Archive for October 2009

The bacteria that kills only male butterflies!

23 October 2009

If you think the swine flu virus was scary, this one makes it look like a Fairy Godmother! Fortunately it is restricted to arthropods and as such is harmless to humans.

But introductions first.

You, Wolbachia does not recognise as you are NOT an arthropod. For Wolbachia, we’ll let Wikipedia do the talking :-

Wolbachia is a genus of inherited bacteria which infects arthropod species, including a high proportion of insects. It is one of the world’s most common parasitic microbes and is possibly the most common reproductive parasite in the biosphere. One study concludes that more than 16% of neotropical insect species carry this bacterium and as many as 25-70% of all insect species are estimated to be potential hosts.”

Wolbachia inside an insect cell.

Wolbachia inside an insect cell.

Now this is really mindboggling. When you say 25 to 70% of all insect species we mean between 1 million to four million ”species” as per the conservative estimate of Gaston (1991) That means Wolbachia is a potential infectant of literally trillions of organisms.

Wolbachia is everywhere, you can’t get away from it.

But so what, we did not know anything about Wolbachia till right now. Why bother?

Because Wolbachia is an organism which detests males, and, by a variety of means, systematically deprives a population of males.

Now, like all males, I am sensitive about my virility, gonads, maleness or what you will. So I instantly recoiled with horror to learn about this organism which specifically targeted the male sex for elimination, albeit in arthropods.

It all started harmlessly when I chose a post from “Not exactly rocket science” in the Science Blogs RSS feed in my Google Reader.

The post states that Wolbachia has seriously affected populations of Hypolimnas bolina, a Nymphalid butterfly called as the Great Eggfly in India or the Blue Moon elsewhere.

The male Blue Moon or Great Eggfly

In grave danger – the male Blue Moon or Great Eggfly.

Commonly found in India, the Great Eggfly is extant from Madagascar in the west across South and Southeast Asia to parts of Australia, Japan and New Zealand and even remote South Pacific islands such as French Polynesia, Tonga, Samoa and Vanuatu.

The female Great Eggfly, once infected, cannot mate successfully with uninfected males.

The female Great Eggfly, once infected, cannot mate successfully with uninfected males.

It appears that this butterfly has been affected severely by Wolbachia. In some islands, notably the Polynesian islands of Ua Huka and Tahiti, Wolbachia, which was virtually absent in the past, is common now and consequently, male butterflies are extremely rare here.

Wolbachia are present in mature eggs, but not in mature sperm. Hence it can propogate only thrugh females and not males; hence the reason for the bacteria developing violently anti-male attitudes!

Only infected females pass the infection on to their offspring. Wollbachia acts in four different ways –

* Firstly, it kills infected males.
* Secondly, it causes infected males to develop into females or infertile pseudo-females.
* Thirdly, it permits reproduction of infected females without males.
* Lastly, the bacterium causes cytoplasmic incompatibility between infected and non-infected insects. Wolbachia-infected males are unable to successfully reproduce with uninfected females or females infected with another Wolbachia strain.

Of this, I find the fact that enables female butterflies to mate without males extremely interesting! Some scientists have suggested that parthenogenesis may always be attributable to the effects of Wolbachia. Parasitic bacteria like Wolbachia have been noted to induce automictic thelytoky in many insect species with haplodiploid systems. They also cause gamete duplication in unfertilized eggs causing them to develop into female offspring.

An example of a parthenogenic species would be the Trichogramma wasp. This wasp has evolved to procreate without males with the help of Wolbachia. Males are rare in this tiny species of insect, possibly because many have been killed by that very same strain of Wolbachia.

All this has been proven thanks to the fact that hundreds of pinned, preserved and catalogued specimens of Great Eggflies can be found in today’s museums. These are from all over and from the heyday of collecting (before Independence).

Emily Hornett, a biologist at UCLA, asked the question –

“How have the ratios of male butterflies to female ones changed over time?”

Concentrating on specimens from the Pacific islands, she observed a number of cases where males reduced in numbers as time passed. Since the DNA of these specimens was still viable, she invented a test which detected the gene sequence of Wolbachia in the genome of the dead insects. She found a very high increase in Wolbachia infection with corresponding effect on the ratio of males to females. From her research, it was clear that Wolbachia steadily went from island to island decimating the males.

