Sciaridae Research Articles

Life table of Gaeolaelaps aculeifer (Acari: Laelapidae) feeding on larvae of Lycoriella auripila (Diptera: Sciaridae) with stage-specific estimates of consumption

ABSTRACTGaeolaelaps aculeifer (Canestrini, 1883) is a soil-dwelling predatory mite with potential for use as a biological control agent of fungus gnats (Diptera: Sciaridae) in mushroom production. The life table, predation rate and population growth rate of G. aculeifer on a diet of larvae of the sciarid fly, Lycoriella auripila, at 23 ± 1°C, 60 ± 5% RH and a photoperiod of 0:24 (L:D) h was investigated. The results revealed that the duration of egg, larva, protonymph, deutonymph, females and males of G. aculeifer were 3.8 ± 0.1, 1.4 ± 0.1, 3.9 ± 0.1, 4.1 ± 0.1, 67.7 ± 2.8 and 60.3 ± 3.1 days, respectively. Net reproductive rate (R0) was 54.8 ± 7.1 offspring, intrinsic rate of increase (r) was 0.12 ± 0.01 offspring day−1, finite rate of increase (λ) was 1.13 ± 0.01 day−1and mean generation time (T) was 32.3 ± 0.6 days. The predator consumed a mean of 0.08 ± 0.05, 1.73 ± 0.18, 3.16 ± 0.28 and 75.9 ± 7.1 third instar L. auripila larvae during the larval (1.3 ± 0.1 days), protonymph (3.9 ± 0.1 days), deutonymph (4.1 ± 0.1 days) and adult (52.6 ± 2.2 days) stages. Population parameters and consumption rates suggest that G. aculeifer has good potential as a biological control agent of L. auripila in mushroom production.

The mushroom sciarid fly, Lycoriella ingenua, benefits from its association with green mold disease (Trichoderma aggressivum) in commercial mushroom production

The mushroom fly, Lycoriella ingenua Dufour (Diptera: Sciaridae), is a pest in white button mushroom (Agaricus bisporus) farming in North America. The main risk associated with sciarid flies inside mushroom farms is that the adult can potentially vector mushroom green mold disease caused by the pathogenic fungus Trichoderma aggressivum Samuels & W. Gams (Hypocreales). Flies are attracted to T. aggressivum-infected compost and, through subsequent movement, are suspected to spread the spores. The present study evaluated whether there is a fitness benefit for the sciarid flies from their association with T. aggressivum. Lycoriella ingenua was reared on three substrates: (1) spawned mushroom compost inoculated with the T. aggressivum, (2) spawned mushroom compost and (3) unspawned mushroom compost. Developmental time from larva to adult, adult longevity, adult fecundity and female body size were used as indicators of fly fitness. There was a fitness benefit for the sciarid fly when larvae develop on spawned mushroom compost parasitized by green mold, including higher adult emergence rate, faster development time from larva to adult and larger adult females. Fly fitness declined when the compost was fully colonized by A. bisporus mycelia and T. aggressivum was not present. This suggests that sciarid larvae benefit from the T. aggressivum parasitism on A. bisporus and the green mold. Benefits may include improved nutrition, defense suppression or pre-digestion.

The Compression Mating Fossil of Sciarid Fly (Diptera: Sciaridae) from Shiobara, Tochigi Prefecture, Japan

Abstract. Preservations illustrating insect reproductive behaviors are much rarer in compression fossils than in amber. We discovered a copulating compression fossil of the sciarid flies from the Pleistocene Shiobara Group, Tochigi Prefecture, Japan, which is briefly described herein. The specimen represents one of the rare examples of a compression fossil showing mating dipteran insects. This finding implies that the small bodies of sciarid flies which readily fall onto the water surface may have contributed to the preservation of our copulating fossil. Moreover, the depositional environment of the paleo-Shiobara Lake was the main factor that served to preserve this specimen.

