Mozambique Diary: Photoshop or not?

Rock scorpion (Hadogenes granulatus) from Bunga Inselberg in Gorongosa, one of the largest scorpions in the world.

Rock scorpion (Hadogenes granulatus) from Bunga Inselberg in Gorongosa, one of the largest scorpions in the world.

One of the more entertaining consequences of posting images of obscure, rarely seen animals on this blog or on my Facebook page is that I am sometimes accused of faking them, especially if a Google search by those who doubted the veracity of my photos did not produce similar pictures taken by other photographers. This happens particularly often with animals that are the largest of their kind, be it a giant land crab or, more recently, a parasitic bat fly. I wonder if the photos in this post will be met with similar incredulity.

Bunga Inselbergs in Gorongosa National Park, Mozambique

Bunga Inselbergs in Gorongosa National Park, Mozambique

Last month I lead (lured) a group of researchers to a remote corner of Gorongosa National Park to continue the documentation of the biological richness of this remarkable place. Our camp was at the foothills of the Bunga inselberg, one of several small, isolated mountains in the western part of the park. These inselbergs have never been biologically explored and although we did not expect to find any endemic species there was always a chance of encountering rare or new to science organisms. These inselbergs are, in an essence, giant piles of volcanic rock, covered with a very thin layer of topsoil and a dense carpet of woody vegetation. Such a habitat is heaven for a lot of animals but, to my great relief, not lions and elephants. This meant that we could roam freely around the inselbergs in a relative safety, not constrained by the need to be always accompanied by armed park rangers. I say “relative” because Africa is rich in things that can get you, and Bunga inselbergs were no different – on my first visit there my friends and I were attacked by a cloud of wild honey bees, and on the following day I pulled nearly 150 stingers from my arms and neck. (It was a close call – I remember thinking “At least this is the end fit for an entomologist,” before losing consciousness.) Thankfully there were no similar incidents during this survey, although I did make sure that every person carried an Epipen kit to treat potential anaphylactic shock.

The median ocelli of the rock scorpion (Hadogenes granulatus) are protected from scratching against rocks by elevated ridges (green arrow). These are absent in species that live in equally constrained but softer environments, such as this Opistacanthus (below) found under tree bark.

The median ocelli of the rock scorpion (Hadogenes granulatus) are protected from scratching against rocks by elevated ridges (green arrow). These are absent in species that live in equally constrained but softer environments, such as this Opistacanthus (below) found under tree bark.

Lifting heavy volcanic rocks to look for animals during the survey was hard work, but it was also immensely rewarding. Each flat piece of basalt could have been hiding a cool gecko, a snake, a family of crickets, some awesome beetles, or a scorpion, and it was the last one that gave me the biggest surprise. Rock scorpions of the genus Hadogenes are considered the largest, or at least the longest, scorpions in the world. Some species can reach the length of 22 cm and several individuals from Bunga were at least this big. Granted, a large portion of the body is the long and thin telson (“tail”) of the animal, but it is still a spectacular beast, which will make you pause when you see it scurrying around your fingers. All species of Hadogenes are obligate lithophiles; in other words, they love rocks. Their bodies are perfectly adapted to squeezing into narrow crevices, and their feet carry stiff setae and strongly curved claws that allow them to cling to even the smoothest rocks (and hang from rocks upside down, something that few other scorpions can do). Their median ocelli – the main pair of eyes – are protected by elevated ridges that prevent them from scratching against the rocks, and the entire body is flatter than in any other scorpion of similar size.

Like many scorpions, members of the genus Hadogenes display a beautiful, blue fluorescence if exposed to ultraviolet light. A recent study suggests that this helps these nocturnal animals detect and avoid light.

Like many scorpions, members of the genus Hadogenes display a beautiful, blue fluorescence if exposed to ultraviolet light. A recent study suggests that this helps these nocturnal animals detect and avoid light.

But, as it is often the case, a large size and a scary appearance do not necessarily translate into true ability to inflict harm. The giveaway is the telson, which in rock scorpions is long and thin, betraying the presence of weak muscles and a small venom gland, and thus the lack of reliance on venom for capturing prey and defense. They can and do sting, of course, but the strength of their venom is no greater than that of a bee (and, thankfully, scorpions do not move in large swarms and are far more friendly than those pissy little bits of flying pain). A few species of Hadogenes have the ability to spray venom towards the attacker, which can cause painful irritation if the droplets get into your eyes, but otherwise they are harmless. In fact, an article (pdf) describing the medical importance of rock scorpions puts more emphasis on their ability to pinch your fingers then to envenomate.

Scorpions of the genus Hadogenes occur in rocky habitats across southern and East Africa, often on isolated mountains, leading to frequent allopatric speciation and a high number of endemic species. When I first found rock scorpions on Bunga I was hoping for a new, undescribed species but, alas, this turned out not to be the case as they were all members of H. granulatus, a species known from other places in Mozambique.

I photographed one of the individuals sitting on a vertical rock next to my hand. I knew that the animal was pretty harmless but I still was not looking forward to comparing its venom to that of a bee, and decided not to shoot it sitting directly on my hand. And, of course, it made it much easier to manipulate the image in Photoshop to make the scorpion appear bigger. (Kidding!)

