Awesome bee flies

Bee flies, Bombylius major have emerged in the warm weather and I have come across them in several places. Bee flies are early spring fliers, the peak of adult activity is in April and May. They are found throughout the UK, where this species seems to be expanding north. Thee are some cool facts about them.

A male at rest.

Parasitism. Bee flies are parasitoids of several species of ground-nesting solitary bees, including Andrena mining bees. Their larvae crawl into the bees' nests and feed on larvae of the host bee once it is fully developed. Only large populations of mining bees are able to sustain a parasitoid population, so the presence of the bee fly is an indicator of healthy mining bee populations.

Female loading her sand-brush

Egg shooting. Bee flies collect sand or dust at the tip of their abdomens (which looks a bit like a brush) to coat their eggs before laying, as the one above is doing. Why? It is unclear if it is to camouflage them or to make them heavier. Females lay eggs in a curious way. Instead of just getting into the bee nest to lay, they fly low over bee aggregations, and throw their eggs against dark spots resembling nest entrances, including shadows swinging their bodies against it. Bee flies can afford some inaccuracy when egg laying though, as females can lay thousands of eggs per day. Their unusual egg laying behaviour might have something to do with the fact that they are soft-bodied insects, and could be too susceptible to the bee's sting to actually risk a one-to-one confrontation with the female bee. This is how they do it, note the sand-brush at the tip of the abdomen:


Mimicry. As their name strongly suggests, Bee flies are flies that look like bees, that is they are bee mimics like many hoverflies: they are similar in size to a honeybee, brown-tawny and as furry, with quite long hairs, as a bumblebee. It is unclear though if they mimic bees to get close to their nests unnoticed or to avoid predation from insect eating birds or other predators. Other mining bee parasites do not resemble bees at all (I'm thinking the wasp-like Nomada bees) and actually get inside nests to lay eggs.
Look into their eyes. You can tell male and female bee flies in the same way that hoverflies: males eyes are larger and actually meet a the top of the head, while in females they are smaller and separated by a hairy patch. This suggests that males use the sense of vision to look for females. Males actually hover in particular spots some times high up, near flowers, possibly to meet females.

 

male

female

Male feeding on Lungwort showing the fully extended tongue

Look at that tongue! One of the most impressive features of bee flies are their proboscis. These spear-like, non-retractable structure at the front of their head looks positively dangerous (like a giant mosquito!), however, it is harmless, its only purpose is to allow the fly to reach and suck nectar from flowers with deep, narrow corollas. Their mouth parts can be extended further as they feed to as long as their total body length.

A male feeding on grape hyacinth on Monday

Fantastic fliers. Bee flies are very fast and agile fliers, they hover a lot and can fly in any direction, including backwards. They don't settle to feed on flowers like hoverflies, instead, they behave more like a Hairy footed flower bee, or a Hummingbird Hawkmoth: their wings never stop moving when they feed from flowers, they are actually virtually invisible. They use their spindly legs to stabilise themselves in front of the flower. Males will hover at height, as many hoverflies do, and spin when they meet females.

Bee fly feeding on primroses on Monday

Pollinators. Bee flies feed on early spring flowers: Primroses, Grape-hyacinths, Forget-me-Nots, Violets, Lung-wort, Lesser Celandines and Wood Anemones. They will also feed on Blackthorn and sallows. Bee flies not only feed on nectar, they also consume pollen, with females feeding on pollen to a larger extent than males. They can be effective pollinators of these early plants.

A basking Bee fly yesterday.

Basking. Bee flies are active in warm, sunny days, and they like to bask to thermoregulate, sitting still, with their wings kept open at an angle. Then, you can try and identify the species as the wing patterns - hard to see in flight - can be diagnostic. The most common species, the large bee fly, Bombylius major, has a distinctive dark edge at the front of their wings.

More information
An identification sheet of British Species by the BRC. Click here.

Natural History Museum page. Click here.

