What doesn’t kill you, doesn’t always make you stronger! If you are a bee.

Some pyrethroid insecticides have in the past been considered safe for bees because they have a repellent effect which is thought to keep the bees away from insecticide-covered flowers. The chemical drives them off. But it has been known that when pyrethroids are applied in the presence of foraging bees this results in a reduction in their activity (1). Scientists have now found that the affected bees slow down markedly, travel less and spend less time interacting with other bees – vital for bee colonies. They used video-tracking software to quantify these differences in bee behaviour (2).

In the USA, honey bees are carted about the country in vast numbers, to ‘service’, i.e. pollinate, a wide variety of crops like almonds, sunflowers, oil seed rape, apples, grapes and so on. Most crops in fact. A market that was worth an estimated $626 million dollars in 2012 (USDA: Link 3).

The bees didn’t get a penny! In fact, nearly 40% of these American colonies died off last year (2015), although they are quickly replaced with new ones (4). Many of the colonies are placed in orchards which have been sprayed with pyrethroids. Over one million acres of U.S. orchards are sprayed with pyrethroids (5). Whilst the bees are not killed outright by the insecticides, it is now becoming clear that they suffer sub-lethal effects. And although these effects don’t kill them, they definitely don’t make the bees stronger either! Although the link is not proven, it does not seem surprising to me that many of them die after suffering this stress, particular if they experienced heavy doses; together with the additional stress of being transported for thousands of miles on the back of lorries (3).

This study carried out in Nebraska, showed that the effects of the chemicals we put into the environment can be subtle; more subtle that was at first thought and shows that the risks need to be assessed carefully to pick up these sort of low-level effects. In this case it took careful experiments using video-tracking and computer software to quantify differences that might not be obvious to the unaided eye. After all, we can’t ask the bees how they are feeling! Or more accurately, they cannot reply.

It would of course be better if all of our crops round the world were pollinated by native wild pollinators; some of them are, but we need a more sustainable type of agriculture that focuses more on the impact of farming practices on the environment and less on maximizing profit. But farmers have to make a living and we might have to pay more for such a system? Or accept less production. In the meantime, spare a thought for the bees which gave their lives so that we can could enjoy our Californian grapes and cherries!

  1. http://www.agro.basf.co.za/agroportal/za/media/l6/productcatalogue/products/insekdoders/fastac_sc.pdf
  2. Ingram, E. M., Augustin, J., Ellis, M. D., & Siegfried, B. D. (2015). Evaluating sub-lethal effects of orchard-applied pyrethroids using video-tracking software to quantify honey bee behaviors. Chemosphere, 135, 272-277.
  3. http://www.ers.usda.gov/media/1679173/special-article-september_-pollinator-service-market-4-.pdf
  4. http://www.globalresearch.ca/death-and-extinction-of-the-bees/5375684
  5. https://entomologytoday.org/2015/05/29/pyrethroid-insecticides-alter-honey-bee-behavior/

Orchids come and go!

Common spotted orchid (Dactylorhiza fuchsii) 3 July 2016
Common spotted orchid (Dactylorhiza fuchsii) 3 July 2016

Orchids flower over quite a long period, with the dates of the flowering season varying somewhat with latitude. In Scarborough, I spotted (sic) my first Common spotted orchid – in the meadows of Scarborough Castle – on the 9th June this year (2016). See below.

Common spotted orchid coming into flower on 9th June 2016
Common spotted orchid coming into flower on 9th June 2016

There must be quite a lot of individual variation between flowers, as in any population, with some flowering early and others coming along later. There is an abundance of this orchid on the slopes of North Bay, Scarborough. One of the best sites I found was behind the public lavatory on the Royal Albert Drive! There was a profusion of orchids behind the building in early July when I took these picture (they are probably still flowing there now in late July).

Common spotted orchid (Dactylorhiza fuchsii) 3 July 2016
Common spotted orchid (Dactylorhiza fuchsii) 3 July 2016

The Common spotted orchid flower is of course an inflorescence composed of many flowers on a spike. The individual flowers are made up of a three-lobed lip, two sepals on either side (a bit like ears!), and petals which make the hood above the reproductive bits! See below.

Common spotted orchid (Dactylorhiza fuchsii) 3 July 2016
Common spotted orchid (Dactylorhiza fuchsii) 3 July 2016

These orchids rely on insects to pollinate them and the red markings on the lip are thought to be guides for insects to follow, towards the source of the nectar. The plants are hermaphrodites, meaning that they have both male and female reproductive organs; there is one stamen (male) and two stigma (female) on each flower. The shape of these tiny little organs looks rather suggestive, or am I imagining it? See below.

