May 282015

Check out this video that Matthew Cobb of Why Evolution is True just found and posted. While it’s primarily showing a pair of swifts (Apus apus) being reunited after a 9 month hiatus in Africa, check out who crashes the party (most easily seen around the 1:10 mark).

That little scuttling thing playing peekaboo from the neck feathers of the male is actually an adult fly in the family Hippoboscidae, and most likely a male Crataerina pallida, the swift louse fly. These flies are ectoparasites of birds, where they bite and feed off the blood of both nestlings and adults.

Hippoboscids, like bat flies in the family Nycteribiidae (sometimes considered a subfamily of the Hippoboscidae) that Piotr Naskrecki has been showing off this week, give birth to live, late-stage maggots that the female has reared and nourished one at a time in her abdomen. The maggots are deposited into the swift’s nest, where they pupate and then scuttle onto their nestling host. According to Hutson (1981), fly populations peak in mid June when the swift nestlings are just beginning to hatch, and steadily fall off from there until most flies are dead by mid to late August, and he stated the flies do not make the migration with the birds.

But, since these flies don’t lay eggs, they must be spending the winters in the nest boxes as pupae, awaiting the return of their hosts year after year. Hutson found that males are more prevalent early in the spring, with females to follow. This leads us to an interesting question of how this louse fly got onto this bird! The fly was already aboard the bird when it entered the box (if you watch closely you can see a white blob that moves around neck is first visible at 0:06, immediately after the male bird approaches the sitting female). This means that one of two things happened: either the male bird has in fact carried its little parasite friend down to Africa and back (something that neither Hutson nor Walker & Rotherham (2010) believe to be the case) (and assuming this was the first nestbox that the bird stopped in, which I take to be the presumption of the ornithologists who posted the video and stated it shows a male reuniting with its mate from last year in last year’s nestbox), or alternatively, the male bird did stop for a time in another nestbox where it picked up its little hitchhiker, and then proceeded on to its longterm mate. This of course raises questions about how committed these birds really are to their mates, and whether they may be getting a little action on the side (or at least exploring their other options) before settling down for the season. Since I know pretty well nothing about bird biology, if someone knows more about swift mating, bonding, and extra-pair copulation, let me know in the comments if I’m way off.

Either way, catching a glimpse of a louse fly playing peekaboo on the neck of its host may raise more questions than the initial emotional response of “WHAT IS THAT THING?!?”, and that’s pretty darn cool.

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Jul 242012
Virginia Ctenucha - Ctenucha virginica moth

Virginia Ctenucha – Ctenucha virginica

I may be nearly useless with moth identification, but this is one I know by heart. Of course, this isn’t really brag worthy since there aren’t many moths with an iridescent blue thorax and yellow head, but I’m working on baby steps here.

Just because I can identify it doesn’t mean I can place it in the correct family however! When I was an undergrad (back in the day when I had to walk 10 miles uphill both ways, etc) I was taught the tiger moths were a family unto themselves. Since then however, they’ve been sunk into the family Erebidae, causing me much confusion.

The Virginia Ctenucha feeds on a variety of grasses and sedges as a caterpillar, and adults are active from late spring to mid summer.

What feeds on Virginia Ctenucha though? Compsilura concinnata, a tachinid fly that was introduced to North America to combat Gypsy moth (Lymantria dispar) in the late 19th and early 20th century. As is wont to happen with poorly understood ecology and introductions, Compsilura concinnata turned out to be a broad generalist, and is right at home within a wide diversity of caterpillar hosts. There’s concern that this “new” parasitoid is a contributing factor to declining saturniid moth populations in eastern North America, but the fly appears to be under heavy pressure from a hyper-parasitoid species of trigonalid wasp, which appears to be keeping fly populations low enough to prevent eradication of native moths.
Kellogg, S.K., Fink, L.S. & Brower, L.P. (2003). Parasitism of Native Luna Moths, (L.) (Lepidoptera: Saturniidae) by the Introduced (Meigen) (Diptera: Tachinidae) in Central Virginia, and Their Hyperparasitism by Trigonalid Wasps (Hymenoptera: Trigonalidae), Environmental Entomology, 32 (5) 1027. DOI: 10.1603/0046-225X-32.5.1019

Apr 112012

Urophora affinis Tephritidae Fruit Fly


Urophora affinis, a fruit fly in the family Tephritidae, was introduced to Ontario in the 1970’s as a biological control agent for invasive European knapweeds. When the researchers went back to check on the population a few years later, they were unable to find the species again, and concluded that the population failed to become established (at least in Ontario, a similar introduction in British Columbia did survive).

