On the use of Pesticides

Silent Spring was published  in 1962. In it Rachel Carson   raised an accusing  finger at the indiscriminate use (often as an aerial spray) of the insecticide DDT, (dichloro diphenyl trichloroethane). She shook the  collective conscious of the society to take note of the environmental deterioration happening around; what the pesticide was doing to the bees and birds.  The use of  DDT as a pesticide  was finally banned in the US in 1972.  Half a century later we are still struggling  with pesticides; should we or shouldn't we?    In 2012 alone over 3500 research papers have been published on the lingering effects of pesticides  in the environment. Even so   in 2012 the pesticides' sale stood at several billion dollars ( the break up goes like this . Herbicides: 40%  , Insecticides: 33%, Fungicides: 10%, Others: 10%)
  
This is the current state with ~6 billion population. Another three and a half decades and human population will touch the 9 billion mark.  Farm lands  will shrink to yield space for   housing colonies and offices. With limited agricultural land,  how to feed  the 9 billion? Quite a challenge and many  living today will  get a chance to witness it, because 2050 is near future. The question is can we repose faith in fertilizers and pesticides alone  to double, triple or quadruple the farm output? As facts stand today this will be suicidal. Because fertilizers don't distinguish between crop and weeds and pests have developed resistance to several pesticides. Besides in many places environmental accumulation of pesticides have begun to spell disaster for human beings as well.    

What alternatives do we have? Or do we have alternatives? It is indeed true that science and technology have been our constant companions  helping us  to improve quality of life in many different ways.  However it is necessary that we exercise caution and discretion, or   else  we land up  in greater dangers.  August 16th issue of  Science has reviewed the current situation with respect to pesticides. Several articles reiterate the need to adopt  an Integrated Pest Management Program worldwide .Two reports one is from down under and the other from Vietnam,  are eye openers. 

Ryegrass
Courtsey : Wikipedia 

Ryegrass menace has been with us from biblical times.It is a persistent weed which grows alongside wheat crop. And the weed enjoys unhindered growth in Australia.  Initially Hoegrass, a herbicide  could contain  the weed. Then gradually the dosages had to be increased  and ultimately  the weed developed  resistance to the herbicide. Then farmers switched to other herbicides,  but to no avail, because continuous use and large doses again led to herbicide resistance. Then AHRI (Australian Herbicide Resistance Initiative), set up by Powles, himself a farmer,  took up the responsibility  to educate farmers.  First of all, the farmers were told that they MUST read the label and follow precisely the directions on the label regarding the  usage and dosage. They must not exceed the recommended doses.  Second, just like crop rotation, they must   keep changing the herbicide every year, so that the weed doesn't get time to develop  resistance. These steps together with mechanical destruction of the weed seeds have proved   immensely useful. 

Brown Planthopper
Courtsey:
RRI supports Thai move to stop insecticide use in Rice

The other story comes  from the lush green  rice fields of Mekong delta in Vietnam. With help from the International Rice Research Institute (IRRI, Philippines), farmers here have learned to cut down on pesticides by almost 80% through the practice of Integrated Pest Management Program. Planthoppers (Nilaparvata lugens) is the biggest enemy of rice crop  and bees and wasps are its predators. Now  along the field dividers, farmers grow a variety of plants including flowering plants.  The flowers attract bees and wasps  which   feast on the planthopper larvae on the rice plants then settle on the flowers for the dessert of nectar. 

We may not be able to say NO to pesticides altogether but we can definitely reduce and even eliminate  their ill effects by judicious usage. 

Reference 

1. Silent Spring : Rachel Carson,  Penguin Classics ISBN:9780141184944 
2.Science  16 August 2013 special section on Pesticides

Tales of Adaptation

"The reasonable man adapts himself to the world, but the unreasonable one persists in trying to adapt the world to himself. Therefore, all progress depends on the unreasonable man."- 

So spake George Bernard Shaw.  Biologically  we are   hard  wired to  adapt, but mentally we are determined  to resist and conquer   Adaptation   is not an accident, but an  intentional evolutionary trick, in other words a  time tested  route to survival.  Recent  research papers highlight this unique trait  the  quintessential characteristic of evolution,  instances when adaptation becomes  the best form of resistance. Here are a few such tales. 

