Lac cultivation is a complicated process, so the cultivators should know well about the inoculation, swarming period and harvesting of lac.
Inoculation of Lac:
The first procedure in the lac cultivation is the inoculation of lac insect. Inoculation is the process by which young ones get associated properly with the host plant.
Inoculation is of two types:
1. Natural Inoculation:
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The inoculation taking place normal routine or in natural way is very simple and common process during which the swarmed nymphs infect the same host plant again and start to suck the juices from the twigs.
The natural incubation of swarmed nymphs has some drawbacks, which are as follows:
(a) Incomplete Nutrition:
Lac insects with their piercing and sucking mouth-parts, pierce into succulent twigs and suck the cell sap of the same host plant is further sucked out by the swarmed nymphs of the second crop continuously, the growth of the host plant would be retarded. In this way lac insect may not be able to get enough nutrients from the same host plant. The lac insects due to lack of sufficient nutrients lose their proper development, thereby affecting the production of lac also.
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(b) Irregular Inoculation:
During the natural inoculation it is not sure that uniform sequence of inoculation takes place. If inoculation is not of continuous fashion, a regular crop of lac may not be obtained.
(c) Unfavourable Climatic Conditions:
At the time of swarming a number of factors like high Intensity of sunlight, heavy rainfall, flow of wind etc. affect the proper inoculation of nymphs. These natural environmental factors may also affect the host plant at the same time and may cause a gap of inoculation resulting in irregularity of the lac crop.
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(d) Multiplication of Parasites and Predators:
Lac insects have certain enemies in the form of parasite and predators. If the crop is not harvested in time and lac is allowed to remain on the same twig, the multiplication of parasites and predators take place which hampers the population growth of lac insects.
Thus, keeping in view the above drawbacks the natural procedure of inoculation is avoided and certain devices have been developed to ensure artificial method of inoculation.
2. Artificial Inoculation:
Artificial inoculation of lac in the plant gives a better and regular supply as well as the amount of lac received is also much higher than that of natural inoculation. The quality improves along with the healthy insects. To rear them artificially a good and planned crop of host plant is required for culture of the insects. Generally two systems are applied during this process.
Coupe System:
In such a system the plants are grouped in small contingents and these contingents of plants are called coupe. The ratio of plants per coupe varies according to the variety of host plant and type of lac corp. Usually Palas and Ber are grouped in three coupes in a ratio of 1:3:3 while the kusum trees are divided into 4 coupe.
The smaller group is always kept in the middle and the plants are inoculated at different intervals according to the lac crop, e.g., the Kartiki crop is cultured on the smaller coupe while the Baisakhi is taken on the bigger coupe. In case of kusum plants the crop is grown alternating with each other group of plants. So a plant gets 18 months resting period for its proper growth.
The total strategy behind such a system is that the plant must get proper rest and should develop in normal ways. In natural inoculation the plant never gets rest. The coupe system is supposed to be the best as during rest period when there is no inoculation or infestation on the plant. The plant develops in its natural way and its pruning and manuring helps in developing new, tender, succulent branches which are the best for inoculation.
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Inoculation of lac is done only a few days before swarming of the larva. The period of swarming varies in different species and in the same species on different host plants. It can be recognised by tearing. The twig, full of egg, it taken from the infested plant and is tied with the new plant in such a way that it must touch the plant, to be inoculated at 3 or 4 points.
The larvae are small and tender and cannot move for long so they are arranged in such a way that should get a new succulent twig at the minimum distance. The inoculation twig should of medium size about 20-30 cm. and placed in proper position among the new branches. Over infestation, irregular infestation and sick and parasitized inoculation should be avoided.
Cropping of lac is again a technical job. It is done in such a way that minimum damage to the plant is done by the same time brooding and swarming of lac insects is also kept in the mind, removal of premature lac- ARI Lac is a loss to the grower. The lac insect produces lac up to the last moment so it must not be disturbed. Lac should be scrapped in the earlier possible days after cropping. This helps in killing the enemies. Such a lac is called Stick Lac.
