Glimpses of Nature and Culture

Red meat or white meat? No, I want BLACK meat!

Yes, the inhabitants of Jhabua and Dhar districts of Madhya Pradesh can enjoy black meat of Kadaknath chicken which is locally appreciated as Kali Masi (which means ‘fowl having black flesh’). Although the old chicks are bluish to black, adults are mostly black or bluish black in color. The comb, wattle, and tongues are purplish and feet are greyish. KadakanthThe striking feature of this bird is many of the internal organs are black in color. The black coloration is due to excess deposition of melanin pigment skin and several other tissues or organs such as blood vessels, muscles, gonads and tracheas because of a genetic condition known as fibromelanosis or dermal hyperpigmentation. Black breeds are also found in other domesticated chicken breeds, such as Ayam Cemani in Indonesia, Kadakhnath in India, Black H’Mong in Vietnam, Argentinean, Tuzo type in Argentina, and Svartho ̈na in Sweden.

Kadaknath is a native breed whose range extends from Madhya Pradesh to the neighboring districts of Rajasthan and Gujarat. Considered as sacred among tribals, they used to rear this bird for sacrificial purpose during the festivals. The black meat is not only taste bud tickler but also has high nutritive and medicinal value. No wonder, this famous Kadaknath chicken has earned a geographical indication (GI) tag that denotes that the product is culturally associated with a specific geographical area, and often enhances its commercial value. However, largely owing to its high consumption rate its population has declined drastically in recent times. A ray of hope: an organized breeding is in full swing in some areas that may cater consumer needs.

So, instead of shuttling between red and white, let’s go for black (not dog) chicken.

Photo: Press Trust of India (PTI)

Collector: Avik Ray

 

Microscopic Da Vincis and the Curious Case of Photokinetics

Leonardo da Vinci, the Renaissance polymath from Italy, might have left us in 1519 AD, but a million of microscopic da Vincis have painted a miniature replica of his masterpiece Mona Lisa in 2018! Sounds crazy? Hold your thoughts and ask Dr. Giacomo Frangipane, a post-doctoral researcher of physics at the University of Rome, Italy, if you don’t believe me!

The minute da Vincis in question are none other than the famous Escherichia coli bacteria, found in the lower intestine of warm-blooded animals naturally and a favourite among scientists. These bacteria (many strains) are mobile and they move by the help of a specialised, whip-like appendage called flagellum (plural: flagella). Flagella are primarily used for locomotion by single-cell organisms, and they are propelled by a motor, a rotary engine made of proteins. Like any other engine, this motor requires energy to function, and in the case of E. coli it operates by using oxygen. Recently, scientists discovered a protein (proteorhodopsin) in some marine bacteria which absorbs light to power the motor in their flagella, through a process called photokinetics.

All good and fine. So, how did the E. coli paint the Mona Lisa? The clue lies in the light! To remotely control their movement, Frangipane and colleagues genetically modified their E. coli to produce the photo-sensitive proteorhodopsin. This made the otherwise oxygen-modulated flagella to now move by the help of ambient light, much like mounting a solar panel on a car! Monalisa Next starts the painting. For that the scientists projected light through a microscope lens, and explored how the bacteria change their speed while swimming through areas with varying degrees of illumination. “Much like pedestrians who slow down their walking speed when they encounter a crowd, or cars that are stuck in traffic, swimming bacteria will spend more time in slower regions than in faster ones,” explained Frangipane. “We wanted to exploit this phenomenon to see if we could shape the concentration of bacteria using light.” They projected the light uniformly onto a layer of bacterial cells for five minutes, before exposing them to a more complex light pattern – a negative image of the Mona Lisa. They found that bacteria started to concentrate in the dark regions of the image while moving out from the more illuminated areas. After four minutes, a recognisable bacterial replica of the masterpiece emerged. After creating the Mona Lisa, Frangipane and his team manipulated the E. coli into a face-changing portrait that transformed from a likeness of Albert Einstein to that of Charles Darwin in just five minutes face-changing portrait

Although using photokinetic bacteria to paint famous portraits is fun, there are serious implications of this research as intended by the scientists. Controlling bacteria in this way means it could be possible to use them as microbricks for building the next generation of microscopic devices. For example, they could be made to surround a larger object such as a machine part or a drug carrier, and then used as living propellers to transport it where it is needed. Furthermore, they can be applied for creation of biomechanical structure or microdevices for the transport of small biological cargoes inside miniaturised laboratories.

Source and Photo:

  1. Press release: Light-engineered bacterial shapes could hold key to future labs-on-a-chip 
  1. Original research: Dynamic density shaping of photokinetic E. coli

Collector: Subhajit Saha

 

