Asilidae Research Articles

A new robber fly from the Lower Cretaceous (Aptian) Crato Formation of NE Brazil (Insecta: Diptera: Asilidae)

Araripogon pulchrus sp. nov., a new fossil species of the Diptera family Asilidae, is described and illustrated based on a very well preserved specimen from the Crato Formation (Aptian, Lower Cretaceous) of NE Brazil. This is the second known species of Asilidae from the Crato Formation (from which only one species, Araripogon axelrodi Grimaldi was previously known) and the fourth species of Asilidae known for the entire Mesozoic.

The phylogeny of robber flies (Asilidae) inferred from ultraconserved elements

ABSTRACTRobber or assassin flies (Asilidae) are a diverse family of venomous predators. The most recent classification organizes Asilidae into 14 subfamilies based on a morphological phylogeny, but many of these are not supported by molecular data. To test the monophyly of various clades in Asilidae, we used the recently developed Diptera‐wide ultraconserved element bait set to compile seven datasets comprising 151 robber flies and 145–2496 loci. We also compared the performance of various nodal support metrics. Our Maximum Likelihood phylogeny was fully resolved and well supported, but partially incongruent with the coalescent phylogeny. Further examination of datasets suggested that GC bias had influenced gene tree inference and subsequent species tree analyses. The subfamilies Brachyrhopalinae, Dasypogoninae, Dioctriinae, Stenopogoninae, Tillobromatinae, Trigonomiminae and Willistonininae were not recovered as monophyletic. The inter‐subfamily relationships are summarized as follows: Laphriinae and Dioctriinae (in part) successively sister to the remaining subfamilies, which form two clades: the first consists of a grade of Stenopogoninae (in part), Willistonininae (in part), Bathypogoninae+Phellinae, Stichopogoninae, Leptogastrinae, Ommatiinae and Asilinae; the second clade consists of a paraphyletic assemblage of genera from Dioctriinae (in part), Trigonomiminae, Stenopogoninae (in part), Tillobromatinae, Brachyrhopalinae and Dasypogoninae. This phylogeny demonstrates that the higher classification of Asilidae is far from settled, but does provide a much‐needed foundation for a thorough revision of the subfamily classification.

ROBBER FLIES (DIPTERA: ASILIDAE) AS PREDATORS OF HARVESTER ANT WORKERS (HYMENOPTERA: FORMICIDAE: POGONOMYRMEX) IN EASTERN NEW MEXICO AND WEST TEXAS

Three species of robber flies (Asilidae) are recorded as preying on workers of Pogonomyrmex harvester ants in eastern New Mexico and western Texas: Cerotainiops abdominalis, Saropogon combustus, and Saropogon pritchardi. Of 379 prey records for C. abdominalis, 66% were Pogonomyrmex workers. Two species of Saropogon were collected in association with a large number of harvester ant workers: S. combustus (40% of 263 prey records) and S. pritchardi (94% of 288 prey records). All three species show a statistical preference for Hymenoptera, specifically for harvester ant workers, and avoidance of Diptera, Hemiptera, Lepidoptera, and Orthoptera prey. A brief review of invertebrate predators of Pogonomyrmex workers is given, with emphasis on asilid predators. For the three asilid predators mentioned in the article, seasonality, observed behaviors, and a list of known prey taxa are included.

Stark trade-offs and elegant solutions in arthropod visual systems.

Vision is one of the most important senses for humans and animals alike. Diverse elegant specializations have evolved among insects and other arthropods in response to specific visual challenges and ecological needs. These specializations are the subject of this Review, and they are best understood in light of the physical limitations of vision. For example, to achieve high spatial resolution, fine sampling in different directions is necessary, as demonstrated by the well-studied large eyes of dragonflies. However, it has recently been shown that a comparatively tiny robber fly (Holcocephala) has similarly high visual resolution in the frontal visual field, despite their eyes being a fraction of the size of those of dragonflies. Other visual specializations in arthropods include the ability to discern colors, which relies on parallel inputs that are tuned to spectral content. Color vision is important for detection of objects such as mates, flowers and oviposition sites, and is particularly well developed in butterflies, stomatopods and jumping spiders. Analogous to color vision, the visual systems of many arthropods are specialized for the detection of polarized light, which in addition to communication with conspecifics, can be used for orientation and navigation. For vision in low light, optical superposition compound eyes perform particularly well. Other modifications to maximize photon capture involve large lenses, stout photoreceptors and, as has been suggested for nocturnal bees, the neural pooling of information. Extreme adaptations even allow insects to see colors at very low light levels or to navigate using the Milky Way.

