Entomology, hot and dry

A couple of weeks ago, I had the privilege of travelling to Malawi to assist with setting up some new activities on our ongoing Darwin Initiative and McKnight projects in Eastern and Southern Africa. Previous activities on the project had taken place in northern Tanzania, around the slopes of Mt Kilimanjaro, which is climatically quite an interesting place – the altitude means the evenings are pleasantly cool (bring a sweater!) and the higher elevation farms are really quite wet! Many of the fields were small, and edged on all sides by trees or other vegetation, with a fair few uncultivated margins and other patches of unused land all around. As a result, even between cropping cycles there was a huge amount going on in and around fields in terms of the biodiversity.


Milkweed locusts are particularly striking. I asked if these were ever eaten (they are so enormous and numerous, it seemed like a pretty impressive protein resource going on), but apparently they have a foul smell/flavour and a greasy consistency, so people prefer the smaller grasshoppers, crickets and katydids for eating.


(Incidentally, this one seemed to have some sort of parasitoid or entomopathogen – we saw a lot like this, the abdomen shrivelled, the legs clinging tightly to vegetation).

Also impressive in Tanzania was the diversity of pollinators – Xylocopa carpenter bees were extremely common and always spectacular, but we also came across cuckoo bees, little Amegilla, and a variety of tiny solitary and stingless bees. The project aims to evaluate how margin management can increase the abundance and diversity of pollinators further, so we’ve been gathering data about them and how they interact with wild plants as well as the crop.

Malawi is quite different. Around Lilongwe, the annual rainfall is really concentrated into a space of just a couple of months. When we visited, right at the end of the dry season, it meant that there had been next to no rain for about 9 months. It was relatively hot (exacerbated by the lack of shade), very dry and very windy – so also very dusty.The agriculture is different too, and brings new challenges. Farmers have to contend with the windiest part of the year also being the driest part – and the point in the cropping cycle when the fields are bare. Soil fertility suffers. Many of the fields have no margin at all – it’s literally crop after crop running right from the road at one side to a footpath at the other side, with fields demarcated from their neighbours by (if you’re lucky) a single tree or path.



Some of the sites do have nearby semi-natural areas, so we’re focusing on characterising the benefits derived from this in terms of pollinators and natural enemies. At this time of year, there weren’t a lot of either, but a few male Amegilla seemed to be patrolling a patch of Combretum we found, and of course there are always ladybirds to be found.



Some of the most fascinating areas were the graveyard sites. Because of the cultural importance, these patches of forest were left relatively pristine and untouched compared to any other woodland (which tended to be used for firewood and non-timber products) and so the plant and insect diversity in and around them could be extremely high compared to almost anywhere else in the landscape.

Forays into Spring

This has been the first convincingly springlike day in the UK on which I’ve had chance to get outside and see what’s happening in the local woodlands and grasslands.

And what a fun little walk it was.

The highlight for me was discovering a rather fantastic multi-species aggregation of ladybirds in a local woodland nature reserve.

There appear to be individuals of 6 species in the little cluster: 7-spot ladybird (Coccinella 7-punctata), Harlequin (Harmonia axyridis), Pine (Exochomus 4-pustulatus), 2-spot (Adalia bipunctata), Orange (Halyzia sedecimguttata) and 14-spot (Propylea quatuordecimpunctata). The pine ladybirds and 7-spots were already waking up – indeed, the pine ladybirds already seemed to be making progress creating the next generation. The others, I assume, will follow soon after. I suppose the photo is also an example of the size variation even in the common UK ladybird species, from the big harlequins and 7-spots to the smaller species like the 2-spot. Sadly none of the smaller, more easily overlooked microladybirds today!

I’ve personally never seen a multi-species aggregation like this before, although the books we have show many fantastic pictures of single species hibernating en masse, and I’ve heard that ladybirds do do this fairly frequently. I suppose it makes sense – if the conditions are favourable in a crack or hole so one ladybird chooses to hibernate there, it would follow logically that other individuals might make judge the conditions to be favourable for them too. Of course, this is a perennial problem that turns up in laboratory experiments when multiple individuals are being tested – trying to decide whether finding 20 beetles in that part of the arena or that arm of the apparatus means all of them find that odour/colour attractive, or whether a single individual liked the odour and the rest just prefer to cluster with other individuals. It’s why I personally prefer to work with single individuals as far as possible, but in some applied contexts it’s important to bear in mind that conspecific and, indeed, interspecific interactions are very important in determining insect behaviour.

The other major sightings of the day were the early spring bees – the charming solitary bee Anthophora plumipes, the Hairy-footed Flower Bee – we found one female in a daffodil that had sadly taken some damage to her proboscis, but it shows just how long it is on this species, hence why they use long-corolla flowers like comfrey and pulmonaria (and also Cerinthe when it’s available). And 4 species of bumblebee, the ones one might expect in late March: Bombus terrestris, B. lucorum, B. pratorum (including a rather tatty one on a fencepost) and B. hypnorum.

Antho damaged

B pratorum damaged

Edit: I’ve since read that multi-species aggregations in ladybirds are not necessarily a hibernation thing at this time of year – i.e. it’s unlikely those ladybirds hibernated like that – but that they do tend to cluster up as the weather begins to improve, prior to dispersing properly up into more preferable feeding habitats.