Boesi, Roberto, Carlo Polidori, and Francesco Andrietti. "Searching for the right target: oviposition and feeding behavior in Bombylius bee flies (Diptera: Bombyliidae)." Zoological Studies 48.2 (2009): 141-150.

Jacquemyn, Hans, et al. "Biological flora of the British isles: Primula vulgaris Huds.(P. acaulis (L.) Hill)." Journal of ecology 97.4 (2009): 812-833.

A scarily beautiful ichneumon

This is the largest and most spectacular ichneumon I see in my garden, Pimpla sp. They are parasitoids of moth caterpillars. The females walk jerkily over the vegetation, constantly tapping the surface of leaves with their twitchy antennae searching for caterpillars. Once they find a suitable host, they use their dagger-like ovipositor to hypodermically inject the caterpillar with an egg, which will develop into the wasp larvae. The larvae feeds on the caterpillar's organs and kills it before emerging like an adult wasp. There are over a thousand ichneumon species in the UK, and they are often difficult to determine without microscopic examination. They are also quite tricky to photograph due to their nervous disposition, so I cooled this one in the fridge for 20 minutes before photographing, and it only took a couple of minutes to fly away!

A bee fly in the garden

I have always wanted to see a Bee Fly (Bombylius major). Yesterday I had a glimpse of one in the garden, but being unable to get a photo I later thought that I had mistaken a bee for one of them. Today, early in the morning, probably the same one came to bask on the wall, flying amongst two Anthophora plumipes males, and I had my camera with me. The bright white background wasn't ideal, but I was happy enough to get a few shots. Bee flies are bee mimics, with furry brown bodies of about 12 mm long and their proboscis is almost as long as their bodies and they carry it sticking out forward while they fly or at rest. They are very good flyers and feed while hovering. Males and females feed on nectar, but females also need to feed on pollen to produce eggs. Their long proboscis, which is also adapted for sucking and it is quite movable, allows them to exploit flowers with deep corolla tubes, such as primroses, Aquileguia, lungwort, grape hyacinths and wallflowers, and they are important pollinators of them. I wonder if the abundance of these flowers in my garden, which I grow to attract A. plumipes, has been a factor in attracting the Bee Fly to the garden.
 Bee Fly larva are ectoparasites of ground-nesting bees, (the genus Andrena, Halictus, Lasioglossum and Colletes have been reported). Bee Fly females lay their eggs dropping them in or nearby the tunnels of bees, even on flowers if the female can't find suitable nests. When the larvae hatch they either find the nest and go into an open cell, or latch themselves to a passing bee when they hatch on flowers.

The Bee Fly about to land

A bumper year for 7 spot parasites?

In the last few days I have found quite a few 7 spot ladybirds parasitized by the wasp Dinocampus coccinellae in the garden: live ladybirds snared to a silky cocoon underneath them. Today I did a quick count and found eight. You can see their portraits on this post. This is being a successful year for 7 spots: there are so many around it is hard not to get one or two ladybirds in the background of any bug photo I take! It is no surprise that ladybird parasites are enjoying this ladybird bonanza. If you want to find out more about the rather gruesome Dinocampus life cycle click here.

One on sage

on the conservatory frame

a second one on the spurge

one under a Lamb's Ears leaf

An odd one, with the cocoon on one side on a bougainvillea leaf in the conservatory

one on an orchid in the conservatory

a second one on sage

The maladapted parasite

There is a corner in my local park which is always teeming with Harlequins. At this time of the year adults ready to hibernate and grown larvae about to pupate dot the railings and fenceposts. A couple of days ago I came across this individual dragging a strange large lump behind as it sluggishly walked on top of a railing. I took a photo and wondered if it was a parasite. Parasites in Harlequins are very interesting, as, this ladybird being an invasite species, they might be adapting to the newcomer and helping keeping this species in check. Richard Comont, from the Centre for Ecology and Hydrology in Wallingford, after checking the photo commented:

It looks like a Dinocampus which has got caught up in the ladybird's wings - I think you can just about see some segmentation at the bottom of the yellow lump. Dinocampus seem to be a bit disorientated in Harlequins - they seem less able to fully paralyse the adults on the way out - so possibly might sometimes emerge from the top of the abdomen, from between the tergites rather than the sternites, which could result in the emerging larva ending up in the wing like this.
Dinocampus, on emerging, usually parasitise their host ladybird, cutting the nerves connecting the legs to the nervous system, and potentially also the tendons of the leg abductor muscles which allow the ladybird to move its legs away from its body (so that when the parasitoid's cocoon is spun between the ladybird's legs it can only be clutched tighter). However, Harlequins with Dinocampus are often not fully paralysed, and instead stumble around slowly, almost drunkenly.