Rock scorpions’s body is strongly flattened, perfectly adapted to squeezing into the narrowest crevices.

Rock scorpions’s body is strongly flattened, perfectly adapted to squeezing into the narrowest of crevices.


Flavio Artur, Ricardo Guta, and I, 24 hours after being attacked by a swarm of wild African honey bees. On that morning I pulled out nearly 150 stingers from my skin.

Flavio Artur, Ricardo Guta, and I, 24 hours after being attacked by a swarm of wild African honey bees. On that morning I pulled out nearly 150 stingers from my skin.

 

Mozambique Diary: Red-headed flies

Red-headed flies (Bromophila caffra) are striking and common animals in East and southern Africa, but little is known about their biology.

Red-headed flies (Bromophila caffra) are striking and common animals in East and southern Africa, but little is known about their biology.

Two months, that’s how long I have been neglecting this blog. Some people had even sent me messages to check if I were still alive. But I am alive and the reasons for my silence were good – until last week I was in Mozambique, working at the Wilson Lab and busily preparing for the next biodiversity survey of Gorongosa National Park. While there I had precious little time to write or take photos, but I did manage to take some shots of a few interesting critters. It is the rainy season in Gorongosa now and insect life is exploding. I had set up an ultraviolet light in front of my office to collect all members of my target groups (orthopteroid and dictyopteroid insects) and to cherry-pick the more interesting species from orders that we don’t yet collect systematically. On some nights the sheet was sagging under the weight of hundreds of species of insects and for a while mysterious redheads kept coming to the light.

Red-headed flies, which in Mozambique emerge at the end of the rainy season, like to hang in clusters on leaves.

Red-headed flies, which in Mozambique emerge at the end of the rainy season, like to hang in clusters on leaves.

I recognized them from my earlier trips to Gorongosa as Red-headed flies (Bromophila caffra) – large, slow moving insects, reluctant to take to the air, and much happier to hang in clusters from low tree branches. They are truly striking animals, showy and clearly unconcerned about attracting anybody’s attention, including that of potential predators. There were many birds and grabby vervet monkeys in the camp, who not so much as looked in the direction of the flies who slowly spun in clusters on leaves.

Adult Red-headed flies feed on dung and other decaying organic matter.

Adult Red-headed flies feed on dung and other decaying organic matter.

But for an insect as conspicuous and common as the Red-headed fly, shockingly little is known about its biology. In fact, the last scientific paper that mentions it by name (according to an extensive MetaLib cross-database search) is from 1915, and it does so only to compare the fly’s strikingly red head to another species. As already pointed out in an excellent post about this species by Ted C. MacRae, there exists only anecdotal evidence that the larvae of this species might be feeding on the roots of Terminalia trees, potentially sequestering toxic cyclic triterpenes, which would explain the adult flies’ aposematic coloration. But, as is the case with so many African invertebrates, nobody really knows.

There is also another possibility. One morning while in Gorongosa I woke up to find my arms covered with big, painful blisters. The night before I had spent a couple of hours searching for insects in tall grass and remembered seeing many contrastingly colored, red and black beetles of the genus Mylabris. “Oh, that’s why they are called blister beetles!”, it dawned on me, a little too late. While walking through the grass I must have brushed against some of these insects, and a mere touch against my skin caused the blisters, which lasted for over a week, to appear. The beetles themselves are highly toxic, deadly even, and no bird or other vertebrate will try to eat them. It is therefore quite possible that the flies are fakers – not toxic at all but simply counting on predators’ reluctance to try a potentially harmful meal. This phenomenon, known as Batesian mimicry, is common in the animal kingdom and I strongly suspect that the flies are an example of it.

I strongly suspect that Red-headed flies are Batesian mimics of blister beetles of the genus Mylabris. These beetles not only cause painful, long-lasting blisters but are also potentially deadly toxic.

I strongly suspect that Red-headed flies are Batesian mimics of blister beetles of the genus Mylabris. These beetles not only cause painful, long-lasting blisters but are also potentially deadly toxic.

When I return to Gorongosa next month the flies should still be around. It will also be the time when many young house geckos (Hemidactylus mabouia) are hanging around the lights of the camp, having hatched in January and February. It might be a bit evil on my part, but I think I will do some feeding experiments to see if the lizards, which at that point should still be naive about the flies, have any adverse reaction to eating them. Watch this space.

One peculiar morphological characteristic of the Red-headed flies is the absence of the ocelli, which are typically found on the head of other flies.

One peculiar morphological characteristic of the Red-headed flies is the absence of the ocelli, which are typically found on the head of other flies.

Dermatobia Redux

Raising two dipteran children was an interesting experience. It was embarrassing on a few occasions, when both of my arms started bleeding profusely in public; painful at times, to the point of waking me up in the middle of the night; and inconvenient during the last stages of the flies’ development, when I had to tape plastic containers to my arms to make sure that I will not lose the emerging larvae. But other than those minor discomforts it was really not a big deal. Perhaps my opinion would have been different had the bot flies decided to develop in my eyelids, but I actually grew to like my little guests, and watched their growth with the same mix of pleasure and apprehension as when I watch the development of any other interesting organism under my care.