Galar putul – story of a dying industry

The enriched cultural heritage of Bengal is resonated not only in old architectures, literature, paintings and cuisines but also in its unique toys. Galar putul – shellac coated clay dolls is one such heritage toy.Galar Putul These bright coloured toys represent a diverse socio-cultural history of the rural Bengal. The toy making procedure itself is a delicate and skilled artwork. Soil for making galar putul are collected from termite hills as it is relatively gravel free and adhesive in nature. The moist soil is kneaded, cleaned, pressed and pinched to form models. Baked models are coated with long sticks of painted shellac. Finally, Guna work (thin shellac threads making from lac sticks) is done to decorate the figurines. Nose, eye-ball, hair, moustache, ear-ornaments, etc. are formed by coloured shellac drops. The toys include small dolls, elephant rider (hatishowar), horse rider (ghorashowar), animals, fruits, votive figurines or folk goddesses like shasthi. A full range of these toys represent the contemporary society and art forms of the south-western rural Bengal. The specific geographic conglomeration of this art form is due to the availability of natural resources in the region. Shellac, the essential raw ingredient for Galar Putul is a resin secreted by the female lac bug (Kerria lacca) while sucking tree sap. The insect secrets it as a tunnel-like tube while moving through the tree branches. The main host trees used for its cultivation are Palash (Butea monosperma), Kul (Ziziphus mauritiana) and Kusum (Schleichera oleosa). Mature crop along with branches are harvested, lac encrustations (sticklac) are scraped off and processed to form shellac. Generally, the lands unsuitable for agricultural purposes are used for lac cultivation. Lac cultivation is being done in Bengal since ancient times in the districts of Purulia, Midnapore, Bankura & Birbhum. Lac industry was in its glory days back in 1787, when David Erskin founded Erskin & Co. company in Illumbazar, Birbhum. It lasted till 1882. But situation declined with the shortage of raw material and competition from other toys by 1920 when many artists have forsaken the profession. Rabindranath Tagore attempted to revive the art by holding training sessions at Sriniketan but the situation didn’t improve.
Nuris of Birbhum and Shankharis of Bankura and Medinipur districts are the communities engaged in making galar putul. Sadly, this colourful toy industry has been losing the battle against cheap plastic dolls. Most of the artisans have changed their professions and their remains very few to carry forward the legacy of this folk art.

Photo: Abhik Sarkar, Wikipedia
Collector: Debarati Chakraborty

 

The rolling balls of life

‘Wild Wild West’ – hearing these words we immediately link ourselves with the Western arid North America with its rugged terrain, dry environment, rolling weeds and obviously cowboys in hats and tights. Thanks to Hollywood for this globally acknowledged collage. Pretty TumbleweedOne of the obvious components of this picture is rolling weeds aka Tumbleweeds. The Tumbleweeds are bushy plants/plant bodies which after finishing their reproductive function becomes dry and gradually detach themselves from their place of association. The detached bush often appears as dry and thorny ball of various sizes then tumbles by the wind and rolls over a great distance along the deserted landscape. The underlying reason of this curious activity is the dispersal of seeds so that they can spread across a vast area and can avoid harsh competition for resources. Moreover, this frantic movement helps these plants to establish their colony throughout Western North America and forces people to take them as a serious menace to public life.

This tumbling activity has been reported from a number Tumbleweed Doorstepof flowering plants and even from lower group of plants like fungi and pteridophytes. Some well-known members are, Salsola kali subsp. tragus (Russian thistle), Artiplex rosea (tumbling oracle), Centaurea diffusa (tumble knapweed), Gypsophila paniculata (baby’s breath), Selaginella lepidophylla (pteridophytes) and members of earthstar mushroom family (Geastraceae).

Tumbleweed has a significant presence in American socio-cultural life especially in western part of the continent. Be it music, literature, painting or movie, the Western arid landscape has been vividly portrayed with these moving plant forms.

Source : Wikipedia

Photo: Getty images, New York Post

Collector: Rajasri Ray

 

Biodiversity through sound

Sound GraphThe term “Biodiversity” becomes popular to all niches of the society, thanks to active media involvement for awareness generation. Today, we all know that biodiversity encompasses variety of life forms, ranges from microscopic to macroscopic, unicellular to multicellular, gene to biome level. It is not restricted in species check list preparation, it also includes distribution, function, maintenance, evolution, society, economics even politics.

The basic unit of biodiversity measurement is species. However, the concept is ever changing and there are multiple ways to measure the biodiversity of any area of interest. But “Sound”!!!!!!  How can sound help us to measure the state of biodiversity in any particular area? Sound Diversity It is possible, at least recent research says so. In Papua New Guinea, a comparative study on eco-acoustic profile of fragmented and continuous forests has shown that there are distinct differences in dawn and dusk choruses at these forests. While searching for the reason behind these differences, ecologists uncovered an interesting point: forest fragmentation seems to have a major role in this difference. It has been detected that continuous and less disturbed forest areas have more saturated and complex soundscape (i.e. more complex and diverse acoustic relationship among organisms) than its fragmented and disturbed counterparts. The reason behind this richer soundscape seems to be presence of diverse insect and avian communities responsible for this grand opera whereas fragmented forests are impoverished in this regard. Interestingly, conventional estimation of avian diversity in fragmented forests has not shown much decline in avian members. To solve this riddle, researchers opined that, time and space constrained conventional methods may not be able to capture the entire spectrum of biodiversity, a problem, can be complemented through acoustic approach which is cost effective and result oriented.

Source: Using soundscapes to detect variable degrees of human influence on tropical forests in Papua New Guinea.

