The marvels of chocolate

Have you ever wondered where chocolate comes from and if it is possible that there will be a chocolate shortage in the future? Have you ever wondered if chocolate has anything to do with entomology? According to the Telegraph newspaper the average person In the UK spends a minimum of £57 on chocolate per year. It is therefore no surprise that the Theobroma cacao tree, from which we get most of our chocolate, is the second most important tropical cash crop, being worth $5 billion, providing employment for approximately 40-50 million farmers in Africa and Asia. (Schawe et al. 2013). Chocolate is processed from cocoa beans which grow on the 5-8 metre tall T. cacao tree (Young, 1982). As well as chocolate the cocoa beans are also processed into many well-known products such as cocoa powder and cosmetics (Schawe et al. 2013). Chocolate is not only delicious, but it has actually played a major role in human society by representing power and celebration and was even historically used as a currency.

The red/ brown egg shaped cocoa pods containing the cocoa beans are only produced if the flower is successfully pollinated by a particular insect. For once we are not talking about bees. Although you probably will not believe me, the pollinator is actually a fly, well, two species of the biting midge. Their Latin names are Forcipomyia quasiingrami and Lasiohela nana and they both belong to the Ceratopogonidae family (Young,1982). Can you believe it! Chocolate production is solely reliant on a biting midge!

The biting midge is 2-3mm long, about the size of a grain of rice (Young, 1982). Considering how important the midge is it lives quite a secretive life, the larvae (maggot) feed on dead organic matter and fungus and the adults require pollen and blood for egg production (Leston, 1970). The midge larvae click and jump so maybe that has made you rethink your opinion of maggots (Frimpong, 2009). Well when you think of flies you may automatically think of their larvae the maggot. I am writing this to show you wonder of chocolate, I certainly don’t want to put you off it. But without the midge larvae there would be no chocolate! Therefore if we destroy this annoying midge we would have no chocolate. Which would be worse?

So when you think of chocolate what do you imagine the flowers would be like? Well actually they are 5 pink sepals, holding 5 pouch like yellow petals. The petals conceal a ring of 5 staminodes, infertile stamens which enclose a central ring of 5 stamens covered in pollen. The flower’s ovaries are in the centre. The midges hover and weave around the aromatic flowers before crawling into the petal. The red nectar lines guide the midge towards the central narrow nectaries, where it feeds on nectar. The pollen from the previous flower visited is transferred to the ovary, fertilising the seed. When the midge crawls out of the flower it consumes some of the stamens pollen, but a large majority of pollen sticks to the midges long caudal hairs (Young, 1985). The midge then flies up to 6m away or is blown 100m-3km away from the flower, to another flower (Frimpong, 2009; Klein et al. 2008; Groneveld, 2010) and so it continues.

So far so good, but what if I was to tell you this midge is becoming rare, then what would you say? And what should we do about this? What if I was also to tell you that these midges also depend on rotting bananas and fungus growth on them for larvae growth (Leston, 1970) would you change your mind about fungus? The main reason for the midges decline appears to be loss of its microhabitat of dead leaves and discarded cocoa pods. The farmers are keeping their plantations too clean, banana peel may be the answer.

There is an additional problem. This particular tree (T. cacao ) is inefficient at producing fruit. Flowers must be pollinated on their first day of bloom. Otherwise, after 2 days, the flowers drop to the ground. As a result less than 5% of the 10% of flowers that are successfully pollinated develop into fruit (Groneveld, 2010). So next time you open a 100g chocolate bar remember it took 1 pod with 30-40 seeds to produce it. In a year alone the cocoa industry uses about 35 trillion cocoa pods. And so perhaps it is no wonder chocolate can be loosely translated to “the food of the gods”. So, next when you hear someone talking about the importance of bees just stop for a minute and consider the midges and how without them there would be no chocolate. And, next time a midge bites you think of their cousins the insect pollinators.

By Ruth Carter


References

Encyclopedia of Life. 2015. Theobroma cacao. [On-line]. Encyclopedia of Life. Available from: http://eol.org/pages/484592/overview [01/11/2015].

Frimponga, E., Gordona, I., Kwaponga, P. and Gemmill-Herrena, B. 2009. Dynamics of cocoa pollination: Tools and applications for surveying and monitoring cocoa pollinators. International Journal of Tropical Insect Science, 29 (2), pp. 62-69.

Groeneveld, J., Tscharntke, T., Moser, G. and Clough, Y. 2010. Experimental evidence for stronger cacao yield limitation by pollination than by plant resources. Perspectives in Plant Ecology, Evolution and Systematics, 12 pp. 183-191.