The things that made us ecologists

Ecologists can be a diverse bunch, from a variety of backgrounds. Some of them were indeed involved in conservation clubs from school age onwards, or keen gardeners at the age of five, or collecting snails in boxes under their bed. Others manifested their interest later, or in different ways. Some discovered an interest much later in their life.

I always liked playing in the garden. I always found living things interesting. As a child growing up in Sheffield we were lucky enough to live close to Ecclesall Woods, a gorgeous ancient woodland, and so I have many fond memories of trampling around there in search of the Woodcutter’s Grave (well, strictly speaking, charcoal burner’s grave), and one particularly memorable guided fungus walk in which I learned that sulphur tufts look pretty but do not taste very nice.

But I’ve come to recognise later that I was also very lucky in the choice of books floating around the house when I was small, and I’ve recently tracked down a few of my childhood favourites. As Simon Leather recently highlighted on his blog, well-written children’s books on biological and ecological topics can get the first sparks of interest lit in the minds of curious young people.

Flower Fairies of the Wayside by Cicely Mary Barker was first published 67 years ago now, so by some people’s standards is rather dated, but it has an enduring charm. The Flower Fairies series featured the poems of fairies associated with different British wildflowers, illustrated with beautiful butterfly-winged fairy paintings. I think poetry can be a really cunning way of sneaking facts into children’s brains – to this day, I remember some of the fairy poems fondly:

Why are we called “black”, sister
when we’ve yellow flowers?

I will show you why, brother:
See these seeds of ours?
Very soon each tiny seed
Will be turning black indeed!
The Black Medick Fairies

And so I learned that black medick was yellowed-flowered, but could be recognised by seeds that turned black as they ripened.

And of course, my favourite:

O, what a great big bee!
Has come to visit me!
He’s come to find my honey!
O, what a great big bee!

O, what a great big clover!
I’ll search it well, all over,
And gather all its honey.
O, what a great big clover!
The Red Clover Fairy

(Leaving out that a bee visiting clover is probably more likely to be female…though in the painting, I could be convinced that the bee depicted is a male B. terrestris…) Perhaps it’s not so surprising I ended up in pollination.

It’s not just the Flower Fairies, though. I also had a wonderful book called How to Hide a Butterfly, by Ruth Heller. It’s another book all in rhyme, this time about how invertebrates camouflage themselves. It featured diverse taxa, including moths, butterflies, praying mantids, stick insects, and hoverflies.

I forgot a lot of the rhymes, but the one that stuck in my head was something along the lines of:

“…the fly has just one pair of wings
While bees, you see, have two…”

…and a memorable snipped like that serves you amazingly well into adulthood. It’s not always easy to see the second set of wings in Hymenoptera, but if you can be certain there isn’t a second pair when looking at a chunky yellow-and-black insect, you know enough to look again before assuming it’s an unfamiliar bee species.

Perhaps more scientists should be encouraged to stretch their creative writing muscles and write appealing children’s books, to get the next generation informed and interested early!

Ivy bees. Or, it isn’t always about things dying.

A lot of conservation and ecology seems to consist of reminding people about all the things that are dying and how awful it is. And while this is really important to act on right now, sometimes it’s nice to reflect that it’s not all doom and gloom.

The ivy bee, Colletes hederae, is one of my favourite examples of an insect that is actually doing rather well. In fact, they’ve enjoyed an almost meteoric rise in the southern UK ecology. In 1990, they weren’t even a known species – C. hederae was only described as a new species distinct from the related C. halophilus (which prefers sea aster) and C. succinatus (which visits various things but especially heather) in 1993. More information about their key differences has appeared even more recently1.

They first appeared in the UK in 2001, a similar time to the harlequin ladybird (2004; a rather less welcome invasion) and the tree bumblebee (2001; seem to be fitting into the ecology fairly seamlessly so far), but seem to have really boomed in the last 5 years or so.

Bees cropIvy bee, with a honey bee (left) for comparison.

To me, they are a sign that autumn is here, but one of the more cheerful aspects of autumn. Their phenology is well-timed to coincide with the ivy flowering, and for a few weeks of frantic activity, they appear almost from nowhere. We have just come to the end of their annual period of activity; such is their local success in Medway that almost any flowering ivy around here seemed to have at least a few and possibly lots. Stand underneath a particularly large, well-visited plant and you found yourself in a gently-humming rain of knocked-off anthers and pollen. That said, apparently they don’t limit themselves exclusively to ivy, so if their timing is a little bit off you probably don’t need to worry too much: they’ve also been recorded using various yellow Asteraceae, clover, medick, goldenrod and autumn crocus3 – though we’re not sure how well the larvae do on non-ivy pollen.

