Fungus Gnats Research Articles

The Black Fungus Gnats (Diptera, Sciaridae) of Norway - Part I: species records published until December 2019, with an updated checklist.

Black Fungus Gnats (Sciaridae) are a megadiverse, cosmopoliltan family of bibionomorph Diptera. Even in Europe, the continent with the longest tradition in sciarid taxonomy, numerous taxonomic issues remain unresolved and countless species await discovery and description. The fauna of Norway is in these respects no exception. Recognising considerable knowledge gaps, the Norwegian Biodiversity Information Centre provided substantial funding for a detailed inventory of the Sciaridae species occurring in Norway, which was realised in 2014–2018. The results of this project will be published in a series of papers, of which the first is presented here, summarising available data on the taxonomy, faunistics, and autecology of Norwegian Sciaridae beginning with Zetterstedt’s pioneering work in 1838 and ending with 31 December 2019 as the cut-off date. All published records from that period were analysed. The result is a list of 143 species and four unplaced names. Following a consistent scheme, verified locality details are provide including alternative spellings, habitats, and flight times of adults in Norway, literature citations for the faunistic records, and general taxonomic references for classification or identification. A checklist of the sciarid fauna of Norway and a complete list of the relevant literature are also presented.

Effect of Plant-growing Media on Western Flower Thrips, Frankliniella occidentalis, Pupae and Fungus Gnat, Bradysia sp. nr. coprophila, Larvae under Laboratory Conditions

Western flower thrips, Frankliniella occidentalis, and fungus gnats (Bradysia spp.) are major insect pests of greenhouse production systems. Both insect pests have life stages that reside in the soil or plant-growing medium: prepupae and pupae of western flower thrips and fungus gnat larvae. There are unsubstantiated allegations made by a manufacturer that certain plant-growing media that contain a bacterium, Bacillus pumilus, and arbuscular mycorrhizal fungus, Glomus intraradices, negatively affect the survival of western flower thrips pupae and fungus gnat larvae. Therefore, we conducted a study involving laboratory experiments replicated over time (2019 and 2020) to investigate the influence of the plant-growing media Pro-Mix BX + Mycorrhizae and Pro-Mix BX + Biofungicide + Mycorrhizae on western flower thrips pupae and fungus gnat larvae. All experiments involved placing western flower thrips pupae or fungus gnat larvae (second and third instar) into 473-mL deli containers with the different treatments (plant-growing media). A 5 × 4-cm section of a yellow sticky card was affixed to the lid of each deli container. After 21 days, the number of western flower thrips or fungus gnat adults that emerged from the growing media and were captured on the yellow sticky cards was recorded. The use of the yellow sticky card was an indirect assessment of western flower thrips pupal or fungus gnat larval mortality. We found none of the plant-growing media tested that contained a bacterium and/or arbuscular mycorrhizal fungus affected the survival of western flower thrips pupae or fungus gnat larvae. Therefore, greenhouse producers should be leery of information provided by manufacturers that does not contain valid, scientifically based data.

New species of Stenomacrus (Hymenoptera: Ichneumonidae: Orthocentrinae) reared from Bradysia impatiens (Diptera: Sciaridae) in The Netherlands

ABSTRACT A new parasitoid wasp species, belonging to the genus Stenomacrus (Hymenoptera: Ichneumonidae: Orthocentrinae), was found in several Dutch plant nurseries. Here we describe, illustrate and discuss the biology, morphology and molecular characterisation of Stenomacrus meijeri sp. nov. It was reared from < 24 h old larvae of the fungus gnat Bradysia impatiens (Diptera: Sciaridae). http://www.zoobank.org/urn:lsid:zoobank.org:pub:DB48ABEC-2429-4C51-8297-A23D11DC4DF9

A new species of Exochomoscirtes Pic, 1916 from Malaysia (Insecta: Coleoptera: Scirtidae) with biological notes on the bamboo-inhabiting members of the genus