We don't consider cockroaches intelligent, even when told that in the event of a nuclear war, they will be the sole survivors. We  lay all kinds of traps for them, to wipe them from the surface of the earth.  However, the tiny cockroach is smart enough to see through all such  tricks and in turn develops its own defense strategy. Sugar   is the key  additive in  the bait recipes to lure cockroaches  and  would you believe it, German cockroaches (blattella germanica) have evolved a clever way of saying "NO" to these sweet poisons.   Wada-Katsumata and his team carried out a  comparative study of two populations of cockroaches over several years.   The test group,  was consistently and continuously exposed to  glucose containing insecticide and the control group   was reared free of  restrictions. The lifespan of these insects could be as long as  9 months. After several years,  using glucose and caffeine for sweet and bitter taste the team monitored the responses of both populations of   cockroaches. That is, they monitored the responses of four specific GRNs, ( Gustatory Receptor Neurons, or simply the  taste buds) of cockroaches. GRNs are the quality control lab for edibility and taste.   In normal unbiased cockroaches  GRN1 responds exclusively  to sweet taste, and GRN2   exclusively to bitter , while GRN3 and 4 could be titillated by both sweet  and bitter taste.  Analyzing the  resultant neuronal signals generated at these GRNs,   the  investigators  found that years of continued exposure to  sweet poison,  triggered glucose aversion in the test  population. Their  GRNs had undergone modifications with the result that sugar   tasted  bitter and they consciously avoided the baits.   And this   information was built into their genetic make-up and passed on to  successive generations. 

Just as,  thousands of years ago,  natural selection favored a deliberate mutation in the hemoglobin gene of the sub Saharan Africans faced with a deadly form of malaria. This mutation  turned the nice spongy disc like hemoglobin into a sickly looking sickle shape  but bestowed resistance to the disease and thus  ensured survival. It is  suggested  that  sickle cell hemoglobin molecules don't confront the  malaria parasites at all, they simply raise the tolerance factor of  human blood to these parasites (2). This heritable trait is passed onto the offspring.  However there is a catch. We carry  two copies of every gene.  A combination of normal plus  mutated gene works as a protective armor, but if  both are mutated  then  other lethal complications set in.

So what is the dynamics of adaptation?  A rather elaborate study on evolving yeast populations has yielded at least  some of the answers.  Lang et al who pioneered this study found that when faced with challenges, the organisms split into groups and  try several pathways all at once  and the best one survives. (3). 

Rats, in a similar fashion can rewire their metabolic capabilities when the need arises. Stylopoulos and his team  were studying rats which underwent GBP. GBP in more explicit terms is gastric bypass procedures. GBP, (and there are several types)  is a medical procedure to down size stomach.  It is  being recommended  as a treatment for weight reduction for  obesity and possibly obesity related diabetes.    Surgically,   top portion  of the stomach    is sliced off and then  directly connected to   the small intestine (jejunum), thus bypassing almost 90% of the stomach pouch. Smaller the stomach, lesser the food intake, that is the logic.  But then stomach is not just a passive receptacle for food, it  plays a crucial  functional  role in human machinery. So what happens when the major portion of stomach is eliminated and   undigested food is  tipped into the small intestine ? Stylopoulos and his team  observed that the gut almost immediately  adapts to improve glucose homeostasis, by slightly enlarging itself and enhancing glucose expenditure. 

But alas the benefits of the GBP stops  with the individual, their offspring  still retain the risk of obesity and diabetes(4).  Being inclusive of next generations, doesn't make business sense either, does it? 

1. Changes in taste neurons support the emergence of an adaptive behaviour in 
    cockroaches. Wada-Katsumata etal Science p. 972- 975 24 May 2013,
2.Sickle Haemoglobin confers tolerance to Palsmodium infection.Marguti et al.Cell           
   145(3)398-409    
3. Pervasive genetic hitchhiking and clonal interference in forty evolving yeast populations 
    Lang et al Nature 29 August, 2013, pages 571-574
4. Reprogramming of intestinal glucose metabolisk and glycemic control in rats after   
    gastric bypass. Seidi et al Science page 406-410, 26 July 2013
5. Heavy toll of stomach surgery :Nature 29 August 2013 page 504

Stockholm archipelago: view from the ship

Time for the return of the Prodigal Child.