Ethology of Proctacanthus gracilis Bromley, 1928 (Diptera: Asilidae) in Northeastern Florida, U.S.A.

Proctacanthus gracilis Bromley, 1928 forages primarily from vegetation, capturing prey in flight, and immobilizing them in flight or on the ground. Identified prey is in eight insect orders (Coleoptera, Diptera, Hemiptera, Hymenoptera, Lepidoptera, Neuroptera, Odonata, and Orthoptera), with Othoptera making up 63.0%. Mating occurs in the tail-to-tail position and oviposition is in the ground. This species exhibits a distinct daily rhythm of activity for feeding and mating. Grooming behavior resembles that described for other species of robber flies. Morphology, habitats and distribution in Florida, resting behavior, and predators and parasites also are discussed.

Pick Your Poison: Molecular Evolution of Venom Proteins in Asilidae (Insecta: Diptera).

Robber flies are an understudied family of venomous, predatory Diptera. With the recent characterization of venom from three asilid species, it is possible, for the first time, to study the molecular evolution of venom genes in this unique lineage. To accomplish this, a novel whole-body transcriptome of Eudioctria media was combined with 10 other publicly available asiloid thoracic or salivary gland transcriptomes to identify putative venom gene families and assess evidence of pervasive positive selection. A total of 348 gene families of sufficient size were analyzed, and 33 of these were predicted to contain venom genes. We recovered 151 families containing homologs to previously described venom proteins, and 40 of these were uniquely gained in Asilidae. Our gene family clustering suggests that many asilidin venom gene families are not natural groupings, as delimited by previous authors, but instead form multiple discrete gene families. Additionally, robber fly venoms have relatively few sites under positive selection, consistent with the hypothesis that the venoms of older lineages are dominated by negative selection acting to maintain toxic function.

Seasonality of predatory insects (Diptera: Syrphidae and Asilidae) in pasture monoculture and silvopastoral systems from Southeast Brazil

In this long-term study we evaluated the diversity and seasonality of predatory insects (Diptera: Syrphidae and Asilidae) in Brachiaria decumbens monoculture and silvopastoral systems in Southeast Brazil. The study was conducted in Coronel Pacheco municipality, Minas Gerais state, Brazil, between February 2010 and January 2015. Insects were collected with malaise traps installed in both monoculture and silvopastoral systems. Specimen abundance, family diversity, seasonality assessed by circular analysis, the degrees of association between specimen number and climatic variables measured by Spearman’s correlation, and the constancy and similarities of Syrphidae and Asilidae were analyzed in the monoculture and silvopastoral systems. Eleven species of hoverflies (Diptera: Syrphidae) were collected, five and three of which were exclusive to the silvopasture and monoculture, respectively. The number of specimens within the monoculture was significantly greater than that in the silvopasture. Twenty-four species of robber flies (Diptera: Asilidae) were collected, two of which were exclusive to the monoculture and eight to the silvopasture. The abundance of robber flies in the silvopasture was not significantly different from that in the monoculture. Syrphidae diversity was greater in the monoculture and was not significantly different from robber fly family diversity. Circular analysis revealed seasonality, with the distribution grouped during dry periods for hoverflies and dispersed for robber flies. Most hoverflies and robber flies were accidental in each of the systems. Further studies on the capacity of these predator species to act as biological control agents of pasture pests are required. This study presents important and promising results for understanding the dynamics of the Syrphidae and Asilidae community in monoculture and silvopastoral systems in Brazil.