Having two bot fly larvae embedded in my skin have also made me ponder once again the perplexing element of the human psyche that makes us abhor parasites but revere predators. Why is it that an animal that is actively trying to kill us, such as a lion, gets more respect than one that is only trying to nibble on us a little, without causing much harm? I strongly suspect that it has to do with our genetically encoded sense of “fairness” – we perceive parasites as sneaky and underhanded, whereas predators attack us head-on and thus expose themselves to our retaliation. They are brave, or so we think. This, of course, is a very naive and anthropomorphic interpretation of nature. A lion is no “braver” than a bot fly, who has to skillfully hunt mosquitos to assure the dispersal of her eggs and risk more dangers than a lion, a top predator with no natural enemies. Most importantly, to a bot fly we, humans, are a renewable resource – it is in the bot fly’s best interest that we live a very long life and thus can be “reused” – hence the minimum amount of suffering that this species causes. To a lion we are nothing more than a one-time meal. But we should not judge either species for their actions – there is no “good” or “bad” in nature – nature is amoral.

I am saying this to prepare you for a short video that I have made about my experience of raising a bot fly. I don’t want you to think that it is “creepy” or “weird”. It is simply a documentation of an interesting organism, who happens to develop in the skin of large mammals. But please be forewarned that this video includes a few sequences that some viewers may find disturbing. If you don’t want to have nightmares about things living inside you (which they already do, by the way), please don’t watch it. But if you are prepared to be open-minded and appreciate God’s wonderful creations in all their amazing glory, enjoy the show!

Puppy-killing scientist smuggles rainforest babies in body cavity

I am pretty sure that taking this very photo in Belize was the beginning of my adventure with the Human bot flies.

I am pretty sure that taking this very photo in Belize was the beginning of my adventure.

I almost got away with it – for five days I had covered my body and slathered insect repellant onto my skin with an almost religious zeal, but on the last day I faltered. I was in Belize, teaching macrophotography at the Bugshot workshop. The course was almost over, and so I relaxed and decided to shoot some red-eyed tree frogs in the rainforest around the lodge. I rolled up my sleeves but, because I had misplaced my insect repellant and was too lazy to look for it, I did not put any DEET on. Big mistake. As I photographed the frogs, clouds of mosquitos, perhaps sensing a new, unprotected warm body, went to town on my arms and face. But, this being my last day in Belize, I decided to ignore the little vampires and kept taking pictures. Later that day my arms were quite itchy, but it was nothing new or unusual.

That's a nice-looking butt – I knew that something was amiss when a strange tube started poking out of my skin. This turned out to be a bot fly's breathing tube.

That’s a nice-looking butt – I knew that something was amiss when a strange tube started poking out of my skin. This turned out to be a bot fly’s breathing tube.

Things started veering off course after I got home. Some of the mosquito bites kept itching and, rather than disappearing, started to get bigger. It didn’t take me long to realize that I had brought with me, embedded in tiny holes in my skin, larvae of the Human bot fly (Dermatobia hominis). This was not the first time for me to have this parasite. What was new was the number of these animals that had made my body their home – at least six of them were feeding on both my arms, with four spaced only a millimeter apart on my right forearm. In the end, only three of them survived the first week. One of the surviving larvae was on my elbow. It was a nasty little thing, very active and painful. It had to go. But I decided to keep the two remaining larvae. As strange as it sounds, I felt bad about killing them, but I also had never seen an adult bot fly, and this was my chance.

Human bot flies are well known to entomologists and people living in warm, tropical parts of Central and South America. I cannot think of any of my biologist friends working there who didn’t have a torsalo living in their skin at some point or another, often in such very inconvenient places as the eyelid, the upper lip, or the top of the head. These get extracted through a variety of methods that often involve suffocating the larva with glycerine jelly, raw steak, or duct tape, and then pulling or squeezing the larva out of the skin. These methods usually work, but there is always a risk of leaving a part of the bot’s body in the wound, which may lead to infection. On those occasions where I needed to remove a larva, I preferred to use a suction venom extractor, which enlarges the opening of the wound (warble) and pulls the larva out, still alive and in one piece. I only discovered this method, first described 13 years ago (Boggild et al. 2002. Clin. Infect. Dis. 35: 336-8), after a visit to my doctor. Her solution was to perform a surgery by cutting my arm open. I said “thanks, but no thanks” and did my own research on furuncular myasis.

A mature larva of the Human bot fly (Dermatobia hominis) is an impressively armored animal. And yet it caused relatively little discomfort when feeding, deeply embedded in the skin of its host, me.

A mature larva of the Human bot fly (Dermatobia hominis) is an impressively armored animal. And yet it caused relatively little discomfort when feeding, deeply embedded in the skin of its host, me.