Alternation of Host Plant:
In this process various types of plants are grouped together and the brood is developed alternating with each other host plant. This gives rest to the host plant as well as the product received is also of different type.
Period of Infestation:
For Kartiki crop infestation is done in June and only on smaller coupe while for Baisakhi crop inoculation is done in October. The trees are inoculated alternately for Kartiki and Baisakhi crop. Kusum trees are inoculated in September for Jethi crop and month of August for Aghani crop.
Uses of Lac:
Lac is used in a variety of ways, bangles, toys, woodwork, sealing waxes, bad conductors, records, varnishes, polish, inks, filling the spaces and silvering the mirror are some of the uses where lac is needed.
Inoculation Period of Lac:
In India two types of crops viz., Rangini and Kusumi are grown in a year. The Rangini crop is of two types called as kartiki and Baisakhi crop, which produce Kartiki and Baisakhi lac respectively. The Kusumi crop is also of two type’s viz., Agahani and jethi which produce Agahani and Jethi lac respectively.
Thus the inoculation periods of all the four types of crops are different. The inoculation of Kartiki, Baisakhi, Agahani and jethi crops are recommended in months of June of July, October to November, July and January to February respectively. But if continuously four crops are taken, the plant would not get any rest which may cause less production of lac.
Swarming of Lac:
It is very important phase in the life history of lac insect. So one should have accurate knowledge about the actual date of the swarming. At the time of swarming, the upper surface has yellow spot on the anal region. At this stage muscle contracts and insect gets detached from the place of attachment.
Thus, it leaves a hollow cavity which later on gets covered with wax also. When these eggs are to be hatched out they become orange coloured .Thus, it is an indication that swarming has taken place. Thus, by trials and learning methods i.e. by practice on could know about the exact date of swarming by looking at the colour of the eggs.
Factors Affecting Lac Cultivation:
Lac cultivation is destroyed by biotic and a biotic factor:
1. Abiotic Enemies:
These are high intensity of light, high temperature, high humidity, heavy rainfall and flow of wind.
2. Biotic Enemies:
The main biotic enemies of lac cultivation are mammals and insects. Krishna swami et. al. (1957, 59) and Gepulpure et. al. (1963), have reported that squirrel, rats, and monkeys cause great damage to the lac crop.
The insects are very powerful enemies of lac crop. Annual loss due to the insect enemies is to the tune of about four lakh maunds.
The insects damage the crops in different ways:
I. Parasites:
The lac insects are parasitised by eight species of chalcidoid parasites like, Parenchthrodryinus clavicornis, Erencyrtus dewitzii, Tachardiaephagus tachardiae, Tachardiaephagus tachardiae var. somervilli, Eupelmus tachardiae, Coccophagustschirchii, Mariettajavensis and Tetrastichus purpureus. These parasites lay their eggs into lac insects and parasitised 4.8 to 9.9% of lac insects per year and 1/3 of the parasitised cells are males. Thus, it may be concluded that parasitization is not a major cause of the damage to the lac cultivation.
II. Predators:
Predators cause very severe damage to lac cultivation and 35% of the lac cells are damaged by two predators viz., Eublemma amabilis Moore (Lepidoptera: Noctuidae) and Holocera pulverea Meyr (Lepidoptera: Blastobasidae). Female lays eggs near encrusted twigs from where larva emerges and feeds on lac insects.
Precautions for Lac Cultivation:
1. Twigs for inoculation should be cut just before the swarming to get healthy brood.
2. Twigs used for inoculation should be free from predators and parasites.
3. Twigs tied for inoculation should be removed form inoculated host plants after a maximum period of 20 days.
4. Lac left on the host tree for swarming should be removed in October and November.
5. The brood lac after swarming should be destroyed along with predators and parasites on it.
6. The lac scraped from the tree should be taken away from the area of lac infected trees.
7. Fumigation and water immersion of lac, before removing from twig, should be done.