Diversity of robber flies (Diptera: Asilidae) in a tropical deciduous forest of central Mexico

Robber flies are an important group in ecosystems, because of their ecological role as predators, thus contributing to maintain a balance in insect populations. Nevertheless, little is known about their diversity and ecological interactions in Mexico. In this study, we analyzed the structure of a community of robber flies collected during three years in a tropical deciduous forest of central Mexico. In this type of vegetation, the dry and rainy seasons are contrasting and generate drastic biotic and abiotic changes that could impact on robber fly populations. Therefore, we compared the structure of the robber fly community across three seasons: cold, dry, and rainy. We collected a total of 191 individuals which included eight species and 21 morphospecies. The rainy season presented higher species richness and diversity, as well as a species composition that differed from that of the cold and dry seasons. However, abundance did not vary significantly across seasons. We also record 14 genera and ten species previously unregistered in the state of Puebla.

Heteromorphosis associated to host-exploitation in an atypical parasitoid, Mallophora ruficauda (Diptera: Asilidae)

In this work, we provide morphological illustration and descriptions of the immature stages of the ectoparasitoid robber fly Mallophora ruficauda. Additionally, we studied the ecological aspects of its life cycle through the correlation between the morphology and function performed in each phase of the consumption of their host, the white grub Cyclocephala signaticollis. For the morphological description and quantification of length and width of the egg and larval instars I–II, images were used through optical and scanning electron microscopy. Individuals from larval instars III–V were weighed and measured with digital calibre directly. Finally, images were taken of the cephalic structures of the larval instars and through the use of image processing software we measured in each instar the size of cephalic structures. In addition, the changes in the width of cephalic capsule and the relative size of the maxillary palps and labrum with respect to the width of cephalic capsule were studied for each larval instar through GLMs, to relate the morphology of the cephalic structures with the function they perform. We found that the cephalic structures of the larva undergo changes when moulting to the next instar, according to their relationship with the host, matching with the stage of development where the processes of orientation to the host and attachment to its cuticle take place. These observations reveal, for the first time in a parasitoid asilid larva, the correlation between cephalic morphology and ecological function during the parasitism process and host use.

RECORDS OF ASILIDAE AND MUSCIDAE (DIPTERA) AS PREDATORS OF PLATYCERUS CARABOIDESAND PLATYCERUS CAPREA(COLEOPTERA LUCANIDAE) LARVAE IN DEADWOOD IN NORTHERN ITALY

The present paper reports cases of predation on two Italian species of stag beetles, Platycerus capreaand Platyceruscaraboides, by saproxylic Diptera of which preys were seldom reported or unknownin the litera-ture. Resulting from eight years of collections in many sites in northern Italy, the robber flies Laphria meridiona-lisandChoeradessp.eclosed inrearing boxes of P. caraboides, and the muscid fly Phaonia palpataemerged from deadwood inhabited byboth Platycerusspecies. These Dipteradeveloped in deadwood ofbroadleaves species,wherethey wereuncommon predators of Platycerusimmaturestages.Predator-prey interactions betweenAsilidaeandMuscidae larvae andPlatycerusimprove the knowledge on thecommunity of these species with hidden habitsin the saproxylic scene.

Desolation comes from the sky: Invasive Hymenoptera species as prey of Chilean giant robber flies (Diptera: Asilidae) through field observations and citizen science

• Robber flies are important predators of many insects species, mainly Hymenoptera. • Obelophorus terebratus concentrated the majority of hunting behavior on invasive bee. • Bombus terrestris was the prey more common among Chilean robber flies. • Three giant robber fly increasing his distribution thank to citizen science records. Robber flies (Asilidae) are the main predatory fly family feeding on beetles, butterflies, other flies for true flies, and even spiders; however, Hymenoptera is the most common prey. Invasive Hymenoptera species are common in central and southern Chile; however, few predators of these are known. The hunting behavior and prey of Chilean robber fly species are also poorly known. The aim of this study is to provide the first hunting behavior records of five Chilean giant robber fly species on invasive Hymenoptera. In addition, an updated distribution of these species is provided. Records of hunting behavior were based on fieldwork collections and citizen science observations. The historical distribution was compared with citizen science observations using chi-square analyzes. Twelve predation events were recorded. Obelophorus terebratus was the most common predator. Bombus terrestris was the invasive Hymenoptera most preyed upon. Both the extension of occurrence of Lycomya germainii as Obelophorus species showed changes in his distribution. Only O. landbecki shown changes in area of occupancy. Citizen science is playing a key role in the knowledge of biological interactions and distribution of endemic and native Chilean robber fly species.