Human bot flies (D. hominis), despite their name, are not interested in our species only. They will gladly feed on other primates, as well as ungulates and other large mammals. Similarly, other members of the bot fly family (Oesteridae), who preferentially target small mammals, will occasionally find themselves on humans. But we get infected with D. hominis more often than with other bot flies because of this species’ unusual strategy of dispersing its eggs. Rather than laying them on the ground in the vicinity of mammalian burrows, the way other bot flies do, the D. hominis female catches and lays her eggs on other exoparasites: mosquitos, ticks, and deer flies. The eggs hatch while on the intermediate host and drop onto the skin of the ultimate host, often a human, when they sense its body heat. Frequently they will use the hole made by the mosquito to enter the skin but they can also use a hair follicle to get inside. Even the newly hatched larvae are covered with spines that point up, which makes pulling them out from the warble very difficult.

The puparium of the Human bot fly. The tufts on the front of the body are anterior spiracles that allow the animal to breathe when it matures in this stage underground. As the puparium ages it changes color from light brown to black. Remarkably, the spiracles stay the same, orange color.

The puparium of the Human bot fly. The tufts on the front of the body are the anterior spiracles that allow the animal to breathe as it matures  underground. As the puparium ages it changes color from light brown to black. Remarkably, the spiracles stay the same, orange color.

Once in the skin, the larva undergoes three molts and in 7-10 weeks grows from the size of a grain of sugar to that of a peanut. Throughout this time the warble enlarges and occasionally bleeds, but otherwise it is relatively painless, unless the larva decides to munch on nerve endings. These wounds rarely get infected as the larva very likely produces antibiotic secretions. Once fully grown, the larva crawls out of the warble and falls to the ground, where it quickly buries itself and turns into a puparium. The wound usually heals completely within a couple of days. All in all, not a big deal. But some people, for whatever reason, don’t like to have a squishy, almost harmless animal living in their skin.

Although we don’t think about them as such, Human bot flies are beautiful rainforest animals, as much a part of that ecosystem as howler monkeys and Morpho butterflies.

A mature Human bot fly (Dermatobia hominis). Although we don’t think about them as such, these flies are beautiful rainforest animals, as much a part of that ecosystem as howler monkeys and Morpho butterflies.

A mounting body of research indicates that many parasites have evolved a way of manipulating the behavior of their hosts. A parasitic horsehair worm will make its otherwise terrestrial grasshopper to jump into the water, where it then ruptures the grasshopper’s body and swims away. Parasitoid wasps who have just left the emaciated body of a caterpillar will be actively protected by their brain-washed host. Humans also fall victim to parasitic manipulation – there is evidence that toxoplasmosis, a disease caused by protozoan Toxoplasma gondii, makes men less intelligent and prone to take greater risks (it has to do with increasing the likelihood of ending up as food for large cats, Toxoplasma’s ultimate host; inexplicably, the effect on women is a statistically significant increase in their intelligence.)

After I had decided to keep two of my botflies and let them reach maturity, I began to wonder – have the generations of entomologists, who let these flies live in their skin as a kind of geeky right of passage, inadvertently selected for a strain of bot flies that manipulate human behavior towards letting the flies live? Or do I just have toxoplasmosis?

A newly eclosed Human bot fly, with traces of the ptilinum on its head, a reversible pouch that gets inflated with hemolymph to help the young fly break free from the puparium.

A newly eclosed Human bot fly, with traces of the ptilinum on its head, a reversible pouch that gets inflated with hemolymph to help the young fly break free from the puparium.

In any case, the flies survived in my skin for nearly 10 weeks, successfully emerged, pupated, and are now enjoying a brief life as adults. Brief, because adult bot flies have no functional mouthparts and cannot feed, which means that they only live for a few days. They are quite pretty – I would go as far as to say that, among insects, they undergo one of the most dramatic transitions from ugly to cute during their development.

It was an interesting experience and I am glad that I managed to bring these insects to maturity. But rest assured that the next time I am in Belize my bottle of DEET will never leave my pocket.

Stay tuned for a video with some awesome sequences showing the development of my bot fly!

Update: The video is now available.

 

A composite photo showing the stages of the Human bot fly’s development. The size difference between the first and the third larval instal is particularly striking.

A composite photo showing the stages of the Human bot fly’s development. The size difference between the first and the third larval instars is particularly striking.

 

Postscript
I let my bot flies live and I went to great pains to make sure that they survived their inadvertent exodus from their native land of Belize. Will this endear me to people who wanted to crucify me for killing a puppy-sized spider a few months ago? I am guessing, no. Do I give a crap? Take a guess. Incidentally, now that the dust has mostly settled, I can repeat that I did not kill the puppy-sized spider – another scientist collected and preserved it – although this bit of information somehow didn’t register with the online media. There was no point in clarifying this because it is completely irrelevant to the issue of scientific collecting – I have killed and preserved my share of specimens, and I will always defend biologists who have the unpleasant duty to do so.

Postscript 2
Gil Wizen has written about his experience of raising a dipteran child on his blog.

So long, 2014

It was an interesting, busy year, which explains in part why I have been neglecting this blog recently. I am not going to give a month-by-month account of 2014 but thought that a few highlights might be in order.