Kew. 2015. Theobroma cacao (cocoa tree). [On-line]. Home Science & Conservation, Discover plants and fungi. Available from: http://www.kew.org/science-conservation/plants-fungi/theobroma-cacao-cocoa-tree[01/11/2015].

Klein, A., Cunningham, S., Bos, M. and , S., I. 2008. Advances in pollination ecology from tropical plantation crops. Ecological Society of America, 89 (4), pp. 935-943.

Schawe, C., Durka, W., Tscharntke, T., Hensen, I. and Kessler, M. 2013. Gene flow and genetic diversity in cultivated and wild cacao (Theobroma cacao) in Bolivia1. American Journal of Botany, 100 (11), pp. 2271-2279.

Young, A. 1985. Studies of cecidomyiid midges (Diptera: Cecidomyiidae) as cocoa pollinators (Theobroma cacao L.) in Central America. Proceedings of the Entomological Society of Washington, 87 (1), pp. 49-79.

Young, A. 1982. Effects of shade cover and availability of midge breeding sites on pollinating midge populations and fruit set in two cocoa farms. Journal of Applied Ecology, 19 (1), pp. 47-63.

Young, A., Severson D. 1994. Comparative analysis of steam distilled floral oils of cacao cultivars (Theobroma cacao L., sterculiaceae) and attraction of flying insects: Implications for a Theobroma pollination syndrome. Journal of Chemical Ecology, 20 (10), pp. 2687-2703.

 

 

 

What’s the point of wasps?

‘But seriously, what is the point of wasps?’ This is a question I often find myself being asked. Unlike their cute, somewhat fluffy cousins, the bees, it seems people have a much harder time accepting wasps. Indeed, they often find themselves on the wrong end of extreme prejudice with people willing to swat them without hesitation; there is even an ‘anti-wasp’ internet meme! This ‘speciesism’ should hardly be surprising given the emphasis placed on pollination services provided by the Apiformes. Wasps however, also play an important role in the functioning of our ecosystems; the health of which we rely upon for our very survival.

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Perhaps the single most important thing that wasps do for us is the provision of ecosystem services though pest control. Many species of social wasp are veracious generalist predators, with each nest capturing and removing many kilograms of arthropod prey from an ecosystem every year (Harris, 1996). Much of this removed biomass is that of species which would otherwise represent significant pests to our agricultural and forestry systems. Wasps can be so efficient at predating on arthropods that in some ecosystems where they have been introduced they actually represent a conservation concern by out-competing native insectivorous birds (Beggs, 2001).

Given this ability to help maintain the functioning of ecosystems, social wasps have occasionally been deliberately employed or encouraged as pest control agents. The introduction of nests has been used to provide successful biological control in production of cotton, tobacco, cabbage, coffee, fruit and timber (Spradbery, 1973). In fact, it is surprising how under-utilised they are considering their apparent ability to effectively control pests. Due to their generalist nature, in many ways social wasps are more highly suited for bio-control than some of some of the specialist species which are currently more widely used. For example, not only will they help maintain populations of multiple pest species below the levels that might affect yield, they are also able to maintain their own populations by utilising various other food sources. This means that their population is not tied to that of the pest species thus there is no ‘lag time’ between the initial outbreak and the time when there are sufficient numbers of predators to have a controlling effect. Furthermore, the social foraging behaviour of wasps causes them to return to sites with abundant food resources, meaning they will concentrate disproportionately at sites with highest pest densities, unlike other biological control agents which tend to distribute themselves more evenly (Richter, 2000). This will allow for more efficient control as the most damage occurs at the sites of greatest pest densities, which will be targeted first by the wasps.

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Contrary to what some people might believe, it is not just bees which pollinate! In fact, any insect which visits flowers has the potential to act as a pollinator. This includes beetles, butterflies, moths, flies and yes, even wasps. In fact, some plants, such as the Chiloglottis orchids, can only be pollinated by a single specific species of wasp (Peakall, 1990). Wasps normally pollinate during their search for carbohydrate rich nectar, but will occasionally frequent flowers during their search for prey. Sometimes they are even tricked into visiting flowers in reaction to volatiles released by the plant! Some species have evolved the ability to produce chemicals to attract male wasps by mimicking female sex pheromones (Schiestl et al., 2003) or by releasing damage signal volatiles to mimic pest damage to attract hunting wasps (Brodmann et al., 2008).

Wasps also have much to teach us. It was by watching wasps create their nests by mulching wood that Cai Lun, an official of the Chinese court of the Han Dynasty, first developed the idea of paper around 105AD. This now ubiquitous technology underlies much of the functioning of our society and owes its inspiration to the remarkable wasps. Even today we are learning much about social evolution by examining the range of socialities exhibited by wasps along with the underlying genomics.