Silent, underground warfare of flies: an endoparasitic bee fly (Diptera: Bombyliidae) larva parasitising a predatory assassin fly (Diptera: Asilidae) larva

AbstractAssassin or robber flies (Asilidae) and bee flies (Bombyliidae) are two of the largest and most diverse fly families with over 7400 and 4700 described species worldwide, respectively. Adult assassin flies are predatory, feeding on smaller insects captured on the wing, and larvae predate on soft‐bodied arthropods in the soil or rotting wood. Adult bee flies feed on nectar and pollen. Almost all bee fly larvae are external or internal parasitoids of other insect larvae, usually in the soil. Although the interaction between bee fly larvae and their hosts has been rarely observed, we recently discovered assassin fly larvae hosting bee fly Lepidanthrax linguatus (Anthracinae: Villini) endoparasitoids in riverine sandy soil in southern NSW, Australia. While bee fly larvae have been known to attack other fly larvae, Asilidae is an uncommon host group. Furthermore, to find bee fly larvae inside the host is even less common because most bee fly larvae are ectoparasitoids. Here we describe and illustrate the host assassin fly (Bathypogon nigrinus: Bathypogoninae) larva and pupa, as well as the first instar bee fly larva (planidium) though careful external examination of the surface of the asilid larva, which is translucent, allowing us to see the internal parasite. This is the first larva and pupa from Bathypogoninae to be described. We also illustrate the bee fly larva in detail based on scanning electron microscopy of a larva in situ, after dissection from the host. Finally, we describe the late instar larval and pupal exuvia of the endoparasitoid. Like other endoparasitoid bombyliid larvae in the Villini, the first instar larva causes the host to produce a breathing tube that surrounds the posterior half of the parasitoid, allowing the parasitoid to maintain contact with atmospheric oxygen.

Revision of the endemic Australian robber fly genus Daptolestes Hull, 1962 (Diptera: Asilidae) and description of Humorolethalis gen. nov.

AbstractDaptolestes Hull, 1962 is a small genus of distinctive, ornate robber flies (Asilidae) endemic to Australia, currently placed in the subfamily Brachyrhopalinae, containing three described species, D. limbipennis, D. nicholsoni and D. sergius. Adults of Daptolestes species (except D. sergius) have patterned wings, brown and yellow integumental colour and a waisted abdomen and could be mistaken for vespid wasps when foraging for insect prey on flowers. Here, we present a phylogeny based on a morphological survey of adult specimens. Based on the phylogenetic results, we provide a description and revised diagnosis for Daptolestes and describe four new species: D. leei Robinson & Yeates, sp. nov. D. bronteflavus Robinson & Yeates, sp. nov. D. feminategus Robinson & Yeates, sp. nov. and D. illusiolautus Robinson & Yeates, sp. nov. We also erect a new genus, Humorolethalis Robinson, Li & Yeates, gen. nov. to accommodate Dasypogon sergius Walker [=Daptolestes sergius (Walker)]. For all species of both genera, we illustrate external features of the adults and male and female terminalia. Key to all Daptolestes species.