Surprisingly, she also detected Wolbachia-resistance in today’s individuals and also in the past in the Phillipines and Samoa. There was evidence of a full scale drawn-out battle beteen Wolbachia and its hosts. In one case, resistance to Wolbachia developed over a very short period of time. This is of great import to us.

The infection mechanism of Wolachia is being extensively studied with the hope of employing this mechanism to halt another killer disease in India, this time of humans, namely malaria.

It is also used to kill the worms which cause filiarisis (elephantiasis). The worms require highly toxic chemicals to kill but a simple antibiotic will kill the Wolbachia in them and they’ll just die because of that!

So, in every cloud, there’s a silver lining. Wolbachia’s hosts have very short lifespans – so it is possible to study evolution in action by researching Wolbachia. And it may possibly help us solve the malaria problem.

Read more about Wolbachia on cheshire’s and hotbacteria’s blog!

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The forcibly adopted child!

21 October 2009

I have a great respect for the God of Lesser Things! The actual God, not the book, I mean. He is kind, he is just and he is fair. Since he rewards us in suitable measure, we should indeed proclaim him as the deity of all amateur naturalists.

To the compulsive lister of species, he sends hordes of small warblers, difficult and challenging to identify and extremely satisfying to record. To the casual bird watcher, who wants to enjoy nature without too many hassles,  he will direct a mother Spotbill with ducklings swimming across his binocular’s view. A beginner will be blessed with a Paradise Flycatcher which will surely make him gaga about the rare wonderful bird that he saw! But this God is especially kind to that least and most obscure community of birdwatchers –  the kitchen window birdwatchers.

To be a member of this club you have to be a hard-working housewife and the glances through the kitchen-window or from the balcony or terrace are the only ornithological indulgences that are allowed  in between the drudgery of chores. I really respect these kitchen-window bird watchers. My mother, my aunt, my wife, my cousin sister – they are all members of this venerable clan.

The gracious God sends them ‘Tit-bits’ (pun intended) to lighten their long labour. My mother was rewarded with the sight of a Jungle Crow with overlong curved upper beak which she attempted to feed to the great happiness of the squirrels. My aunt enjoyed the sight of sunbirds nesting year after year in the bush outside her kitchen window. My sister saw a Spotted Owlet in Pune city in the tree opposite her verandah which wasn’t – it was a Scops Owl which all will agree is a rare and delicious find!

Just a few days ago, my wife, who has a keen eye for sound, heard a harsh call amidst the noisy cackle of the babblers.

The babblers are a familiar feature of Maharashtra’s landscape.  They are earthy-brown, generally unkempt and noisy birds which are always seen in a flock, hence their colloquial name of “Saat bhai” or “Saat behen” (‘seven brothers’ or ‘seven sisters’ in Hindi).

Large Grey Babbler (Turdoides malcolmi)

Large Grey Babbler (Turdoides malcolmi)

The babblers in our garden are the Large Grey Babblers (Turdoides malcolmi). They squabble around our courtyard and never seem to leave our garden. Who can blame them? Here they find – a neatly tended lawn, profusely bloomed flower beds with interesting flowers (both coloured and fragrant), din -k- raja, raat -ki-rani, plumeria, papaya, a small pond deliberately run wild with bulrushes all around it, a variety of trees all around the fence both inside and outside, an interesting garbage heap, a neglected garden patch, a servant’s quarter with its associated fireplace and litter, and long weedy verges aside the driveway. Though they  deign to favour our neighbours from time to time,  its ””’our””’ garden they occupy and I proudly call this flock ”mine”.

Since they are such a constant part of the background, I tend to take them for granted. “Ghar ki murgi dal barabar” so goeth the old adage ( a rough translation of this Hindi proverb is – the delicious chicken dish if cooked at home is considered equal only to the lowly lentil! ).

After all, they are only ”babblers”; virtually the first bird a new birdwatcher learns about and soon tires of. They aren’t as gaudy as the Golden Oriole which flies across our clearing. Or as distinct as the Bharadwaj  (Coucal) that struts across the fence-lawn-pond-papayas route four times a day in his tireless, rapacious search for food! Or as spectacular as the Grey Hornbills which play catch-me-if-you-can amongst the ”Gliricidia” trees. They are plain ashy-coloured biscuit brown birds who cackle and perform but soon tire you of their antics.