Common spotted orchid (Dactylorhiza fuchsii) 3 July 2016 close up
Common spotted orchid (Dactylorhiza fuchsii) 3 July 2016 close up

Pyramidal orchids come into flower a bit later than Common spotted orchids. I photographed the one below in early July; it was just starting to open, from the bottom upwards.

Pyramidal orchid (Anacamptis pyramidalis) Scarborough early 3rd July 2016
Pyramidal orchid (Anacamptis pyramidalis) Scarborough early 3rd July 2016

Later on, they take on their more pyramidal shape, although they can also be quite rounded.

Pyramidal orchid (Anacamptis pyramidalis) on 19th July 2016
Pyramidal orchid (Anacamptis pyramidalis) on 19th July 2016

Small black pollen beetles can be see on one of these flowers (below).

Pyramidal orchid (Anacamptis pyramidalis) with pollen beetles on 11th July 2016
Pyramidal orchid (Anacamptis pyramidalis) with pollen beetles on 11th July 2016

These common but nevertheless, beautiful orchids will all too soon be over, but they are perennials, so die back down to their tubers in the ground, ready to spring up again next year. Just an everyday miracle we call Nature!

Such good parents!

Black-legged kittiwake parent and chick on 20th July in Scarborough
Black-legged kittiwake parent and chick on 20th July in Scarborough

Kittiwakes are such good parents! They each spend roughly the same amount of time on the nest looking after the chick(s), whilst the other goes in search of food. During the day, each bird is away from the nest for about 2 hours and 48 minutes (on average) apparently, searching for food to bring back to feed the hungry mouth, or mouths. There may be one or two chicks, occasionally three.

Black-legged kittiwake parent and chick on 20th July, Scarborough harbour
Black-legged kittiwake parent and chick on 20th July, Scarborough harbour

They have a delightful greeting ceremony when one birds returns to the nest and reinforces its bond with the remaining partner. A short while after the greeting, without any ado, they change round and the other bird flies off.

Black-legged kittiwakes (Rissa tridactyla) greeting each other on return to nest
Black-legged kittiwakes (Rissa tridactyla) greeting each other on return to nest
Black-legged kittiwakes (Rissa tridactyla) bonding on return to nest
Black-legged kittiwakes (Rissa tridactyla) bonding on return to nest

The chicks get four or five feeds per day on average (data obtained from the Farne Islands) which provides them with up to 125g of fish per day, although this drops off as they approach fledgling. Despite the hard work of the parents, the chicks seem to beg continuously, even when the parent is dozing!

Black-legged kittiwake chick on 13th July
Black-legged kittiwake chick on 13th July

There is a week between the photographs above and below, of birds nesting in an old, disused electrical junction box by Scarborough harbour.

Black-legged kittiwake chick begging for food
Black-legged kittiwake chick begging for food

The parents are also very dutiful; one parent is almost always present on the nest until the chick is about 33 days old and a reasonable size. In situations like in Scarborough, where there are greedy Herring gulls living cheek by jowl with kittiwakes, the parent needs to protect the growing chick from being predated.

Black-legged kittiwake parent and chick on 20 July, Scarborough harbour
Black-legged kittiwake parent and chick on 20 July, Scarborough harbour

In some sites in Scarborough, including by the lighthouse and on the window sills of the Grand hotel for example, kittiwakes have nests which are very close to where people walk by. They have presumably adapted to the stares and gazes of humans, but the parent birds are occasionally flushed off the nest by a disturbance, but they soon return. Unlike Herring gulls, kittiwake chicks seem better adapted to urban life and don’t seem to fall off their ledges very often!

Kittiwake chick on 20th July
Kittiwake chick on 20th July

We are I think, extremely fortunate to have this beautiful bird living with us in Scarborough. I for one, love their iconic call, and relish witnessing their live cycle every year. The fact that they can survive the rigours of the North Atlantic during the winter (see link 1 to previous blog), yet sit on a ledge above a shop every summer, increases my admiration for this remarkable bird.

  1. https://rcannon992.com/2015/10/26/kittiwake-kittiwake/
  2. Facts and figures taken from: Coulson, John. The kittiwake. A&C Black, 2011.