New Distribution Records of Archilestris Loew in Mexico (Diptera: Asilidae) and Key to Mexican Species

New Distribution Records of Archilestris Loew in Mexico (Diptera: Asilidae) and Key to Mexican Species

New Records of Ground and Tiger Beetles (Coleoptera: Carabidae) As Prey for Asilidae (Diptera) in the High Plains of New Mexico and Texas

One hundred and fifty records of Carabidae (three subfamilies, six tribes, 16 genera, and 24 species) preyed upon by 23 species (in seven genera) of robber flies (Diptera: Asilidae) in the High Plains of eastern New Mexico and adjacent west Texas are listed. Five species of cicindelines represented 42% of all carabid records, while 19 non-cicindelines comprised 58%. Four species of ground/tiger beetles represented 66% of all records: Cicindelidia punctulata (Olivier), 22.7%; Selenophorus pedicularius Dejean, 21.3%; Cicindelidia ocellata (Klug), 11.3%; and Harpalus amputatus amputatus Say, 10.7%. These four species were preyed upon by 9, 11, five, and four species of robber flies, respectively. The top four asilid predators of Carabidae, based on percentage of total records, were Saropogon combustus Loew, 14.7%; Heteropogon patruelis (Coquillett), 14.0%; Efferia helenae (Bromley), 12.7%; and Proctacanthus milbertii Macquart, 10.0%. Twelve species of carabids are represented by only one or two records. No robber flies were identified as specialists on ground beetles; most species, notably in Efferia Coquillet, are considered generalist predators. These new records represent a significant addition to the previous knowledge of carabid prey taken by robber flies, particularly for the non-cicindelines. Asilid predation on tiger beetles may be more significant than previously thought. A review of previously published records on carabid prey taken by Asilidae is given.

Weaponisation ‘on the fly’: Convergent recruitment of knottin and defensin peptide scaffolds into the venom of predatory assassin flies

Many arthropod venom peptides have potential as bioinsecticides, drug leads, and pharmacological tools due to their specific neuromodulatory functions. Assassin flies (Asilidae) are a family of predaceous dipterans that produce a unique and complex peptide-rich venom for killing insect prey and deterring predators. However, very little is known about the structure and function of their venom peptides. We therefore used an E. coli periplasmic expression system to express four disulfide-rich peptides that we previously reported to exist in venom of the giant assassin fly Dolopus genitalis. After purification, each recombinant peptide eluted from a C18 column at a position closely matching its natural counterpart, strongly suggesting adoption of the native tertiary fold. Injection of purified recombinant peptides into blowflies (Lucilia cuprina) and crickets (Acheta domestica) revealed that two of the four recombinant peptides, named rDg3b and rDg12, inhibited escape behaviour in a manner that was rapid in onset (<1 min) and reversible. Homonuclear NMR solution structures revealed that rDg3b and rDg12 adopt cystine-stabilised α/ß defensin and inhibitor cystine knot folds, respectively. Although the closest known homologues of rDg3b at the level of primary structure are dipteran antimicrobial peptides such as sapecin and lucifensin, a DALI search showed that the tertiary structure of rDg3b most closely resembles the KV11.1-specific α-potassium channel toxin CnErg1 from venom of the scorpion Centruroides noxius. This is mainly due to the deletion of a large, unstructured loop between the first and second cysteine residues present in Dg3b homologues from non-asiloid, but not existing in asiloid, species. Patch-clamp electrophysiology experiments revealed that rDg3b shifts the voltage-dependence of KV11.1 channel activation to more depolarised potentials, but has no effect on KV1.3, KV2.1, KV10.1, KCa1.1, or the Drosophila Shaker channel. Although rDg12 shares the inhibitor cystine knot structure of many gating modifier toxins, rDg12 did not affect any of these KV channel subtypes. Our results demonstrate that multiple disulfide-rich peptide scaffolds have been convergently recruited into asilid and other animal venoms, and they provide insight into the molecular evolution accompanying their weaponisation.

First Record of Ophiocordyceps dipterigena Berk. &amp; Broome (Ophiocordycipitaceae) in the Himalayas

The Himalayas host a variety of unique species; however, their diversity and ecology have yet to be explored. We are reporting Ophiocordyceps dipterigena Berk. & Broome for the first time from the Indian Himalayas; stromata of the species emerging from the thorax and stroma with Hirsutella anamorphs emerging from the anus of an adult Robber fly; as well as the ecological notes pertaining to the status of this parasitic species in the Sikkim Himalayas, and also the potent medicinal properties of the species are discussed here.