Early in the year I made a brief visit to Quirimbas National Park in northern Mozambique where I found Pardalota karschiana, one of the most remarkable and beautiful katydids in the world.

Early in the year I made a brief visit to Quirimbas National Park in northern Mozambique where I found Pardalota karschiana, one of the most remarkable and beautiful katydids in the world.

The most important event of 2014 for me was, unquestionably, the opening of the E.O. Wilson Biodiversity Laboratory in Gorongosa. This facility, which I now direct, is quickly becoming a hub of renewed scientific and educational activity in Mozambique. Here our technician Ricardo Guta teaching kids from nearby schools about insects of Gorongosa.

The most important event of 2014 for me was, unquestionably, the opening of the E.O. Wilson Biodiversity Laboratory in Gorongosa. This facility, which I now direct, is quickly becoming a hub of renewed scientific and educational activity in Mozambique. Here our technician Ricardo Guta is teaching kids from nearby schools about insects of Gorongosa.

I have my first encounter with the African lungfish. This animal appears to be more resourceful than I ever suspected. Here a PBS cameraman John Benam and producer James Byrne witness its amazing ability to escape.

I have my first encounter with the African lungfish. This animal appears to be more resourceful than I ever suspected. Here a PBS cameraman John Benam and producer James Byrne witness its amazing ability to escape.

In April E.O. Wilson and I published a book on the biodiversity of Gorongosa and the efforts to restore this unique place on Earth.

In April E.O. Wilson and I published “A Window on Eternity“, a book on the biodiversity of Gorongosa and the efforts to restore this unique place on Earth.

During a BugShot macrophotography workshop on Sapelo Island in Georgia I find my first zorapteran!

During a BugShot macrophotography workshop on Sapelo Island in Georgia I find my first zorapteran!

Back in Gorongosa, with the help our mammalogist Jen Guyton, I learn how to shoot bats in flight.

Back in Gorongosa, with the help of our mammalogist Jen Guyton, I learn how to shoot bats in flight.

A short trip to Belize in September gives me a chance to meet Uo, the mythical rain caller.

A short trip to Belize in September gives me a chance to meet Uo, the mythical rain caller.

A successful sting operation leads to the rescue of a pangolin and her baby from a poacher – I finally get to see and touch the animal I had been dreaming of seeing all my life.

A successful sting operation leads to the rescue of a pangolin and her baby from a poacher – I finally get to see and touch the animal I had been dreaming of seeing all my life.

The internets go batshit crazy over a single specimen of a common arthropod collected for scientific research.

The internets go batshit crazy over a single specimen of a common arthropod collected for scientific research.

That’s about it – I am looking forward to 2015, which promises to be even more exciting. Watch this space and thank you for reading!

Mozambique Diary: Not all flies fly

Tsetse fly (Glossina sp.) from Gorongosa feeding on my blood. Luckily, tsetses in this area do not carry the dreaded sleeping sickness (but it does not make it any less painful).

Tsetse fly (Glossina sp.) from Gorongosa feeding on my blood. Luckily, tsetses in Gorongosa do not carry the dreaded sleeping sickness.

After a long hike in the scorching heat of the African savanna the cool, shady patch of tall miombo forest looked like heaven to us. I was in the southern part of Gorongosa, looking with a few friends for some elusive species of arthropods. But we were having little luck finding any and after several hours of strenuous walking the morale was low. As we stepped under the dark, inviting canopy of the forest, the drop in the temperature was palpable and we all relaxed, slowed down the pace, and the mood in the group immediately improved. But then, suddenly, somebody yelped “Ouch!” and at the same moment I felt a painful pin-prick at the back of my neck. Crap, tsetse flies! We looked around – they were everywhere. Clouds of them. We could see groups of dozens clumping on vegetation, taking into the air the instant they noticed the movement of our bodies. We ran.

A painting (undoubtedly the first and only) of a bat fly (Penicillidia sp.) burrowing in the fur of a Long-winged bat (Miniopterus).

A painting (undoubtedly the first and only) of a bat fly (Penicillidia sp.) burrowing in the fur of a Long-winged bat (Miniopterus).

Tsetse flies have long had a reputation for being one of the scourges of Africa, alongside malaria, crocodiles, and the plague of locusts. And deservedly so – some species of tsetses, all members of the genus Glossina, are vectors of nasty protozoans, including Trypanosoma brucei, the cause of the deadly sleeping sickness. Luckily for us, Gorongosa tsetses carry a different Trypanosoma species, T. congolense. This protozoan does not affect humans but unfortunately causes the chronic Nagana disease in cattle and horses, which explains the nearly complete absence of these animals around the park and in almost the entire region of central Mozambique. But knowing that tsetse bites are not going to kill us did not make them any more pleasant. Tsetses are large flies, about the size of a bee, and their skin-piercing mouthparts are much thicker than those of a mosquito. In other words, it hurts like hell when one jabs you with its proboscis, and you flail your arms like a madman to shoo it away while the fly escapes unharmed.