It appears that some native ladybird parasites are also attempting to parasitize the newcomer invasive Harlequin, which is encouraging. Evolutionary success for parasites in expanding their host range to include Harlequins however, will only come if the parasite is successful completing its life cycle in the new host. The offspring of the parasite must actually be able to become a successfully reproducing individual in the new host, and the disorientation of the Dinocampus in Harlequins, which could often result in their larvae being unable to spin its cocoon under the host - which is walking around dragging it - suggests that their success in surviving and actually becoming an adult parasite might still be far lower than in the native ladybirds. They still might have some way to go.

I am most grateful to Richard Comont for allowing me to reproduce his comments in this post and to Lori Lawson Handley for kindly forwarding my photo to some knowledgeable ladybird experts.

UPDATE
From an e-mail from Richard Comont (15/11/11):

I’ve found a couple of these ‘parasitised’ Harlequins today – and the ‘parasite’ was just a pool of reflex blood, which the wing had folded around into a kind of bag – no evidence of parasitism at all!

That's science for you!

The little Brown Argus complex tale of range expansion

Climate change is making a measurable impact on the distribution of many organisms. The populations of some species are disapearing or becoming more fragmented, increasing extinction risk, others are actually expanding their range north with the increasing temperatures. Insects - and particularly butterflies - are very sensitive to changes in climate, and amongst the winners of climate change is a lovely, tiny butterfly, the Brown Argus, Aricia agestis. In the last few days, I have spotted this butterfly in two new locations in East Yorkshire, including my local wildlife garden, where it is unlikely I would have overlooked it, indicating recent colonisation.

Distribution of Brown Argus (Aricia agestis) in Britain. Black circles show that the species was present in 1970–1982; open circles show newly colonised areas (1995–1999 records, not present in 1970–1982). Circles represent 10 km grid cells (from Menéndez et al 2008)

This species has increased markedly in range in the U.K in the last 30 years, expanding around 10 km per year since the early 1990s, reverting a previously declining trend. This could be seen as a direct response to climate change. But the story is not that simple, the positive response to temperature has been facilitated by changes in the interactions of this butterfly with other organisms. Before the expansion, the predominant caterpillar foodplant of the Brown Argus was the Common Rock Rose, Helianthemum nummularium, a plant that grows on sheltered, south facing, sunny hillsides in chalk and limestone grasslands. Some southern populations used several species from the geranium family, especially Geranium and Erodium. These plants grow on lowland, in cooler habitats than the Rock Rose, so only after temperature increased were these populations able to colonise and exploit these areas. Chris Thomas and collaborators established that expanding populations had a preference to lay their eggs on the more available geraniums, even when they came from populations in hills using Rock Roses. This diet/habitat shift allowed the butterfly to recolonise distant Rock Rose areas, using lowland geranium habitat as stepping stones, which single dispersing butterflies would have been unlikely to reach. A niche model - based on preferred temperature and established food plant - of the predicted range expansion would have grossly underestimated the recent expansion of this butterfly.
 A further complexity stems from an "enemy release" effect. Invasive populations - often translocated by man from distant areas - are hypothesized to expand unchecked as they have left behind their natural enemies: specialist predators, parasites or parasitoids might be absent, and generalist ones might not have the right "search image" for them. Rosa Menéndez and her collaborators tested if this applied to an expanding native population, where the distance travelled from the nearest population is smaller, and there are related species whose parasites might also infect them. They used the Brown Argus and its parasitoids as models. The Brown Argus shares its range with a very common and related species, the Common Blue, Polyommatus icarus, and four parasitoids use both species as host, therefore there is potential for the parasitoids to use the expanding butterfly. They compared the rates of parasitism of old established populations and newly colonised populations. Although both were parasitised by a similar number of parasitoid species (old, six parasite species, new, five), the new Brown Argus populations had an overall lower parasitism rate than the established ones.