New Record of a dark-winged fungus gnat, Sciaria thoracica Matsumura, (Diptera: Sciaridae) from Korea

Sciaria thoracica Matsumura belonging to the family Sciaridae is recorded from Korea for the first time. This species is a conspicuous species having the rufous thorax in Palearctic region. The morphological diagnosis and photos of adult, and the result of DNA barcoding inferred from the Korean and the Japanese populations of S. thoracica are provided.

The effect of ambient temperature on larvae of Scatopsciara cunicularius (Diptera: Sciaridae) feeding on the thallose liverwort Marchantia polymorpha

Herbivory on liverworts is rarely reported. We studied the effects of feeding by larvae of the sciarid fly Scatopsciara cunicularius on the growth of the thalloid liverwort Marchantia polymorpha at two different constant temperatures, 12°C and 22°C. Larvae reared at the lower temperature fed slower and over a longer period of time, which resulted in more damage and a greater reduction in the growth of the liverwort than that caused by those reared at the higher temperature. The reduction in growth of the liverwort was positively density-dependent in terms of number of larvae at both temperatures. These results indicate that the larvae of S. cunicularius are likely to be an effective means of controlling M. polymorpha, which is a common weed in plant nurseries and greenhouse cultures.

Life History Traits of the Liverwort HerbivoreScatopsciara cunicularius(Diptera: Sciaridae)

We studied the behavior, life cycle, and reproductive biology of the sciarid fly Scatopsciara cunicularius (Lengersdorf, 1943) under two constant temperatures . The sciarid was reared at 12.3 ± 0.6°C and 22 ± 1.7°C on its host, the liverwort Marchantia polymorpha L. Our results show that the sciarid fly is able to complete its life cycle with liverwort tissue as its only source of food. The egg-laying potential of the insect ranged from 70–174 eggs per female (mean 110 ± 31 eggs). Reproduction was digenic, meaning that one female can produce both male and female progeny. The overall sex ratio did not depart from 1:1, although the progeny sex ratio was highly variable. The developmental period of S. cunicularius was considerably longer in the colder than the warmer temperature. Mean development time of the egg, larva, and pupal stages, and adult longevity in the warm regime was 4, 20, 4, and 5 d, whereas mean development time of each juvenile stage and adult longevity in the cold regime was 13, 95, 11, and 8 d, respectively. The results suggest that the phenology of S. cunicularius is temperature dependent. Scatopsciara cunicularius could constitute a promising agent for biological control of M. polymorpha .

New Record of Arctoseius cetratus (Sellnick, 1940) (Mesostigmata: Ascidae) Phoretic to Sciarid Fly from Mushroom Culture in Korea

【The Mesostigmata is an order of Subclass Acari either parasiting to diverse invertebrates or free-living predatory in terrestrial ecosystem. Phoresy is one of the unique behaviors of wingless arthropod dispersal by attaching winged arthropods. We collected mites attached on the dorsal part of abdomen adult sciarid fly, from mushroom culture. The mites were identified as Arctoseius cetratus Sellnick, 1940 in the family of Ascidae. Arctoseius cetratus has short J2, Z1, Z2, and S1, S2 setae, not reaching the bases of following setae. Posterior half of dorsal shield with longitudinal garland of puncta between J and Z setae, peritremes extending anteriorly to midlevel of coxaII. The genus Arctoseius and species Arctoseius cetratus are the first record in Korea. We provided the detail description of the species including the identification key in the family with some ecological notes.】