Photo: Burivalova et al. 2017(fig1), Rajasri Ray (fig2)

Collector: Rajasri Ray  

Termite Mound an Engineering Marvel

Walking in the wild or even in a metro city like Bengaluru it is impossible to miss giant structures made up of mud. These are termite mounds (Figure 1). Mound of Odontotermes obesusTermite mounds are conspicuous features of landscapes in Asia, Africa and Australia and can be upto 10 metres tall. They are built by tiny insects called termites which are few millimeters in size. At a human scale this kind of construction would correspond to a building ten kilometers tall (taller than Mt. Everest)!! Moreover, termite mounds seem to remain unaffected by rain even though they are made up of mud. These termite mounds made with cemented soil last for several decades (Zachariah et al., 2017) and their remains can last for several centuries (Erens et al., 2015). Unlike bricks made by humans they are not even baked at high temperatures in a kiln. What is more interesting is that termites make these structures without an architect, without a masterplan and in fact without even seeing the structure they are making — yes termite workers do not have eyes… So how do tiny termites achieve all this? The mystery remains.

Termites are social insects — they live in colonies with upto a million individuals. These individuals are divided into morphologically distinct castes — king and queen, workers, soldiers, nymphs (or young ones) and alates. The king and queen mate, lay eggs which form all other castes of the colony. The soldiers guard the colony against intruders like ants. The workers are involved in mound building, foraging, rearing the young ones and tending to their fungus gardens (Figure 2; Bose, 1984).

Construction of the mound, in general, can be envisioned as a three-part process involving material selection, transport and assemblage. Odontotermes obesus workers and soldiersResearchers have tried to understand these process during mound construction in the species Odontotermes obesus (Zachariah et al., 2017). They found that termites take moist soil, mix it with their secretions (which acts as an adhesive) and make tiny balls — about a millimetre in length — and carry them to the site of construction (Figure 3). These are analogous to bricks used in human construction and have been termed as boluses. Further it turns out that termite workers of O. obesus are of two different castes — major workers with a large body and a large, dark brown coloured head and small workers with a small body and a light brown head (Figure 2; Bose, 1984). These castes make two different types of boluses — major workers make larger boluses than minor workers (Figure 3). But how do you make a building with two different sizes of bricks? To understand this, researchers made an intentional breach at a termite mound and video recorded the process of breach repair. types of boluses Upon analysing the video and marking the spatial location of the bricks deposed by major and minor workers, they found that both kinds of boluses were spatially interspersed suggesting a kind of packing (Figure 4). The larger boluses made a scaffold and the smaller boluses filled the gaps or voids between them — something similar to a glass jar filled with golf balls and marbles filling the space between them. This imparts tight packing and high strength to the mound (Figure 5; Zachariah et al., 2017). It also points towards a possible mechanism of coordination between termite individuals called stigmergy. Stigmergy is the coordination between individuals by modifying a shared environment.

a termite mound as recorded by videographyResearchers have tried to understand this phenomenon by building robots that carry out a task by mutual coordination simply by sensing and modifying their shared environment (Werfel et al., 2014). In case of termite mounds the presence of voids can act as a similar cue for bolus deposition helping in large scale construction (Zachariah et al., 2017).

Further, researchers offered glass beads to termites instead of soil and surprisingly termites used glass beads to make boluses the way they used soil. Schematic diagram of termite mound constructionIt turned out that termites could use a wide range of materials such as metal powders, paraffin, sand grains, polymers like agar and fibrous materials like tissue paper for making boluses (Figure 6). But all of them were not equally easy to handle. The materials that were easiest to handle has certain properties common in them — they were all granular, hydrophilic, osmotically inactive, non-hygroscopic materials with surface roughness, rigidity and contained organic matter. Granular materials had the highest ease of handling followed by polymers and fibrous materials. Soil with organic material present in it had higher ease of handling than soil devoid of organic material suggesting that organic matter, apart from termite secretions, plays a role in cementation in termite mounds. Since termites have to moisten and adhere particles of materials with their secretions, hydrophilic materials such as glass beads and soil were easier to handle than hydrophobic materials such as paraffin. Thus material properties, in the presence of moisture and favourable climatic conditions, make a certain geographic region conducive for termite mound construction (Zachariah et al., 2017).

Boluses made with different materials

From the above description it doesn’t seem obvious why granular materials should be preferred over polymers and fibrous materials. Granular materials have been regarded as the fourth state of matter by engineers; thus we have solid, liquid, gas and granular materials. Here, a single granule is a solid but as an aggregate it acts as a fluid. So you can bury your hands in sand or you can fill a bucket with sand and it takes the shape of the bucket. Granular materials can be cemented by depositing adhesive only at the junction of the particles or they can be embedded in a matrix. They can be packed tightly or loosely (Duran et al., 2012; Weitz, 2004; Sowers 1979). All these can have bearing on the kind of construction termites carry out.

Surprisingly, termite mounds built with such great efforts is not the dwelling place for termites. The actual termite colony lives underground. Then why do termites make mounds? For any organism living underground, ventilation is a challenge. In case of termite colony, mounds act as an organ of ventilation — just like our lungs. They harness diurnal temperature oscillations for ventilation. Termite mound consists of a central chimney and several peripheral flutes. During the night, hot air from the colony rises in the central chimney. As the air rises up, its temperature drops and the cool air comes down through the peripheral flutes. During this time gaseous exchange take places through the porous walls of the termite mound. During the day time, the peripheral flutes get heated up due to sun’s heat and the direction of flow reverses. Thus, an efficient ventilation mechanism is established where the architecture itself helps in gaseous exchange (King et al., 2015).

