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Type Information

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Type from Salisbury Cove, Maine, July 17, 1913 (C. W. Johnson). It is deposited in the collection of the Boston Society of Natural History.
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Brues, C. T. 1924. Notes on Some New England Phoridæ (Diptera). Psyche 31: 41–44. doi:10.1155/1924/42175
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Katja Schulz (Katja)
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Brief Summary

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Apocephalus borealis is a species of North American parasitoid phorid fly that parasitizes bumblebees, honey bees and wasps (Brues 1924, Ennik 1973, Brown, 1993, Otterstatter et al. 2002). The association with honey bees has so far only been documented from California and South Dakota (Core et al. 2012); elsewhere, they are primarily associated with bumblebees (Otterstatter et al. 2002).

Female flies land on the abdomen of their host and pierce the cuticula with a sharp, swordlike ovipositor. As the larvae develop, they attack the host's brains and cause it to become disoriented, fly at night and exhibit other unusual behaviors. Whether these changes in host behavior increase parasite fitness remains to be established (Core et al. 2012). Mature larvae emerge from the junction of the head and thorax, often decapitating the host (the generic name Apocephalus refers to this grim result). A. borealis has been suggested as a possible vector promoting the spread of the pathogens responsible for colony collapse disorder in bees (Coghlan 2012, Core et al. 2012).

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Original Description

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♀. Length, including ovipositor 2.2 mm. Pale yellow, the central portion of the abdomen with an orange tinge and the legs pale brownish yellow; first segment of abdomen brownish, with pale hind margin; second segment with a brownish blotch at the middle of the lateral margin; third and fourth each with a larger darker spot; fifth entirely fuscous; sixth with the anterior angles brown; ovipositor brownish black, paler at tip, the membrane covering its upper side pale. Wings hyaline, venation pale fuscous. Front barely as high as wide; with only eight bristles below the ocelli; lowest row consisting of two reclinate post antennal ones and a lateral one next to the eye, median pair of the row above further apart than the post-antennals, this row curved upwards at the sides with the lateral bristle rather close to the eye margin and nearer to one of the median bristles than these are to one another. Ocellar row of four. All bristles strong, subequal. Median frontal suture distinct; lower half of front with scattered minute black bristles. Postocular cilia moderate, but the upper one on each side much enlarged. Antennae pyriform, obtusely pointed, as long as the front; arista no longer than the third joint, very stout, especially at base, nearly bare. Palpi rather broad, weakly bristled; cheeks each with two downwardly directed macrochaetae. Mesonotum sub-shining, with one pair of dorsocentral marcrochaetae; scutellum with one pair of bristles, the lateral pair very minute, scarcely visible. Propleura with two slender bristles above the insertion of the coxa and two minute ones near the humeral angle; mesopleura bare. Front coxa with a noticeable stripe of minute bristles along the anterior edge; middle tibiae not distinctly setulose; hind tibiae with a line of very delicate, closely placed setulae inside the posterior edge; all tarsi slender. Abdomen broad; second segment elongated, twice as broad as long, bare laterally; third to fifth segments gradually shorter, longer at the sides than along the median line; sixth longer and narrower, almost semicircular, with a few small marginal bristles medially at apex. Ovipositor of peculiar form; in dorsal view projecting beyond the sixth segment for a distance half the length of the abdomen; consisting of two chitinous pieces united at their apices, the upper one straight, issuing from the underside of the fifth and sixth segments and bearing below near the base a number of strong bristles; lower piece curved upward to meet the upper one and connected to it at the base by a large chitinous tooth originating at the extreme base of the upper piece. Viewed from the side (Fig. 1, A) the upper piece is seen to be nearly circular in section and the lower one greatly flattened; in ventral view (Fig. 1, B) the lower piece is spatulate, with truncate tip. Wing (Fig. 1, C) unusually narrow, costa not quite attaining the middle of the wing; first section of costa twice the length of the second; third very short, the minute second vein nearly perpendicular to the costa; fourth vein very slightly and evenly curved; fifth faintly bisinuate; sixth and seventh similarly sinuate; costal cilia rather long and set moderately close together.
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cc-publicdomain
bibliographic citation
Brues, C. T. 1924. Notes on Some New England Phoridæ (Diptera). Psyche 31: 41–44. doi:10.1155/1924/42175.
author
Katja Schulz (Katja)
original
visit source
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EOL authors

Apocephalus borealis

provided by wikipedia EN

Apocephalus borealis is a species of North American parasitoid phorid fly that attacks bumblebees, honey bees, and paper wasps. This parasitoid's genus Apocephalus is best known for the "decapitating flies" that attack a variety of ant species, though A. borealis attacks and alters the behavior of bees and wasps.[2] These flies are colloquially known as zombie flies and the bees they infect are colloquially known as zombees.[3] Association with honey bees has so far only been documented from California, South Dakota, Oregon, Washington, British Columbia (Vancouver Island), and Vermont.[4][5]