양송이버섯 재배에서의 긴수염버섯파리(Lycoriella ingenua)의 발달과 피해

검정날개버섯파리과에 속하는 긴수염버섯파리(Lycoriella ingenua)는 우리나라 양송이버섯 재배에서 심각한 피해를 주는 주요해충의 하나이다. 본 연구는 양송이버섯 재배에서의 긴수염버섯파리의 온도별 발달과 피해양상을 조사하고자 실시하였다. 버섯파리는 균사를 배양한 페트리디쉬에서 사육하였고 16, 20, 24, <TEX>$28^{\circ}C$</TEX> 온도에서 알에서 성충까지 소요기간은 각각 35.2, 25.8, 23.5, 22.2일로 조사되었다. 버섯파리 성충은 버섯재배사를 침입하여 종균이 접종된 배지에 알고 낳고 1-7 mm의 부화된 유충에 의해서 균사와 생육하고 있는 버섯의 갓과 대를 섭식하여 가장 큰 피해를 입힌다. 성충은 자실체의 외관을 더럽히고, 여러 가지 곰팡이와 세균병을 전파시키며, 응애 등을 옮긴다. 적절한 해충방제 없는 조건에서 버섯파리에 의한 피해가 증가하면서 자실체 수량은 27%까지 감소하였다. Mushroom sciarid fly Lycoriella ingenua (Dufour), syn. L. mali (Fitch) is one of the most common fly pests affecting the mushroom cultivation in Korea. This study was carried out to investigate the development at different temperatures and damages of L. ingenua in A. bisporus mushroom cultivation. Rearing of mushroom flies were carried out on mycelial culture in Petri dishes. The development of L. ingenua from egg to adult at the temperature of 16, 20, 24, <TEX>$28^{\circ}C$</TEX> were 35.2, 25.8, 23.5, and 22.2 days, respectively. Adult flies invade mushroom farms and oviposit in freshly spawned compost. Damages are mainly caused by the larvae of 1-7 mm, which feed on growing mycelium and also developing stipes and caps of mushrooms. Adult flies spoil the appearance of the fruiting bodies, spread various fungal and bacterial disease, and transmit mites. The damages by mushroom flies increased without pest control causing yield loss of up to 27%.

Checklist of the family Sciaridae (Diptera) of Finland.

A checklist of the family Sciaridae (Diptera) recorded from Finland is provided. The genus Sciarosoma Chandler with a disputed family placement is also included in the list.

Entomopathogenic nematodes for the control of phorid and sciarid flies in mushroom crops

The objective of this work was to evaluate the efficacy of two nematodes, Steinernema feltiae and S. carpocapsae, to control mushroom flies and to evaluate the effect of these treatments on Agaricus bisporus production. Two mushroom cultivation trials were carried out in controlled conditions, in substrate previously infested with the diptera Megaselia halterata and Lycoriella auripila, with two treatments: 106infective juveniles (IJ) per square meter of S. feltiae and 0.5x106IJ m-2S. feltiae + 0.5x106IJ m-2S. carpocapsae. Another experiment was carried out using the same treatments to evaluate the possible nematode effect on mushroom yield. The number of adults emerging from the substrate was evaluated for each fly species. No decrease in the population of M. halterata was detected with nematode application, whereas the number of L. auripila was reduced in both treatments, particularly in the individual treatment with S. feltiae. The application of entomopathogenic nematodes has no adverse effect on mushroom production.

Sciarid and shore flies as aerial vectors of Fusarium oxysporum f. sp. cucumerinum in greenhouse cucumbers

AbstractThe options for managing Fusarium wilt in greenhouse cucumbers are limited by our poor understanding of the modes of survival and dissemination of the pathogen. This study uses a specific quantitative real‐time PCR assay for Fusarium oxysporum f. sp. cucumerinum to investigate the significance of flying insects as aerial vectors of the pathogen in a commercial cucumber greenhouse. Shore flies were more frequently detected (35.5%) carrying F. oxysporum f. sp. cucumerinum than sciarids (25%), with both species carrying between 1 × 102 and 1 × 106 pathogen genome copies/individual. Sciarid and shore flies acquired F. oxysporum f. sp. cucumerinum following exposures to agar cultures of the pathogen of up to 94 h. Light microscopy revealed that spores were carried externally on the bodies of the adult flies. The ability of adult sciarid flies to vector the pathogen from peat‐grown diseased cucumber plants and infect healthy cucumber plants was demonstrated in a caged glasshouse trial. An inoculum density trial showed that vascular wilt disease was initiated after inoculation of peat‐grown seedlings with as few as 1000 conidia. We conclude that sciarid and shore flies play significant roles as vectors of F. oxysporum f. sp. cucumerinum in greenhouse cucumbers and need to be recognized in developing integrated crop management strategies.