Not only do termites engineering their magnificent mounds, they also engineer entire ecosystems (Prusty, 2010). Their presence has been associated with increased soil fertility and drought resistance to climate change (Prusty, 2010; Bonachela, et al., 2015). However, we are yet to get a full picture of the ecosystem services provided by termites. When it comes to understanding the construction of termite mounds, researchers have barely scratched the surface. Further studies into mound construction will inspire the construction of energy efficient buildings, biosynthesized cementing agents for construction and robots and algorithms that will self-organize and can be used for traffic regulation and construction in inaccessible places. Termites also act as farmers and grow their own food (fungus) inside their mounds. They have a highly specialised mechanism of weed control (Katariya et al., 2017) which is likely to inspire agriculture practices in the near future. Therefore, it is in our best interest not to disturb termite mounds in natural landscapes… we never know what treasures they are holding for us!!

References

1) Bose G (1984) Termite Fauna of Southern India. Zoological Survey of India, Calcutta.  

2) Bonachela JA. et al. (2015) Termite mounds can increase the robustness of dryland ecosystems to climatic change.  Science 347, 651–655.

3) Duran J (2012) Sands, Powders, and Grains: An Introduction to the Physics of Granular Materials. Springer Science & Business Media.

4) Erens H. et al. (2015) The age of large termite mounds—radiocarbon dating of Macrotermes falciger mounds of the Miombo woodland of Katanga, DR Congo. Palaeogeogr. Palaeoclimatol. Palaeoecol. 435, 265–271.

5) Kandasami RK, Borges RM & Murthy TG (2016) Effect of biocementation on the strength and stability of termite mounds. Environ. Geotech. 3, 99–113.

6) Katariya L, Ramesh PB, Gopalappa T, Desireddy S, Bessiere JM & Borges RM (2017) Fungus-farming termites selectively bury weedy fungi that smell different from crop fungi. J. Chem. Ecol. 43, 986–995.

7) King H, Ocko S & Mahadevan L (2015) Termite mounds harness diurnal temperature oscillations for ventilation. Proc. Natl. Acad. Sci. USA 112, 11589–11593.

8) Prusty AKB (2010) Termites as ecosystem engineers and potentials for soil restoration. Current Science, 99, 11.

9) Sowers GF & Sowers GB (1979) Introductory Soil Mechanics and Foundations. Macmillan Publishers.

10) Weitz DA. (2004) Packing in the Spheres. Science 303, 968–969.

11) Werfel J, Petersen K & Nagpal R (2014) Designing collective behavior in a termite-inspired robot construction team. Science 343, 754–758.

12) Zachariah N, Das A, Murthy TG, Borges RM (2017) Building mud castles: a perspective from brick-laying termites. Scientific Reports doi:10.1038/ s41598-017-04295-3.

 

About Author :

Nikita ZachariahNikita Zachariah

Centre for Ecological Sciences

Indian Institute of Science, Bangalore

E-mail : nikitaz@iisc.ac.in

 

Craft on Cast: Commensalism between Mud dauber and Earthworm-A primary Investigation

Nest making is a vital instinct of several species of animal kingdom. An animal usually makes nest to protect its offspring and sometimes themselves. In evolutionary biology there is only one scale to measure the fitness of an individual i.e. the number of healthy and fertile offspring it can produce. So better nest making and offspring rearing technique of an individual increases its fitness.

Insects tend to use different materials for nest making. Honey bees use wax which they secrete from their own body, while colony-forming wasps use paper like substance which they produce by chewing plant materials of various kinds. Similarly, some ant species build nest by leaves, whereas insects use existing cavities after a bit of modification, such as beetle tunnels in wood, abandoned nests of other Hymenoptra, or even man-made holes like old nail holes and screw shafts on electronic devices). Apart from plant materials, mud is another commonly used ingredient for nest formation. A fine example of this group is the termite, they make huge nest with complex architecture by mud only. For insects, the size and shape of their nest varies. Some make pitcher shaped nest, while others are cylindrical. Easy availability and durability underlie the widespread use of mud, besides, mud wall is porous and poor conductor of heat, inside nestmicroenvironment (i.e. humidity, temperature and oxygen level) is perfectly maintained.

The black and yellow mud dauber (Sceliphron caementarium, family Sphecidae) are very common solitary wasp, widely distributed in America, Asia Europe and Australia, which make nest with mud (Figure 1) (Krombein et al.1979, Harris 1997). In India, the species has been reported from East Indian states (Chatterjee 2015).

Sceliphron caementarium (henceforth mud dauber) is a black wasp with yellow markings and a very thin, long pedicel, and tawny brown wings (Figure 2). Yellow markings vary among individuals but are likely to be found on the base of the antenna (the scape), the dorsal side of the thorax, the pedicel, and the legs.  Females are larger than males, measuring 23 to 25 mm in length, while males are approximately 21 mm in length (Evans 2011, Kim et al. 2014). Adults are diurnal and most active in the late spring and summer in temperate regions, though in the tropics they are active throughout the year (Coville 1987). These nests can be recognized by their clustered, rectangular structure (Figure 3).