Seven Exochomoscirtes species inhabiting phyto- or lithotelmata in West Malaysia and North Thailand were reared from larvae. E. hashimi spec. nov. from W. Malaysia was described and E. carinensis and E. meghalayensis were new records for Thailand. Larvae of E. meghalayensis inhabited water-filled tree holes and forest rock pools, while E. hajeki, E. jaechi, E. chiangmaiensis, E. carinensis, E. cf. luteosuturaloides and E. hashimi spec. nov. occurred in water-filled bamboo stems. Bamboo-inhabiting species occupied different types of bamboo habitats such as mature bamboo stems (inhabited internodes up to 21 m high), dead bamboo stems or bamboo stumps. Internodes of nutrient-rich bamboo shoots were not colonized. Adult Exochomoscirtes entered enclosed internode cavities through holes created by insects, woodpeckers and other animals or cracks in bamboo walls. Larvae living in open phytotelmata such as water-filled tree holes or bamboo stumps created pupal chambers made of soil or detritus in the vicinity of their habitats. In species inhabiting enclosed internodes pupal chambers were absent. Larvae pupated inside the internodes firmly attached to the bamboo walls close above water surface. Total development time of bamboo-inhabiting species was about 3 months. Predators of Exochomoscirtes species dwelling in enclosed internodes were chironomid larvae (Dasyhelea), mosquito larvae (Toxorhynchites), small water striders (Lathriovelia), rove beetles (Acylophorus), jumping spiders (Paracyrba), web-building spiders (Theridiidae) and web-building larvae of fungus gnats (Truplaya).&#x0D; &#x0D; Taxonomic acts&#x0D; E. hashimi spec. nov.– urn:lsid:zoobank.org:act:4D2AA5A6-DB2D-4B5F-AE91-E8C985FFA4DD

Hidden in Plain Sight: Comprehensive Molecular Phylogeny of Keroplatidae and Lygistorrhinidae (Diptera) Reveals Parallel Evolution and Leads to a Revised Family Classification.

We provide the first molecular phylogeny of Keroplatidae and Lygistorrhinidae, families of fungus gnats (Diptera: Bibionomorpha: Sciaroidea). Phylogenies reconstructed by Maximum Likelihood and Bayesian methods, based on four nuclear and four mitochondrial gene markers (5106 base pairs) sequenced for 75 genera and 105 species, show Keroplatidae as monophyletic only with the family Lygistorrhinidae included, herewith treated as the subfamily Lygistorrhininae stat. nov. The subfamily Arachnocampinae is retained in the family, although lowering its overall support. An early branching clade, comprising species of Platyura Meigen, 1803 and Paleoplatyura melanderi Fisher, 1941, forms subfamily Platyurinae Loew, 1850 stat. nov. The subfamilies Sciarokeroplatinae and Macrocerinae grouped together with three genera considered here as Keroplatidae incertae sedis. Subfamily Lygistorrhininae forms a sister clade to subfamily Keroplatinae, both retained monophyletic with high support. The traditional division of the subfamily Keroplatinae into the tribes Orfeliini and Keroplatini appears as outdated, resting largely on adaptive characters prone to parallel evolution. We find support for an alternative tribe corresponding to the Cloeophoromyia–Asindulum genus group, but a tribal reclassification of the Keroplatinae is left for future studies. The genus Heteropterna Skuse, 1888 is considered as identical with Ctenoceridion Matile, 1972 syn. nov.

Rabbit in the moon, monkey in the flower

Rabbit in the moon, monkey in the flower

It's a trap!

Jack-in-the-pulpit (Arisaema spp) have flowers shaped like the flowers of carnivorous pitcher plants. Unlike pitcher plants, however, Arisaema species do not absorb nutrients from insects. Instead, the trapped insects (frequently fungus gnats; various genera within the family Mycetophilidae) become part of a unique pollination system. Victims are handled differently between Arisaema sexual morphs: the male plants allow fungus gnats to escape unharmed, but the gnats die when they are trapped in female flowers. In Shizuoka, Japan, we observed corpses of fungus gnats trapped at the bottom of the spathe (the large bract that surrounds the inflorescence) of the female Arisaema stenophyllum.