Bee crop 2Bee crop 1

Around here in Kent, they seem to have some nesting preferences: they like to nest in well-drained banks, preferably south facing or at least sunny, with light soil and a decent bit of threadbare grass. Less manicured lawns, churchyards and some sloping road verges seem quite good. When they’ve found a place they like, the numbers can get quite enormous; we walked down a street for about 300m and almost every front garden was, in mid-September, “swarming” with them. The busy-ness is usually mostly the males patrolling the site for virgin females emerging, along with females trying to nest and avoid the harrassment, and frequent dramatic “mating balls” as multiple males pounce on a female and roll down the bank in a cluster. Apparently a species of blister beetle has “hijacked” this phenomenon – they release very similar pheromones and as a result, the poor, desperate ivy bee males attempt pseudocopulation with the young larvae of the beetle, Stenoria analis, resulting in the tiny beetle larvae getting stuck to the bees and carried off, so they can go on to become nest parasites of the ivy bees3.


They’re fascinating to watch, not least because they’re harmless – you can stand right next to one of these “swarming” banks without concern, with bees bouncing off your trousers, and just enjoy the spectacle. And as a figurehead for solitary bees, they certainly are photogenic, with their cute furry faces and striking markings.


I suppose they’re doing something nice for the wider ecology, too. While wasps and bumblebees are also ivy pollinators, this level of activity must surely increase ivy fruit-set, leading to more berries over winter, which I’m sure the birds appreciate. I don’t have any evidence, but perhaps our ivy bees are also doing our overwintering birds a favour?

While Britain may not enjoy spectacular mass phenomena like the Monarch butterfly migration, perhaps we should rebrand the impressive coming of the ivy bees as our symbol of early autumn.

BWARS have been tracking the spread of ivy bees for the last few years, so records from future years can be recorded here.


1Kuhlmann, M., Else, G. R., Dawson, A., & Quicke, D. L. (2007). Molecular, biogeographical and phenological evidence for the existence of three western European sibling species in the Colletes succinctus group (Hymenoptera: Apidae). Organisms Diversity & Evolution, 7(2), 155-165.
2Westrich, P. (2008). Flexibles Pollensammelverhalten der ansonsten streng oligolektischen Seidenbiene Colletes hederae Schmidt & Westrich (Hymenoptera: Apidae). Eucera, 1(2), 17-29.
3Vereecken, N. J., & Mahé, G. (2007). Larval aggregations of the blister beetle Stenoria analis (Schaum) (Coleoptera: Meloidae) sexually deceive patrolling males of their host, the solitary bee Colletes hederae Schmidt & Westrich (Hymenoptera: Colletidae). Annales de la Société entomologique de France 43(4), 493-496.

Of ladybirds great and small

Everyone likes ladybirds, right? Certainly they’ve been a flagship group for citizen science, and often appear in art and lifestyle products a (wellies, umbrellas, jewellery…). My info is out of date, but I am pretty sure that someone from iSpot told me that Harmonia axyridis, the harlequin ladybird, is the single most frequently posted species on iSpot. I guess it’s the way ladybirds obvious, colourful, and don’t bite/sting/fly in your face with long gangly legs.

They’re a good group for people trying to learn insect ID, at least in the UK. There are apparently 46 species in the UK, which is a manageable sort of number, and 26 of them are obviously ladybirds and big and conspicuous enough to start recording even for a relative beginner. There are lovely identification resources available from the Field Studies Council and the UK Ladybird Survey – including ID of larvae, which adds a new element of excitement to the process, as ladybird larvae are pretty cool creatures too.

But…if we have 46 species, and 26 of them are “obvious”, what of the other 20? Well, that’s a whole new adventure, and if you ask me, an even more exciting one. Many of these species are considered rare, scarce or notable in some way…but whether they’re really that uncommon, or whether they’re just under-recorded and often missed in standard surveys is a good question.

Of the “micro-ladybirds”, one of the cutest is the horseshoe or inconspicuous ladybird, Clitostethus arcuatus. Up close, it’s definitely a ladybird…after a fashion. But it’s a far cry from a familiar seven-spot! For one thing, it’s about 2mm long. For another, it’s brown. For another, it’s hairy. But otherwise…definitely a ladybird.

Clitostethus arcuatusScreen capture from a BBC South-East report featuring the little chaps.

The adults and larvae are hungry little predators, though for Clitostethus the prey of choice is not aphids but whitefly (especially larvae). It was thought to be extremely rare, but then Simon Springate found it near Dover…and then we went looking on ancient woodland and other habitats all around Kent and kept finding it again and again. It might not be in every ancient woodland we check (inland ones in Kent seem a bit too cool), but certainly there seems to be a checklist of features that make finding a few Clitostethus quite likely. I’ve seen it in the wild on honeysuckle (eating honeysuckle whitefly), on wild cabbage (eating cabbage whitefly), and by some amazing fluke, in my father’s back garden on Welsh poppy, which is another host for honeysuckle whitefly. In Kent it seems to be mostly likely to turn up on a good, old, established thicket of honeysuckle in a nice warm, sheltered bit of ancient woodland, ideally in mild climatic regions (such as Kent coastal areas), and the best time to look is September. In winter, it can sometimes be found on ivy in sheltered nooks and crannies. The larvae are relatively immobile and white – but you can get away with not moving too fast when your prey are 0.5mm long immobile whitefly larvae!

Clitostethus seems to be at the northern edge of its range in the UK, with the most northerly records from Yorkshire and the Manchester area. Mostly, it’s been seen in the south-east…but I suspect there’s a good chance we’d find it in the south-west too if we went looking. So is it rare, or just under-recorded? Is it just that its habits make it hard to pick up by conventional sampling methodologies?