Bees knees and tongues!

Bombus hortorum on sea clover, Galicia, Spain
Bombus hortorum on sea clover showing long tongue or proboscis, Galicia, Spain

Since it’s Bees Needs week, I thought that I would put together a blog about bees using photographs I have taken recently in Scarborough and Spain. Taking photographs of bees is fun, but it is a bit of a hit and miss process and you need to take quite a lot of shots to get some good ones. Well at least I do! One thing that strikes one when looking at photographs of bees feeding (nectaring) on flowers, is their tongue, or proboscis. In the following photo, a common carder bee does not look like it is having any problem obtaining nectar from a Birds-foot-trefoil flower, but it might be challenged by flowers with long corollas (the tube leading down to the nectar).

common carder bee (Bombus pascuorum) on Birds-foot-trefoil
Common carder bee (Bombus pascuorum) on Birds-foot-trefoil, UK

The bumblebee tongue or proboscis is a complex organ which consists of a tongue proper – with a hairy or feathery end adapted for absorbing nectar – sheathed in a pair of palps and the maxilla (1). For a fantastic close-up photograph of a bumblebee tongue, click on the link below (link number 2) to the site of macro photographer, Adrian Thysse. The Early bumblebee, in the following photograph, has a relatively short tongue compared to some other species, but it still looks quite long in this image.

Early bumblebee (Bombus pratorum) with tongue showing
Early bumblebee (Bombus pratorum) with tongue showing

The hard, shiny maxilla which sheathes the tongue can be seen in the following photograph of a Garden bumblebee, Bombus hortorum. The tongue can be well over one centimeter long in this species (see below).

Bombus hortorum proboscis or tongue. Galicia, Spain.
Bombus hortorum proboscis or tongue. Galicia, Spain.

Bumblebees with long tongues are in general able to access nectar from a greater variety of flowers than those with short tongues, and as a consequence they feed on a larger number of species (3), assuming that they are available in a given habitat. The long-tongued bumblebees have also been found to forage significantly faster than bees of shorter proboscis length on flowers with long corolla tubes (4). Bumblebees with shorter tongues, not surprisingly perhaps, preferred to forage on flowers with short corolla tubes and were more efficient at getting nectar from them.

Common Carder Bee (Bombus pascuorum) on Sea vetch
Common Carder Bee (Bombus pascuorum) on Sea vetch

Relative tongue lengths of worker bumblebees are shown in the following table taken from the www.bumblebee.org site (1), although it is worth remembering that the glossa is a flexible and somewhat elastic organ. The data come from Brian (1957) I think (5).

Species

Tongue length mm

Bombus hortorum

12.0

Bombus lapidarius

6.0

Bombus pascuorum

7.6

Bombus pratorum

6.4

Bombus terrestris/lucorum

5.8

As well as having different tongue lengths and visiting a different range of flowers, bumblebees of different species have been found to collect a different range of pollen (6). The pollen is carried in a pollen sac, or pollen basket, which is just a flat area on the leg surrounded by a cage of spiky hairs. I am always impressed how bumblebees are seemingly able to multitask: feeding on nectar at the front end; walking with their forelegs; and scraping/combing pollen towards the basket on the rear legs, with their middle legs! The sacs of pollen look so large sometimes, the aerodynamics of the bee must change depending on whether the pollen basket is full or empty!

White-tailed bumblebee (Bombus lucorum) with pollen sac landing on kidney vetch
White-tailed bumblebee (Bombus lucorum) with pollen sac landing on kidney vetch

Another White-tailed bumblebee (below) has an empty pollen sac, and it is possible to see the fringe of hairs on the hind leg, which form the basket.

White-tailed bumblebee (Bombus lucorum) showing an empty pollen basket
White-tailed bumblebee (Bombus lucorum) showing an empty pollen basket

Another feature which sometimes becomes apparent when taking photographs of bumblebees, is the presence of tiny mites clinging on to their bodies. One can be seen, just under the wing, in the following photograph of a Common carder bumblebee.

Common Carder Bee (Bombus pascuorum) with phoretic mite highlighted
Common Carder Bee (Bombus pascuorum) with phoretic mite highlighted

These are generally assumed to be fairly harmless, in that although they live in bumblebee nests, they only feed on the detritus, wax, pollen and rubbish discarded by the bees! They use the bees as a form of transport and can get on and off as they please; a bit like getting off one bus and boarding another; the bus stop in this case, being a flower! If they cling on until the bumblebee returns to its nest, they can move home in this way. The technical term for this behaviour is called phoresis, so they are phoretic mites. They are also called commensals, which means that they are involved in a symbiotic relationship in which one species (the mites) is benefited while the other is unaffected (the bees).