Host plant nutrient contents influence nutrient contents in Bradysia cellarum and Bradysia impatiens.

The chive maggot Bradysia cellarum and the fungus gnat B. impatiens are two primary root pests of plants, which can coexist on the same host plants and are the devastating pests on liliaceous crops and edible fungi. Their growth and development are affected by the nutrient contents of their host plants. In this study, we assessed the effects of different host plant nutrients on the nutrient contents of these two Bradysia species. The nutrients of the chive (Allium tuberosum Rottl. ex Spreng.), board bean (Vicia faba L.), lettuce (Lactuca sativa L. var. ramosa Hort.), cabbage (Brassica oleracea L.), wild cabbage (Brassica oleracea var. capitata rubra) and pepper (Capsicum annuum L.) roots were determined, and their effect on nutrient content of the two Bradysia species after feeding on the host plant for three continuous generations were evaluated. The results show that chive and B-bean contained higher levels of protein, free amino acid, soluble sugar and starch than others. As a result, the soluble sugar, fat and protein contents were significantly higher in both Bradysia species reared on chive and B-bean than on cabbage, lettuce, W-cabbage and pepper, suggesting nutritional preference of these insects. Based on our results, we concluded that the two Bradysia species displayed nutrient preference toward chive and B-bean, which provides a reference for understanding their host plant range and for control of the insect species via field crop rotations.

Entrapment of Bradysia paupera (Diptera: Sciaridae) by Phaseolus vulgaris (Fabaceae) plant leaf

Flies of the genus Bradysia (Diptera, Sciaridae) are considered as major insect pests of greenhouse-grown horticultural crops. The ability of hooked trichomes of the French bean Phaseolus vulgaris to impale and entrap herbivorous insects thus resulting in insect reduced longevity, reproduction and larval mortality is well known. The present study investigates under laboratory conditions the ability of hooked trichomes of bean leaves to entrap fungus gnats Bradysia paupera, in order to estimate the reduction of their population. We characterized the entrapment mechanism of hooked trichomes towards B. paupera using cryo-scanning electron microscopy, and evaluated the silicon distribution in hooked trichomes with the energy dispersive X-ray microanalysis. We evaluated the trapping efficiency of hooked trichomes in fertilized and unfertilized bean plants towards B. paupera, in comparison with insects feeding on the plant leaf such as black bean aphid Aphis fabae and young stages of the southern green stinkbug Nezara viridula. For B. paupera, we recorded about 30% of entrapped insects in unfertilized plants. Considering the number of entrapped insects in relation to the leaf surface, the percentage of entrapped insect was higher in unfertilized than in fertilized plants having lower density of hooked trichomes. The presence of P. vulgaris plants in greenhouses could represent a useful method in integrated pest management to reduce Bradysia spp. population.

Sciarid pests (Diptera: Sciaridae) from undercover crop production in South Africa

