ZOO510 assignment 2 solution spring 2020
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ZOO510 assignment 2 solution spring 2020
Question. 1
A. What is Kusumi Lac
and different forms of Lac?
The Lac which grows on Kusum plant is called as “Kusumi lac"
Different froms of Lac are:
. Stic Lac
. Seed Lac
. Shell Lac
. Button Lac
. Garnet Lac
. Bleached Lac
B. Describe the life
cycle of Bombyx mori?
Bombyx mori:
Biology of Bombyx Mori:
The mulberry silk moth, Bombyx
mori belongs to the family Bombycidae. China is the native place of this moth,
but now it is totally domesticated and successfully reared in India, Japan,
Korea, Italy, France and Russia. In India 92% of country’s silk production
comes from mulberry moth.
The worm or larva of this moth
solely feeds on leaves of mulberry plant, so named as, mulberry worm. Its wild
ancestor B.mandarina still occurs in some isolated areas of Himalaya’s
foothill.
Life Cycle of Bombyx Mori:
Bombyx mori being a holometabolous insect, undergoes complete
metamorphosis with four stages in its life cycle, viz., egg, larva, pupa and
adult . Sexual dimorphism is present in adult, pupal and larval stages of life
cycle.
The duration of each stage
varies according to inherited characters of the race and also with the
available environmental conditions, quality of food provided, etc. Here, the
life cycle of most prevailed race of Bombyx mori in India will be discussed
with the following headings.
Adult moth:
The adult Bombyx moths do not take any food and incapable to fly.
Their life-span is only 3-6 days. The whole body along with wings remains
covered with epidermal scales and the body is divisible into 3 parts, viz.,
head, thorax and abdomen.
(i) Head:
The small head bears mouth at
ventral side and two prominent bipectinate and serrate antennae on two sides.
Below the base of antennae, two compound eyes are present on either side of the
head. Mouthparts are located between the compound eyes, which include inactive
coiled proboscis.
(ii) Thorax:
Thorax has 3 segments – prothorax, mesothorax and metathorax of
which mesothorax is the largest.
Each thoracic segment bears a
pair of 5-jointed legs. The meso- and metathorax bear two pairs of wings, the
larger, triangular forewings remain attached to mesothorax while smaller
hind-wings are attached to the metathorax. Thorax also bears spiracles.
(iii) Abdomen:
The male moth has eight abdominal segments with a pair of hooks
‘harps’ at the caudal end which help in copulation. The female has larger and
fatter abdomen than that of the male which has seven segments.
A knob like projection covered
with sensory hairs at the caudal end of female is present. It can secrete
pheromone.
Copulation:
Following emergence from the cocoon, the females rest on the
cocoon, spreading out her feeble wings and immediately begin to scent by
exuding pheromone from her abdominal projection. The males being attracted by
the pheromone find the female and start mating. Thus they remain over for 12-24
hours when the females get inseminated by the male.
Egg laying:
After mating for 12-24 hours,
the pair gets separated and the female starts laying eggs while the male moths
die. Most females lay 150-300 eggs over the course of 1-2 days, some can lay as
many as 1000 also.
According to the race, B. mori
can lay two types of eggs-diapausing or hibernating and non-diapausing or
non-hibernating eggs.
Egg:
The clustered eggs always remain covered with gelatinous secretion
of the female moth. The colour of eggs depends on moth-race. In diapausing
eggs, the colour changes from light yellow to deep brown when they enter
diapause. In non-diapausing races, the colour of eggs does not change till the
development is complete.
The eggs are ovoid, spherical
or ellipsoid in shape and are flat on one side (dimple) through what eggs
remain attached to the substratum. The centrolecithal eggs remain covered by
chorion having two layers, outer exochorion and inner endochorion. Each egg has
an opening, called micropyle at the anterior end.
Hatching:
The hatching time of silk moth
eggs varies with voltinism and environmental conditions. Diapausing eggs under
natural conditions remain dormant for months till next spring. If diapause is
broken by acid treatment, the eggs have to be incubated at a temperature of
23-25°C for 11 to 14 days for completion of embryonic development and the
larvae to hatch out. Non-diapausing eggs normally take 9-12 days to hatch into
larvae.