Resource Opportunities from the Nest of Dying Subterranean Termite (Isoptera: Rhinotermitidae) Colonies: A Laboratory Case of Ecological Succession

Abstract Subterranean termites such as Coptotermes formosanus Shiraki inhabit underground nests consisting of a complex network of galleries resulting in a highly modified environment relative to the surrounding soils. A healthy colony can maintain homeostatic conditions within the nest, limiting opportunities for pathogens, parasites, and predators to exploit the termite colony as a resource. However, a stressed or senescent colony can display a lack of nest maintenance, leading to the colonization of the nest as an opportunistic niche by other organisms. In this study, we described the nest colonization by microbes and arthropods during the collapse of three dying C. formosanus laboratory colonies. The carton nest and the tunnel lining that are mostly made out of termite fecal material were invaded by a variety of fungi, and Acari and Collembolan populations quickly increased during the senescence phase of the termite colony, presumably scavenging on the fungal material. Finally, the carton colonized by fungal mycelia hosted numerous larvae of a sciarid fly, Bradysia sp. (Diptera). This fungus gnat used the decomposing carton material as a breeding site, and numerous adults of this fly were found hovering above the dying termite colony. Bradysia larvae also showed infestation by parasitic nematodes, suggesting the presence of multiple trophic levels in the resource utilization of the nest of a declining termite colony. We concluded that a dying subterranean colony represents a resource opportunity for scavenging organisms and that the nest structure represents an opening niche that initiates an ecological succession.

Histone H3 phosphorylation and elimination of paternal X chromosomes at early cleavages in sciarid flies

In sciarid flies (Diptera, Sciaridae), one or two paternally derived X chromosomes are discarded from the soma at early cleavages to determine the sex of the embryo (XX, females; X0, males). X chromosome(s) elimination is achieved by an abnormal anaphase segregation so that X sister chromatids do not reach the poles and are not included in the daughter nuclei. A cis-acting locus (CE) within the heterochromatin proximal to the centromere is known to regulate X chromosome elimination. By immunofluorescence analysis in early embryos from Sciara ocellaris and Sciara coprophila, we investigated histone H3 phosphorylation at Ser10, Ser28 and Thr3 prior to, and during, the X elimination process. We found that the regular syncytial nuclear divisions are characterized by a gradual loss of H3S10 phosphorylation along the chromosome arms at anaphase. Importantly, the eliminating X chromosomes show a retardation in anaphase chromatid segregation and high levels of H3S10 phosphorylation in the chromosome arms. In the present study, we provide the first evidence linking the hyper-phosphorylated H3 status of the X chromosome with a delay in sister chromatid separation at anaphase. Our findings support the idea that the CE induces a deficiency in H3 dephosphorylation in the paternal X chromosomes to be eliminated.

Molecular phylogeny of black fungus gnats (Diptera: Sciaroidea: Sciaridae) and the evolution of larval habitats

The phylogeny of the family Sciaridae is reconstructed, based on maximum likelihood, maximum parsimony, and Bayesian analyses of 4809bp from two mitochondrial (COI and 16S) and two nuclear (18S and 28S) genes for 100 taxa including the outgroup taxa. According to the present phylogenetic analyses, Sciaridae comprise three subfamilies and two genus groups: Sciarinae, Chaetosciara group, Cratyninae, and Pseudolycoriella group+Megalosphyinae. Our molecular results are largely congruent with one of the former hypotheses based on morphological data with respect to the monophyly of genera and subfamilies (Sciarinae, Megalosphyinae, and part of postulated “new subfamily”); however, the subfamily Cratyninae is shown to be polyphyletic, and the genera Bradysia, Corynoptera, Leptosciarella, Lycoriella, and Phytosciara are also recognized as non-monophyletic groups. While the ancestral larval habitat state of the family Sciaridae, based on Bayesian inference, is dead plant material (plant litter+rotten wood), the common ancestors of Phytosciara and Bradysia are inferred to living plants habitat. Therefore, shifts in larval habitats from dead plant material to living plants may have occurred within the Sciaridae at least once. Based on the results, we discuss phylogenetic relationships within the family, and present an evolutionary scenario of development of larval habitats.