For Albert Hofmann, chemistry was his  hobby as well as his  profession. Employee of  the drug company Sandoz, in Basel, Switzerland,  Hofmann's toys were organic molecules. In 1938, while playing with a rather unstable chemical,  lysergic acid,    he made   a series of its derivatives,    with the hope that at least  one among these  might prove to be a potential cardiovascular drug. None proved satisfactory, except that the  25th compound in the series, a colorless tasteless solid,  made the guinea pigs  unusually restless. Hofmann labeled the compound   LSD25 in his notebook and soon forgot about it.  But in 1943, on a hunch  he synthesized the molecule, LSD25,   lysergic acid diethylamide,   again. Here is what happened in his own words 

"I was forced to interrupt my  work in the laboratory in the middle of the afternoon and proceed home being affected by a remarkable restlessness combined with a slight dizziness. At home I lay down and sank into a not unpleasant intoxicated like condition characterized by an extremely stimulated imagination. In a dreamlike state with eyes closed (I found the daylight to be unpleasantly glaring), I perceived an uninterrupted stream of fantastic pictures, extraordinary shapes with intense, kaleidoscopic play of colors. After two hours this condition faded away." 
(Albert Hofmann, LSD : My Problem Child)


Hofmann was bothered, he had  to clear the nagging doubt in his mind, so  three days later he carried out a self experiment. The mystic chemist  intentionally dissolved what he then considered a very small  amount,  250 microgram in water and consumed it. A very precise scientist, he wrote down the time and observation:  19th April 1943, 16.20 hrs: "Tasteless". Forty minutes later is the next entry in the note book:   dizziness, anxiety , visual distortions, unable to move limbs and an uncontrollable desire to laugh. He had to be escorted home by his colleague. The news spread like wild fire, and before long  Hofmann realized that his Problem Child was born. Labelled as hallucinogen and psychedelic drug  LSD fell into wrong hands  was misused, abused and  finally   disgraced, denigrated and shunted out of public view. 
                                        
It is now 75 years since LSD was first synthesized. The medical curiosity didn't die down completely. Of late  there is a renewed, though  subdued interest in LSD  as an anxiety alleviator  and some of the credit for this should go to Serotonin, a neurotransmitter. Serotonin is a tiny organic molecule, an amine,  originally isolated from  human  blood serum and hence the name.   Much later serotonin received a more scholarly and chemically precise name, 5-hydroxytryptamine, which soon  became  just 5-HT, short and sweet.  5-HT proved to be  very mischievous and got  implicated in several diverse and contradictory physiological and psychological functions. For example it could induce migraine or a  general sense of well being, it could induce appetite or nausea.  Intrigued, scientists    prodded on; once released what does it do and where  does it go and sit?   It  was soon found out  that there are,   at least 15 sites along the central and peripheral nervous system, where 5-HT can dock.  These docking stations  are referred to as 5-HT receptors. It is now known that LSD has a preference to the receptor 5-HT2A. Detailed structural information about  5-HT2A receptor and   how  LSD binds to it will unravel most of the mysteries.  

Hofmann died at the age of 102,  to the very end he believed in the therapeutic value of LSD. 

Reference 
1.  LSD: My     Problem Child  by Albert Hofmann. 
2. Structural Basis for Molecular recognition of Serotonin receptors 
    Wang et al Science 3rd     May vol. 340, pages 610-614,  2013 
3. Structural features for functional selectivity at serotonin receptors.
    Wacker etal Science 3rd May Vol. 340, pages 615-618.  2013

Have we Murder'd Sleep ?

Still it cried "Sleep no more!" to all the house 

"Glamis hath murder'd sleep and therefore Cawdor 

Shall sleep no more, Macbeth shall sleep no more!"

(Macbeth Act 2, Scene 2)

Greed and ambition robbed  Macbeth  ( and his Lady too) of his sleep. Among other things it played havoc with his  decision making capability and drove him to commit heinous crimes. Once mental peace is lost, sleep is hard to come and vice verse. ,  Then the vicious cycle starts and soon it is hard to say what was lost first, the sleep or the mental peace?  And so we use a general term Stress . Sleep deprivation doesn't add up as in simple arithmetic, we need to resort to complex mathematics to see the cumulative effect.  Recent issue of Nature (1)  has a special section on Sleep. 

Life evolved on earth with Sun the energy source as the sole reference point. Under nature's supervision work-life balance also evolved,  day light hours for work  and  night for sleep and rest.  The circadian clock was embedded in the suprachiasmatic nucleus (SCN), which took orders from the retina in the morning and  responded to the melatonin level build up after sunset. Melatonin is secreted by the pineal gland which preferentially works during the night shift.  Everything must have  gone on well, till Prometheus stole fire from the heaven and man realized that fire could be used not only to cook delicious food and keep warm but also to light up the dark night. From then on we have been trying to extend daylight hours, literally burning the midnight oil to make the night as bright as the day could be and the advent of electricity was the greatest triumph of all.  But that upset the carefully built in circadian clock within the human body.   