But all of a sudden that day, they pulled a rabbit out of a hat. In this case, it was an adopted child! And it was my beloved kitchen window-birdwatcher (my better 99% – for those joining in now) who spotted it!

A forlorn squawk drew her attention to the branches above where the flock foraged on the ground. Above, on the branch of the tree in our backyard, was perched a grey bird heavily striated on its chest. It was a juvenile “Brainfever bird“!

My wife caught her breath, because just then a babbler flew up and deposited a meal in the gaping maw of the young ‘un. The babblers were feeding the bird.

The 'adoped child' and his mom (?).

The 'adoped child' and his mom (?).

There is a simple explanation for this! The “Brainfever bird” is a cuckoo. Most of us will know it as the “papeeha” while birdwatchers call it the Common Hawk-cuckoo (Heirococcyx varius) because it resembles very closely our resident Indian sparrow-hawk – the Shikra.

The Brainfever Bird adult.

The Brainfever Bird adult.

The Shikra (Accipiter badius) which the hawk-cuckoo resembles.

The Shikra (Accipiter badius) which the hawk-cuckoo resembles.

The papeeha is a brood parasite of the Turdoides babblers. When the female babblers are not looking, the female Hawk-cuckoo will deposit its egg in their nest.

Cuckoos are known to roll off some or all of the genuine eggs to make place for their egg. Usually a cuckoo’s egg resembles the host species’ egg very closely in colour and pattern though it may be larger in size. Sometimes birds recognise the eggs as ‘strange’ and eject them but in the majority of the cases they do not.

Looking away - the adopted child's orange bill and indistinct eye-ring are visible.

Looking away - the adopted child's orange bill and indistinct eye-ring are visible.

In some species, the cuckoo’s egg hatches earlier and the young cuckoo fledgeling kicks off the eggs or nestlings of the host species and makes itself the lord of the nest.

The cuckoo sibling is ravenous. Its gaping maw resembles that of the babbler’s nestlings and the plaintive cries trigger the feeding instinct in the babblers. Though it grows larger and looks different from the babblers, the hosts are trapped in their instinctive response which the cuckoo has evolved to take advantage of.

This phenomenon is called “brood parasitism” and is considered a form of “kleptoparasitism” where birds steal resources from others to gain an advantage in  propagating their kind.

A very poor photo with cuckoo and babbler in the same frame.

A very poor photo with cuckoo and babbler in the same frame.

Our brain-fever bird is quite large now. It is larger than its adopted parents but yet it follows the pack around positioning itself at a vantage point above where the babblers forage. Soon it will be able to fend for itself and the babblers will be free from feeding such a hungry brute. Lets hope the next time they are able to raise their own kind.

Fortunately Large Grey Babblers are irregular in habit in breeding while cuckoos breed as per season so they have a far chance of raising their kind. The breeding season of the Common Hawk Cuckoo varies from place to place and is very dependent not only on its hosts but its very competitive cousin, the Pied Crested Cuckoo (Clamator jacobinus) who also parasitises the same hosts – the babblers.

Brainfever birds are relatively benign parasites. On many occasions the host is able to raise its own chicks as well as that of the cuckoos. The babblers are known to collectively rear the young. Parent babblers often rejoin the flock after the fledgelings have flown. However, the adopted child of the Brainfever bird is dependent for much longer and hence our observations in CME. As per T.C. Jerdon, Brainfever birds often do not eject the eggs or young and permit the host to breed its children alongwith them.

This is not so in the case of its relative, the Great Spotted Cuckoo (Clamator glandarius) of Europe. The female of this species exhibits an extreme form of aggressive brood-parasitism, referred to as the “Mafia hypothesis“. She revisits the nests of the host birds where she has laid an egg. If that egg has been ejected, she lets loose her anger and destroys the nest. This is a very good move on her part – if a nest is destroyed early in a season,  the nesting pair of the host species may rebuild the nest and lay another clutch. This will give her a chance to breed once again. She will again visit the new nest repeatedly to ensure her egg is safe and repeat her destruction if the egg is mising.

This is however an extreme case of animal behaviour and shared by one another species only – the Brown-headed Cowbird of subtropical North America.