Fast forward to 2008 when Adam Brunke (a beetle specialist, ironically) collected a specimen in his parent’s backyard, nearly 200 kilometers away from the original introduction site! Clearly Urophora affinis had not only survived, but had even managed to expand it’s range across a large portion of central Ontario, a story which I reported in my paper on Ontario Tephritidae last spring.

Later on in the summer, I accompanied Adam and Steve Paiero (of tongue parasite fame) out to Northumberland County (much closer to the original introduction site) where they were conducting a survey, and happened to find a thriving population of Urophoa affinis in a nice sunny clearing. Nearly every composite flower had an individual or two on top feeding and/or mating, and we collected a long series to place in the University of Guelph Insect Collection. I also walked away with a number of nice photos documenting the species in a new location.

It just goes to show that a species can find a way to survive and prosper, even if they go unnoticed by us!


Jan 042012

ResearchBlogging.orgIt’s not often that flies make headlines, and when they do it’s usually in a negative connotation (malaria, mosquitoes, black flies, etc). A new paper published Tuesday in PLoS ONE (Core et al, 2011) is certainly not helping this Detrimental Diptera Dillema (DDD), announcing that a species of scuttle fly (Phoridae) has been discovered parasitizing honey bees (Apis mellifera), one of the most loved insects on the planet.

Images of Apocephalus borealis and honey bees from Core et al., 2012

Fig. 2 - Images of Apocephalus borealis and honey bees from Core et al., 2012

Of course things attacking honey bees isn’t in itself news, especially in the age of Colony Collapse Disorder (CCD). The real news here is that the scuttle fly, Apocephalus borealis, has seemingly switched hosts, previously known to be parasitic in bumble bees, paper wasps, and even black widow spiders (Brown, 1993). Other Apocephalus flies are better known as ant-decapitating flies, who’s larvae will pupate in the dismembered heads of their ant hosts. As for A. borealis, it’s association with honey bees was thanks to a serendipitous natural history observation:

(John) Hafernik, who also serves as president of the California Academy of Sciences, didn’t set out to study the parasitized bees. In 2008, he was just looking for some insects to feed the praying mantis that he had brought back to SF State’s Hensill Hall after an entomology field trip. He scrounged the bees from underneath the light fixtures outside the biology building.

“But being an absent-minded professor,” Hafernik joked, “I left them in a vial on my desk and forgot about them. Then the next time I looked at the vial, there were all these fly pupae surrounding the bees.”

San Francisco State University Press Release, January 3, 2012

After further observation, a few behavioural trials and some interesting molecular techniques, the research team found that not only were these scuttle flies parasitizing honey bees in the San Francisco Bay area, but also in migratory bee colonies housed in the Central California Valley and South Dakota, and also that infected honey bees would leave their colonies at night to fly away and die (often congregating at man-made lights and acting strangely); that all of the parasitized bees had been exposed to Nosema ceranae (a fungus which can lead to death from diarrhea and malnourishment) and/or Deformed Wing Virus (a disease that can cause malformation of a bee’s thorax and wings during pupation); and that some of the flies had evidence of these bee pathogens in their systems.

This is a lot of really interesting information for one study, but it’s not hard to see where the authors were going next with their story: scuttle flies could be contributing to CCD and posed a “new threat” to honey bees. The authors proceeded to pose a long series of questions regarding future areas of research, and how all of their findings could be detrimental to honey bee populations and the potential role these flies play in CCD. Overall, this is a very cool piece of natural history research, with a bit too much CCD hype for my liking!