The circadian clock is delicately balanced by the interplay of  neurotransmitters such as acetylcholine,  , orexin, noradrenalin, serotonin, histamine, dopamine  etc during the " Arise awake" phase. When pineal gland senses no more light is coming through the retina,  it starts secreting melatonin which in turn gives the signal for the build up of a simple molecule gamma amino butyric acid or GABA for short. GABA  lulls us to sleep. But mind you,  all these neurotransmitters hold several other  jobs too.  Professor Charles Cziesler is convinced that artificial lighting has interfered with this delicate balance. Retina perhaps never experiences total darkness and that impairs the build up of melatonin. and hence GABA. But can we go back in time to be cave men, hunting by the day and sleeping by the night?  Of course not. Especially when we have learned to cross continents and time zones. So what is the quickfix? Sleep inducing pills? But they are not without side effects. 

Macbeth couldn't do much to get back his sleep, but we could and should. Can we be coached and coaxed into better sleep behavior?   Prof. Espie  is exploring the possibility of putting Cognitive Behavioral Therapy (CBT) to use.  He has developed an online program called the Sleepio which aims to do exactly the same.  A  good night's sleep  could do wonders and could be a simple remedy for several ailments. That is why the crucial question of sleep hygiene is doing the rounds. To begin with, have you removed those audiovisual distractions  from your bedside?

Reference 

1. Sleep: Nature  23rd May 2013 vo. 497 pages S1-S20

Nature (still) Leads

With products  perfected over billions of years (of painstaking evolution), to suit  every tiny creature, in accordance with its unique  life style,  Nature never  ceases to amaze us. In her ever open house   unlimited treasures are  flung around with such joyous abandon   for us  to see,  to feel,  to experience and to learn and above all to mimic.  Two recent  research reports   reiterate this undeniable  truth further.

Karp etal (1) in their recent paper  discuss  a marvelous  biomedical adhesive, inspired by  Pomphorhynchus laevis,   indeed  too big a name for  a tiny parasitic  that infects fresh water fish.  But  once you realize how cleverly   it uses its head ( both  literally and figuratively ), you will concede the name. Since the parasite  has no hands nor feet to cling to its host, it uses  its proboscis, the elongated part of its head. Proboscis is an interesting word and  its genesis is from the Greek word proboscis( προβοσκίς ) which means, somewhat like move  forward to feed.  The clever  worm inserts its head which as an array of sharp nanotips into the host’s intestinal wall, the outer cover of the nanotips then swell, thus ensuring not only a well cushioned anchoring, but also smooth back tracking, whenever necessary.

  

Inspired and excited by this and the umpteen possibilities in soft tissue repair and restoration,   Karp's team    built a prototype. A  simple  elastomer sheet  with polystyrene spikes each with a  sheath of poly( styrene)- poly(acrylic acid) block copolymer. Acrylic acid is extremely hydrophilic and sticky  organic molecule; and poly (acrylic acid) is even more so.  In fact  poly (acrylic acid) is the predominant segment in  most of the super absorbent polymers.  So the sheath takes up water, swells and sticks in place.    Now imagine the immediate   possibilities : first  medicating the hydrogel sheath, next controlling the pore size of the hydrogel for controlled  drug delivery, then  built-in mechanism for timed hydration and subsequent dehydration of the sheath so that the spike naturally falls of like a dry leaf.   .

Arthropods (houseflies, ants, bees etc.) are invertebrates with segmented bodies.  This  tribe,  has been taunting mankind for long,   with their  compound eye. A Compound eye is made up  of a  cluster of small simple eyes  (singular ommatidium, plural ommatidia).    Ommatidia may lack the fine resolution  of the mammalian eye,  but  it bestows  a  panoramic view with unlimited depth of vision low aberration and  above all instantaneous ability to detect motion,  features extremely desirable in cameras.  But then you need  hemispherically configured   imaging elements to achieve this.   Even the latest digital cameras work on principles of  planar sensors and conventional optics.   

  

                                                         Ommatidia of the arthropod

The team demonstrates ”how a camera can accurately and simultaneously render pictures  of multiple objects in a field of view , even at widely different angular positions and distances.”A  cross disciplinary global team has surmounted the difficulties(2) by combining the advantages of  stretchable electronics with hemispherical photodetector arrays.   The prototype  digital camera has tiny lenses molded out of a flexible sheet of  poly (dimethylsiloxane, PDMS for short), connected to a  stretchable  mesh  of silicon photodiodes and blocking diodes appropriately placed and connected with  whiskers of metal embedded polyimides. Each Microlens  with its own photodetector and electrical connections  is equivalent to an  ommatidium and the manmade ommatidia might roughly look like the  bubble wrap, but several orders of magnitude smaller.  A perforated black silicon cap over the microlens array and a black support below the assembly effectively cuts off stray light. The team has demonstrated ”how a camera can accurately and simultaneously render pictures  of multiple objects in a field of view , even at widely different angular positions and distances.”