By examination of the services that an organism provides us, it may become easier to justify why we should respect and safeguard them. This carries with it however, the danger that we should only value an organism by what it contributes to ourselves. This narcissistic view is dangerous as in reality human-kind knows very little about the complex world we inhabit. Surely species have a right to exist that is not solely determined by their detectable utility to one other particular species? Even if wasps did not provide us with all of these fantastic services free of charge, I would argue that they are beautiful creatures in their own way. Each individual organism we see around us represents the culmination of millions of years of evolution. Surely it should be a pleasure to share the planet with these creatures. This, I would argue, is ‘the point of wasps’.

By Liam Crowley.

References:

Ballou, H.A., 1913. Report on the prevalence of some pests and diseases in the West Indies during 1912. Barbados, West Indies, Bull. 13, pp.333-357.

Beggs, J., 2001. The ecological consequences of social wasps (Vespula spp.) invading an ecosystem that has an abundant carbohydrate resource. Biological Conservation, 99(1), pp.17-28.

Brodmann, J., Twele, R., Francke, W., Hölzler, G., Zhang, Q.H. and Ayasse, M., 2008. Orchids mimic green-leaf volatiles to attract prey-hunting wasps for pollination. Current Biology, 18(10), pp.740-744.

Harris, R.J., 1996. Frequency of overwintered Vespula germanica (Hymenoptera: Vespidae) colonies in scrubland‐pasture habitat and their impact on prey. New Zealand journal of zoology, 23(1), pp.11-17.

Peakall, R., 1990. Responses of male Zaspilothynnus trilobatus Turner wasps to females and the sexually deceptive orchid it pollinates. Functional Ecology, pp.159-167.

Richter, M.R., 2000. Social wasp (Hymenoptera: Vespidae) foraging behaviour. Annual review of entomology, 45(1), p.142.

Schiestl, F.P., Peakall, R., Mant, J.G., Ibarra, F., Schulz, C., Franke, S. and Francke, W., 2003. The chemistry of sexual deception in an orchid-wasp pollination system. Science, 302(5644), pp.437-438.

Spradbery, J.P., 1973. Wasps. An account of the biology and natural history of social and solitary wasps, with particular reference to those of the British Isles. London: Sidgwick and Jackson Limited, pp.282-283.

Taxonomy bytes back: are insect avatars the solution to tackle the classification bottleneck?

We have been naming and describing the natural world around us for millennia, but how does this age-old science relate to the 21st century? Computers have revolutionised the modern world and smart phones have lead to global connectivity. Ideas shared, data accessed and unity of knowledge achieved at the tap of the finger. With growing interest in biodiversity and conservation many technological advances are assisting within these fields. Despite racing against the deteriorating environment, new species are being discovered at a record rate. It seems therefore, that it has never been more important to put the right name to the right species and to do so quickly.

We are currently facing a classification bottleneck. This is an issue of time, money and accessibility, constraining upon sheer number of new specimens being collected. That is not to mention the number of synonyms and misidentified species that need some serious TLC. As ever, time is money and experts are scarce, so this really is a problem of exponential proportion.

 

Alice_collection.jpg

Author with her own collection submitted for our Entomology MSc Diversity and Evolution of Insects module

The latest revolution sits in the hands of digitalisation, of avatars and of so called 3D cybertypes. The new age of taxonomy is well and truly upon us. Focal stacking software amalgamates a series of two dimensional images to create an otherwise impossible focal range, whilst visual-hull algorithms carve into three dimensional space, stitching these stacks into tangibility. A 3D replica, an avatar, is thrust into digital existence, with full natural colour and incredible intricacy. High resolution microtomography (microCT) can then be used as a non-invasive means to map internal morphology. The result: a high resolution colour, interactive 3D interface, with the ability to explore within, differentiating between systems.

These advancements have caused some stir. With rapid characterisation of species morphology and subsequent preservation in the digital domain there is scope for broad spectrum application within entomology and beyond. These visual aids can be complemented with quick access to distribution data, DNA barcodes, research on behaviour or whatever published data required. Just as existing tools can be accessed remotely by the global community, these avatars too are accessed online and utilised in a similar way. Data banks can be pooled and comprehensive catalogues of data created, eternalised online, accessible 24/7, all at the click of a button. Recent advancements in producing data miners to sift through academic journals online have already be noted for their potential in the field of medicine. One such data miner, launched by the Seattle-based institute AI2, is already in use. Currently capable of trawling computer science literature, developers aim to scale up the programme, with extension to medical, biological and other scientific disciplines.   Imagine the applications; to request a specimen from the collections and for it arrive instantaneously, perpetuated in digital perfection, to your desktop. It would contain with it a plethora of data, pooling prior research, amalgamating it to one dashboard. This is not to say that a digitalised avatar would replace the crucial type specimen. These new digital techniques are a means to acquire more data, to be more exhaustive and to enable greater ease of access, leading to higher efficiency within our field.