Great Spotted Cuckoo, a.k.a. the Mafia cuckoo

Great Spotted Cuckoo, (clamator glandarius) a.k.a. the Mafia cuckoo

Before you get all furious over our cuckoos, remember enough of their hosts breed so as to maintain a large enough population to bring up the next generation of cuckoos. Too high a success rate in nest-parasitism is its own death knell.

Besides, the host birds develop behavioural patterns to reduce the effectiveness of the brood-parasites – an evolutionary battle constantly rages between the hosts and the brood parasites.

Most of all we should not denigrate these birds because it is they who provide the beautiful bird calls which warn of the onset of India’s summer, monsoon or spring.

The koel’s crescendo and the “brain-fever brain-fever” call of the papeeha are known to all.

My favourite memory of cuckoo-calls is that of   the liquid four notes of the Indian Cuckoo in the Himalayan spring which remind me of the first four notes of the popular Ventures tune “Popcorns’ which once accompanied Sports Roundup in the good old days of black and white TV! Many’s the time I returned tired from a run at the Indian Military Academy when the Indian Cuckoo luled me to sleep.

Listen to it here!

Besides this, we have the Plaintive Cuckoo, the Drongo-Cuckoo and so many, many more.

They too are the gems of Indian biodiversity.

Some references.

1.    Gaston, AJ & Zacharias VJ. (2000). “Hosts of the Common Hawk Cuckoo”. Forktail Vol 16, pg 182. Pulication of the Oriental Bird Club.[url=http://www.orientalbirdclub.org/publications/forktail/16pdfs/Gaston-Cuckoo.pdf].

2.    Jerdon, T.C. (1862). “The birds of India”. Volume 1 (pg 330). Pub – Military Orphan Press. Calcutta.[http://www.archive.org/stream/birdsofindiabein01jerd#page/330/mode/1up].

3.  Payne, R.B. (2005). “The Cuckoos”. Oxford University Press. ISBN 0198502133.

Credits

* All pix of “forcibly adopted child” and that of the Large Grey Babbler mine. See my license publicly declared on the blog.

* Brainfever Bird adult – nidhingpoothully Creative Commons Attribution License 2.0 . On Wikimedia Commons here.

* Shikra – J.M. Garg. Creative Commons Attribution ShareAlike 3.0 license On Wikimedia Commons here.

* Great Spotted Cuckoo (Clamator glandularius). 1905 Naumann encyclopaedia. Public domain. Wikimedia Commons link.


Do you know – Mushrooms?

11 October 2009

As a gesture of thanks to all the visitors  to the post “Mushrooms – by Sylvia Plath“, this ‘Do  You Know?’ has been placed.

Did you know that –

* the mental picture we have of a mushroom with cap, gills and stalk is typical only of the Agaricales, (an example being the store-bought White mushroom). The wide variety of shapes a mushroom can take can be understood from their names – polypores, puffballs, jelly fungi, coral fungi, bracket fungi, stinkhorns, and cup fungi.

Fungi such as this one is considered as a mushroom.

Polypore fungi such as this one are considered as mushrooms.

Unidentified mushroom growing on a decaying log in Calais, France

Unidentified filamentous mushroom growing on a decaying log in Calais, France

Woody bracket fungus - also considered a mushroom!

Ungulina marginata, a woody bracket fungus - also considered a mushroom!

Yellow Coral Mushroom

Yellow Coral Mushroom

* not all mushrooms are edible, the vast majority of these produce a vast array of toxins and allergens. You should only eat a commercially produced mushroom or a known edible mushroom reliably identified by an expert.

Shiitake - an edible Japanese mushroom whch was the subject of word play in an Austin Powells movie.

Shiitake - an edible Japanese mushroom whch was the subject of word play in an Austin Powells movie.

* many mushrooms produce secondary metabolites that render them toxic, mind-altering, or even bioluminescent.

Foxfire is the term for the bioluminescence created by a few species of fungi, such as 'Omphaltos nidiformes' that decay wood.

Foxfire is the term for the bioluminescence created by a few species of fungi, such as Ghost Mushroom 'Omphaltos nidiformes' that decay wood.

Panellus stipticus, a green bioluminescent bracket fungus.

Panellus stipticus, a green bioluminescent bracket fungus.

* the term ‘toad-stool’ was used in earlier times for poisonous mushrooms.

Fly agaric (Amanita muscaria) is the quintessential mushroom of British folklore.