One of my other favourite micro-ladybirds is Scymnus interruptus. It’s a tiny bit bigger and a bit more generalist in its habits than fussy Clitostethus, and once you get close enough to see it, it’s quite unmistakeable – two triangular red marks, one on either elytra. They’ll nibble at whitefly, aphids, whatever’s going.

Scymnus interruptus on Stachys
Scymnus interruptus on Stachys

Scymnus interruptus adults pootling around on Stachys

The larvae are absolutely amazing. They look like a 2mm long version of one of those fluffy telescopic dusters on a stick you can buy. And by goodnesss, they can move! We’ve affectionately nicknamed them “Zoom larvae” because, relative to their size and given they’ve hardly even got legs, they can certainly zoom! Unfortunately, all the Scymnus larvae are pretty much the same, so you need adults to ID really.

Almost all the records for S. interruptus in the UK so far are from the south-east. Our area seems to be a bit of a stronghold…which may be why we’ve got a little colony in the garden. At this time of year, if I wander outside in the evening after work, I’ve got a good chance of finding two or three without putting a lot of effort in (the other day I managed a new record of six at once). They seem particularly fond of the Stachys, for some reason (it does host tiny aphids), although they’re also partial to our strawberry plants (probably reflecting the aphid infestation we developed in spring).

Scymnus interruptus on Stachys

Still pootling…

S. interruptus isn’t even the only Scymnus in our tiny 20m2 garden. We’ve also seen two other species from the genus, the redder (and more common) S. suturalis, and the blacker and larger S. femoralis, the female of which has a rather endearing red head.

Scymnus suturalisScymnus suturalis

Scymnus femoralisScymnus femoralis

A similar Coccinellid group, which we sadly haven’t seen in our garden yet, but have seen munching on scale insects at a local bus station, is the genus Nephus. They’re a bit bigger than Scymnus, and you have to double-check the shape and position of the red patches to avoid confusion (Nephus quadrimaculatus, for example, can superficially resemble S. interruptus, but has four red patches rather than two, they don’t reach all the way to the outer edges of the elytra, and are less triangular).

Are we doing something magical? Personally, I doubt it. Yes, we’ve got lots of wildflowers and generally a good diversity of plants relative to the total area available, the garden is quite sheltered, and we don’t use pesticides, but I suspect the secret is just sitting and looking, and paying attention to the small things. How much wonder exists in even the smallest outdoor space.

Outreach, and reaching out further

It’s summer, and summer seems to be peak time for outreach events. This follows on from my previous post about communicating science to the willing and the unwilling, but I think outreach is more than just communicating science. I’d like to think it’s also about communicating passion, inviting people to feel part of science and nature and, hopefully, planting the seeds of interest in science, nature, biodiversity, whatever, in the minds of people outside the field – especially children.

I’ve participated in a few events so far this year. One was a Bioblitz type event, which are normally structured around the idea of trying to get as many biodiversity records for a site in a 24 hour period as possible, but this one also had a big public engagement element, with walks, talks, stands and family activities. In actuality, we were so busy manning the stall, giving talks and taking families for a guided walk around the site that we didn’t have much chance to hunt down anything too unusual, but that was fine. Taking a bunch of kids (and their parents) for a walk that really just looks at common species can be rewarding in its own right – species that have become so typical they’re almost mundane to me can be magical and captivating to someone who’s not encountered them before, whether it’s describing to a 10 year old in gruesome detail how a parasitoid wasp life cycle works (sorry, parents!) or giggling at the “bodybuilder” legs of Oedomera nobilis. We came away with a respectable number of species by the end of the day – nothing terribly unusual, but all interesting in their own way.

Another outreach event, taking somewhat of a different format, was the Fascination of Plants Day. This is an international scheme, with universities and research centres signing up and putting on activities for the general public to try and sell the appeal of plant science and plant research. It was the University of Greenwich’s first attempt at this day, so we went in not knowing whether we’d get 4 people or 400. In the end, we got about 130, and I think everyone had a really nice day – I got to have some great conversations with adults and children about cocoa, chocolate and cocoa pollination, which was great. There were games with plant-insect interactions, vegetable-derived baked goods, coffee and chocolate tasting, DNA extractions, trichomes, photosynthesis, aquaculture, raffles…

The question I do sometimes find myself pondering at the end of such events, however, is whether some of these activities are the same groups of people coming together over and over. You meet some wonderful people and lovely families at these events, but a lot of them seem to be the families who already have opportunities and the types of parents who encourage academic knowledge, such as homeschooling parents and parents who are in research and teaching themselves. This can make for some really stimulating conversations (I learn loads!), but I wonder how we can connect with the harder to reach families, the ones who wouldn’t normally think to come to a science- or nature-related event?

Certainly, research on engagement schemes such as citizen science programmes show that while they’re a good link between science and the public, an excellent way to generate data, and a good way to make the already-interested more interested, they tend not to turn the disinterested into the enthusiastic. On the other hand, having citizen science in a community can confer benefits such as engagement in local issues and development and increased policymaking influences of the community

Some organisations are having some success with connecting nature with harder-to-reach groups. One of the key aims of OPAL (Open Air Laboratories Network), the national citizen science scheme, is to reach more than just the “usual” people and engage with a diversity of people from a diversity of backgrounds. They’ve done this by linking up with other organisations like TCV, who have a lot of experience with working with “invisible” groups such as rural communities and inner city teenagers. As a result, many people did nature surveys through OPAL for the first time – I don’t know how many of those people went on to do more than one, but breaking down that first barrier must be important. They’re now expanding out from England and Wales to Scotland and Northern Ireland, so that’s great.