Our natural history collections represent centuries of passion, of exploration and of pioneers within their fields. More than just prestige, collections carry with them invaluable data, added to by centuries of continuing research. Taxonomy is not an archaic tradition, refined to dusty old cabinets behind the closed doors of museums. Taxonomy is as current today as it has ever been. It is time for taxonomy to once again hold its own, to invoke collaboration and inter-disciplinary interaction. Ultimately, we are working for the same cause. Let’s move into the digital age and grant accessibility to all. If knowledge is power and communication is key its time we join forces to liberate our knowledge in this time of rapid environmental change.

By Alice Mockford

 

References

Akkari, N., Enghoff, H. and Metscher, B.D. (2015). A New Dimension in Documenting New Species: High-Detail Imaging for Myriapod Taxonomy and First 3D Cybertype of a New Millipede Species (Diplopoda, Julida, Julidae). Plos One [Online] 10:e0135243. Available at: http://dx.plos.org/10.1371/journal.pone.0135243.

Erwin, T., Stoev, P., Georgiev, T. and Penev, L. (2015). ZooKeys 500 : traditions and innovations hand-in-hand servicing our taxonomic community. 8:1–8.

Godfray, H.C.J. (2002). Challenges for taxonomy. Nature 417:17–19.

Marshall S.A., Evenhuis N.L.   (2015) New species without dead bodies: a case for photo-based descriptions, illustrated by a striking new species of Marleyimyia Hesse (Diptera, Bombyliidae) from South Africa. ZooKeys 525: 117-127 (05 Oct 2015) doi: 10.3897/zookeys.525.6143

Nguyen, C., Lovell, D., Adcock, M. and La Salle, J. (2014). Capturing natural-colour 3D models of insects for species discovery and diagnostics. PLoS ONE 9:1–11.

Nguyen, C., Lovell, D., Oberprieler, R., Jennings, D., Adcock, M., Gates-Stuart, E. and La Salle, J. (2013). Virtual 3D models of insects for accelerated quarantine control. Proceedings of the IEEE International Conference on Computer Vision:161–167.

Qian, J., Lei, M., Dan, D., Yao, B., Zhou, X., Yang, Y., Yan, S., et al. (2015). Full-color structured illumination optical sectioning microscopy. Scientific Reports [Online] 5:14513. Available at: http://www.nature.com/doifinder/10.1038/srep14513.

La Salle, J., Wheeler, Q., Jackway, P., Winterton, S., Hobern, D. and Lovell, D. (2009). Accelerating taxonomic discovery through automated character extraction. Zootaxa 55:43–55.

Winterton, S.L., Guek, H.P. and Brooks, S.J. (2012). A charismatic new species of green lacewing discovered in Malaysia (Neuroptera, Chrysopidae): The confluence of citizen scientist, online image database and cybertaxonomy. ZooKeys 214:1–11.

 

Does Mother Always Know Best? – An Aphid’s Perspective

 

We all remember those teenage years, mum shouting from the doorway to get up and go to school, giving her tit bits of advice and usually finishing a sentence with ‘Don’t argue, I know what’s best for you!’ But what about insects, I’ve never read a study where they try to get their young out of bed early: so, do they know best?

If an insect could talk, would they say ‘thanks mum’? Probably not, more likely ‘who are you’ and have to go onto the Jeremy Kyle show to be told ‘You ARE the mother!’ So, what should a good reporter do? You guessed it, an interview. After hours of searching (okay, ten minutes – I couldn’t find my shoes), an aphid was found (a small pear shaped true bug with sucking mouthparts) 7 and she was not impressed with what I had to say!

After staring hard at her proboscis (wow, suddenly my nose seems very inadequate) we launched into it:

“Can you explain why you are a good mother?”

She huffed. “Honestly have you never read Craig and Ohgushi,2 well, it’s called the naïve adaptatonist hypothesis (something in the way she said naïve makes me think she was directing that right at me, seriously, I’m getting sass off a bug). She continued “It explains that mothers will pick the best site for oviposition (turns out this meant egg laying, I didn’t want to admit it at the time that she had a better vocabulary than me) and by having this plant preference the young laid on these sites have the best survival rates to adulthood.”3 She added breezily “There’s been loads of studies on it.”