The genus Bradysia Winnertz (Diptera, Sciaridae) in New Caledonia, with the description of thirteen new species

The following species of the genus Bradysia Winnertz, 1867 are recognized from New Caledonia, all newly described: Bradysia aequispina sp. n., B. centidens sp. n., B. clavistylis sp. n., B. filigera sp. n., B. gemellata sp. n., B. gibbosa sp. n., B. melina sp. n., B. nudilobata sp. n., B. paucidens sp. n., B. planistylata sp. n., B. seticornis sp. n., B. spissa sp. n. and B. stricta sp. n. A key to the species is given.

Chromatin Structure of Ribosomal RNA Genes in Dipterans and Its Relationship to the Location of Nucleolar Organizers

Nucleoli, nuclear organelles in which ribosomal RNA is synthesized and processed, emerge from nucleolar organizers (NORs) located in distinct chromosomal regions. In polytene nuclei of dipterans, nucleoli of some species can be observed under light microscopy exhibiting distinctive morphology: Drosophila and chironomid species display well-formed nucleoli in contrast to the fragmented and dispersed nucleoli seen in sciarid flies. The available data show no apparent relationship between nucleolar morphology and location of NORs in Diptera. The regulation of rRNA transcription involves controlling both the transcription rate per gene as well as the proportion of rRNA genes adopting a proper chromatin structure for transcription, since active and inactive rRNA gene copies coexist in NORs. Transcription units organized in nucleosomes and those lacking canonical nucleosomes can be analyzed by the method termed psoralen gel retarding assay (PGRA), allowing inferences on the ratio of active to inactive rRNA gene copies. In this work, possible connections between chromosomal location of NORs and proportion of active rRNA genes were studied in Drosophila melanogaster, and in chironomid and sciarid species. The data suggested a link between location of NORs and proportion of active rRNA genes since the copy number showing nucleosomal organization predominates when NORs are located in the pericentric heterochromatin. The results presented in this work are in agreement with previous data on the chromatin structure of rRNA genes from distantly related eukaryotes, as assessed by the PGRA.

Damage and biological control of dark winged fungus gnats, Lycoriella ingenua (Diptera: Sciaridae) in a shiitake cultivation

Monitorings and management experiment of adult Lycoriella ingenua (Diptera: Sciaridae) in artificial sawdust grown shiitake mushroom cultivation were carried out by using yellow sticky traps and Hypoaspis aculeifer (Acari: Laelapidae) at Hwaseong, Buyeo and Cheongwon in 2012. The larvae of L. ingenua reduced commercial value of the mushroom by direct eating or retarding the growth of mushroom by spongifying the sawdust medium. The number of L. ingenua caught by traps showed the highest peak in late september resulting in 127.5~1,025.7, 87.4~743.6 and 133.7~650.4 individuals per trap in Hwaseong, Buyeo and Cheongwon, respectively. Damage rate of fruiting bodies in shiitake mushroom by L. ingenua were 7.7~30.3% in Hwaseong, 6.7~25.3% in Buyeo and 5.3~26.0% in Cheongwon and showed the highest peak in late september. L. ingenua were effectively controlled when 30.3 individuals of H. aculeifer per inoculated for three time with 7 to 14 days of interval. In Hwaseong, Buyeo and Cheongwon, density of L. ingenua which were caught on the yellow sticky traps were 168.2, 126.1, 132.5 individuals, respectively. And, damage rate of fruiting bodies by L. ingenua were 5.9%, 5.5% and 5.4% respectively. Both of the L. ingenua density and damage rate of mushroom reduced more than 60% in all experimental site in contrast to the control treatment.