1. "A bio-inspired swellable microneedle adhesive for mechanical interlocking with tissue". Nature Communications  4 (1702). April 2013.

2. Digital cameras with designs  inspired by the arthropod eye. Song et al Nature  , 497, 95-99. 2^nd May 2013

Scientific Misconduct : Is there a gender bias?

It has become a routine affair to celebrate  International Women’s Day on the 8th of March.  Several scientific  magazines carried  special sections highlighting  the  challenges faced by hiring authorities as well as  by women scientists.  Proportion of women   in  the scientific community  is moving up at snail's space.   It is becoming increasingly hard not only  to attract  but also  retain women in science.    Of course there are a few , with a Will of their own, self motivated or encouraged by teachers,parents or mentors   who seem to find a way, in spite of all  obstacles.  But  what  is it that  restrains  women from  opting for a scientific carrier ?      Valian’s book aptly titled Why so slow? makes   quite an interesting reading, in this context(1).  She states that “adults often misperceive and misevaluate each other often  underrating  women and overrating  men,” and argues for the necessity to  look beyond the XX and XY chromosomes and associated hormones.  

It was more than a 100 years ago that Marie Curie  received her  Nobel Prize. Since its inception ,  839 individuals , across all disciplines have received the  Prize,  among them  only 44 are women (counting Mme Curie twice), a mere 5 %. In every which way you try to take a sample, males are overrepresented. Is it because as Valian says women are underrated and men are overrated ? Or  isn't this a mere reflection of the skewed gender ratio within the scientific community? (We will repeat these questions again).    The brightly lit stage of honor, glory and recognition on which the scientific achievers  share space   has an equally intense and dark underbelly, which houses  the fraudsters, cheaters and other criminally minded. What is the female representation there?   Here is a partial answer  “Males are overrepresented among life science researchers  committing scientific misconduct. ” (2)   Fang  et al had come to this conclusion   after  pouring over  two decades  of data on scientific misconduct, procured  from the United States Office of Research  Integrity. Of the 215 cases  put under the scanner Fang and his team  found that 65%  were committed by  male. Time for us to repeat the question:  Isn't this a mere reflection of the skewed gender ratio within the scientific community?   Fang et al don’t  discount that altogether. They do admit the sample size is too small  to warrant generalizations. 

Anna Kaatz  is a postdoctoral research  associate  and    is probing     why so many women researchers  quit biomedical research careers. She would like to understand the  undercurrents, if any, of unconscious gender biases  which might put female research scientists  at a disadvantage. In a follow up study  Kaatz et al  ask the provocative question “Are men more likely to commit scientific misconduct ?”(3) How do female scientists  cope with professional pressures  at workplace?. Ambitious and competent,  how do they  respond and react to the temptations   to  forge, to misrepresent   or to cosmetize the scientific  data?, In other words, whatever be the motivations and temptations, does  the tendency  to engage in  scientific misconduct  have   clear gender based   divergence ?  Kaatz et al  too are  noncommittal  as  they conclude “Maybe, Maybe not.”   

A few  very pertinent, though inconvenient questions need to be answered here. Could  it be that , when it comes to scientific  misconduct  just as  in achievement,    male is overrated and  female underrated?   Does the overwhelmingly  male scientific community  brush aside female offenders as inconsequential  the same way   they do   the female achievers?  Or does the scientific community condone  female scientists more easily than male scientists?   Alas as of now we don't have answers, but someday someone will find the answers. 

Let us   move out of the narrow  and restrictive confines of the scientific community  into the  wider crime space;  do we get a clearer picture? Freda Adler emeritus professor at The Rutgers University School of Criminal Justice noted way back in 1977 that   “as a result of the push towards equality of the genders, more women entered the workforce and the political arena, reducing the gap between the genders in terms of power, pay, and social standing”.    To her it has been a foregone conclusion that gender equity can’t be confined to work space alone, it will inevitably  pervade every social space including the crime zone. This concept  is  popularly  known as the   hypothesis of convergence. Adler was forthright when she prognosticated that    “If present social trends continue women will be sharing with men not only ulcers, coronaries, hypertension, and lung cancer (until recently considered almost exclusively masculine diseases) but will also compete increasing in such traditionally male criminal activities as crimes against the person, more aggressive property offenses, and especially white-collar crime” .