Members of the family Streblidae, such as this Raymondia sp., collected from the Hildebrandt's horseshoe bat (Rhinolophus hildebrandtii), often exhibit interesting adaptations in their wing morphology, such as the ability to fold them longitudinally along the back. This presumably helps them move swiftly in the pelage of their hosts.

Members of the family Streblidae, such as this Raymondia sp., collected from the Hildebrandt’s horseshoe bat (Rhinolophus hildebrandtii), often exhibit interesting adaptations in their wing morphology, such as the ability to fold them longitudinally along the back. This presumably helps them move swiftly in the pelage of their hosts.

But count yourself lucky. Imagine instead that you cannot shoo them away. You try to smack one but it runs, hides in your hair or some place where you are not able to reach, and it continues to bite. It only leaves your body to give birth somewhere in your house but then immediately runs back, guided by your scent and body heat. Oh, and imagine that this fly is the size of your fist (or a small puppy). Welcome to the world that bats are forced to live in.

Tsetses are members of a large group of flies, the superfamily Hippoboscoidea, all of which are exclusively hematophagous – blood is the only food that they are interested in. The tsetse family (Glossinidae) is the most basal (unsophisticated, one might say) member of this lineage of insects – they are always looking for a blood meal but never evolved the ability to stay with their tasty host. Bats are unlucky to have been colonized by two much savvier families of flies, the Nycteribiidae and Streblidae. These insects know the value of a good host and, once they landed on the furry back of a bat, they never leave it again. Over millions of years of coevolution with their mammalian hosts the bat flies have undergone a remarkable transition. From a free-flying ancestor, most likely very similar to today’s tsetse flies, emerged several lineages of highly modified, often completely wingless, spider-like creatures. Their body became flattened and very hard, making it almost impossible to squash them against the skin. In the family Nyctiberiidae the head turned into a small appendage that can be safely tucked away in a protective groove on the back and all traces of wings completely disappeared. These flies cannot survive for long outside of their host’s body and only feel at home when scurrying at an alarming speed in its dense fur. Their feet are armed with large claws that make it almost impossible to dislodge them from the hair of their host. They really don’t look like flies and when a friend spotted one on the body of a bat she called me to collect the bat’s “pet spider.”

In the closely related family Streblidae the wings may or may not be present, but even in the winged species the body is modified for squeezing through the fur, and members of the subfamily Ascodipterinae go even further in their commitment to the host. Much further. Once a female lands on a bat she sheds her wings and legs (yes, legs) and burrows head-first into the skin. Once there, her head and thorax sink into her own abdomen, and the skin of the bat overgrows her body. She becomes one with her host.

Penicillidia bat flies (Nycteribiidae) are some of the most unusual members of the order Diptera and hardly resemble their winged relatives. This individual was collected from a Long-winged bat (Miniopterus natalensis) in Gorongosa, Mozambique.

Penicillidia bat flies (Nycteribiidae) are some of the most unusual members of the order Diptera and hardly resemble their winged relatives. This individual was collected from a Long-winged bat (Miniopterus natalensis) in Gorongosa, Mozambique.

Female bat flies, like their relatives tsetse flies, are remarkably good mothers. The great majority of insects relies on what ecologist call “r-selection” in their reproduction – they lay hundreds or thousands of eggs, betting on one or two of them making it to adulthood. Bat flies, on the other hand, rely on “K-selection” – like humans, they prefer to invest a lot in a much smaller number of offspring, hoping that they will all make it to the reproductive age. They are larviparous – instead of laying eggs the female gives birth to a single, fully developed larva, which immediately turns into a pupa. While in her mother’s body, the larva feeds on “milk glands”, analogous to the mammalian mammary glands (if they were located in the uterus), and develops safely protected from the elements and predators. When the time comes for the mother to give birth she walks off the bat’s body and attaches the larva to the wall of the bat’s roosting place, usually a cave (which explains why bats that roost in rolled-up leaves and other less permanent places have fewer ectoparasites). Then she turns back and runs towards her host, guided by the smell and the heat of its body.

The recent Ebola crisis brought back the attention of the medical community to bats as potential reservoirs of the virus. Although there is no evidence that bats are in fact harboring the virus, there seems to be some correlation between instances of the outbreak and the presence of large numbers of bats in the affected areas. While reading the literature on both Ebola and bat flies I found it rather curious that nobody has tested bat flies for the presence of the virus – these are relatively very long lived (195 days on average) insects, who always stay (as pupae) at the roosting sites of bats, even when the hosts leave to forage elsewhere. They often move from one host species to another and, this point makes me really wonder why nobody has seriously looked at these flies as potential vectors, occasionally drop on and bite people. We know that they harbor a slew of pathogens – a recent study conducted in Gorongosa National Park on bats Rhinolophus landeri and Hipposideros caffer showed that flies living on these animals are vectors of Trypanosoma species that are ancestral to those that cause Chagas disease. Add to this the fact that one of the first cases of Marburg disease in Zimbabwe (caused by a virus related to Ebola) was caused by a bite of an arthropod (by default all unidentified bites seem to be classified by the medical community as “spider bites” and spiders in the area were tested, predictably unsuccessfully, for Marburg). It is far more likely that the bite was caused by a fly that fell off a bat.