History

This phorid fly is native to North America, attacking bumble bees and paper wasps.[2] The infection of European honey bees in North America by A. borealis is a recent development that was first discovered by Dr. John Hafernik, who collected some dead specimens near a light source at San Francisco State University's campus. These were placed in a vial and forgotten. About a week later larvae emerged from the dead bees.[6] Information is insufficient to explain why the parasitic fly jumped to its new host, but concern exists that this new host provides an opportunity for the fly to thrive and further threaten the decreasing honey bee population.[7] To identify this fly, DNA barcoding was used, demonstrating that the phorids that emerged from Apis and Bombus had no more than 0.2% (1 bp) divergence among samples. What variation was found was from among those phorids reared from honey bees, rather than between flies reared from honey bees versus bumble bees. Other analyses gave similar results, including morphological criteria, sequencing of 18S rRNA genes, and cross-infection of honey bees using phorids that had emerged from both honeybees and bumblebees, thus confirming that the phorids attacking honey bees are the same species as those attacking bumble bees.[2]

As a vector for pathogens

To make matters worse for the infected hosts, microarray analyses of honey bees from infected hives reveal that these bees are often infected with deformed wing virus and Nosema ceranae. Unfortunately, both larvae and adult phorids have tested positive for these pathogens, implicating the fly as a potential vector or reservoir host of these honey bee pathogens.[2] A. borealis has also been suggested to be a possible vector promoting the spread of the pathogens responsible for colony collapse disorder.[2][8]

Life cycle

Eggs are laid in the abdomen of the bee; when the larvae hatch, they feed on flight muscles in the thorax and hemolymph. Development of larvae takes an average of one week. Mature fly larvae typically emerge from the host between the head and thorax (but rarely result in decapitation), and the larvae pupate outside the host body. About 28 days are needed for the entire life cycle.[2] Infected bees can be found walking in circles, as well as losing the ability to stand. Disorientation is likely caused by mechanical interference or by pressure of the growing larvae on the internal organs and nervous system. Inactivity during the daytime, along with activity during cold or inclement weather, has been observed in infected bees.

Hive abandonment, particularly at night, has been implicated as a behavior modification of A. borealis. Reasons for abandoning the hive remain unclear. Researchers hypothesized that infected bees may be ejected by their hive mates, with chemosensory particles playing a possible role in detection of infected bees. It is also possible that infected bees altruistically remove themselves from the hive in efforts to stop the spread of disease to the bee colony.[2][9]

A bee leaving the hive and going towards a light source at night has yet to be observed. However, many dead bees have been observed near light sources, and when collected many of these bees show evidence of being parasitized, leading to the conclusion that parasitized bees might be drawn to light sources at night. The mechanisms of this phenomenon have yet to be analyzed, but possible culprits are mechanical interference of the larva growing within the bee or a response to chemical signals the larva are emitting in the bee.

Effect of seasons

The rates of infection in honey bees fluctuate as A. borealis populations increase and decline over the seasons. No adults of the fly were found within hives, indicating that phorids do not survive in large numbers in the late winter when foraging bees are inactive.[2]

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The initial description of the species by Charles Thomas Brues, 1924.[1]

Zombee Watch

A citizen science project, "Zombee Watch", uses a social media framework for people to report sightings of potentially parasitized bees.[6] The stated goals of the project are to determine where in North America the zombie fly is parasitizing honey bees and how often honey bees leave their hives at night (even if they are not parasitized) and to engage citizen scientists in making a significant contribution to knowledge about honey bees and in becoming better observers of nature.[10]

References

  1. ^ a b Brues, C. T. (1924). "Notes on Some New England Phoridæ (Diptera)". Psyche: A Journal of Entomology. 31: 41–44. doi:10.1155/1924/42175.
  2. ^ a b c d e f g h Core, Andrew; Runcke, Charles; Ivers, Jonathan; Quock, Christopher; Siapno, Travis; DeNault, Seraphina; Brown, Brian; DeRisi, Joseph; Smith, Christopher D.; Hafernik, John. "A new threat to honey bees, the parasitic phorid fly Apocephalus borealis". PLoS ONE. 7 (1): e29639. doi:10.1371/journal.pone.0029639. PMC 3250467. PMID 22235317.
  3. ^ Kayla Figard (August 2, 2012). "Seeking Zombee Hunters". The San Francisco Examiner. p. 12.
  4. ^ Ben Gittleson (January 30, 2014). "'Zombie' Bees Surface in the Northeast". ABC News.
  5. ^ Sandi Doughton (September 26, 2012). "Start's first case of 'zombie bees' found in Kent". The Seattle Times.
  6. ^ a b TedTalk (October 31, 2012). "Flight of the Living Dead: Dr. John Hafernik". TedTalk.
  7. ^ Anton Preston Arce, Rojelio Pedraza (2012). "Evaluation of Phorid Fly (Apocephalus borealis) Parasitism of Feral Honey Bee (Apis mellifera) Colonies in South Orange County". KSBR and the Department of Biological Sciences, Saddleback College.
  8. ^ Andy Coghlan (January 3, 2012). "Parasitic fly could account for disappearing honeybees". New Scientist.
  9. ^ Castro, Joseph. "Fly Parasite Turns Honeybees Into Zombies | LiveScience".
  10. ^ "Zombee Watch". Zombee Watch.

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Apocephalus borealis: Brief Summary

provided by wikipedia EN

Apocephalus borealis is a species of North American parasitoid phorid fly that attacks bumblebees, honey bees, and paper wasps. This parasitoid's genus Apocephalus is best known for the "decapitating flies" that attack a variety of ant species, though A. borealis attacks and alters the behavior of bees and wasps. These flies are colloquially known as zombie flies and the bees they infect are colloquially known as zombees. Association with honey bees has so far only been documented from California, South Dakota, Oregon, Washington, British Columbia (Vancouver Island), and Vermont.

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