The National Parks have been exploring a strategy to encourage BME (black and minority ethnic) people to make use of and enjoy national parks. While around 10% of the UK population are considered BME, BME people make up only about 1% of National Park users. It seems one of their key findings is that building personal relationships is important – leaflets and cold-calling may not work well, but sending someone along in person to visit regularly and create trust can succeed. Sadly, heading out into the local community and getting to know people is one thing university academics often don’t have a lot of time to do (even though we’d love to do it more), but perhaps we need to think about ways we can do it.

On a less immediately scientific but equally valuable level, there is a growth in schemes that get people from marginalised backgrounds gardening, submerged with nature, interacting with plants and so on. When I was finishing my PhD in London, Grounded Ecotherapy was just getting off the ground and I thought it was ace – a bunch of people, some who are or have been homeless, some with substance issues, some with mental health issues, transforming bits of London cityscape into living, breathing, growing places. They’ve re-invigorated nature gardens, started rooftop gardens with a mixture of wildflowers and vegetable growing, enlivened forgotten spaces – all with an ethos of promoting biodiversity as well as urban food. The folks running it have a really great appreciation for nature. I guess it’s a lovely example of management for ecosystems services right from the provisioning (food), through pollination and biodiversity to the cultural – helping people “get back on their feet” in their words. It would be great, I think, to quantify both the natural and the social benefits of these sorts of schemes. What species benefit, and to what extent? (I expect that the effects on urban bee diversity are measurable.) How do people benefit, both within the schemes and by interacting with them?

So what should I/we do? It seems it’s easy to reach out to our academic colleagues’ children, and usually very rewarding. But we probably have to think outside the box more, link up with local charities or community groups if we want to extend our enthusiasm to less traditionally nature-friendly groups of people in the community.

Monkey slugs and their cousins

I’m not a natural Lepidopterist – over recent years I’ve come to appreciate some of the less aesthetically appealling taxa and their fascinating ecology, so find beautiful butterflies a bit too ostentatiously pretty for my tastes! Moths, on the other hand, I find rather good fun – often (though by no means always) the adults are dull shades of greyish brown (though the wing patterns can often be wonderful), while the caterpillars can be bizarre to the point of otherworldly.

Hairy, spiky, multicoloured, mimicking something else or perhaps just resembling a fantastical piece of conceptual artwork, moth caterpillars can provide endless variety for a globetrotting ecologist.

One particularly memorable encounter in recent years for me has been with the caterpillar of a Caribbean species of cup moth (Lepidoptera: Limacodidae), probably a Phobetron species. We came across it in Trinidad and its appearance was so utterly weird it took me a minute to figure out what I was actually looking at. It was brown and hairy, with six to eight false “legs” and some whorls of hair that almost looked like suckers, and was crawling slowly across a small tree. I decided it would be inadvisable to touch it (which, as it turned out, was probably a good decision on my part, as various sources claim their spines can be irritant/toxic 1).

(Clicking links to a video of the creature walking down a tree)

I assume it’s trying at least half-heartedly for tarantula mimicry – if I was a hungry bird I’d definitely think twice.

Other closely related species can be even odder, with up to nine pairs of legs.

Their ecology is actually nothing particular special: they munch on various ornamental and horticultural plants, especially small trees. Although the coolest seem to come from the Americas, the family is also present in Asia, where one species is a pest of coconut trees as well as coffee, cocoa and oil palm2. Although there was once a bit of an outbreak of them3 in Panama following a rather severe drought, which makes for some pretty interesting mental images.

The diversity of Limacodidae caterpillars is pretty mind-blowing – lurid colours, hairy spines at strange angles. I suppose they remind me of what happens when a toddler gets to play in a particularly well-appointed dressing-up box!

Really, who needs sci-fi when you have Limacodidae?

With a caterpillar like that, what must the adult look like? Well, as is frequently the case with moths, this most wondrous caterpillar pupates into medium-sized, hairy but by comparison relatively uncharismatic adult moth. It has been suggested that the hag moth (Phobetron pithecium) is a bee-mimic, which I suppose is possible, though it’s perhaps not the most convincing I’ve ever seen!

Virginia Tech/Virginia State have produced a nice little factsheet on the North American species.

1Murphy, S. M., Leahy, S. M., Williams, L. S., & Lill, J. T. (2010). Stinging spines protect slug caterpillars (Limacodidae) from multiple generalist predators. Behavioral Ecology, 21(1), 153-160.
2Chenon, R. (1982). Latoia (Parasa) lepida (Cramer) Lepidoptera Limacodidae, a coconut pest in Indonesia. Oléagineux, 37(4), 177-183.
3Van Bael, S. A., Aiello, A., Valderrama, A., Medianero, E., Samaniego, M., & Wright, S. J. (2004). General herbivore outbreak following an El Nino-related drought in a lowland Panamanian forest. Journal of Tropical Ecology, 20(06), 625-633.