An adult mud dauber & dauber nest

After mating, females start to gather balls of mud in their mandibles and fly to the selected nest site. They have remarkable vision and hence are able to identify landmarks to locate their nests (Ferguson and Hunt 1988). Once a single cell is completed, they begin to hunt for spiders asfood for that cell (Shafer 1949). Female mud dauber paralyzes the prey by injecting venom (near the subesophageal ganglion) and keeps it inside the cell for further use (a máximum of 25 spiders can be kept in a cell) (Obin 1982). It lays one egg, generally, on the first spider placed in the back of the cell and gathers more mud to cap the cell and move on to commence building the next cell (Shafer 1949). The larva comes out from egg and gets live spider. Recent study reveals that different strains of Streptomyces spp are found in mud daubers nest. The antibiotics released from those bacteria protect the larva and the paralyzed prey from fungal and bacterial attack (Poulsen et. al. 2011).

The nest making behavior of mud dauber inspired curiosity among the naturalists and entomologists. In India, naturalist Gopal Chandra Bhattacharya spearheaded the research on nest making and observed that mud dauber generates a characteristic humming sound during nest making. He also reported that mud daubers generally collect mud from the edge of ponds, canals located within 40 meter from the nest making point.  However, in absence of nearby source, she may continue her search further on.

In this article, we report some lesser-known facts related to mud dauber nest making.  Following Bhattacharyya’s work, we identified the location of nest by tracking the humming sound and came across distinct behavioral sequences in the nest making with wet soil as well as with earthworm cast (which is hitherto unreported else).

 Backyard of our house in Abhirampur village of Bardhaman district, West Bengal, India was our study site where observations were recorded during the end of the monsoon of 2016. The site was shady and soft and wet fresh earthworm casts were in great numbers. An insect was wandering at the nook of the backyard-facing window in search of suitable place for nest.  It went to the ground, rested on multiple places for 2-3 minutes and visited. both soil as well as earthworm cast in a repetitive manner (Figure 4). Finally, it preferred the earthworm cast for mud ball preparation and prepared a mud ball of 1-2 mm in diameter with mouth appendages and fore legs. After few seconds, the ball was carried by the insect towards the selected site for nest making (Figure 5). At the site, a cell was created from that mud ball (Figure 6). The ball preparation, transportation and cell making processes were repetitive and continued almost 7 hrs.

Earthworm cast collection

Our previous observation, on the same site, highlighted that an extra step of cleaning was performed if mud selected for nest making. The act of cleaning was so neat and meticulous that all unwanted materials like grass, leaf remains, hay sticks, stone chips was thoroughly removed prior to mud ball preparation. The entire nest making process was observed independently for five times at several places over the study site. It appeared that the mud daubers had a preference for earthworm cast over the plain soil for its nest building.  Our observation seems very similar to the descriptions made by Nachtigall (2001) on of mud-collecting behavior of Sceliphron spirifex. He described the whole process of mud collection in the following four behavioral sequences.

  1. Local inspection of a site.
  2. Choosing a point and cleaning by removal of leaf remains, hay, little sticks, and stones.
  3. Making a mud-ball with the wet soil.
  4. Flying back to the nest before positioning.

In addition to that, we find that the insect also collect earth worm cast for making her nest. As it was free from undesirable items the mud dauber can straight away build the nest.

Literatures on ethology and ecology of black and yellow mud dauber reveal that there are diverse sources for mud for nest making. It can be mud puddle (Chatterjee 2015), from banks of reservoirs, puddles or other water sources (Fateryga and Kovblyuk 2013), sea sand mixed with silt etc.  Conducting a comparative study on mud ball making of four different species of mud dauber wasp of genus Sceliphron, Chatenoud et. al. (2012) singled out wet soil as the preferred material. Likewise, many other examined nesting material e.g., Polidoriet. al. (2005) made granulometric analysis of mud dauber nest material, but the use of earth worm cast by Sceliphron spp has not been reported

So, a relevant question pops up in our mind, whether the earthworm cast is a batter material for nest making than soil? A comparative study on physical and chemical properties between earthworm cast and soil reveals some interesting facts about the structural stability of the former (Table 1). When 65 rain drops are sufficient to destroy the structural aggregates of soil, the number of drops shoots up to 849 for earth worm cast. Moreover, the density of the earthworm cast is 13.3% less than that of soil, thus, offers an easy carriage. It is free of twigs and small stone so mud daubers that saves a lot of energy. Summarizingly, it is a durable, energy and time saving nesting material for mud dauber. But the story doesn’t end here. Earthworm cast is rich in exchangeable Calcium and Potassium ion, soluble phosphorus and total nitrogen, and micronutrients (Ayoola and Olayiwola 2014). It can act as a good culture medium for Streptomyces bacteria that play a vital role in protection of the nest from the pathogen attack.  Better the durability and protection in the next, more is the survival rate of healthy offspring and survival.  The outcome is an enhanced fitness of the mud dauber.

Table 1. Comparative Characteristics of Earthworm Cast and Soil (Average of Six Nigerian Soils).