“…I mean its easier when we eat the same food as our young, you eat until you want to lay and then just find a good place to do it, perfect. But some of my friends don’t stay here the full year round. They like to travel and have two host plants.3 My friend Mary spends the summer in a tree but each year she pops back to shrubs when she lays eggs to overwinter.”

I sit and think. So are they truly good parents, more importantly, are they better than us?

She continued – “There’s no swanky hospital for us insects, I have to make decisions, I mean, obviously one plant is going to be more nutritious, but what happens if there’s another plant that offers better protection from predators?!”1

“So what happens if you pick the wrong plant” I enquired, I mean how bad could it be?

“Slow growth mostly…”

“Well, that doesn’t sound so…”

“… OR death, from predators or we might not be able to feed from the right leaves.”

I’m feeling guilty; death seems a bit much for just laying your egg in the wrong place. But I’m a reporter and time to play my trump card.

“I’ve heard you just lay your eggs in places which are only beneficial to you.”6

“Where’d you hear that?” she replied.

I shrugged “It’s just a theory.”

“What about the theory that states we lay young elsewhere in order to increase their lifespan?”

Touché! I had to admit I had looked, there are lots of studies out there with conflicting evidence! Some argue larval survival is connected to the mother’s oviposition choice, 5 others have found a weak or no effect.3 How are you suppose to make sense of all this?

“Have you read the latest meta-analysis?”

“Meta-what-now?”

“Analysis, it’s a study which analyses the significance all written studies to see an overall effect, it’s fantastic, explains what I’ve been saying all along, we pick a site that best helps our young.”4

“What about the experiments that don’t work then?” Surely she couldn’t have an answer for everything!

She sighed. “Maybe when it didn’t work it was the research that had problems such as bad weather (though you should already be used to that), wrong plants so you had to make the best of a bad situation, too few insects involved or maybe these lab experiments are not as representative of the wild as you seem to think.”8

Well didn’t this just take a complex turn, I thought I had it all figured out. I don’t think I could make all these right choices, some days I can’t even find two socks that match.

“Nothing’s ever that simple, much to learn you still have, young writer” (wait, did she just quote star wars at me?) and then she was gone.

Turns out I’ve learnt lots, mums like to huff; they like to be right and as it turns out, they usually are, (but don’t tell mine that). So next time your mother gives you some advice, maybe you should listen to her; after all, mother knows best!

By Christina Faulder

References

  1. Björkman, C., Larsson, S. and Bommarco, R. 1997. Oviposition preferences in pine sawflies: a trade-off between larval growth and defence against natural enemies. Oikos, 79 (1), pp.45–52.
  2. Craig, T.P. and Ohgushi, T. 2002. Preference and performance are correlated in the spittlebug Aphrophora pectoralis on four species of willow. Ecological Entomology, 27 (5), pp.529-540.
  3. Friberg, M. and Wiklund, C. 2009. Host plant preference and performance of the sibling species of butterflies Leptidea sinapis and Leptidea Reali: a test of the trade-off hypothesis for food specialisation. Oecologia, 159 (1), pp.127-137.
  4. Gripenberg, S., Mayhew, P.J., Parnell, M. and Roslin, T. 2010. A meta-analysis of preference–performance relationships in phytophagous insects. Ecology Letters, 13 (3), pp.383-393.
  5. Ishiwara, M. and Ohgushi, T. 2008. Enemy-free space? Host preference and larval performance of a willow leaf beetle. Population Ecology, 50 (1), pp.35-43.
  6. Jervis, M.A., Ellers, J. and Harvey, J.A. 2008. Resource acquisition, allocation, and utilization in parasitoid reproductive strategies. Annual Review of Entomology, 53, pp. 361-385.
  7. Kindlmann, P. and Dixon, A.F.G. 2010. Modelling population dynamics of aphids and their natural enemies. In: Kindlmann, P., Dixon, A.F.G and Michaud, J.P. In. Aphid biodiversity under environmental change: patterns and processes. London: Springer Science & Business Media. pp.1-20.
  8. Mayhew, P.J. 2001. Herbivore host choice and optimal bad motherhood. Trends in Ecology & Evolution, 16 (4), pp.165-167.

 

 

Winter’s Tales in the Insect World

Ruffled and stung by a sharp, icy wind, I decide to turn back. The watery yellow light on the horizon is threatened by thick grey clouds, which seem to be dragging an early evening in their wake. Prickly lines of hawthorns are strung out in lines across the bare fields.