Proteo-Transcriptomic Characterization of the Venom from the Endoparasitoid Wasp Pimpla turionellae with Aspects on Its Biology and Evolution.

Within mega-diverse Hymenoptera, non-aculeate parasitic wasps represent 75% of all hymenopteran species. Their ovipositor dual-functionally injects venom and employs eggs into (endoparasitoids) or onto (ectoparasitoids) diverse host species. Few endoparasitoid wasps such as Pimpla turionellae paralyze the host and suppress its immune responses, such as encapsulation and melanization, to guarantee their offspring’s survival. Here, the venom and its possible biology and function of P. turionellae are characterized in comparison to the few existing proteo-transcriptomic analyses on parasitoid wasp venoms. Multiple transcriptome assembly and custom-tailored search and annotation strategies were applied to identify parasitoid venom proteins. To avoid false-positive hits, only transcripts were finally discussed that survived strict filter settings, including the presence in the proteome and higher expression in the venom gland. P. turionella features a venom that is mostly composed of known, typical parasitoid enzymes, cysteine-rich peptides, and other proteins and peptides. Several venom proteins were identified and named, such as pimplin2, 3, and 4. However, the specification of many novel candidates remains difficult, and annotations ambiguous. Interestingly, we do not find pimplin, a paralytic factor in Pimpla hypochondriaca, but instead a new cysteine inhibitor knot (ICK) family (pimplin2), which is highly similar to known, neurotoxic asilid1 sequences from robber flies.

Phenology and Ethology of Adult Lasiopogon slossonae Cole and Wilcox Robber Flies (Diptera: Asilidae) in a New York Riparian Habitat

Seasonal abundance, daily activity, and behavior of adults of the robber fly Lasiopogon slossonae Cole and Wilcox were assessed with a capture-mark-recapture procedure for a population along 1 km of riverside in the Adirondack Mountains near Lake Placid, New York. Over the 2015 season, a total of 240 individuals were uniquely marked at this site; 73 were re-sighted at least one more time. The overall emergence window for this population in 2015 spanned 47 days with a maximum individual lifespan observed of 23 days; adult seasonal phenology periods for three other years are also summarized from presence/absence observations. In 2015, the adult sex ratio was slightly male-skewed (58%), but there was no significant difference between the sexes in home range size or perch distance from water. Flies packed more tightly into microhabitat patches as the overall abundance increased, and individuals showed some fidelity to relatively small home ranges (the median area of activity for marked individuals was 20 m2). However, longer dispersal also occurred rarely—the farthest movement we observed was 726 m over nine days. Individuals were active from morning to evening (usually 10:00 to 18:00) with a daily activity period that appeared to depend on both light intensity and temperature. Prey consisted mostly of Empididae, but also included Simuliidae, Anthomyiidae, and Cicadellidae. Both males and females were observed mating with multiple partners on different days.

Review of the Nearctic genus Wilcoxia James (Diptera: Asilidae: Stenopogoninae), with descriptions of three new species.

The robber fly genus Wilcoxia is revised based on external morphological features of adults. For each species the following is provided: type specimen information, diagnostic features, description, natural history including associated prey data, and geographical distribution (derived from georeferenced localities for both examined specimens and literature records). A key to adults of Wilcoxia, supplemented with photographs of habitus and selected morphological features, is included. The genus comprises eight species, distributed primarily in the southwestern United States. Three new species are described: W. apache (type locality: New Mexico, Quay County, Apache Canyon), W. flavipennis (type locality: Arizona, Pima County, Organ Pipe Cactus National Monument), and W. forbesi (type locality: New Mexico, Doña Ana County, 1 mi. NW Tortugas Mt.). There appear to be two reasonably well-defined species groups (cinerea and martinorum groups, with four species in each), based on structural features, seasonality and natural history. Identified prey items (for W. apache, W. forbesi and W. martinorum) include representatives from Hemiptera (eight families), Coleoptera (one family), Hymenoptera (five families) and Diptera (10 families). A discussion on the structural heterogeneity of Wilcoxia and a history of its classification are provided.