Larvae of Bombyx Mori:
The newly hatched larvae are about 3 mm long, black in colour and
is covered by bristles situated on tubercles in each body segment. Young larvae
soon after hatching start feeding on mulberry leaves and grow. This period is
called first instar. After about 3 days, larvae stop feeding and undergo
ecdysis (shading off old cuticle). This period of ecdysis is called moulting.
After moulting, the larvae
start feeding again and grow rapidly in size. They repeat the moulting process
usually for 4 times and thus the larvae or caterpillars get changed into
second, third, fourth and fifth instar stages during the whole larval
period It takes about 21-25 days after hatching in case of multivoltine
moths or 24-48 days in case of uni- or bivoltine moths.
The fifth larval stage is the
longest stage when the larvae show maximum consumption of mulberry leaves and
high growth. Of the total ingestion during the entire larval period, nearly 85%
is taken during 4th and 5th in stars and a larva can take mulberry leaves
weighing 30,000 times of its body weight to reach 5th instar stage from 1st
instar.
The full grown 5lh instar
larvae are 7.5-10 cm in length. Its body is divisible into 3 parts, small head
with special spinneret through which silk is exuded; thorax with 3 segments,
each with a pair of clawed true legs which are not used for walking but for
holding the leaves while feeding; and abdomen with 11 segments.
The 9th, 10th and 11th
abdominal segments are fused together to form the apparent 9th segment, anal
plate and paired caudal prolegs. Each 3rd, 4th, 5th and 6th segment bears a
pair of fleshy, un-jointed muscular protuberances, known as pseudolegs or
prolegs, each bearing curved hook on the outer edge of leg tip disc. The eighth
abdominal segment has a projection on dorsal side, called
caudalhorn.
The most characteristic feature
of silkworm is their silk gland which is well- differentiated in 4th and 5th
instar stages. There are nine pairs of spiracles or stigmas placed laterally on
either side of the larval body. Besides this, larva has a number of projections
or nodules all over the body and markings on the skin which is race-specific.
The larvae have sexual
dimorphism. In female larvae, the sexual marking appears as a pair of milky
white spots known as Ishiwatas’ gland, one each in the right and left sides of
8,h and 9,h abdominal segments. In male larvae, the reproductive gland appears
as a small milky white protuberance at the centre of the vental side between
8th and 9th abdominal segments . This gland is known as Herold’s gland.
Ripe larva:
The full grown final 5th instar that has stopped feeding and ready
to spin the cocoon is called ripe worm or ripe larva. This stage is attained
after 6-7 days of feeding in 5th instar stage for bi- and multivoltine races in
tropics and 7-9 days for uni- and bivoltine for subtropical races.
It is translucent as the gut
discards all of its green content. The body of ripe worm shrinks in length and
a visible constriction appears at 4th and 5th segments. The worm stops feeding
and usually moves towards the edge of rearing tray.
Cocooning/spinning:
The ripe worm after being shifted to mountage passes last excreta
which are red in colour due to presence of tryptophan metabolites. After
emptying its gut, it first secretes a tiny droplet of silk – the anchorage
spot, which hardens and sticks onto the mountage. The larva then anchors itself
to that spot and spins a loose hammock forming the framework of the cocoon.
This loose, tangled mass of
filament is called blaze or floss which is not reelable . After getting a good
foothold in the hammock, the larva lays down the cocoon . During spinning, the
larva moves its head in a typical pattern; so the filament is spun either in
the shape of or a.
The former is found in the
outer layer, whereas the latter type is common in middle and inner layers of
cocoon. In this way, after forming a compact cocoon, the larva shrinks and
covers itself with a thin layer of silk. Then it detaches itself from the
shell, moults and transforms into pupa. The last layer of thin silk is called
pelade layer of cocoon which is unreelable.
During spinning, the secretions
from two silk glands come out through the spinneret independently as fibres and
called brins. The secreted sericin of both glands cements these two brins in a
single thread, called bave.