A tiny spot of red, stands out against the pale brown of a dried tall grass; nestled in the crook of the bent leaf are a small cluster, or aggregation, of five Coccinella septumpunctata, the 7-spot ladybird. I don’t envy the winter ahead for these hardy little beetles, but they have a few survival tricks under their wings. The secret is in a suite of anti-freeze compounds which accumulate in their body as the days get colder, particularly glycerol, a sugar alcohol. If you asked them what their superpower was, this would be it; and appropriately enough, it is called supercooling, and allows them to withstand temperatures several degrees below zero.¹ They are not, however, invincible: cold enough temperatures (the ‘supercooling point’) will kill them, although as winter progresses, this point gets lower.²

I hurry on, as much as the squelchy ground will let me, edging closer to the hedge where the sloping ground is drier to avoid jumping puddles. Not everyone has the ladybird’s cold temperature abilities, and some well-drained, even-temperatured underground spot could be just the place to sit out winter. I know that down there, somewhere, a remarkable little winter scenario will be playing out: the female common earwig, Forficula auricularia, will be in a burrow, having mated and dispensed with her mate’s help, and be showing an astonishing amount of vigilance in guarding the several dozen pale oval eggs she has laid, regularly licking them clean from fungus to increase the chances of survival.¹ I wish I had a window to glimpse into that world.

Jackdaws and rooks swirl and call overhead, but I can’t even see the gnats that persist into winter today, and it is over a month since I last saw hover flies feeding on ivy flowers, or a large queen bumblebee searching, somewhat late, for a hole in which to hibernate. Being active through the winter months isn’t everyone’s thing.

A lot, like the earwig, head underground, but for many, they spend the winter months in diapause, a state of physiological change in their bodies which stops development for a while, and so prolongs survival, a particularly useful trick if your lifecycle is short, food is scarce, and you only fit one generation into one year. There is not a single mechanism that makes this happen: different mechanisms point to the fact that different species of insect developed the same solution to a common problem, but their bodies found a variety of ways to get there. Generally speaking, hormones are involved, and these are triggered by a combination of genetics and a number of environmental factors: day length and change in temperature are particularly important ones.³ Ladybirds do it; bumblebees do it; but others enter diapause as larvae, pupae, or even eggs.

Closer to home now, my route takes me through a graveyard, full of Victorian gravestones. The sculpted pupa of a small white butterfly, Pieris rapae, green with black flecks, is attached by a silken thread to the weathered face of an old stone. The process of reorganising its body from caterpillar to butterfly inside the pupa is one that can potentially last just a few weeks, but this one is in diapause. Metamorphosis has temporarily stopped, but when diapause ends, normal business will be resumed; but now instead of just weeks, the whole stage lasts about eight months.

As I reach home, I notice the large oak tree seems to have lost its leaves overnight; the underside of many are speckled with little dark red, raised spots. I can’t resist picking one up. This has got to be, in my opinion, one of the best winter’s tales in this neck of the woods: inside, a tiny wasp is developing. The spot, a spangle gall, grew as a result of the interaction of the chemicals from the mother and the plant itself. She laid her egg, inserting it inside the leaf itself, and as the larva hatched, the gall grew around it, providing it with food and protection. Safety is not totally assured, though, for this diminutive, round, black wasp, Neuroterus baccarum, as other species of wasp like to take advantage of this pre-packed snack capsule, and lay their eggs through its walls. At least, though, they do not hunt out the galls once they have fallen to the ground.⁴ The Neuroterus baccarum’s spring and summer tale also does not disappoint, but that’s another story.

I employ my winter strategy, and head indoors.

By Chloe Aldridge

References

1. Gullan, P.andCranston, P. 2014. The insects – an outline of entomology. 5th Chichester:Wiley Blackwell.

2. Barron, A. and Wilson, K. 1998. Overwintering survival in the 7-spot ladybird, coccinella septumpunctata (coleoptera:Coccinellidae). European Journal of Entomology, (95), pp. 639-642.

3. Chapman, R.F., Simpson, S.J., Douglas, A.E. 2013. The Insects – Structure and Function. 5th Edition. Cambridge: CUP.

4. Askew, R. The Biology of Gall Wasps. [On-line]. Available from: http://www.nhm.ac.uk/resources/research-curation/projects/chalcidoids/pdf_Y/Askew984b.pdf [25 November 2015].

Who’s said it’s all over after death? Power to the rot!

Imagine you’ve baked a cake but it didn’t turn out as you planned. The nearest shop is 1.5h away and the cake needs to be ready within 4h. You’ve got no time to replace the ingredients and also bake another cake. Fortunately, you can separate all the ingredients used and start again. The decomposition process does just that.

