Toxomerus

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Toxomerus
Toxomerus marginatus (female).jpg
Toxomerus marginatus female
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Diptera
Family: Syrphidae
Subfamily: Syrphinae
Tribe: Syrphini
Genus: Toxomerus
Macquart, 1855
Type species
Toxomerus notatus
Macquart, 1855

Toxomerus is a very large genus of hoverflies. They are found in many parts of North and South America. [1] [2] Most larvae are predators on soft bodied insects, though a few species have been shown to feed on pollen. [1] Adults feed on the pollen of a wide range of flowers. [3]

Contents

Morphology

The majority of species are 6–9 mm in length. A common trait of species within the genus is their mimicry of stinging Hymenoptera to avoid predators. [4] [5] What distinguishes Toxomerus from other hoverflies is the posterior indentation of their eyes and unique abdominal patterns; the abdominal patterns are diagnostic at the species level within the genus. Eyes are large (taking up approximately 2/3 of head) and range from red to black in color. [1] Males and females can be distinguished by the dorsal spacing of their eyes, with males having a narrow gap and females having more space showing their ocelli. [6]

Classification and distribution

Both molecular and morphological analysis have been used to establish Toxomerus monophyly. Not all of Toxomerus species have been described, though over 130 Neotropical species and 6 endemic Nearctic species are known. [7] Some species have been discovered in the Old World in the afrotropics and are assumed to have been introduced due to their high genetic similarity to South American species. [8] Toxomerus species are the most abundant hoverflies (or syrphid flies) in the Americas. [9] Toxomerus marginatus is the most ubiquitous species in the North and is polyvoltine, brooding multiple times per year. Toxomerus dispar is the most common in the tropics, though T. pulchellus is more common in some areas. [10]

Biology and ecology

Although they are high fidelity hymenopteran mimics [11] they do not engage in behavioral mimicking such as leg waving, wing wagging, and mock-stinging. [5] They also have significantly less hair than bees. As in all flies, Toxomerus species have 4 life stages: egg, larva, pupa, adult. The lifespan of the average adult is about a month and can vary depending on the season with shorter spans in the summer and longer in the winter. Mating can occur midair or on the ground depending on species. [6] A female can lay up to hundreds of eggs at a time and will place them where prey or pollen food sources are readily available. [12] [6] [3] They can be found in a wide variety of habitats. Adults can be encountered in dense ground cover including grasses and leaves. [12] [13] Some can do well in urban environments and can be responsible for some pollination in gardens. [14]

Toxomerus larvae are known to typically feed on aphids. [15] [8] Predatory Toxomerus larvae have also been found to feed on other Hemiptera, Acari, and Thysanoptera, along with Lepidoptera larvae. Though Toxomerus larvae are generally predatory, there are three known exceptions: Toxomerus apegiensis , Toxomerus politus , and Toxomerus floralis. [3] [8] T. politus larvae feed on the pollen of Zea mays (corn), and T. apegiensis larvae feed on the pollen of Olyra obliquifolia (bamboo). T. floralis, the larvae of which feed on pollen from Cyperus rotundus (Java grass) and Mitracarpus hirtus (tropical girdleweed), is the only species whose larvae are known to feed on plants from different families. [8] Generally, little information is known about the larval biology of Toxomerus species. Research suggests that other phytophagous Toxomerus species may be found by searching plants related to rainforest Olyra species.

After the larval stage, Toxomerus species typically become pollinivorous as adults. [16] Their diets as adults had made some species responsible for pollination in a variety of plant families, including Poaceae, Scrophulariaceae, Ericaceae, Cyperaceae, and Orobanchaceae. [17] [18] [19] [8] Adults and larvae will forage for pollen during the early daylight hours while their activity drops off at around late afternoon. [12]

Toxomerus marginatus mating on a flower. Syrphids - Toxomerus marginatus, Catahoula National Wildlife Refuge, Louisiana.jpg
Toxomerus marginatus mating on a flower.

Species

List of Toxomerus species

Related Research Articles

<span class="mw-page-title-main">Hoverfly</span> Family of insects

Hoverflies, also called flower flies or syrphids, make up the insect family Syrphidae. As their common name suggests, they are often seen hovering or nectaring at flowers; the adults of many species feed mainly on nectar and pollen, while the larvae (maggots) eat a wide range of foods. In some species, the larvae are saprotrophs, eating decaying plant and animal matter in the soil or in ponds and streams. In other species, the larvae are insectivores, preying on aphids, thrips, and other plant-sucking insects.

<span class="mw-page-title-main">Microdontinae</span> Subfamily of flies

The subfamily Microdontinae contains slightly more than 400 species of hoverflies and, while diverse, these species share several characteristics by which they differ from other syrphids. The Microdontinae are myrmecophiles, meaning they live in the nests of ants. Larval Microdontinae are scavengers or predators in ant nests, and, in contrast to other syrphid larvae, have no readily apparent body segmentation. Some species also do not exhibit the typical adult flower-visiting behaviour of other hoverflies, but instead remain near their larval host colonies.