Fungus gnats (sciarids) are among the most important pests in undercover crop production. They cause direct physical damage to plant roots, transfer fungal pathogens and create entry points for soil-borne plant pathogens. In 2007, Bradysia impatiens, an important fungus gnat pest was found in association with major tree nursery beds in the Mpumalanga and KwaZulu-Natal Provinces of South Africa and was considered invasive. In this study, eight greenhouses were surveyed in the Western Cape Province and B. impatiens was found to be present in all the greenhouses. Similar to the results of the previous studies, a high haplotype diversity was identified for B. impatiens, which may indicate multiple strain introductions into South Africa. Two other fungus gnat species, Lycoriella sativae and Lycoriella ingenua – globally important sciarid pests of mushroom cultures – were identified as new from South Africa. Through a laboratory culture, the life cycle of B. impatiens was observed to be approximately 21 days at 25 °C. Females laid between 100 and 250 eggs. Possible introduction sources include contaminated vegetative material and growth media, thus there maybe need to revise the importation restrictions on these commodities. The identification of two novel species of sciarid pests that have only previously been identified in the Holarctic region could further emphasise this need. However, the recent discovery of such high sciarid diversity could also be due to only a few studies having been previously done on sciarid pests in South Africa.&#x0D; Significance:&#x0D; &#x0D; The fungus gnat species Bradysia impatiens is reported as present in several undercover crops in the Western Cape Province of South Africa, including cucumbers, tomatoes, chrysanthemums, mushrooms, blueberries and various herbs.&#x0D; Lycoriella ingenua and Lycoriella sativae were also found to be present in mushroom gardens – the first report of Lycoriella from the Afro-tropical region.&#x0D; The three fungus gnat species are some of the most important sciarid pests in undercover crop production worldwide. This study highlights the need for more studies on the distribution of these sciarids and possible invasion history.&#x0D; &#x0D; Open data set:&#x0D; https://www.ncbi.nlm.nih.gov/popset?DbFrom=nuccore&amp;Cmd=Link&amp;LinkName=nuccore_popset&amp;IdsFromResult=1654675097

Black fungus gnats (Diptera: Sciaridae) of Queensland, Australia. Part II. Genus Pseudolycoriella Menzel amp; Mohrig, 1998.

In this second part on the black fungus gnats of Queensland, Australia, nine species are described as new for science. These are: Pseudolycoriella angustoantennata sp. n., Psl. breviradiata sp. n., Psl. consectaria sp. n., Psl. fuscovenosa sp. n., Psl. globostylata sp. n., Psl. notanda sp. n., Psl. paucispinata sp. n., Psl. secura sp. n. and Psl. unispinata sp. n. The following three species are new for Australia: Psl. bisulca Vilkamaa, Hippa Mohrig, 2012, known from New Caledonia; Psl. snellingi Mohrig, 2013, reported from Papua New Guinea and Psl. horribilis (Edwards, 1931), described from Sumatra. All species are illustrated and keyed.

Quantifying the regularity of a 3D set of points on the surface of an ellipsoidal object

Several natural and artificial structures, such as human skin and mammals cortices, exhibit a compound organization, with basic elements being distributed along a surface. The problem of quantifying the geometrical uniformity of this type of biological and physical compound structures is addressed in this work. This required the solution of several problems, including the detection, along the surface, of the borders of the compound system, defining the adjacency between the elements in the 3D space, and obtaining a reference of uniformity for calculating the polygonality. Specific approaches were devised and applied to address each of these difficulties, including connectivity criteria ensuring the adjacency to remain within the considered surface as well as the extension of the polygonality, originally suggested for 2D structures, to 3D compound systems. The potential of the so-obtained method is illustrated with respect to compound eyes of fungus gnats (small, forest dwelling flies), and interesting results are reported and discussed, including the fact that the uniformity tends to increase toward the center of the system, and the absence of correlation with two measurements traditionally used for characterizing this type of eyes.

Exploring the visual world of fossilized and modern fungus gnat eyes (Diptera: Keroplatidae) with X-ray microtomography

Animal eyes typically possess specialized regions for guiding different behavioural tasks within their specific visual habitat. These specializations, and evolutionary changes to them, can be crucial for understanding an animal's ecology. Here, we explore how the visual systems of some of the smallest flying insects, fungus gnats, have adapted to different types of forest habitat over time (approx. 30 Myr to today). Unravelling how behavioural, environmental and phylogenetic factors influence the evolution of visual specializations is difficult, however, because standard quantitative techniques often require fresh tissue and/or provide data in eye-centric coordinates that prevent reliable comparisons between species with different eye morphologies. Here, we quantify the visual world of three gnats from different time periods and habitats using X-ray microtomography to create high-resolution three-dimensional models of the compound eyes of specimens in different preservation states—fossilized in amber, dried or stored in ethanol. We present a method for analysing the geometric details of individual corneal facets and for estimating and comparing the sensitivity, spatial resolution and field of view of species across geographical space and evolutionary time. Our results indicate that, despite their miniature size, fungus gnats do have variations in visual properties across their eyes. We also find some indication that these visual specializations vary across species and may represent adaptations to their different forest habitats. Overall, the findings demonstrate how such investigations can be used to study the evolution of visual specializations—and sensory ecology in general—across a range of insect taxa from different geographical locations and across time.