You can see why the media has fallen in love with this paper; it includes flies (which no one likes on principle), honey bees (which everyone likes on principle), CCD (which scares the daylights out of everyone) and zombies (which also scare the daylights out of everyone). At the time that I wrote this post (midnight-ish Wednesday morning), I found 13 major news outlets or blogs from around the world which had covered the story (see list below).

This is where we have a problem though. Of the 13 stories I looked at, 8 of them had errors in their reports, of varying severity. What’s worse, all of the erroneous accounts were in major reporting outlets, potentially misinforming thousands of readers! It’s not surprising however, to see that 7 of the 8 stories that got things 100% correct were all science-focused publications/blogs, while one was a small-market news affiliate:

The Good

KQED News – ‘Zombie’ Parasite Preys on Bay-Area Honeybees, by Lauren Sommer

Observations (Scientific American Blog Network) – “Zombie” Fly Parasite Killing Honeybees, by Katherine Harmon

New Scientist LifeParasitic fly could account for disappearing honeybees, by Andy Coghlan

Science NowParasitic Fly Dooms Bees to Death by Maggots, by Erik Stokstad

MyrmecosDid a parasitic fly cause Colony Collapse in bees?, by Alex Wild

Not Exactly Rocket ScienceParasitic fly spotted in honeybees, causes workers to abandon colonies, by Ed Yong

The Bad

MSNBC (WebCite copy) – Stated bees which foraged at night were more likely to be parasitized than bees that foraged during the day (misinterpretation of Fig. 3A of Core et al., 2012)

Mirror (WebCite copy) – Stated that the parasite “is similar to one being found in bumblebees” (it’s not just similar, it’s the same species)

Press Association (WebCite copy) – Title states that the flies are linked to bee losses (not true, the connection between fly parasitism and CCD is simply proposed by the authors); Implied that bees are immediately turned into light-seeking zombies after the female fly lays her eggs (it appears to take up to a week for this to happen)

Daily Mail Online (WebCite copy) – Title states link between flies and global decline of bees (see above); Didn’t italicize species names (minor I know, but it bugs me)

CBC News (WebCite copy) – Implies that bees which foraged at night were more likely to be parasitized than bees that foraged during the day (see MSNBC)

io9 (WebCite copy) – “This parasite is a likely culprit (in reference to CCD – MDJ) because it does indeed force bees to abandon their colony” (authors say the fly may contribute to CCD, not that it is the likely culprit)

Daily Express (caching not allowed) – Implies that bees are parasitized in their hives and that they immediately “abandon their hives in a crazed state” (the authors are unsure of where the flies attack, but they know it’s not in the hive, and see the Press Association above); didn’t italicize species names (argh)

While I doubt that heads will roll at these institutions because of these errors (sorry, a little Apocephalus humour there), the moral of this story is that the science content the majority of the public is exposed to is not exactly the best science content available! Hopefully, as scientists and science writers continue to use social media and blogs, the good stories I featured here will reach more of the people who would normally only see the “bad” versions, imparting a correct and positive experience with the fantastic research being done every day around the world!


Update (Jan. 07, 2012, 20:30) Brian Brown, a co-author on this study and the world’s expert on these flies, has expanded on the natural history and taxonomy of the flies involved in this research on his blog ‘flyobsession’. The remainder of the research team behind this study will be setting up a FAQ to help ‘clarify’ some of the errors I reported on above, and are also beginning a new citizen science project to begin understanding how far flung this parasitism is.

Core, A., Runckel, C., Ivers, J., Quock, C., Siapno, T., DeNault, S., Brown, B., DeRisi, J., Smith, C., & Hafernik, J. (2012). A New Threat to Honey Bees, the Parasitic Phorid Fly Apocephalus borealis PLoS ONE, 7 (1) DOI: 10.1371/journal.pone.0029639

BROWN, B. (1993). Taxonomy and preliminary phylogeny of the parasitic genus Apocephalus, subgenus Mesophora (Diptera: Phoridae) Systematic Entomology, 18 (3), 191-230 DOI: 10.1111/j.1365-3113.1993.tb00662.x PDF Available HERE