         Population

Observed parasitism (%) of Aricia agestis caterpillars (i.e. sum of parasitism by 

all parasitoid species) during the first generation in 2004 populations that differ in the 

position within the butterfly range (established vs. new parts of the range). Values are mean + SE and numbers within bars show sample sizes (numbers of caterpillars collected) (from Menéndez et al 2008)

The northward expansion of the Brown Argus is therefore not a direct response to temperature, but the result of a complex interaction including both a diet shift and a partial release of their parasites. This complexity of the biological interactions of each species makes it even more challenging to predict the responses of species to climate change.

References
MENÉNDEZ, R., GONZÁLEZ-MEGÍAS, A., LEWIS, O., SHAW, M., & THOMAS, C. (2008). Escape from natural enemies during climate-driven range expansion: a case study Ecological Entomology, 33 (3), 413-421 DOI: 10.1111/j.1365-2311.2008.00985.x
Thomas CD, Bodsworth EJ, Wilson RJ, Simmons AD, Davies ZG, Musche M, & Conradt L (2001). Ecological and evolutionary processes at expanding range margins. Nature, 411 (6837), 577-81 PMID: 11385570

Parasitic wasps turn ladybirds into their bodyguards

I have covered the ladybird parasitoid Dinocampus coccinellae before. Some recent research, however, has uncovered some fascinating aspects of this little wasp's manipulation of its host behaviour. The parasitoid wasp, below, injects a single egg on a ladybird using its ovipositor (visible in the top photo of a just emerged D. coccinellae).

After hatching, the larva feeds on its host internal organs, and after about 20 days, she emerges from the ventral plates of the ladybird to pupate. She spins a cocoon that tethers the ladybird to the substrate (top photo) and pupates inside. Unlike many parasitoids, Dinocampus does not kill its host. But the ladybird cannot escape, not only she is tethered, in addition, before emerging from the ladybird's body, the larva is thought to produced some chemicals that affect the ladybird's brain and compels it to sit still, and to twitch when disturbed. The parasitized ladybird colours and twitching were through to afford the parasitoid some protection from predators while in the cocoon. Fanny Maure and her collaborators provided the much needed evidence for this hypothesis in some laboratory experiments. They infected ladybirds - Coleomegilla maculata, a Canadian species - with Dinocampus coccinellae, and once the cocoons were spun under the ladybirds, they split the coccoons into three groups. In the first group of cocoons, they removed the ladybird, in the second, they killed the ladybird and in the third they left the ladybird untouched in the usual position on top of the cocoon. Then they exposed their cocoons to a predator, third instar green lacewing larvae Chrysoperla carnea and counted how many cocoons were predated in each group.

Percentage of Dinocampus coccinellae cocoons eaten by larval green lacewing, Chrysoperla carnea, when parasitoid cocoons were exposed alone, covered by a dead ladybird (Coleomegilla maculata), or attended by a living ladybird. Probabilities were obtained using the Fisher exact test, ***p , 0.0001. Numbers refer to sample sizes (from Maure et al 2011).

Parasitoid cocoons alone or sheltered with a dead ladybird suffered significantly more predation by lacewing larvae that did those protected by living ladybirds, supporting the hypothesis that the parasitoids manipulate the ladybird's behaviour to their own advantage, effectively converting them into their own bodyguards. The ladybird protective colours made little difference, although these are thought to protect against bird, not insect, predators.