Dragging – a physical process
is also responsible for the coagulation of liquid silk to the fibre. The
process of spinning the cocoon takes about one to two days in case of
multivoltine and two to three days in uni/bivoltine races.
Pupa of Bombyx Mori :
Once the cocoon formation is over, the larvae moult inside and
transform into pupae . This is known as pupation. Papal stage is also called as
resting or inactive stage in the life cycle of silkmoth. Actually it is a
transitional stage during which some changes take place in the body of mature
larvae (ripe worms).
Before transforming into proper
pupa, the mature larvae pass through a pre-pupal stage during which dissolution
(histolysis) of many larval organs like silkgland, moulting gland, abdominal
appendages take place.
It is followed by the formation of adult organs (histogenesis)
during pupal stage when a pair of large compound eyes, a pair of large
antennae, fore and hind wings, legs, etc. become prominent. The cuticle of
newly formed pupa is soft and pale yellow in colour which gradually becomes
darker.
In the female pupa, a fine
longitudinal line joining the 8th and 9th abdominal segments is present on the
ventral side. In male pupae such line is absent; instead a small opening is
present in the 9th segment . Usually female pupae are larger and heavier than
the male pupae.
The pupal stage continues about
10-12 days during which development of full grown moth is completed. The adult
moth then secretes mild protease from their salivary gland to dissolve the
cocoon membrane in the form of a small opening through which they emerge out.
In this way Bombyx mori
completes its life cycle through the above-mentioned stages and concomitant
activities.
C. How bee sting can be
avoided during honey harvesting?
Bees Can be Dangerous
Bees can be dangerous, a beekeeper must take several safety
precautions when working around a honey bee colony.
– A hat or veil is commonly
used to keep the face and neck protected from
stings.
– Gloves are another popular
form of beekeeping protection, although many
beekeepers complain that gloves
restrict their movement.
– A hooded suit, typically made
from a light colored fabric to help distinguish the
beekeeper from the honey bee’s
natural predators, may also be used.
While working with a honey bee
colony, a beekeeper uses a smoker to help calm the bees.
– Smoke is useful in beekeeping
because it masks the guard bee’s alarm
pheromones and encourages the
other bees to feed by tricking them into
thinking they’ll soon need to
abandon their hive.
– The smoke gives the beekeeper
enough time to inspect the colony and
perform any needed maintenance.
– use Pine needles for fuel
in bee smoker.
What to do to avoid being stung
• proper clothing
• smoker
• best environmental conditions
• scrape sting out promptly
• slow movements- no jerking or
• extra care around
hive/flowers
• don’t remove veil too soon
• keep gentle bee stock
Question. 2
A. What is silk gland
and silk filament?(2+3) Marks
Definition of silk gland:
A gland that produces a viscid fluid which is extruded in
filaments and hardens into silk on exposure to air: such as
a.
either of a pair of greatly enlarged and modified salivary
glands of an insect larva that produce a compound filament from which a larval
or pupal cover (such as a cocoon) is spun
b.
any of two or more abdominal glands of a spider that open
through spinnerets and produce a filament used chiefly in the spinning of webs
Silk filaments:
Silk filaments are processed in manual reeling of several
filaments, whereby uniformity in diameter of the reeled silk is aimed at.
Silk filaments obtained from
the cocoon of the silkworm have been used for textile production since
sericulture was originally developed in China many centuries ago. And since
braided silk filaments have been used as surgical sutures for several decades,
silk is recognized as a biocompatible and cytocompatible biomaterial.
B. What are the
functions of fat in fishes?(2) Marks
Functions of Fat
1Providing energy
2-Cushions for vital organs
3-Energy reserves
4-Insulators & lubricants
5-Transports of fat-soluble
vitamins
C. Describe the life of
worker Bee? (3) Marks
A worker bee is any female (eusocial) bee that lacks the full
reproductive capacity of the colony's queen bee; under most circumstances, this
is correlated to an increase in certain non-reproductive activities relative to
a queen, as well. Worker bees occur in many bumble bee Bombus species other
than honey bees, but this is by far the most familiar colloquial use of the
term.