Characteristics Earthworm cast Soil
Silt and Clay (%) 38.8 22.2
Bulk Density (Mg/m3) 1.11 1.28
Structural Stability* 849 65
Cation exchange capacity (cmol/Kg) 13.8 3.5
Exchangeable Ca2+  (cmol/Kg) 8.9 2
Exchangeable K+ (cmol/Kg) 0.6 0.2
Soluble P (ppm) 17.8 6.1
Total N (%) 0.33 0.12

 *Number of rain drop required to destroy structural aggregates.

Source: Brady N.C. The Nature and Properties of Soil. 10Th Edition. 2002

Our study reveals some interesting facets of nest making but stimulates several questions on behavioural patterns of insect community. As we have seen, utilization of  earthworm cast for nest making is beneficial for mud daubers whereas it is neither beneficial nor harmful to earthworm, In other words, it  is commensalism that is not an obligatory relationship. Now the question arises whether utilization and preference of earthworm cast is a character of the species or only a few populations exercise this and enjoy better evolutionary fitness? Powell and Taylor (2017) reported that in a single population of S. caementarium where all individuals had access to the same resources, there are an evidence of strong individual specialization; individuals utilized different resources (with respect to prey taxa, prey ecological guild, and prey size) to provision their nests. The extent of individual specialization differed widely within the population with some females displaying extreme specialization (taking prey from a single species) while others were generalists (taking prey from 1-6 spider families). So, there is a possibility in case of mud daubers, that some specialist female (taking only earthworm cast for nest making) and generalist female (taking humid soil as well) within the population. That inevitably promote the specialist female to produce fitter offspring than generalists owing to relatively protected nest. That deserves further examination, however.

Reference:

1) Ayoola PB, Olayiwola AO (2014) Trace elements and major minerals evaluation of earthworm casts from a selected site in southwestern Nigeria. ARPN J of Agri and BiolSci 9(6)

2) Brady NC (2002) The Nature and Properties of Soil. Prentice Hall of India Pvt. Ltd. New Delhi

3) Chatenoud L, Polidori C, Andrietti F (2012) Mud-Ball Construction by Sceliphron Mud-Dauber Wasps (Hymenoptera: Sphecidae): A Comparative Ethological Study. Zool Studies 51(7): 937-945

4) Chatterjee N (2015) The chronicle pertaining to the nests of the natural Arachnidicide Sceliphron caementarium (mud dauber) collected from four different districts of West Bengal, India. Quest J Journal of Res in Agri and Animal Sci 3(4): 2321-9459 

5) Ferguson CS, Hunt JH (1989) Near-nest behavior of a solitary mud-daubing wasp, Sceliphron caementarium (Hymenoptera, Sphecidae). J of Insect Behav 2: 315-23

6) Fateryga AV, Kovblyuk MM (2013) Nesting Ecology of the Wasp Sceliphron destillatorium (Illiger, 1807) (Hymenoptera, Sphecidae) in the Crimea. Entomo Rev 94(3): 330–336

7) Harris AC (1997) A nest and life-history stages of Sceliphron caementarium (Hymenoptera: Sphecidae) intercepted in Fiordland. Weta 20: 6-8

8) Krombein KV, Hurd Jr PD, Smith DR, Burkes BD (1979) Catalog of Hymenoptera in America north of Mexico. Vol. II. Smithsonian Institution Press. Washington

9) Nachtigall W (2001) Formation of clay globules and flight departure with the building material by the thread-waisted potter wasp Sceliphron spirifex (Hymenoptera: Sphecidae). Entomol Gen 25(3): 161-170

10) Obin MS (1982) Spiders living at wasp nesting sites: What constrains predation by mud-daubers? Psyche 89: 321-336

11) Polidori C, Trombino L, Andrietti F (2005) The nest of the mud-dauber wasp, Sceliphron spirifex (Hymenoptera, Sphecidae): application of geological methods to structure and brood cell contents analysis. Italian J of Zool 72(2): 153-159

12) Poulsen M, Oh DC, Clardy J, Currie CR (2011) Chemical Analyses of Wasp-Associated Streptomyces Bacteria Reveal a Prolific Potential for Natural Products Discovery. PLoS One, 6(2), p.e16763

13) Powell EC, Taylor LA (2017) Specialists and generalists coexist within a population of spider-hunting mud dauber wasps: BehavEcol 28(3): 890–898

14) Shafer GD. 1949. The ways of a mud dauber. Stanford University Press. Stanford, CA   

About Author:

Atmadeep Chakrabarti   Atmadeep Chakrabarti

Abhra Chakrabarti Abhra Chakrabarti

E-mail: abhrachakrabarti@gmail.com

Tales of the night: Chapter I

It is a spectacle to experience the sight of hundreds of bats emerging from the shadow of caves in a perfectly choreographed flight maneuver, before eventually disappearing into the vanishing tinge of the dusky sky. Bats, the only volant mammals form the second largest mammalian order Chiroptera (chiro= hand, pteron= wing) comprising of more than 1300 species (Fenton and Simmons 2014). An Indian flying fox (Pteropus giganteus) colony near Bangalore.They show extraordinary specializations in their ecology, anatomy and physiology and a diverse dietary habit feeding on anything from nectar, pollens, leaves and fruits, to insects, small mammals and vertebrates, other bats, fishes as well as blood (Kunz et al. 2005).  Most bats can echolocate emitting ultrasonic sounds for spatial orientation, social contact as well as for foraging (locating and hunting prey), others have strong sense of smell and are well adapted for herbivory. And a small group of bats (the vampire bats of central and south America) possess thermal sensors to choose prey and feeds on blood of wild mammals as well as livestock and less frequently humans (Kunz et al. 2005; Fenton and Simmons 2014). In this article, I will share some contributions of bats to our ecosystem that ultimately benefits us in many ways. I will also share some concerns regarding their continuous decline due to human mediated alteration of our environment as well as continuous persecution resulting from superstition and ignorance (Figure 1). We will save the discussion of their unique capabilities of time keeping and other idiosyncrasies for another chapter of ‘Tales of the night’. 