Five mitochondrial genomes of black fungus gnats (Sciaridae) and their phylogenetic implications

Sciaridae is a family of great species diversity, distributed worldwide, that includes important agricultural pests of cultivated mushrooms and plants produced in greenhouses. Here we sequenced five nearly complete mitochondrial genomes representing three subfamilies of Sciaridae. The lengths of these mitogenomes range from 13,849 bp to 16,923 bp with 13 protein-coding genes (PCGs), 20–22 transfer RNA (tRNA) genes, two ribosomal RNA (rRNA) genes, and a control region (CR). Compared with other dipteran species, rearrangements in Sciaridae are more common. Inversion or transition is observed frequently of trnL2, and in the tRNA clusters trnI-trnQ-trnM, trnW-trnC-trnY, and trnA-trnR-trnN-trnS1-trnE-trnF. Phylogenetic relationships within the family were reconstructed based on these newly sequenced species, combined with the published mitogenomes of related families, and recovered the topology within Sciaroidea as Cecidomyiidae + (Sciaridae + Keroplatidae). Relationships recovered within Sciaridae were Sciarinae + (‘Pseudolycoriella group’ + Megalosphyinae).

Compatibility of pesticides used in strawberry crops with predatory mites Stratiolaelaps scimitus (Womersley) and Cosmolaelaps brevistilis (Karg).

Stratiolaelaps scimitus (Womersley) and Cosmolaelaps brevistilis (Karg) (Acari: Laelapidae) are predatory mites of soil-inhabiting pests, mainly small insects. Fungus gnats fly species are found in greenhouse strawberry production and may be controlled with predatory mites, being important to know their compatibility with the pesticides used in strawberry crops. In this study, the compatibility of seven commercial pesticides used in strawberry cultivation with the predatory mites S. scimitus and C. brevistilis was assessed in laboratory conditions. Survival and oviposition rates were evaluated between 0.5 and 120 h after treatment (HAT). The results demonstrate that lambda-cyhalothrin treatment resulted in the lowest survival rate for both mites in the first evaluations, being moderately harmful, while spinetoran was slightly harmful to C. brevistilis. On the other hand, abamectin, azadirachtin, azoxystrobin + difenoconazole, iprodione and thiamethoxam were harmless for both mites and, oviposition rate was significantly different only at 72 and 120 HAT for S. scimitus and C. brevistilis respectively. These results may be used to develop guidelines for the adoption of selective pesticides in integrated pest management programs that conserves predatory mites.

The oldest fungus gnat of the tribe Exechiini in the lowermost Eocene Oise amber (Diptera: Mycetophilidae).

Eoexechia gallica gen. n. and sp. n., oldest record of the fungus gnat tribe Exechiini, is described from the Lowermost Eocene amber of France. It falls as sister group of all the extant Exechiini after its addition to the morphological phylogenetic analysis of the tribe. Its discovery suggests a Paleocene age for the Exechiini, in accordance with the current phylogenetic dating. This new discovery will help to date the whole clade in future phylogenies.

An innovative strategy for control of fungus gnats using entomopathogenic nematodes alone or in combination with waterlogging.