  Presumably, there must be a cost to the larvae to manipulate the ladybird. She must left the ladybird alive and produce chemicals to make it into her bodyguard. Maure and coworkers also tested this, by measuring the relationship between the ladybird lifespan once the parasite emerged and the survival and fecundity of the parasite. Their results show a significant negative correlation between the ladybird lifespan - 25% survived the parasitoid emergence - and the number of mature eggs the parasitoids had in their bodies after emergence as adults. This suggest that indeed there is a cost to making your host into a bodyguard. Overall, though, it must compensate the parasite to shield itself with the live ladybird in terms of predator avoidance.

Reference

Maure F, Brodeur J, Ponlet N, Doyon J, Firlej A, Elguero E, & Thomas F (2011). The cost of a bodyguard. Biology letters PMID: 21697162

Invasive Harlequin parasites

Every day on the way back from work I walk next to this wall. The other day there were plenty of cannibal Harlequin ladybird larvae eating prepupae. Today there were many more pupae and a few prepupae. I have no idea how I noticed this tiny fly on the head of a prepupa. The ladybird pupa shook its body back and forth to no avail. Later I identified the fly as a scuttle fly, genus Phalacrotophora. Some species of this genus are endoparasites of ladybird pupae. The fly mounts guard on a prepupa and when it pupates it lays some eggs underneath. The fly larvae on hatching parasitise the ladybird and when fully developed they emerge and pupate on the ground. A common hypothesis on the rapid spread of invasive species is the "enemy release" hypothesis. This states that the invaders in the new range lack specific enemies - pathogens, parasites or predators and that this allowes uncheckered population growth. The success of the harlequin ladybird has been hypothesized to depend at least in part on escape from natural enemies. Recent studies indicate that generalist ladybird parasites might be starting to attack this ladybird in the invaded range and this includes pathogenic fungi, and endoparasitic nematode worms, wasps (Dinocampus coccinellae and Oomyzus scaposus) and flies. Prevalence can be quite high, with up to 33% of specimens in Danish samples infected with nematodes, but, on the other hand, lower fitness from the parasitoid Dinocampus reared from Harlequins, suggest than some of these enemies have yet to adapt to this invasive ladybird. If you live in the U.K. there is a survey you can take part into, by collecting ladybird pupae and rearing them, and then reporting what comes out of them (see the Ladybird Parasite Survey website).

References
Koyama, S., & Majerus, M. (2007). Interactions between the parasitoid wasp Dinocampus coccinellae and two species of coccinellid from Japan and Britain BioControl, 53 (1), 253-264 DOI: 10.1007/s10526-007-9138-5
Kenis, M., Roy, H., Zindel, R., & Majerus, M. (2007). Current and potential management strategies against Harmonia axyridis BioControl, 53 (1), 235-252 DOI: 10.1007/s10526-007-9136-7
Durska, E., Ceryngier, P., & Disney, H.L. (2003). Phalacrotophora beuki (Diptera: Phoridae), a parasitoid of ladybird pupae (Coleooptera: Coccinellidae) European Journal of Entomology, 100, 627-630 Other: 1210-5759

Cuckoo bumblebee chemical weapons

This time of the year there is an abundance of cuckoo bumblebees. These bumblebees form a group of closely related species, the subgenus Psithyrus, each specialising on one or a few nesting bumblebee species. For example, Bombus vestalis, above, specialises on the common Bombus terrestis, the buff-tailed bumblebee. Cuckoo bumblebees are social parasites. They lack a worker caste and instead rely of workers of their host species for the rearing the next generation of males and female cuckoos. Fertilised female cuckoo bumblebees emerge from hibernation a little later than the host, usually when their host queens have already stated a nest and already have a few workers. Some species 'infiltrate' the hosts nest passively, with little aggression involved. They simply remain peripheral to the combs, initially thought to get the workers used to their smell, and little by little the workers and queen accept them. Then they start participating on the colony workings by grooming larvae or incubating cocoons. At the same time, however, they lay their own eggs, and eat eggs and larvae of the host species, until only their own males and females are reared instead of host worker. The cuckoo female often engages in 'head-rubbing' with the workers in the nest, a behaviour thought to involve some transfer of chemicals between cuckoo and host. Often host queens and males are produced together with the cuckoo's offspring. In other cases there is quite a lot of aggression from the workers to the cuckoo and the other way round. More peaceful nests produce a higher number of cuckoo bumblebees.