The life of the worker Bee
(Day 1-2)
• Cell cleaning - Brood cells
must be cleaned before the next use - cells will be
inspected by the queen and if
unsatisfactory will not be used. Worker bees in the
cleaning phase will perform
this cleaning, if not clean worker bee must do it again.
(Day 3-11)
• Nurse bee - Feed the worker
larvae, worker jelly, secreted from the same glands
that produce royal jelly.
Life of a Worker Bee
(Day 6-11)
• Advanced Nurse - Bees Feed
royal jelly to the queen larva. Drones receive worker jelly for 1 to 3 days at
which time they are moved to honey and pollen.
(Day 12-17)
• Wax production - Build cells
from wax, repair old cells, and store nectar and pollen brought in by other
workers. Early in the worker's career she will exude wax from the space between
several of her abdominal segments. Four sets of wax glands, situated inside the
last four ventral segments of the abdomen, produce wax for comb construction.
• Honey sealing - Mature honey, sufficiently dried, is sealed
tightly with wax to
prevent absorption of moisture
from the air by workers deputized to do same.
• Drone feeding - Drones do not
feed themselves; they are fed by workers.
Bee (Day 12-17) Continued
• Queen attendants - Groom and
feed the queen. They also collect QMP (Queen
Mandibular Pheromone) from the
queen and share it with the bees around them who
also share it spreading its
effects through the hive.
• Honeycomb building - Workers
will take wax from wax producing workers and build the comb with it.
• Pollen packing - Pollen brought into the
hive for feeding the brood is also stored. It must be packed firmly into comb
cells and mixed with a small amount of honey so that it will not spoil. Unlike
honey, which does not support bacterial life, stored pollen will become rancid
without proper care and has to be kept in honey cells.
• Propolizing - The walls of
the hive will be covered with a thin coating of propolis, a resinous substance
obtained from plants. In combination with enzymes added by the worker this will
have antibacterial and antifungal properties. Propolis is also used to
close off excessive ventilation and
entrances.
• Mortuary bees - Dead bees and
failed larvae must be removed from the hive to
prevent disease and allow cells
to be reused. They will be carried some distance
from the hive by mortuary bees.
• Fanning bees - Worker bees
fan the hive, cooling it with evaporated water brought
by water carriers. They direct
airflow into the hive or out of the hive depending on
need. 98 Life of the Worker 2
Visit the life of the Worker Bee
(Days 18 - 21)
• Guard Bees - protect the
entrance of the hive from enemies.
• Soldier bees - Soldiers hang
around near the entrance and attack invaders. They
work in concert with entrance
guards.
• Entrance guard bees - These
inspect incoming bees to ensure that they are
bringing in food and have the
correct hive odor. Other bees will be rejected or
attacked with soldier bees.
• Outside guard bees - Outer
guards may take short flights around the outside of the
hive in response to
disturbances.
• Water carriers - When the
hive is in danger of overheating, these bees will obtain
water, usually from within a
short distance from the hive and bring it back to spread
on the backs of fanning bees.
(Days 22 - 35)
• Foraging bees - The forager
and scout bees travel (2 to 5 miles) to a nectar source,
pollen source or to collect
propolis.
• Die in field - The life span
of worker bees depend on the time of year. Most worker
bees live about 28 to 35 days.
However, workers that are reared in September and
October can live through the
winter.
Question.3
A. Describe pond design
criteria?
. Screened inflow gates at shallow end of pond
. Screened harvest gates at
deep end
. Slope to harvest basin
(0.5-1.0%)
. Water depth 1.25 2.00 M
. Feeding tray piers(docks)
. Rounded or square corners,
steps or ramps for entry
. Primary dikes (levees) wide
enough to accommodate vehicles
B. What are the types
of culture waters in aquaculture?
Aquaculture is the breeding, rearing, and harvesting of fish,
shellfish, algae, and other organisms in all types of water environments.
Types of Aquaculture.
There are two types of
Aquaculture.
• Extensive Aquaculture:
Minimal control, lower density
• E.g.,
ponds, prevalent in third world
countries.
• Intensive Aquaculture:
Highly controlled, high
density, RAS,
raceways, confined • E.g.
industrialized
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