What’s decomposition? You may ask. Well, is the process where animal, plant, fungi or any other organism’s matter breaks down. It’s all natural, with no frills attached, and releases essential nutrients back into the ecosystem. Great part of this process is carried out by our beloved insects with a little help from their symbiotic friends. All organisms on Earth will come to a point when they die. Luckily we can’t live forever and this realisation is reassuring.

Carrion (dead animals) left on ground surface will soon be visited by insects. Blow-flies (Calliphoridae) and Flesh-flies (Sarcophagidae) will first appear to lay their eggs. The hatched grubs (larvae) will feed furiously as if bound by a time constrain. Quite right they are. There’s loads of competition for such a valuable resource. Hide beetles (Dermestes maculatus De Geer, 1774) first appear after a few days or weeks. Although, often considered a pest of dry meats, it provides valuable services to humans. It can deliver an estimated post-mortem interval or be used in skeleton preparations. Ants (Hymenoptera) might not be your first though when it comes to carrion but they also play their part. It could be by direct feeding or emission of odours which signals to other insects the presence of a food source. On a different scale, Mayfly larvae (Ephemeroptera) and Caddisfly larvae (Trichoptera) play a role in the decomposition of submerged carrion.

Have you ever noticed Rose chafers (Cetonia aurata) adding extra beauty to your flowers and wonder where they keep their babies? The larvae might be busy at work breaking down your compost pit. Houseflies (Muscidae) can be a nuisance when you’re trying to eat al fresco. These fast flyers have a bigger interest in laying their eggs in carrion, leaf-litter or dung than in our food. Egg survival rates are unlikely once we ingest egg-fly contaminated food. Dung beetles (Scarabaeoidae) is another example of perfect beauty. Although, as all other insects, they aren’t just a pretty face. They collect mammals’ excreted waste and clean up our green areas.

Dead tree logs left in contact with soil will soon be a home for many insects. Contact with soil is important for maximal enzyme function. Enzymes are proteins produced by living organisms which accelerate a chemical process. Soil contact prevents logs from quickly drying out and makes them suitable for an array of insects. Thus, moisture is thoroughly important. Remember this next time you decide to help our saproxylic friends. You don’t need huge logs. Even wood chips left on top of plant pots filled with soil and wood chips will be better than nothing. You might be rewarded by a Stag beetle, Lesser stag beetle or Rhinoceros beetle peeping out ready for mating.

Through the process of wood decay, parasitoids could emerge and conquer. The slim waist of wasps has evolved in junction with the need of flexibility. Their need to direct the ovipositor (insect’s organ at the end of the female abdomen used to deposit eggs) into decaying wood. Subsequently, in some species, has evolved to egg laying directly into other insects. Wood wasps will pierce dead wood or weaken wood with their ovipositor. They will lay their eggs together with a self-carrying fungus. The Sabre wasp (a parasitoid) makes great use of their slim waist. They can detect Wood wasps’ larvae and lay their eggs into the larvae with great precision. Parasitoids are extremely important in agriculture. In many cases they can replace harmful pesticides.

Ambrosia beetles and Leafcutter ants realized that fungi were efficient at breaking down plant cell walls. Fungi can outcompete other organisms in the decomposition race. So, creating a long lasting relationship with fungi was a great idea. These insects have been cultivating crops for over 50 million years. The Ambrosia beetle will create a habitat for the fungus to flourish and in return has a continuous supply of food by feeding on the fungus itself. Leafcutter ants also feed on the fungus but supplies it with fresh leaves instead of self-build wood galleries. The insects will also make sure that the fungus remains in good health by associating with bacteria.

Sadly, many academic institutions are moving away from traditional fields. Expecting that a true understanding of the natural world is not required. We can’t forget the little things in life. They’ve been successful throughout evolution before we even thought of cooking. When the world was getting ready to welcome natural history the doors to the natural world were shut. Although, the eternal need to save humans is forcing human kind to look at insects again. Such as, better understanding in integrated pest management (IPM) to avoid pesticide resistance and reduce crop wastage or decomposition for novel antibiotics.

Author: Ana Natalio @EntoAim

 

 

 

 

Bank Holiday Special – Why insects are so colourful: The complex business of survival

In the desperate struggle to evade predators, many insects have evolved toxic or bad-tasting skin, a camouflaged body (‘crypsis’), or a startle response to scare away predators. In this “evolutionary arms race”, adaptations on one side call forth counter adaptations on the other side. One such defensive adaptation is to appear toxic using brightly coloured (‘conspicuous’) body coloration- this is known as ‘aposematism’ (“Ay-PO-Sematism”). This idea that signals are sent by prey to predators to indicate toxicity was first suggested by Wallace to Darwin in 1861- they theorised that this evolved to stop predators attacking toxic prey to benefit both sides.