References:

1. Why so slow : Academic advancement of Women(1998) ,by Virginia Valian, MIT Press, ISBN 9780262720311
2. . Males are overrepresented among life science researchers committing scientific misconduct

3. Are Men more likely than women to conduct scientific misconduct? Maybe, Maybe Not

Bosphorus, Istanbul 12th May 2013

Of Bees and Flowers

After all, bees and flies aren’t as dumb  as we thought, nor  flowers  naive.  Did you know that the flower petal is like a touch screen?  Only,  we don’t know how to decode the responses.  But bees and flies are much smarter and they know  how to  carry out   small talk with  flowers.   In brief  such  electrical interactions facilitate communication between   flowers and their  pollinators.

As early as 1900’s Jagadish Chandra Bose had detected the electrical activity in plants.   Compilation of  his findings could be found in his  book RESPONSE IN THE LIVING  AND NON-LIVING written in 1902 ( currently available on line , thanks to gutenberg projectt ). Plant electrophysiology  has since then developed into a very interesting and active area of research.  April 8^th issue of Science  carries a paper by Clarke  et al   which   describes how bumble bees can detect,  read and respond to  floral electric fields.  In combination with color,  texture, scent and  nectar,   the electrical impulses are powerful  signals which  greatly influence the bee behavior.

Normally bees carry a slight positive charge and the flower petals complement with a mild negative charge.  With very sensitive and specialized  instruments Clarke and his team  measured the  charge  carried by the bees. Of the 51 bees   94% of bees were positively charged as expected but  6% proved to be rebels, they carried a  negative charge.( I am certain, experiments are on way to understand more about this rebel group).  An equally delicate set up  was used to  monitor the electrical signature of the flowers. For field trials  the  conformists were let out into a  field of petunias. Averaged over  about 50 bee touch downs,   the team  registered a maximum  value of 25mV  which lasted for roughly 100 seconds in a flower.  In addition the team was amazed at the quickness of the petal   response which occurred within seconds. Perhaps  an instant  signal  to  other visitors that they are not welcome?.

The researchers tried to tempt and confuse  the bees with artificial flowers, which had  steel stems and plastic petals.  Two sets were considered.  One set carried the minimal biologically relevant  electric field  and also sucrose solution as substitute for nectar.   The other set was dummy, no electrical signal and the  sugar solution was replaced with bitter quinine solution.  Naturally bees flocked to the  charged  plastic  flowers. But when both sets were grounded  bereft of a " come, hither" signal the bees strayed away .

Well that is not the end of the story. While reading this paper I was reminded of  another one  which had appeared a month ago on how clever and crafty  the  dainty flowers could be. Wright leading a team  comprising of members from both sides of Atlantic  was intrigued by the presence of  minute amounts of caffeine  in the nectar of  citrus  and  coffee  flowers.  Copious secretion of such bitter alkaloids  is an evolutionary trick perfected by plants to ward of herbivores. But  why traces of it  in the nectar? Within the citrus family Wright and team focused on   grapefruit, pomelo,  and orange blossoms and  among the coffee family  Arabica, liberica and canephora.   They began with the assumption that by providing nectar laced with caffeine, the flowers might be enticing  the bees to return to them, in  other words ensuring  their fidelity. Seems like stretching  a bit too much, isn’t it ?  Well not at all.  Their  carefully controlled experiments  proved  precisely  the same  assumption. I suggest you read the whole paper to fully appreciate  the very logical and time consuming experiments.  

Tailpiece

Did you know  fruit flies  immunize their off springs  at larval stage against possible parasites?.  When mother flies suspect  such a  possibility, they lay their eggs in an alcohol enriched medium. Prof  Prof Schlenke is a pioneer in this field 

1. Detection and Learning of Floral Electric Fields by Bumblebees  D. Clarke   et al Science 5 April 2013: Vol. 340 no. 6128 pp. 66-69 

2.Caffeine in Floral Nectar Enhances a Pollinator's Memory of Reward:                                        G. A. Wright et al Science 8 March 2013: Vol. 339 no. 6124 pp. 1202-1204

3. Fruit flies medicate offspring after seeing parasites                                                                  

Kacsoh etal Science  22 February 2013 Vol.339,  6122, pp 947-950