Adventures in the Caribbean: cocoa and beyond

This blog entry is brought to you, somewhat belatedly, from the lovely island of Trinidad in the Caribbean.

Trinidad and Tobago, while having a big strength in industry, engineering and particularly oil and gas, is mindblowingly biodiverse when you get out of the cities and into the rural areas. The cocoa agroforestry systems are particularly lovely, with new wonders almost around every corner!

Longhorn Orthop4

And it’s cocoa that’s brought me here. It’s an amazing tree, with flowers that come straight out of the trunk, and eventually develop (if pollinated) into vividly coloured pods about eight inches long. Like a lot of crops, it’s dependent on insect pollination – but while we’ve got a reasonable grasp of the pollination systems of crops like strawberry and oilseed rape in Europe and North America, with cocoa there are still big questions that we can only begin to answer with existing knowledge.


Starting with “What pollinates cocoa?”

Accepted wisdom is that cocoa is pollinated by 2mm long Ceratopogonid midges, particularly in the genus Forcipomyia1 – and, indeed, they seem to be the most effective insects for the job on a per-visit basis – lots of evidence suggests that they interact with flowers in the perfect way to pick up and deposit pollen, and that often one midge visit may be suffient to get a cocoa pod 9-odd months later2. However, they’re also relatively infrequent on a lot of cocoa fields, which raises the question of whether there’s really enough of them to account for the number of pods observed. How important are other small flies like Chironomids or Cecidomyiids? Do ants and thrips play a role, particularly in self-compatible cultivars of cocoa where pollen from another tree isn’t necessary for fruit-set? We don’t know nearly as much as we’d like to about the answers to these questions.

Similarly, how the midges find the flower is a bit of an unknown: do they see it, and if so…what are they looking for? Do they smell it – and if so, what are the important chemicals, and how much do they vary? What do they get from cocoa flowers that other flowers don’t (or do they?) provide?

And it seems that the cocoa needs them more than they need the cocoa. Everywhere cocoa has been planted in the world, be it Trinidad, Jamaica, Mexico, Hawaii, Ghana, Indonesia, Australia…, a species of Forcipomyia has shown up to pollinate it3. So clearly they were doing just fine long before the cocoa arrived, but once the cocoa is there they seem to derive some sort of benefit from it.

So…cocoa midges. While getting people interested in anything to do with chocolate is relatively easy, the midges themselves are somewhat less charismatic than other pollinators such as bees, hummingbirds or butterflies. Small, hairy, and closely related to various biting species – oh, and their larval stage is a 2mm long hairy maggoty thing that lives in rotting vegetation such as cocoa pods, rotting banana stem and leaf litter4.

Actually, understanding the larva is pretty important – while it’s the adults we need, we won’t get any if the larvae aren’t happy. That’s what we’ve ended up primarily focusing on this year in my current project out here. CocoaPOP (Cocoa Pollination for Optimised Production, or, formally, Optimizing Cocoa Production For Increased Yield and Income Generation) is a project co-funded by the EU via the ACP group of states, lead by the University of Trinidad and Tobago with partners from Trinidad, Jamaica and the UK. We’re looking at what’s going on with cocoa pollinators in the Caribbean – how healthy are the populations, what species are present, is the management supporting them, and how can we help? We’ve spent the last couple of years doing some fairly intensive insect sampling on 6 sites across 3 islands, to get an idea of what the pollinators do over the course of a year. We’re learning quite a lot and looking forward to publishing papers soon.

Now we’re on to the next phase – trying interventions to see how they affect pollinator numbers and eventual cocoa yield, and trying to understand the midges better. There’s evidence that this should work5, so fingers crossed! Rearing the little creatures in the lab is keeping us challenged, but we’re giving it our best shot! So I’ve spent the last couple of weeks busy in the lab and the field, helping to get the new experiments rolling and seeing what can be done to give us live midges in the lab to study.

I also had the opportunity to attend the first International Fine Cocoa Innovation Centre conference on the Ortinola Estate (formerly a cocoa estate owned by the Cadbury family, apparently). It was a great opportunity to learn about all stages of cocoa, from the genetics underpinning the important traits, through agronomy and then flavour profiles, marketing, small businesses and cooperatives. While the Caribbean is only producing a small amount of cocoa at the moment on a global scale, I think there is some real enthusiasm for increasing the region’s importance as a cocoa producer. I met some fantastic people from all sorts of areas of cocoa: academia, industry, SMEs and cooperatives. There was a pollination meeting/workshop afterwards too, which was an amazing opportunity to talk with lots of equally enthusiastic people about the next few big questions in cocoa production and discuss directions in future research.