Common Carder Bee (Bombus pascuorum) with mite highlighted
Common Carder Bee (Bombus pascuorum) with phoretic mite highlighted

There are of course damaging, parasitic mites, like the Varroa mite, but that is another story. The numbers of phoretic mites per bee can vary enormously and in one study ranged from one individual to over 100 per bumblebee (8); 200 per bee in another (9). Why some bees have so many, and what it means for them in terms of their health and fitness is something that is being studied, and my guess is that there is more to this relationship between bees and mites than we may realise.

  1. http://www.bumblebee.org/bodyTongue.htm
  2. http://bugs.adrianthysse.com/2015/01/in-memorium-the-tongue-that-killed-my-flash/
  3. Harder, L. D. (1985). Morphology as a predictor of flower choice by bumble bees. Ecology, 66(1), 198-210.
  4. Inouye, D. W. (1980). The effect of proboscis and corolla tube lengths on patterns and rates of flower visitation by bumblebees. Oecologia, 45(2), 197-201.
  5. Brian, A. D. (1957). Differences in the flowers visited by four species of bumble-bees and their causes. The Journal of Animal Ecology, 71-98.
  6. Brian, A. D. (1951). The pollen collected by bumble-bees. The Journal of Animal Ecology, 191-194.
  7. https://www.rhs.org.uk/science/conservation-biodiversity/wildlife/encourage-wildlife-to-your-garden/plants-for-pollinators
  8. Chmielewski, W., & Baker, R. A. (2008). Mites (Acarina) phoretic on some common bumblebee species (Bombus spp.) from the Pulawy area (South-Eastern Poland). Journal of Apicultural Science, 52(1).
  9. Matias Maggi, Mariano Lucia, Alberto Abrahamovich. Study of the acarofauna of native bumblebee species (Bombus) from Argentina. Apidologie, Springer Verlag, 2011, 42 (3), pp.280-
    292.

Tiny green metallic wasp

Yellow Dung Fly - Scathophaga stercoraria (right) and tiny green wasp (far left) on umbel
Yellow Dung Fly – Scathophaga stercoraria (right) and tiny green wasp (far left) on umbel

I took a picture of this fly, which I think is a common Yellow Dung Fly (Scathophaga stercoraria), sitting on the inflorescence of an umbelifer plant. When I looked closely I noticed that there was also a tiny little, metallic green wasp in the photograph as well (far left). There is not much to go on, but I think it is a chalcid wasp, perhaps Cecidostiba fungosa. It certainly looks a bit like the one in the photograph which was identified on the iSpot website (1).

Close up of chalcid wasp possibly Cecidostiba fungosa
Close up of chalcid wasp possibly Cecidostiba fungosa

The smallish eyes and yellow legs are the same.  There is also quite a nice photograph on the web of a very similar tiny metallic wasp with yellow legs but no identification. (2). It’s fun to come across unexpected guests and educational to try and identify them, albeit virtually!

This photograph was taken by the car park at Flamborough Head whilst I was visiting the lighthouse (Yorkshire, UK).

  1. http://www.ispotnature.org/node/126830
  2. https://uk.pinterest.com/pin/341569952964359587/

 

 

Spaced out aphids!

Sycamore aphids (Drepanosiphum platanoides) exhibiting spaced out gregariousness
Sycamore aphids (Drepanosiphum platanoidis) exhibiting spaced out gregariousness

I remember being delighted when, as an undergraduate studying zoology, I first came across the term ‘spaced out gregariousness’. This memorable phrase was coined by Professor J S Kennedy (1912-1993) and colleagues to describe organisms such as the sycamore aphid, which are gregarious – they are attracted to the presence of another aphid – but keep a certain distance between themselves. Unlike some other aphids which readers may have noticed, like the black bean aphid – which forms dense clumps – these spaced out aphids “like to be in a crowd but to have their own personal space”, to quote another aphid biologist, Professor Simon Leather (1). As we shall see, they are to a certain extent repelled by each other at a fine scale, but attracted enough to want to be as close together as they are comfortable with! (2).