A friend of mine recently expressed her dismay at “lowly” parasites. I beg to differ – if anything, parasites, including bat flies, are incredible examples of evolution at its best, organisms capable of both adapting to life in the most hostile of environments (the very substrate you live on wants you dead!) and resisting diseases that live inside your body. I cannot promise that I will not try to smack the next tsetse fly that lands on me but at least I promise that I will do it in the most respectful, considerate way.

Louse flies (Hippoboscidae) are close, equally modified for ectoparasitic lifestyle family of flies. This Lipoptena sp. was collected from a Nyala antelope while it was fitted with a GPS collar. Louse flies are parasites of large mammals and birds, and some are considered serious pests of sheep.

Louse flies (Hippoboscidae) are closely related to bat flies and equally modified for ectoparasitic lifestyle. This Lipoptena sp. was collected from a Nyala antelope while it was being fitted with a GPS collar. Louse flies are parasites of large mammals and birds, and some are considered serious pests of sheep.

African Bats: Conservation in the Time of Ebola

A guest post by Jen Guyton

Banana bats (Neoromicia nana) are tiny, insectivorous bats. Their name comes from the preferred roosting habitat of this species – furled leaves of banana plants.

Banana bats (Neoromicia nana) are tiny, insectivorous bats. Their name comes from the preferred roosting habitat of this species – furled leaves of banana plants.

The last fragile wing finally came free from the threads of my mist net. I sank into the sand on the riverbank, took a deep breath, and tugged off my yellow deerskin gloves. Eight cotton bags wiggled as they hung from the line that tethered my mist net to a tree. We’d gotten a swell of banana bats (Neoromicia nana), tiny creatures, no heavier than a large grasshopper, that are thought to roost in the furled leaves of banana plants. They had come in low over the river like a pack of tiny, flittering wolves, hunting the gnats and mosquitoes that hovered in a veil over the water. I’d had to work fast, because the longer the bats stayed in the mist net, the more tangled they became. Some even chewed their way through the nylon thread, escaping in a flurry of teeth and leaving behind a yawning hole for me to mend, its edges fringed with fragrant urine. Now, I just had to wait for my subjects to leave me a few fecal pellets in the cotton bags so that I could analyze their diet.

I looked with relief at Kaitlyn, my assistant for the day, as we took swigs of our beers. I watched the net billow and catch the moonlight, shining silvery-black like a benighted spider web, and listened to the sound of elephants crashing their way through the dense riverine vegetation in the distance.

Out of the corner of my eye, I saw Kaitlyn startle and look down. “I think something just peed on me,” she said, sounding perplexed. I shone my headlamp above her and was greeted by the glittering eyes and bulging cheeks of a large bat, hanging from the branch of the tree above us and happily chomping away on a piece of fruit. From the white patches below its ears and its fawn-colored fur I recognized it as an Epauletted fruit bat, a member of the genus Epomophorus.

A painting of the female Epomophorus wahlbergi that peed on Kaitlyn

A painting of the female Wahlberg’s epauletted fruit bat (Epomophorus wahlbergi) that peed on Kaitlyn

I ran to grab my hand net, a long mesh bag on a circular frame with a handle. The bat was a dozen feet above us, and I didn’t have the handle extension sections, so I quickly duct taped the net to a mist net pole. I raised the net slowly, very slowly, sure that the bat would see me coming and take flight. But it continued to munch merrily, and it disappeared into the net with little more than a metallic peep! of protest. As I collected a fecal sample from it, Kaitlyn cleaned the urine from her clothes.

***

Little collared fruit bat (Myonycteris torquata) from Ghana, a species implicated in harboring the Ebola virus.

Little collared fruit bat (Myonycteris torquata) from Ghana, a species implicated in harboring the Ebola virus.

Stories like these have gotten me into trouble lately. “I study bat communities in Africa,” I’ll say, only to be greeted by wide eyes and mouth poised to speak the word that’s on everyone’s mind: Ebola.

Luckily, I work on the other side of the continent, thousands of miles from where Ebola has now taken almost 5,000 lives. My field site in Mozambique, on the southeastern coast of Africa, is safe from bat-borne diseases, as far as we know. But it’s no secret that bats have been implicated frequently in emerging zoonotic diseases – diseases of animal origin – that are now cropping up among humans: rabies in the Americas, Marburg virus in Africa, Hendra virus in Australia, and Nipah and SARS viruses in Southeast Asia are all harbored by bats.

The recent Ebola outbreak, too, has tenuous ties to our fluttering friends: scientists have found its antibodies in several species of West and Central African fruit bats. We can’t be sure, though, that they are “reservoir” species – organisms that consistently maintain a virus in their bodies without showing signs of illness. This would allow the bats to harbor Ebola, giving it the opportunity to spill over into humans. But, since we haven’t isolated live virus particles from the bats, all we know is that at some point in their lives,they were infected with or exposed to the virus that left its signature on their immune system.