Aposematic warning coloration is a widely utilised form of defence used in all the animal kingdom (not just insects) and has evolved separately from many different evolutionary lines (convergent evolution). It can warn predators of defences such as a painful sting, repellent spray (such as a Bombardier beetle’s noxious chemical spray) or a toxic (or unpalatable) taste. Entomological examples of these bright colours include the malevolent yellow and black of wasps, the familiar black-spotted red body of ladybirds and the monarch butterfly’s bright stripes of orange and black with white dots. Even honeybees and bumblebees are striped to warn birds of their painful sting, although the vile taste of their sting must be learned by the predator through repeated encounters.

But why are toxic insects usually conspicuous and not cryptic? A brightly coloured “lone mutant” in a population of cryptic prey would be more easily spotted by predators, seemingly making the genes coding for bright colour less advantageous. However, bright coloration does give a survival advantage- predators will generally only consume similar-looking items and be wary of prey that are novel or conspicuous. For example naïve birds that have not yet encountered toxic prey may have innate colour biases to stop them eating brightly coloured insects. More experienced birds will be able to remember that eating a particular colour pattern will lead to a bad feeling- that is unless some insects cheat however…

Insects that have evolved to mimic another insect’s body pattern, sound or behaviour, usually resemble a dangerous, aposematic species. This is known as batesian mimicry, and can fool predators into thinking it has defences or a bitter taste, when actually it is harmless (this is not to be confused with Müllerian mimicry, where several toxic species resemble each other). These ‘cheats’ gain a survival advantage without having to produce metabolically costly toxins or evolve a ‘weapon’. An example of this is the hornet moth, a mimic of the yellowjacket wasp- it resembles the wasp’s striking body pattern, which deters predators, but it is not capable of stinging. However more mature predators may be able to detect a fake through experience or social learning. So a scarcity of mimics is actually advantageous for both the mimic and the model insect- too many mimics and the predators will stop responding to the warning signals.

Aposematic colouration as an anti-predator strategy is simply an evolutionary alternative to other forms of protective coloration. Other ‘options’ for predator defence include background matching (a form of crypsis) and disruptive coloration, where bold and contrasting colours on an animal’s periphery act to break up its outline and confuse predators. Another intriguing form of protective coloration is known as ‘masquerade’, where the animal resembles an inanimate object (like a leaf) so the predator sees the prey, but mis-classifies it as something inedible. An extreme form of masquerade can be found in the devious pink orchid mantis, which also utilises this technique for hunting- it will wait until an unsuspecting fly lands on it to drink nectar, and instead be grasped and eaten!

AposematismAbove are examples of the different anti-predator defences that insects can achieve using body colour and pattern. (Clockwise from top left: bombardier beetle, green bush cricket, buff-tipped moth and hawk moth.)

Despite the successes of these other forms of defensive coloration, aposematism remains a widespread and successful alternative anti-predator strategy to being camouflaged, which has evolved to protect prey from predators. Predators’ sensory and cognitive abilities have been important in the evolution of warning coloration, and there are ‘cheats’ that take advantage of these otherwise reliable signals of danger.

Author – Chris Mackin (@EntoChris

Further Reading:

Allen, J. A., & Cooper, J. M. (1985). Crypsis and masquerade. Journal of Biological Education, 19(4), 268-270.

Endler, J. A. (2006). Disruptive and cryptic coloration. Proceedings of the Royal Society B: Biological Sciences, 273(1600), 2425-2426.

Endler, J. A., & Greenwood, J. J. D. (1988). Frequency-dependent predation, crypsis and aposematic coloration [and discussion]. Philosophical Transactions of the Royal Society B: Biological Sciences, 319(1196), 505-523.

Mappes, J., Marples, N., & Endler, J. A. (2005). The complex business of survival by aposematism. Trends in ecology & evolution, 20(11), 598-603.

Schmidt, J. O. (Ed.). (1990). Insect defenses: adaptive mechanisms and strategies of prey and predators. SUNY Press.

Sillen-Tullberg, B., & Bryant, E. H. (1983). The evolution of aposematic coloration in distasteful prey: an individual selection model. Evolution, 993-1000.

Stevens, M., & Merilaita, S. (2009). Animal camouflage: current issues and new perspectives. Philosophical Transactions of the Royal Society B: Biological Sciences, 364(1516), 423-427.