Fly agaric (Amanita muscaria) is the quintessential toadstool of British folklore.

The Death-cap (amanita phalloides) contains amatoxins which are toxi to the liver. It resembles several common edible mushrooms and thus features in many accidental poisoning cases.

The Death-cap (Amanita phalloides) contains amatoxins which are toxic to the liver. It resembles several common edible mushrooms and thus features in many accidental poisoning cases.

* though mushrooms are commonly thought to have little nutritional value, many species have nutritional or medicinal value. Many mushrooms are high in fiber and provide vitamins such as thiamine, riboflavin, niacin, biotin, cobalamines, ascorbic acid. Mushrooms are also a source of some minerals, including selenium, potassium and phosphorus.

White or button mushrooms (Agaricus bisporus) ready for cooking. While common, they are just one of the many types of mushrooms cultivated and eaten.

White or button mushrooms (Agaricus bisporus) ready for cooking. While common, they are just one of the many types of mushrooms cultivated and eaten.

* some mushrooms, if exposed to UV light can become valuable sources of Vitamin D.

* poisonous mushrooms containing hallucinogenic substances are eaten by some people in order to get a ‘high’!

Dried psilocybe mushrooms contain hallucinogenic substances such as Psilocin and Psilobycin and were known to the Aztecs as 'divine mushrooms'. (Notice the characteristic blue bruising by the end of the stems.)

Dried psilocybe mushrooms contain hallucinogenic substances such as Psilocin and Psilobycin and were known to the Aztecs as 'divine mushrooms'. (Notice the characteristic blue bruising by the end of the stems.)

* oyster mushrooms, a widely eaten mushroom,  naturally contain the cholesterol drug lovastatin.

The Oyster mushroom (Pleurotus ostreatus) is the subject of many medical research initiatives.

The Oyster mushroom (Pleurotus ostreatus) is the subject of many medical research initiatives.

* that a large number of valuable drugs such as penicillin, lovastatin, ciclosporin, griseofulvin, cephalosporin, and ergometrine, have been isolated from the fungi kingdom.

Collection of medicinal mushrooms including Enoki, King Oyster mushrooms, and Shiitake.

Collection of medicinal mushrooms including Enoki, King Oyster mushrooms, and Shiitake.

* that in Tolkien‘s trilogy “The Lord of the Rings” the favourite food of hobbits is mushrooms.

A Hobbit - an image by Andre DeWitt

A Hobbit - an image by Andrew DeWitt

Credits –

* All mushrooms – Wikimedia Commons. Original filenames have not been changed for all the photos.

* A Hobbit – Andrew DeWitt, drew this picture at ehow.com to show us how to draw a hobbit! Used non commercially here under ‘fair use’.

Everybody sang!

8 October 2009
Pure joy of flight! Terns at the seashore!

Pure joy of flight! Terns at the seashore!

EVERYBODY SANG!

Everyone suddenly burst out singing;
And I was filled with such delight
As prisoned birds must find in freedom,
Winging wildly across the white
Orchards and dark-green fields; on—on—and out of sight.

Everyone’s voice was suddenly lifted;
And beauty came like the setting sun:
My heart was shaken with tears; and horror
Drifted away … O, but Everyone
Was a bird; and the song was wordless; the singing will never be done.

Capt Siegfried Sassoon, Military Cross

Wild Geese against the setting sun!

Wild Geese against the setting sun!

2/Lt Siegfried Sassoon, Royal Welch Fusiliers in 1915

2/Lt Siegfried Sassoon, Royal Welch Fusiliers in 1915

Another of my favourites! Siegfried Sassoon is a war poet who writes about the futility of war.  Here, in this poem, like in “Waiting for Godot“,  Becket‘s Godot or Sassoon’s freedom and its associated happiness never comes! I feel that by ‘ freedom’ he means ‘freedom from strife’. Though we desire it, we are ultimately never free from war.

This poem was written by Sassoon just after the Armistice, the official end to World War I, was declared.

This diatribe against war comes from the words of a soldier who saw the futility of lives lost in the ‘danze macabre’ that was World War I. Unsuccessfully recommended for a Victoria Cross, Sassoon was an exceptionally brave and soldier and an effective leader of men.

The poem, like all good ones, is open to multiple interpretation.

Credits – Wikimedia Commons, here, here and here.