Dark winged fungus gnats (Diptera: Sciaridae) collected from shiitake mushroom in Korea

Seven species of sciarid flies were collected in shiitake mushroom farm in Korea. Among them, Lycoriella ingenua (Dufour 1839) and Bradysia difformis Frey 1948 were dominant as possible pests of the shiitake mushroom because the larvae were found on both oak bed logs and in the artificial sawdust beds for shiitake cultivation. Five other species, which were collected in lower numbers, are reported for the first time in Korea: Bradysia longimentula (Sasakawa 1994), Bradysia trispinifera Mohrig & Krivosheina 1979, Leptosciarella ( Leptospina) subdentata (Mohrig and Menzel 1992), Scatopsciara camptospina Mohrig and Mamaev 1990, and Xylosciara inornata Mohrig and Krivosheina 1979.

Functional characterization of the sciarid BhC4-1 core promoter in transgenic Drosophila

BackgroundCore promoters are cis-regulatory modules to which bind the basal transcriptional machinery and which participate in the regulation of transcription initiation. Although core promoters have not been extensively investigated through functional assays in a chromosomal context, the available data suggested that the response of a given core promoter might vary depending on the promoter context. Previous studies suggest that a (-57/+40) fragment constitutes the core promoter of the BhC4-1 gene which is located in DNA puff C4 of the sciarid fly Bradysia hygida. Here we tested this (-57/+40) fragment in distinct regulatory contexts in order to verify if promoter context affects its core promoter activity.ResultsConsistent with the activity of a core promoter, we showed that in the absence of upstream regulatory sequences the (-57/+40) fragment drives low levels of reporter gene mRNA expression throughout development in transgenic Drosophila. By assaying the (-57/+40) fragment in two distinct regulatory contexts, either downstream of the previously characterized Fbp1 enhancer or downstream of the UAS element, we showed that the BhC4-1 core promoter drives regulated transcription in both the germline and in various tissues throughout development. Furthermore, the use of the BhC4-1 core promoter in a UAS construct significantly reduced salivary gland ectopic expression in third instar larvae, which was previously described to occur in the context of the GAL4/UAS system.ConclusionsOur results from functional analysis in transgenic Drosophila show that the BhC4-1 core promoter drives gene expression regardless of the promoter context that was assayed. New insights into the functioning of the GAL4/UAS system in Drosophila were obtained, indicating that the presence of the SV40 sequence in the 3' UTR of a UAS construct does not preclude expression in the germline. Furthermore, our analysis indicated that ectopic salivary gland expression in the GAL4/UAS system does not depend only on sequences present in the GAL4 construct, but can also be affected by the core promoter sequences in the UAS construct. In this context, we propose that the sciarid BhC4-1 core promoter constitutes a valuable core promoter which can be employed in functional assays in insects.

Recent discoveries of armyworms in Japan and their species identification using DNA barcoding

Long columns of migrating larval sciarid armyworms were discovered in central and northern Japan, specifically Kanagawa, Gunma, Miyagi and Akita prefectures, as well as Hokkaido. This is the first examination of armyworms in East Asia. In Europe, armyworms have been identified as Sciara militaris, belonging to the family Sciaridae (sciarid flies or black fungus gnats), by rearing them to adulthood. In Japan, we were unable to obtain live samples for rearing; therefore, DNA barcodes were obtained from the samples of armyworms collected in the Gunma and Miyagi prefectures. The DNA barcodes were compared with those obtained from the following samples: pupae of S. militaris from UK, adults of Sciara kitakamiensis, Sciara humeralis, Sciara hemerobioides, Sciara thoracica, Sciara helvola and Sciara melanostyla from Japan, and adults of one undescribed Sciara species from Malaysia. Neighbour-joining, maximum parsimony, and maximum likelihood analyses revealed that the armyworms discovered in Japan are S. kitakamiensis. Although adults of this species have been recorded in several locations in Japan, this is the first report of migrating larval armyworms. DNA barcodes were effectively used to link different life stages of this species. The average intraspecific and interspecific pairwise genetic distances of the genus Sciara were 0.3% and 12.6%, respectively. The present study illustrates that DNA barcodes are an effective means of identifying sciarid flies in Japan.