<i>Syritta pipiens</i> Species of fly

Syritta pipiens, sometimes called the thick-legged hoverfly, is one of the most common species in the insect family Syrphidae. This fly originates from Europe and is currently distributed across Eurasia and North America. They are fast and nimble fliers, and their larvae are found in wet, rotting organic matter such as garden compost, manure, and silage. The species is also commonly found in human-created environments such as most farmland, gardens, and urban parks, wherever there are flowers. This species is an important part of its native ecosystem as adult Syritta pipiens flies are critical pollinators for a variety of flowering plants and the species supports parasitism by various parasitic wasp species. Thus, they play an important role in environmental functionality, and can serve as bio-indicators, in which their abundance can reflect the health of the environment. Syritta pipiens looks like many predatory hoverfly species, yet is not predatory.

<i>Allograpta</i> Genus of flies

Allograpta is a very large and diverse genus of hoverflies present throughout the world except most of the palearctic region. The adults are brightly coloured flower pollinators and most larvae have a predatory feeding mode involving soft-bodied sternorrhynchans. Certain species have diverged from this and their larvae have been found to be leaf-miners, stem-borers or pollen-feeders.

<i>Toxomerus marginatus</i> Species of insect

Toxomerus marginatus, also known as the margined calligrapher fly, is a common species of hoverfly. It is found in many parts of North America.

<span class="mw-page-title-main">Syrphini</span> Tribe of flies

The Syrphini are a tribe of hoverflies.

Rohdendorfia is a genus of hoverflies.

Spazigaster is a genus of hoverflies. The genus was first recorded in 1843 in Iran.

Syrphocheilosia is a genus of hoverflies.

Talahua is a genus of hoverflies.

Tuberculanostoma is a genus of hoverflies.

<span class="mw-page-title-main">Pyrophaena</span> Subgenus of flies

Pyrophaena is a subgenus of the hoverfly genus Platycheirus distinctive enough to sometimes treated as a separate genus in its own right. Indeed a recent study of the phylogeny of the subfamily Syrphinae found it to be closer to other certain other genera – Rohdendorfia, Syrphocheilosia and Spazigaster. Since only a few species were sampled the true systematic structure must await a more thorough survey of Platycheirus and related genera.

<i>Ocyptamus</i> Genus of flies

Ocyptamus is a large and diverse genus of over 200 species of hoverfly mostly found in the Neotropical region. It is likely that many of these species will be discovered to be synonyms though many others await description.

<i>Parasyrphus nigritarsis</i> Species of fly

Parasyrphus nigritarsis is a species of hoverfly, from the family Syrphidae, in the order Diptera. It is known from northern Europe and North America, and has been considered to be a rare species in parts of its range. Adults visit flowers as a source of nutrition, and females lay their eggs on clutches of eggs of leaf beetles. When the Parasyrphus larvae hatch, they first consume leaf beetle eggs and then consume immature beetles until they reach the pupal stage. This species is related to hoverflies that prey on aphids as larvae, and has been investigated in studies of chemical ecology and food web ecology.

<i>Melangyna novaezelandiae</i> Species of fly

Melangyna novaezelandiae is a hoverfly endemic to New Zealand. It is a generalized pollinator of a large range of plants that are both native and exotic to the New Zealand flora. M. novaezelandiae is widespread throughout New Zealand, including in agricultural environments. The larvae of this species feeds on other arthropods and may have uses as a biocontrol agent.

<i>Toxomerus politus</i> Species of fly

Toxomerus politus, commonly known as the maize calligrapher, is a species of hoverfly. It is known from North, Central and South America. Although little is known about the early stages of this species, associations with corn have been noted. The adults and likely the larvae feed on the pollen of the corn plants.

<i>Toxomerus floralis</i> Species of fly

Toxomerus floralis is a species of syrphid fly in the family Syrphidae. Its native range is from the southern US through South America. The fly has been introduced into Africa, where Cyperus rotundus is a host plant for oviposition through pupation. Mitracarpus hirtus is another known host plant for the species, making T. floralis the only species of Toxomerus with larvae known to feed on plants from different families.

Toxomerus basalis, commonly known as the sundew flower fly, is a species of kleptoparasitic fly endemic to Brazil. It was first described by Francis Walker in 1836. It feeds on captured, immobilized insects caught on the sticky leaves of sundew plants, which are carnivorous. Adult flies seem to have some capacity to escape from Drosera leaves if they have not come into contact with too many of the tentacles. The species is non-specific and have been found on large-leaved, semi-erect, and thread-like Drosera species, such as Drosera graomogolensis and Drosera magnifica.

References

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  2. Reemer, M. (2010). "A second survey of Surinam Syrphidae (Diptera):introduction and Syrphinae" (PDF). Tijdschrift voor Entomologie . 153 (2): 163–196. doi:10.1163/22119434-900000295.
  3. 1 2 3 Reemer, Menno; Rotheray, Graham E. (16 April 2009). "Pollen feeding larvae in the presumed predatory syrphine genus Toxomerus Macquart (Diptera, Syrphidae)". Journal of Natural History . 43 (15). UK: Taylor and Francis: 939–949. doi:10.1080/00222930802610576. ISSN   1464-5262.
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