Chive gnat (Bradysia odoriphaga) is a soil-borne pest of Chinese chives, which causes millions of dollars in yield losses per year. Traditional methods, such as chemical pesticides leave detrimental chemical residues on plants, which potentially threaten human health. To find a sustainable method of reducing the chive gnat, the authors evaluated the effects of waterlogging and the addition of entomopathogenic nematode (EPN) on reducing chive gnat in Chinese chives via three pot experiments and one field demonstration. Results indicated that increasing the duration of waterlogging markedly increases chive gnat mortality. The presence of EPN also caused chive gnat mortality to increase with exposure time. Most importantly, the combination of waterlogging and EPN had synergistic effects on chive gnat mortality; the combination led to higher mortality than using waterlogging and EPN alone. The study demonstrated that a combination of two environmental friendly methods of fungus gnat control could lead to synergistic effects, which may provide novel approaches to economic and environmentally sustainable pest management measures.

A New Nearctic Species of Diadocidia Ruthe Fungus Gnat (Diptera: Diadocidiidae)

A new species of Diadocidia Ruthe fungus gnat was discovered in a mixed pine and hardwood forest in the eastern Lower Peninsula of Michigan. Diadocidia longivena Taber is the fourth species recorded from North America and the first new species of the genus described from the Nearctic in 63 years. The fly belongs to subgenus Adidocidia Laŝtovka and Matile, as do both of its congeners that were described in North America.

Development of Lycoriella ingenua and Bradysia impatiens on different phases of agaricus composts

Fungus gnats are small, dark colored, mosquito like fragile insects. They can be encountered all around the world, excluding places with extreme climate. Gnats prefer habitats that are damp with high relative humidity and rich in organic debris. Most of the species are not considered to be harmful in agriculture, but some may cause serious damage, especially in forcing of vegetable or ornamental plants. In mushroom production, however, they are considered as the most destructive pests; the damage caused by them alone can result in huge loss for mushroom farmers. In the Hungarian mushroom industry, fungus gnats damage mainly white-button mushroom, oyster mushroom and pioppino productions. Lycoriella ingenua (Dufour, 1839) and Bradysia impatiens (Johannsen, 1912) are the two most commonly found fungus gnat species from the family Sciaridae on Hungarian mushroom farms.&#x0D; We have conducted an experiment with the two aforementioned species, to find out, whether they can fully develop into adults, feeding purely on Agaricus compost diet. We used unspawned white button mushroom compost (phase 2) and spawned compost which has been colonized by the mycelia of Agaricus bisporus (phase 3). We did not conduct any experiment with the first compost phase, as it undergoes pasteurization, which eliminates any pests in it. We recorded emerging gnats only from phase 2 compost. Neither L. ingenua, nor B. impatiens could complete its development on phase 3 compost diet, furthermore not even pupae were observed in these breeding pots. From pots containing phase 2 compost, a total of 1607 adults emerged. The number of B. impatiens adults was 653, and 954 for L. ingenua. Sex ratios for the two species were different. For B. impatiens, the number of females was 1.36 times greater than that of males, in L. ingenua there were 1.7 times more males than females in total. Swarming took approximately 6 days for B. impatiens and 10 days for L. ingenua. From the experiment we can conclude that phase 3 compost, which is well interwoven with Agaricus bisporus mycelia is not suitable for B. impatiens and L. ingenua to complete their whole life cycle.

Revision of the black fungus gnat species (Diptera: Sciaridae) described by W.A. Steffan from Micronesia.

On the Micronesian Islands 20 species belonging to ten sciarid genera were detected. The revision resulted in the following three new combinations: Cratyna brevipalpis (Steffan) comb. n., Epidapus jaluitensis (Steffan) comb. n., and Epidapus yapensis (Steffan) comb. n. Two species are declared as new synonyms: B. snyderi Steffan, 1969 syn. n. of Bradysia kraussi Steffan, 1969 and Epidapus nanus Menzel, 2007 syn. n. of Epidapus jaluitensis (Steffan, 1969). Bradysia radicum (Brunetti, 1912) was misinterpreted by Steffan and is not yet known to occur in Micronesia. All revised species are figured.