Bats as bioindicators

Bats occupy an amazing array of habitats are found widely across the globe inhabiting major ecosystems. The endangered Mauritius fruit bat (Pteropus niger) endemic to MauritiusThey are keystone species contributing towards the sustenance of eco-systems they inhabit and performs many important ecosystem services (Kunz et al. 2005). However, bats are also extremely sensitive to disturbances to their habitats, ecology and climate. Over the past few decades, volumes of research studies have revealed that bat communities can be specifically tracked to obtain important estimates of biodiversity, level of pollution and effect of climate change (Jones et al. 2009). For example, frugivores and insectivores can be tracked to understand changes in plant and insect communities (Jones et al. 2009). Similarly, mass mortalities in flying foxes due to sudden warming in parts of Australia (Welbergen et al. 2008) indicated adverse impact of climate change over the population. Many island bats like the Dark flying fox of the Reunion and Mauritius islands, the Guam flying fox endemic to Guam, the Christmas Island pipistrelle found native to the Christmas Island have already gone extinct and many other species face imminent risk of extinction (IUCN) (Figure 2). Even, more commonly occurring species experience drastic loss in population size and risk extinction locally as well as globally.

Ecosystem services: agrodiversity, forest regeneration and pest control

Contribution of bats to the ecosystem benefits humanity in many ways. Fruit bats are pollinator for many plant species which are economically important (banana, mango guava, durian, coconut, ficus, cocoa etc.) as well as species critical for eco-system functioning (agave, various cacti species, baobab tree etc.). Flowers of such species employ multitude of tactics to attract and recruit fruit bats, they open in the night, emit strong odor, and are often large and white in color to ensure that they are located easily in the darkness. Agave plants are primarily pollinated by the nectar feeding long-nosed bats, who in turn are heavily dependent of the nectar and pollen of agave mainly to meet their energetic requirement (Arita and Wilson 1987). Compared to many other biotic pollinators, bats are often efficient long-distance pollinator (Fleming et al. 2009). Over 500 species of flowering plants are pollinated by bats (Fleming et al. 2009) (Figure 3).

Sequel for bat pollination

Growing body of evidence proves that fruit bats are excellent agents of fruit and seed dispersal and germination and greatly accelerates regeneration of forest cover over degraded patches. Fruit bats like the flying foxes inhabiting the Old World biomes can aid in dispersal across tens to hundreds of kilometers and often across isolated islands where many times they are the sole pollinators (Jones et al. 2009). In the New World Tropics, dispersal of seeds of pioneer plant species by fruit bats is essential for regeneration of forest cover (Kelm et al. 2008). Research suggests that seeds ingested by bats influences germination, for example, bat-consumed seeds with their pulp removed show better germination in the neotropical tree species, Calophyllum brasiliense (Marques and Fischer 2009). In addition to their role in pollination, dispersal and germination, bats significantly contribute towards the increase of genetic diversity within their host species by mixing gene pools from different and many times faraway populations. Such act helps maximizing agrodiversity among cultivated plant species as well as forest diversity. In the face of the ongoing episode of human mediated habitat fragmentation, long distance pollination by bats are often responsible for maintaining gene flow and connectivity of plant populations (Fleming et al. 2009). Successful management of fruit bats can effectively aid in the regenerating forest cover thereby forming the base of effective conservation and management of native biodiversity.

Majority of bats however are insectivore, either obligatory or facultative and in many cases act as effective biological control agents of arthropod pest management. Studies have shown that insect bats can eliminate tons of insects per night from farm lands. A colony of 20 million Mexican tree-tailed bats can consume 13000 tonnes of insect over one summer (Altringham 1996). Research from North America suggests that bats contribute around 23 billion annually (by consuming pests and reducing pesticide application) to the agricultural industry in US alone. In the absence of bats, agricultural industry would require to spend additional 4–53 billion USD annually on pesticides alone. But these estimates only include the benefits of pest management and do not include other indirect effects to the environment due to reduce use of pesticides (Boyles et al. 2011), which adds more economic value to their services. Additionally, excrements of insect bats, called guano are rich in nitrogenous compounds are acts as effective fertilizer and are regularly mined in countries like providing livelihood for many. Some insect bats are carnivorous, like the false vampire bats commonly found in the subcontinent. These bats prey upon small mammals like rodents and act as biological control for mammalian pest.

