the country for the first time. Geographical distributions and supplementary figures are given.

http://www.zoobank.org/urn:lsid:zoobank.org:pub:B28C521B-2BFE-44F3-9041-1656341F29B6     

Revision of the Alamirinae (Diptera: Phoridae)

Abstract. The genus Couturiera Disney, 1979, only known in the female sex, is synonymized with Perissa Borgmeier, 1967, only known in the male sex, a syn.n., thus solving the problem of the 'missing' males of the Alamirinae. Perissa kensmithi (Disney) comb.n., P.lewisi (Disney) comb.n. and P.orientalis (Disney & Peterson) comb.n. are transferred from Couturiera. Perissa couturieri Disney is synonymized under P. lewisi (Disney) and C.palawanensis Disney under P.georgei Disney. Perissa latiptera sp.n., P.oligoseta sp.n., P.tinglei sp.n. and Perittophora couturieri gen.n., sp.n., are described from Zimbabwe. A key to the twelve species of Alamirinae is provided. It is hypothesized that the Alamirinae may be paraphyletic, by virtue of exclusion of the Termitoxeniinae. The latter is probably polyphyletic, in that each Alamirinae genus is probably the sister group of a different Termi-toxeniin clade.     

Studies on an overwintering population of the mushroom phorid Megaselia halterata (Diptera: Phoridae) parasitized by Howardula husseyi (Nematoda: Allantonematidae)

An overwintering population of the mushroom phorid fly Megaselia halterata parasitized by Howardula husseyi was studied in an attempt to explain the winter decline in incidence of parasitism that has been observed in flies from mushroom farms. Fly larvae from eggs hatching in November developed into pupae in December and flies emerged in May. No selective mortality of parasitized specimens of larvae, pupae, or flies was observed. Dead parasites were found in only 10% of parasitized flies. The incidence of parasitism in the emerging flies (50%) was five times that of their parental generation and although parasitism significantly delayed fly emergence the delay was only 2–3 days. There was no evidence of winter decline in parasitism; instead there was strong evidence that parasitism enhanced phorid survival through the winter.     

Armored cuticular membranes in Brachycera (Insecta,Diptera)

This study describes and quantifies the ultrastructural design of some cuticular protuberances in the Diptera-Brachycera that appear to have a specialized mechanical function. The microsculpture of membranes in the transitional areas of prothorax-neck, neck-head, head-mouthparts, and in the articulations thorax-coxa and coxa-trochanter was investigated in eight species from six families (Tabanidae, Stratiomyidae, Calliphoridae, Syrphidae, Muscidae and Drosophilidae) by means of scanning electron microscopy. The membrane armatures are single or grouped microtrichia, often located on microplates in the flexible membrane. The different membranes were compared using the following details: microtrichia length, microplate length and width, the shortest distance between microplates, and the number of microtrichia per microplate. Five different types of microstructure were observed: (1) single short papilla-like microtrichia directly arising from the flexible membrane, (2) single elongated microtrichia directly arising from the flexible membrane, (3) single microtrichia located on small areas of the inflexible cuticle, here called microplates, (4) microtrichia groups located on the microplates, and (5) microplates without microtrichia in the flexible membrane. The study reveals the differences in the surface ultrastructure of membranes between different parts of body and between different taxa of flies. The prothorax-neck transition is less specialized in membrane armature as compared with the head-neck articulation, and especially with that of the head-proboscis. The head-proboscis transition has the most complex membrane armature of those species studied. The membrane of the basal joints of the legs has larger plates and a higher number of microtrichia per plate than that of the more distal joints. The complexity of the membrane armature depends on the dimensions of the animal: the smallest species have short ungrouped microtrichia or micropapillae, whereas large species have the highest degree of grouping, the longest microtrichia, and the largest microplates. Three main mechanical functions served by the different armored membranes are suggested, based on the specific characteristics of the microsculptural design: (1) fixation of the folds, (2) prevention of folding, and (3) determination of direction of folding. J. Morphol. 234:213–222, 1997. © 1997 Wiley-Liss, Inc.     

Species richness estimations of the megadiverse scuttle fly genus Megaselia (Diptera: Phoridae) in a wildfire‐affected hemiboreal forest

Abstract The species richness of the scuttle fly (Diptera: Phoridae) genus Megaselia was estimated by various non‐parametric estimators from EstimateS, Species Prediction And Diversity Estimation (SPADE) and Ws2m, based on material from a Swedish hemiboreal forest area recently affected by major wildfires, Tyresta National Park and Nature Reserve (TNPNR), south of Stockholm. A total of 21 249 individuals were collected in Malaise traps, of which males constituted 16 976 and females 4 273. The analysed dataset represents 37 samples containing 18 549 specimens sorted into 330 species (184 described, 146 are either undescribed or of unsettled taxonomic status). It was not possible to estimate the total species richness using all samples due to heterogeneity caused by inclusion of different communities and temporal incoherencies between samples within and between years. Even with material obtained from a sampling program that was not designed for species richness estimates, it was possible to obtain reliable results when sample heterogeneity was minimized. By dividing the data into community‐specific datasets – for bog, forest and wildfire – it was possible to obtain asymptotic curves for the smaller of the two wildfire datasets. A total estimate of 357–439 (95% CI) was attained by using the smaller wildfire dataset and adding the 85 unique species from the samples not included in the estimation analysis. TNPNR has one of the richest known scuttle fly communities in Europe, consisting of almost 50% of the currently named Megaselia species; 48 of these species are reported as new records for Sweden in this study.