SUBJECT- ZOOLOGY (HONOURS)
FOR THE STUDENTS OF DEGREE III
PAPER- VI
TOPIC-LAC CULTURE
BY
DR.RITTIKA PANDEY
ASSISTANT PROFESSOR
DEPARTMENT OF ZOOLOGY
JAGJIWAN COLLEGE, V.K.S.U., ARA
LAC CULTURE
Culture of lac insect on large scale for commercial production of shellac is called Lac culture.
SYSTEMATIC CLASSIFICATION OF LAC INSECT
Phylum
Arthropoda
Class
Insecta
Order
Hemiptera
Super family Coccidae
Family
Lacciferidae
Genus
Laccifer
Species
L. lacca
HOST PLANTS OF LAC INSECT
Kusum (Scheichera trijugo)
Palas (Butea frondosa)
Ber (Zizyphus jujuba)
Babul (Acacia Arabica)
Khair (Acacia catechu)
LIFE CYCLE OF LAC INSECT
Female lac insect lives in resinous chamber on branches of host plants. Females are fertilized
by males in their resinous cell. Male enter the female encrusted area through the minute
openings. After mating, male insects die. Males are found both as winged and wingless
forms. After fertilization, female grows fast due to development of egg inside the body. Body
of a female become sac-like and is bright red in colour. Female dies inside the chamber. The
eggs develop into larvae inside the female chamber. Larvae leave the chamber through the
narrow opening. Larvae are also known as crawlers. Crawlers move to find a suitable place
on shoots of host plants. With the help of proboscis, sap of plants is sucked by crawlers.
Crawler, as it grows secretes a resinous material that completely covers it. This resinous
encrustation grows in size with the growth of animal living inside it. After a period of 3
months, larvae develop into adult inside the encrustation. Female never leave the encrusted
cell while male emerges from the chamber and enter into the chamber of female for the
purpose of mating.
When large numbers of crawlers settle side by side and resinous material is secreted around
them, then the whole branch is covered by the resinous cells of lac insect.
PROCESS OF LAC CULTURE/PRODUCTION
Lac culture involves the following steps.
PROPER CARE OF HOST PLANT
Plants that grow naturally do not require much attention. But systemic plantation of host plant
require regular and proper care like application of manure, irrigation of plants, ploughing at
regular intervals along with fencing the plants in order to protect them from herbivores.
REGULAR PRUNNING
Trimming of host tree branches is required before the infestation with the crawlers. As
crawlers suck the plant sap of tender branches, hence pruning facilitate the proper growth of
crawlers. Branches that are less than half inch in thickness are cut from their branching point
while branches with more than half inch in thickness are cut at a distance of 1.5 inch from the
base. Branches of plant that are less than an inch is selected for trimming.
INOCULATION
The process by which the lac insects are established to the new host plant is called
inoculation.
It is of two types
NATURAL INOCULATION
When infestation of lac crawlers occur from one host plant to other by their natural
movement in search of suitable place for sucking the plant sap is called natural inoculation.
ARTIFICIAL INOCULATION
When infestation of insect is supported by artificial means, then it is termed as artificial
inoculation.
It is of three types.
Longitudinal infection
Lateral infection
Interlaced infection
Brood lac stick
The shoot that bears the female cells along with developing eggs inside it is called brood lac
stick.
Brood lac
Presence of eggs in the living female chamber is called brood lac. About two weeks before
hatching out from eggs, brood lac stick is cut. Size of each brood stick is about 6 inches.
Brood lac is kept for two weeks in cool place and when larvae start emerging from brood
cells, they are inoculated by any of the three methods of infection.
SCRAPING AND PROCESSING OF LAC
Twigs that are encrusted with lac insect’s resinous material is called stick lac.
Lac can be scraped from the shoots before or after emergence of crawlers.
Scrapping of lac from twigs can be done with the help of knife.
Depending upon the time of scrapping, lac is of two types
ARI LAC
When lac is scrapped before the emergence of larva, then it is called Ari lac
PHUNKI LAC
If lac is scrapped after emergence of larva from resinous cell, then it is called Phunki lac.
The scraped lac is then powdered in stone mills and undesired material is assorted. For
removal of finer dust particles, the powder is washed repeatedly with cold water. This form
of lac is called seed lac.
Seed lac is exposed to sun for drying. After that, seed lac is melted. The melted lac is sieved
with the help of cloth. Addition of colour or other chemical is done during melting process. It
is then moulded into different shapes.
The processed lac is called Shellac.
USES OF LAC
Lac is used in sealing wax, bracelets, gramophone records, filling ornaments, manufacturing
of varnishes, paints, silvering the back of mirror, encasing cable wires.
By-product during the processing of lac is used in nail polish.