Persecution: superstition and ignorance

While contribution of bats is etched in oriental cultures as positive associations, western cultures nurture largely negative stereotypic myths. Within a large collective mindset across the globe, bats rule the realm of the dark and are usually associated with everything evil. Regardless, many communities not only hunt them and harvest every part of their body in the belief that these could cure almost every possible disease but also consume bats as bushmeat (a source of cheap protein), Endangered Rodrigues fruit bat (Pteropus rodricensis)leading to mass annihilation of colonies often comprising thousands of animals. Such activities act as important stressor for bat communities and significantly contribute towards their decline.

Bats are very gregarious in nature, most species can utilize diverse types of natural formations (also manmade structures), and some like the short-nosed fruit bats from south and southeast Asia can even modify plant-parts to construct simple tents wherein they spend their day (Kunz et al. 2005). Males of the commonly occurring short-nosed fruit in south Asia regularly uses foliage roosts. They chew and modify the underside of leaves of the plant (e.g Palmyra palm) creating a semi-permanent tent-like structure that lasts for years.

Bats often cohabit with humans and livestock. Human contacts are unavoidable due to anthropogenic loss of natural habitats, forcing bats to live in close proximity with humans. However, this association has proven particularly costly for the species as they face merciless persecution and are not only hunted for meat and medicine but also exterminated for their possible role in spreading deadly viruses among humans. Added to this are human mediated destruction of natural habitats and the vagaries of climate change, factors which have collectively resulted in an accelerated loss in their number, diversity, distribution as well as local extinctions in many cases (Figure 4).

Despite the importance of bats towards maintaining an ecological balance, scientific studies of bats are not a prominent component of the peer-reviewed literature. Lack of enough scientific research means that in many cases we are losing precious biodiversity even before they get discovered, a situation particularly acute in South and Southeast Asia (Kunz et al. 2005; Fenton and Simmons 2014). For the little fraction that we are aware of, bats seem to be an enigma gradually enfolding a bewildering array of behavior so intertwined with nature that their demise can certainly spell doom to many natural ecosystems. This has also prompted in many scientific studies addressing their biology, ecology as well as evolution. Among these studies, researches dealing with association of bats with deadly disease outbreaks have become particularly illuminating for humanity in general. Bats carry numerous viruses like SARS, Ebola, Nipah and Rabies virus, but rarely show signs of infection. However, such viruses, if transmitted to livestock or humans causes high mortality, and widespread epidemics (Han et al. 2015; Plowright et al. 2015).  We now know that, direct spread of virus from bats to humans is rare and most infection find their way into humans through livestock. Some studies have also pointed out that bats shed more viruses when under stress. Many documented bat borne disease outbreaks can be linked to close proximity of bats with humans wherein, human settlements have encroached into forest lands and bats are forced to stay close to human settlements, in many cases roosting (nesting) close to livestock. As they shed viruses though excrements, or saliva, the viruses are picked up by livestock and gradually transmitted to humans. Scientists, on a regular basis are discovering novel mechanisms by which bats make themselves immune to viral diseases and believe that bats can form an effective model system to study immunity to virus infections ultimately helping us to devise better technology to combat viral infections and outbreaks.

There is a lesson for us to learn from bats and that is, there are other organisms in this world who are different from us, but nonetheless intelligent and with unique capabilities. The web of life binds us all intricately into a matrix of coexistence that has lasted for over millions of years. It is for us to decide if we still want to cohabit with our neighbors, or consider this diversity as alien, remove them from our surroundings and keep curating the earth as our kitchen garden, to our own peril.

 

References

1) Altringham JD (1996) Bats: Biology and Behaviour. Oxford University Press, New York.

2) Arita HT & Wilson DE (1987) Long-nosed bats and agaves: the tequila connection. Bats 5:3-5.

3) Boyles JG, Cryan PM, McCracken GF & Kunz TH (2011) Economic importance of bats in agriculture. Science 332:41-42.

4) Fenton MB & Simmons NB (2015) Bats: a world of science and mystery. University of Chicago Press, Chicago.

5) Fleming TH, Geiselman C & Kress WJ (2009) The evolution of bat pollination: a phylogenetic perspective. Ann Bot 104:1017-1043.

6) Han HJ, Wen HL, Zhou CM, Chen FF, Luo LM, Liu JW & Yu XJ (2015) Bats as reservoirs of severe emerging infectious diseases. Virus Res 205:1-6.

7) Jones G, Jacobs DS, Kunz TH, Willig MR & Racey PA (2009) Carpe noctem: the importance of bats as bioindicators. Endangered Species Res 8:93-115.

8) Kelm DH, Wiesner KR & Helversen OV (2008) Effects of artificial roosts for frugivorous bats on seed dispersal in a Neotropical forest pasture mosaic. Conserv Biol 22:733-741.

9) Kunz TH & Fenton MB (2005) Bat ecology. University of Chicago Press, Chicago.

10) Marques MC & Fischer E (2009) Effect of bats on seed distribution and germination of Calophyllum brasiliense (Clusiaceae). Ecotropica 15:1-6.

11) Plowright RK, Eby P, Hudson PJ et al (2015) Ecological dynamics of emerging bat virus spillover. Proc R Soc B 282:20142124.

12) Welbergen JA, Klose SM, Markus N & Eby P (2008) Climate change and the effects of temperature extremes on Australian flying-foxes. Proc R Soc B 275:419-425.

About Author: 

Balaji Chattopadhyay, National University of Singapore, Singapore

email: balaji@nus.edu.sg