So far, there’s no record of a bat transmitting Ebola to humans. Humans can get it from other humans, and we have solid evidence that people have become infected through ape carcasses, scavenged and eaten. People in parts of Africa eat bats too, but whether humans can catch the bug directly from bats is still a mystery. Some bat-borne diseases need to pass through what’s called an “intermediate” host – another species that amplifies the virus, allowing it to multiply and become more virulent – before humans can catch it. That is true of Hendra virus, which is found in Australian flying foxes. Contact with the bats poses little known threat to humans, but four people have died after interacting with sick horses. The horses, it seems, fed on fruits from trees where bats roosted.

A colony of Egyptian fruit bats (Rousettus aegyptiacus) from Nzerekore, Guinea, where many people have recently died of Ebola. This species has also been suspected of being the virus’ carrier. But this photo may be the proof of the bats’ innocence – despite spending several hours in the bats’ company and digging through their guano I have never become sick (PN).

A colony of Egyptian fruit bats (Rousettus aegyptiacus) from Nzerekore, Guinea, where many people have recently died of Ebola. This species has also been suspected of being the virus’ carrier but so far no live Ebola virus has been isolated from any species of African bats.

All of this adds to bats’ undeservedly bad reputation. Their mystical association with vampires, nocturnal habits, their seemingly erratic flight pattern, a slew of spooky superstitions, and now a misperception that bats are unusually disease-ridden have earned them a less-than-exalted place in the human consciousness. In some cases, this negative image arouses persecution. In 2007, hysteria stemming from a Marburg virus outbreak in Uganda led to mass extermination of Egyptian fruit bats, leaving heaps of them piled on the floor of the forest. This wasn’t an unprecedented reaction – people have been slaughtering vampire bats in Peru since the 1960s in an effort to control rabies, and a few years ago, the four human deaths from Hendra virus in Australia led to widespread culling of flying foxes.

Wahlberg’s epauletted fruit bat (Epomophorus wahlbergi) from Gorongosa National Park in Mozambique

Wahlberg’s epauletted fruit bat (Epomophorus wahlbergi) from Gorongosa National Park in Mozambique

But does reducing bat populations actually help reduce the risk of bat-borne diseases jumping to humans? Surprisingly, the answer is: probably not. In fact, there’s evidence that it could make things worse. In Uganda, the fruit bat extermination led to a much larger outbreak of Marburg, which is closely related to Ebola, among humans. As it turned out, fruit bats recolonized the caves from which they’d been exterminated, and the new population had a much higher prevalence of Marburg infection than the exterminated one. We’re seeing a similar effect in the Peruvian vampire bats – rabies prevalence is higher in populations that are subjected to culling by a poison called “vampiricide”, which preferentially kills adult bats. That’s probably because killing adults removes individuals that have already been exposed to the disease, making them immune. That allows “susceptible” juveniles, with no immunity, to proliferate, and the infection spreads like wildfire.

Fruit bats like bananas – even when they are being measured, photographed, or otherwise molested by a researcher.

It’s not clear whether bats really are different from other animals that could potentially carry diseases, or whether we’re just paying more attention to them now; there’s currently a debate raging among scientists about whether bats are special as disease reservoirs. Some say yes. This may be because many bat species are very social, which would allow pathogens to spread easily. Or, it could be that bats have a long evolutionary relationship with some virus families. Some scientists hypothesize that it’s linked to bat physiology: an unusual immune system, or the remarkably high body temperatures that bats experience during flight, could play a role in their ability to survive infections and, in the end, become reservoirs of pathogens.

Others argue that the numbers just don’t add up and that bats aren’t any more disease-ridden than other mammal groups. Given that bat research is on the increase it could be the simple result of a twisted treasure hunt: the harder we look, the more we find.

What we do know is that bats are special in a lot of other ways, and they deserve a boost in popular image. They’re the only mammals that have evolved true flight. They’re also one of the few groups, along with some whales, shrews, and birds that use echolocation – the ability to “see” a landscape using reflected sound waves. The combination of flight and echolocation allows them to fill a special role as nocturnal predators of aerial insects, with the potential to suppress insects like mosquitoes or some agricultural pests that aren’t active during the day. That does us humans an important service, and scientists have estimated that bats save U.S. agriculture $53 billion dollars in pest control every year. The high diversity of bats – they’re the second most diverse mammal group after rodents – allows them to fill a number of other important roles in ecosystems, such as dispersing the seeds of rainforest trees or pollinating flowers, including the agave used to make tequila.

We don’t yet know as much about bats and their diseases as we should, but the little evidence we do have suggests that killing bats will actually worsen the problem. It also suggests that the same things that are driving some bats toward extinction are also driving spillover events. Deforestation, for example, forces bats to find new homes in cities and increases the probability of their contact with humans. And eating bats gives their pathogens even easier access to people. We can reduce those risks if we protect bat habitats, halt culling efforts, and convince people to stop hunting and eating bats. None of these are trivial endeavors, but we need to try. In the time of Ebola, bat conservation is more important than ever.

Peters's epauletted fruit bat (Epomophorus crypturus) from Gorongosa National Park

Peters’s epauletted fruit bat (Epomophorus crypturus) from Gorongosa National Park