How does this work? There exists around each stationary (or settled) aphid, a ‘tactile envelope’ and if any appendage of a neighbouring aphid intrudes into this space, they swing their antennae, kick their legs and sway their bodies! (2).  If all that touching gets too much for them they move away! So by a process of contact and jostling they manage to space themselves out so that they are each surrounded by a roughly circular ‘reactive tactile envelope’ – see below (and reference 2). There must be a bit of jostling and readjustment from time to time as they do need to move about the leaf and plug into new feeding sites.

Approximate 'tactile envelope' of a Sycamore aphid (Drepanosiphum platanoidis)
Approximate ‘tactile envelope’ of a Sycamore aphid (Drepanosiphum platanoidis)

Notice in the following image (within the oval) how the left antenna of one sycamore aphid (on the right) is just touching the middle right leg of the individual on the left! Presumably, this sort of touching and testing goes on all the time.

Sycamore aphids (Drepanosiphum platanoidis) close up of spaced out gregariousness with legs and antennae touching
Sycamore aphids (Drepanosiphum platanoidis) close up of spaced out gregariousness with legs and antennae touching

There is some leeway in the system though, because as sycamore aphid populations build up they become more densely spaced on the leaves, or at least there are more individuals close to each other (6). The spacing all seems to be done by touch rather than vision. Researchers found that if you cut off their long antennae they all shuffle up and end up closer together, as their shorter legs do not reach anything like as far as their antennae!

Sycamore aphids (Drepanosiphum platanoides) mainly on one side of a leaf
Sycamore aphids (Drepanosiphum platanoidis) mainly on one side of a leaf

It is apparent from the above photograph that the aphids appear to favour one side of the leaf in this case and seem to be avoiding large – relative to their tiny size – portions of the leaf. This is probably because this unoccupied part of the leaf is unsuitable as a result of being brushed by other leaves when the wind blows. The fact that the aphids would be knocked or brushed off by the regular movement of leaves in the wind, means that the space that they can occupy on favourable leaves, like this new growth, is more restricted than might at first be supposed (4). The apparent abundance of space on the leaves is therefore a bit misleading as the sycamore aphids have to sit and extract their food in a relatively safe and sheltered micro-site, e.g. within folds in the leaf (5). The micro-climate under the leaves is another factor which may determine their distribution; subtle differences in temperature or humidity may occur at a level we large humans cannot detect.

These aphids have worked out a way of being ‘solitary and gregarious’ (2) at the same time! They like their own personal space but benefit from being in a loosely aggregated group, within reach of one another but with enough space to avoid bumping legs and antennae too many times with their neighbours. Very British you might say!

To gauge the size of these aphids, the following image shows a small group of sycamore aphids on the underside of a leaf (pointing the camera upwards) with a fly silhouetted on the other, top side.

Sycamore aphids (Drepanosiphum platanoidis) spaced out gregariousness with fly
Sycamore aphids (Drepanosiphum platanoidis) spaced out gregariousness with fly

To have a very close up look at these aphids – including their different life stages – and their predators and parasites: see the following link (7).

  1. https://simonleather.wordpress.com/tag/spaced-out-gregariousness/
  2. Kennedy, J. S., and L. Crawley. 1967. Spaced-out gregariousness in
    sycamore aphids Drepanosiphum platanoides (Schrank) (Hemiptera,
    Callaphididae). J. Anim. Ecol. 36:147-70.
  3. Brady, John. “JS Kennedy (1912-1993): A clear thinker in behavior’s confused world.” Annual review of entomology 42.1 (1997): 1-22.
  4. Dixon, A. F. G. (1969). Population Dynamics of the Sycamore Aphid Drepanosiphum Platanoides (Schr.) (Hemiptera: Aphididae): Migratory and Trivial Flight Activity.”Journal of Animal Ecology 38(3), 585-606.
  5. Dixon, A., & McKay, S. (1970). Aggregation in the Sycamore Aphid Drepanosiphum platanoides (Schr.) (Hemiptera: Aphididae) and its Relevance to the Regulation of Population Growth. Journal of Animal Ecology, 39(2), 439-454.
  6. Dixon, A. F. G., & Logan, M. (1972). Population density and spacing in the sycamore aphid, Drepanosiphum platanoides (Schr.), and its relevance to the regulation of population growth. The Journal of Animal Ecology,  41(3), 751-759.
  7. http://influentialpoints.com/Gallery/Drepanosiphum_platanoidis_common_sycamore_aphids.htm