1Billes, D.J. (1941) Pollination of Theobroma cacao L. in Trinidad, B.W.I. Tropical Agriculture (Trinidad), 18(8):151-156; . Posnette, A.F. (1944) Pollination of cacao in Trinidad. Tropical Agriculture (Trinidad), 21(6):115-118.
2Falque, M., Vincent, A., Vaissiere, B.E. & Eskes, A.B. (1995) Effect of pollination intensity on fruit and seed set in cacao (Theobroma cacao L.). Sexual Plant Reproduction, 8(6):354-360.
3Winder, J.A., & Silva, P. (1972). Cacao pollination: Microdiptera of cacao plantations and some of their breeding places. Bulletin of Entomological Research, 61(04):651-655.
4Besemer, H.A. & Soria, S. de J. (1978) Laboratory rearing of Forcipomyia spp. midges (Diptera, Ceratopogonidae): 1. Adult feeding, larval feeding and copulation trials; a revision of Saunders method of rearing. Revista Theobroma (Brazil), 8(2):43-59; Winder, J.A. & Silva, P. (1972) Cacao pollination: Microdiptera of cacao plantations and some of their breeding places. Bulletin of Entomological Research, 61(4):651-655.
5Groeneveld, J.H., Tscharntke, T., Moser, G., & Clough, Y. (2010) Experimental evidence for stronger cacao yield limitation by pollination than by plant resources. Perspectives in Plant Ecology, Evolution and Systematics, 12(3):183-191; Adjaloo, M., Banful, B.K.B., & Oduro, W. (2013) Evaluation of breeding substrates for cocoa pollinator, Forcipomyia spp. and subsequent implications for yield in a tropical cocoa production system. American Journal of Plant Sciences. 4(2):204-211.

Communicating science to the willing…and the unwilling

This week I had the privilege to give a talk at a local science/astronomy society not too far from where I live and work. It was a delight – I met some lovely new people, there was a bit of debate at the end and many fascinating and thought-provoking questions. Altogether, a thoroughly wonderful experience and the kind of thing I really value. Getting out of the old ivory tower can be an eye-opener – meeting new people can make you think about your research in a fresh way, and that’s fantastic.

However, a difficulty with communicating science more widely is that the type of people who get involved with public science events often seem to belong to one of three groups: young people who are forced to by their school/university, people of any age who do something related to this as their job anyway, and retired people who have the time and perhaps have rediscovered an old interest they’d always wanted to cultivate. Of course, all these groups offer wonderful opportunities, and the above is a sweeping generalisation with many exceptions. However, the truth of the matter is there there are oodles of people in society who we, as scientists, ecologists, and so on, are not really reaching…ever, in any meaningful way. Presumably most of us would like to communicate well with a diversity of people, because they all have the ability to influence science and environmental policy, they can all consider how their own lifestyles may or may not benefit climate change, biodiversity, etc. And we’d probably all like the scientists of the future to be as diverse as possible in their backgrounds and perspectives.

Studies are finding again and again that people’s relationship with science is very variable and seems to suggest that at the moment we often end up preaching to the choir, if you like – talking to people who were already interested and open to engagement – rather than genuinely seeking out people who weren’t interested in science before and find a way to ignite a spark of fascination in them. Indeed, the link above divides people into four groups, from the ultra-engaged “Fan Boys and Fan Girls” through to the 20% of people who are “Concerned and Disengaged” with respect to science and technology.

“One of the other key findings of the CSIRO study was that the Fan Boys and Fan Girls are further away from the average point of community values than any other segment of the population. This means that Fan Boys or Girls probably have the least idea of what might appeal to the other segments. They know what turns them on, but they are probably only guessing what will work for the other segments.”

So what do we need to be doing better? This wonderful pamphlet from ecoAmerica caught my eye recently – although aimed at US audiences, people are people, and it does highlight a few key truths. As scientists, we may sometimes assume that something should be inherently believable because we’re familiar with the research and the peer review process and we know it to be true, and therefore surely everyone should just see the truth and agree? But it’s not that simple…

Firstly, it reminded us that “the public” are not an amorphous mass: whether you’re talking to (in the USA) mostly Republicans or Democrats, people who identify with a religion or not, married or single people, different educational backgrounds – all these things are pretty important not just with respect to the jargon you choose to leave in or take out, or the topic areas you choose to cover, but also in terms of what values will matter to different people. As an example in ecoAmerica’s report, a lot of environmental messages are pitched by and for liberals as a “care versus harm” type message, which resonates with the message creators, but with more conservative audiences, rephrasing the arguments as a question of “sanctity versus degradation” apparently holds more weight because many of these people have strong moral values to do with protecting what is sacred from defilement. They list a whole load of such continuums that may resonate more or less strongly with different groups – liberty versus oppression, fairness versus cheating, loyalty versus betrayal, etc.

This led to a discussion of the theory of virtues – i.e. things that people in a given group consider to be important. So while one person may consider education, critical analysis and freedom of choice to be highly important traits, another may place a higher value on faith, loyalty and deference to authority. The first person is never really going to engage constructively with the second by building an argument about sustainable farming, for example, on the basis of scientific datasets and published papers, but may perhaps see more success with a case based on respect for the earth and community, interconnectedness of ecosystems such that one person’s actions affect another’s or reference to a respected authority figure endorsing a strategy.

The thing that struck me most is that part of connecting with your audience is creating a sense that you and they are part of a single group, on the same side. Everyone, in the end, wants to do things that they regard as fundamentally decent according to the values of the group in which they feel they fit. So for climate change behaviours, you create a group in which you and the audience all feel a sense of belonging, and then those behaviours feel a lot more appealing than if you’re simply a distant, “other” scientist lecturing them about what they need to do. This means looking for common ground with your audience, especially in cases where at first impressions you may not seem like part of the group (e.g. your accent, age, gender, cultural background or dress style is different).