Cuckoo bumblebee Bombus rupestris

Queen Bombus lapidarius, its host.

Cuckoo bumblebees have often similar colour patterns to their hosts, and this type of mimicry could help them enter a nest. As an example, see above the cuckoo Bombus rupestris and its host Bombus lapidarius. But, given the high levels of aggression involved when conspecific worker intruders try and enter a nest, how do cuckoo females manage to be accepted into the hosts nest? They have another, more recently discovered form of mimicry: chemical weapons. Research by Stephen Martin and collaborators investigated the  surface chemicals of 14 bumblebee species, including 5 cuckoos, from the U.K. and Sweden.

They found out a striking pattern: several of the cuckoo bumblebees match strikingly their hosts chemical profile, in particular the alkene isoforms, which are species specific. A few species differ from this pattern. These species are probably being involved in a host switch, and instead of mimicking their hosts chemical bouquet, they produce a worker repellent chemical. Workers then will avoid, and therefore won't attack the cuckoo female when she enters the nest. This is the case of B. sylvestris, whose normal hosts, B. jonellus and B. monticola, are quite rare in the U.K. and more commonly attacks the common B. pratorum.
All bumblebee photos taken today.
More information
Küpper, G. & Schwammberger, K. (1995). Social parasitism in bumble bees (Hymenoptera, Apidae): observations of Psithyrus sylvestris in Bombus pratorum nests Apidologie, 26 (3), 245-254 DOI: 10.1051/apido:19950306
Martin, S., Carruthers, J., Williams, P. & Drijfhout, F. (2010). Host Specific Social Parasites (Psithyrus) Indicate Chemical Recognition System in Bumblebees Journal of Chemical Ecology, 36 (8), 855-863 DOI: 10.1007/s10886-010-9805-3

Greenflies clouds and networks

There were raining greenflies today, whole clouds of them causing a visible effect on people, talking about them, swatting them and taking them from their clothes, glasses and skin (above). The warm weather has encouraged the winged forms of aphids (greenflies) to take to the air and search for new feeding plants. Aphids are a central part complex ecological networks. For example, a study by Muller and coworkers in an abandoned field in the south of England found:

Twenty-six species of plants were attacked by 25 species of aphid which were parasitized by 18 species of primary parasitoids. The primary parasitoids were attacked by 28 species of secondary parasitoids, of which 18 directly attacked the still living aphid (hyperparasitoids) and 10 attacked the aphid after mummification (mummy parasitoids). The aphids were attended by three species of ants.

Only the bean aphid (Aphis favae) is parasitized (or superparasitized) by no less than 12 species of small wasps which lay single eggs inside individual aphids. Some of the wasps, the secondary parasitoids, lay eggs in parasitized aphids. Then the sweet sap produced by aphids is enjoyed by ants, butterflies and bumblebees. Aphids are eaten by lacewings, ladybirds, hoverflies and small spiders; and swifts and swallows who pick them in the air plankton. You could say that the presence of aphids generates a lot of added biodiversity.

This figure taken from the study mentioned earlier summarised the parasitoid network over two years of monthly study. The middle bar represents the different aphid species (each is a number and the length of each section represents the abundance of each species. The bottom bar are the primary parasitoids and the top bar the secondary parasitoids. The conecting lines represent the strength of the interaction between a particular pair of species.
Back at the garden, on the roses newly growing shoot, covered on rose aphids (Macrosiphum rosae) this was beautifully illustrated.

A 7 spot happily munching a rose aphid 

A hoverfly larvae crawling around also eating them. This one seems to be showing off!

A weeks old garden spider has caught a winged one.

A parasitic wasp lurking about in the rose bush. I cannot say it is an aphid parasitoid for sure, but keep surveying the rose leaves, leaving and coming back to another leaf.