I think some of these ideas of how to connect with people are really good to keep in mind not just when making a speech to a Permanent Secretary, but in a whole variety of areas of science communication – from schools outreach, lectures, talks to the local beekeeping club, meetings with farmers, conference presentations, etc.

Most importantly, perhaps we need to just make fewer assumptions about the people we’re talking to and try and see the arguments from their perspective?

The vulture bee

Today is the annual Verrall Lecture and Supper, a time for entomologists in the UK to gather in the vicinity of the Natural History Museum, looking uncharacteristically well-turned-out, and enthuse about insects over good food and wine. Taxonomists frequently bring pinned specimens of weird and wonderful species for show-and-tell, so it seems appropriate that the post today is all about a weird and wonderful insect. Or rather, three related species of weird and wonderful insects.

As a child, after barbeques on long summer evenings, we’d sometimes be sitting there in the garden when wasp workers (Vespula vulgaris, mostly) would fly down and start gnawing leftover scraps of meat from abandoned chicken legs and flying off with them. Most Vespid wasps are pretty partial to both meat and sugary liquids (hence the success of cola bottle traps). Bees, on the other hand, have given up their carnivorous ways and turned to exclusively plant-based diets.

Or have they…?

I found out about vulture bees recently and I decided they were weird and wonderful enough to warrant a little post.

Vulture bees are not like most bees. They are, to put it delicately, “obligate necrophages”.

Most bees eat nectar and pollen.

Vulture bees eat dead meat.

They were only really appreciated in the early 1980s, but a few people seem to have found them fascinating enough to engage in studies of their behaviour. The majority of work on them that I can find, at least recently, seems to have been done by David Roubik at the Smithsonian (who first published on them) and colleagues.

There are three main species, all in the genus Trigona: T. hypogea, the aptly-named T.
and T. crassipes.

Their behaviour is nicely described by Noll (1997) and Roubik (1982)1, and isn’t so very
different from how common vespid wasps approach food sources, really. Apparently they won’t go for utterly rotten, stinking meat – they like it at least reasonably fresh.

Trigona, of course, are eusocial stingless bees – so after one individual finds a carcass, they rapidly recruit more foragers to the food source and soon you end up with many. It only takes a matter of minutes or a couple of hours after the first visit – till you can have between 40 and 108 bees on the carcass, which if you’re talking about something the size of a rat or lizard is quite some density of bees. They’re flexible – they’ll take brood from wasps’ nests in the right circumstances as well2 (interestingly, as normally it’s wasps doing this to bees!).

A little like flies, they feed by regurgitating saliva with a sort of honey-like concoction of fruit juices on to the food source and then lapping it up. The strange meat-mead mixture, if you can call it that, is then stored in honeypots much as their herbivorous cousins store regular nectar, honey or other sugar solutions! The three species don’t do it exactly the same way – T. hypogea seems to add a lot more nectar/juice, whereas T. necrophaga stores pretty much just meat “solution”.

They’ve completely given up gathering pollen – the workers don’t even have pollen combs on their legs any more. They have, however, occasionally been seen visiting stinkhorn mushrooms3 – if you’ve ever encountered a stinkhorn while walking in the woods, you can probably appreciate why, as they do smell quite convincingly like a dead fleshy thing! Apparently they may actually consume the spores (which are suspended in a goopy icky brown semi-liquid goo), and may also have a role in spore dispersal for these fungi.

Camargo and Roubik4 have looked into their anatomy in a bit more detail – it seems like apart from having fairly good mandibles and the lack of pollen combs, they’re not terribly exceptional, but usefully are able to produce antibiotic compounds in their salivary secretions (as a result of an interesting microbial gut flora). Which, if you’re eating raw meat, is probably helpful. Slightly more worryingly, Camargo and Roubik also comment that these bees produce a “sweet, clear honey…of unknown origin”. I am not altogether sure how they deduced that this honey was sweet, but as much as I like honey, when offered it from a nest where the bees were known to store partially-digested bushmeat broth I’d personally have given it a miss…


1Noll, F. B. (1997). Foraging behavior on carcasses in the necrophagic bee Trigona hypogea (Hymenoptera: Apidae). Journal of Insect Behavior, 10(3), 463-467 and Roubik, D.W. (1982) Obligate necrophagy in a social bee. Science 217 (4564), 1059–60.
2Mateus, S., & Noll, F. B. (2004). Predatory behavior in a necrophagous bee Trigona hypogea (Hymenoptera; Apidae, Meliponini). Naturwissenschaften, 91(2), 94-96.
3Oliveira, M. L., & Morato, E. F. (2000). Stingless bees (Hymenoptera, Meliponini) feeding on stinkhorn spores (Fungi, Phallales): robbery or dispersal. Revista Brasileira de Zoologia, 17 (3), 881-884.
4Camargo, J. M., & Roubik, D. W. (1991). Systematics and bionomics of the apoid obligate necrophages: the Trigona hypogea group (Hymenoptera: Apidae; Meliponinae). Biological Journal of the Linnean Society, 44(1), 13-39.