There are lots of fascinating things about aphids and they surely will come back to these pages in the future.

More information

Muller, C., Adriaanse, I., Belshaw, R., & Godfray, H. (1999). The structure of an aphid-parasitoid community. Journal of Animal Ecology, 68 (2), 346-370 DOI: 10.1046/j.1365-2656.1999.00288.x

An unwelcome bug

I usually enjoy having the chance to write BugBlog posts. Not today. As a parent of school age children, I have had occasionally to deal with lice infestations. One of these was apparent on one of my children during the holidays. A combnitting session today yielded shocking results. Tens of nits (eggs) and a fat adult louse. I couldn't resist the photo opportunity. This is the first adult lice I have seen. In previously infestations I could only see nits. I hope this is the only adult louse and that we can clear it quickly.

The louse clinging to hair. Its dark stomach indicates a recent feed of blood

Anyway, despite my dread of live lice, they are fascinating creatures on their own right. Lice are apterous bloodsucking insects (order Phthiraptera) that are adapted to clinging to hair - hence, they are found only in mammals. They lay their eggs gluing them in a shaft to individual hairs, close to the scalp. The newborn lice are nymphs, they are smaller and simpler than adults and metamorphose slowly into adults in three stages. Individuals live for a month or so and females can lay several hundreds of eggs in their lifetime. The study of such species-specific ectoparasites can provide information on the evolution of their hosts. Humans are the host of two species of lice (wingless insects of the order Anoplura), the pubic louse and the hair/body lice complex. In the past hair and body lice were thought to belong to different species, one adapted to lay their eggs on hair, the other on clothing. It was thought that body lice had evolved with the invention of clothing into a separate species. Molecular analysis have revealed, though that the body louse has evolved several times and that they do not form a monophyletic unit separate from head lice. These studies have revealed more intriguingly that there are three old genetic lineages of lice (only one of them includes body lice) and the authors hypothesized that one of such lineages might have evolved in Homo erectus, and been transferred to modern humans when they met. A fascinating hypothesis that has proven to be difficult to test due to the lack of good calibrations for lice DNA.

A terrifying ladybird tale (part II)

I had completely forgotten I had put the parasitised ladybird (see previous post) on a plastic container to see if the parasite wasp emerged and to be able to take some photos. I checked regularly the first few days and nothing happened. Today, sixteen days later, I came across the container and there was a tiny wasp, flying about! The ladybird was still alive and it could now move its front and middle legs. I managed some shots of the pair together.

The wasp returned to the ladybird again and again, inspecting it with its antennae. I released the wasp in the garden and it settled nearby so I could take one final shot before it flew away.

A terrifying ladybird tale: Dinocampus coccinellae parasitism

It seems like a good year for 7 spot ladybirds. There are many more these days than Harlequins around here. Some ladybirds I see are parasitized. I dug on the web today after taking a few photos of one and noticing the ladybird was actually alive, moving its head and palps, but unable to walk. The indication that it was parasitized was the presence of a silk cocoon underneath it to which it seemed to be tethered. The parasite is a tiny braconid wasp, Dinocampus coccinellae apparently a parthenogenetic species. Shortly after emergence, the wasp lays eggs inside larvae, pupae and adult ladybirds. The larvae hatching from this egg starts by eating the reproductive organs and eggs inside the ladybird, causing little external damage, then it develops a trophic organ that absorbs nutrients from the ladybird. The cycle becomes even more gruesome from now on. When the larvae is ready to pupate it severs the ladybird's leg nerves, by which it becomes paralyzed partially paralises the ladybird through some chemicals. The larvae then emerges from the ladybird through a hole she bores and spins a cocoon between the ladybird's body and the substrate (leaf, twig, etc). The ladybird is alive but paralysed and the parasite pupae enjoys the protection of the ladybird aposematic colors until its emergence a week or so later through the pointy end of the cocoon. Although some ladybirds recover from the parasitism, most presumably die, and it is not known if the survivors will be able to feed and reproduce after this ordeal!
More info and photos here. To be continued here.