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Bsc agriculture entrance exam

Agricultural exams are held at national, state and university level to grant admission to the candidates in various undergraduate and postgraduate agricultural programmes in Indian agricultural universities. At the national level, ICAR is conducted and AGRICET, CG PAT, JCECE, MP PAT are conducted at the state level. The courses offered in agriculture have a great scope. They deal with food production, horticulture, rural economy and development, environmental health etc.......  National Level Agricultural Entrance Exams Indian Council of Agricultural Research (ICAR)  –  AIEEA UG  |  AIEEA PG  |  AICE SRF/JRF (PGS) State Level Agriculture Entrance Exams Andhra Pradesh AP Engineering, Agriculture and Medical Common Entrance Test (EAMCET) AGRICET Chhattisgarh CG Pre Agriculture Test (PAT) Indira Gandhi Agricultural University (IGKV) CET Jharkhand Jharkhand Combined Entrance Competitive Examination (JCECE) Maharashtra MCAER Common Entrance Test (CET) Madhya Pradesh MP Pre Agriculture Test

Topic included (lac insect/species, host plant, biology, enemies (vertebrates’ insect, predators, parasites) and their control (mechanical, chemical, microbial, biological) and lac cultivation

Topic included (lac insect/species, host plant, biology, enemies (vertebrates’ insect, predators, parasites) and their control (mechanical, chemical, microbial, biological) and lac cultivation. 


Taxonomy


Phylum: Arthropoda

Sub-phylum: Uniramia

Class: Hexapoda/lnsecta

Family: Kerriidae

Superfamily: Coccoidea

Genus: Kerria  

Species: lacca 


Lac is a natural resin of animal origin. It is secreted by an insect, known as lac-insect in order to obtain lac, these insects are cultured and the technique is called lac-culture. It involves proper care of host plants, regular pruning of host plants, propagation, collection and processing of lac. Lac insects under the genus Kerria are generally bi-voltine with two broods in a year. But few species like K. lacca mysorensis (host plant-Sal), and K. sharda (host plant-Kusum) are tri-voltine having three broods in a year. Again, species belonging to the genus Paratachardia (host plants-Tea, Sandal, etc.,) are all univoltine. 

Host plant

Pongam or honge (Millettia pinnata) is a native of India and grows in profusion, generally planted as avenue trees by the forest department. It is renowned for its shade and is well known in traditional uses for its medicinal properties. It is also grown as a host plant for lac insects. The tree is also one of the food plants for common cerulean (Jamides celeno).

Kerria lacca can be cultivated on either cultivated or wild host plants. 

  • In India the most common host plants are: 

  • In Thailand the most common host plants are 

  • In China the common host plants include 

    1. Pigeon pea ([Cajanus cajan)

    2. Hibiscus species

  • In Mexico 

  1. Estimated yields per tree in India are 6–10 kg for kusum, 1.5–6 kg for ber, and 1–4 kg for dhak. The bugs' life cycles can produce two sticklac yields per year, though it may be better to rest for six months to let the host tree recover. 

  2. The leading producer of lac is Jharkhand, followed by the Chhattisgarh, West Bengal, and Maharashtra states of India. Lac production is also found in Bangladesh, Myanmar, Thailand, Laos, Vietnam, parts of China, and Mexico


Species

  1. Kerria lacca – the true lac scale

  2. Paratachardina decorella – the rosette lac scale

  3. Paratachardina pseudolobata – The lobate lac scale is a polyphagous and pestiferous lac scale insect, which damages trees and woody shrubs in Cuba, Florida, the Bahamas and the Australian territory, an insect native to India and Sri Lanka.

Life cycle 

The life cycle of lac insect is completed within 6 months and it consists of stages like adult, egg and nymph instars

Female: 

The female lac insect has a pyriform body measuring about 4-5 mm in length. The body is indistinctly divided into head, thorax and abdomen. Head bears a pair of degenerated antennae. Eyes are absent. Mouthparts are of piercing and sucking type. Posterior to mouth lie a pair of spiracles which ensures smooth breathing of the insect during lac secretion. Thorax has degenerated legs and lack wings. At the posterior part of the body, a triangular area the anal tubercle encircling some setae is present. Near to it are present 2 branchial openings and one small chitinous spine called dorsal spine. 

Male: 

The adult male is red in colour and smaller in size than the female insect. The length is about 1.2-1.5 mm. Head bears reduced eyes and ten segmented antennae. Mouth parts are similar to that of the females. Thorax has 3 pairs of legs. The male lac insect may be either winged with one pair of hyaline wing on its thorax or wingless (apterous). The eight-segmented abdomen ends into a short chitinous prominent sheath containing penis. A pair of white elongated caudal seta or filament is present on either side of this sheath. 

Egg: 

The female lac insect is ovoviviparous in nature. So, the laid eggs contain fully developed embryos within it. About 300-1000 such eggs are laid in the chambers (cell) in which the female remains encased. The egg laying period may last from 7 to 10 days. The eggs hatch within few hours of laying. But egg laying ceases if the temperature falls below 17°C in summer and 15°C in winter. 

Nymphs: 

Following hatching, the first instar Boat-shaped nymph very small in size (0.5 mm) and divisible into head, thorax and abdomen. Head bears antennae, ocelli and mouth. Thorax has 3 segments, each with one pair of leg and caudal setae are found at the end of abdomen. The crimson red coloured nymphs, referred to as ‘crawlers’, come out of the cell in search of suitable host plant branch for settlement. On reaching soft succulent twigs, the nymphs settle down close together and start to suck phloem sap through their suctorial proboscis. After one day or so of settling, the nymphs start secreting lac from the hypodermal glands lying under their cuticle keeping open their mouthparts, breathing spiracles and anus. The secreted semisolid lac hardens on exposure to air and the nymph gets fully covered by the lac encasement, called as lac cell. 

Metamorphosis: 

Within the cell, the nymphs moult thrice during first moult both male and female nymphs lose their appendages, legs and eyes. Following this moult, dimorphism appears in their cells. Inside the male cells, the male nymph casts off their second and third moults and matures into adults. 

On maturity, the males lose their proboscis and develop antennae, legs and a pair of wings. The male brood cell is slipper- shaped. It bears a pair of branchial pores on the anterior side and a single large circular pore on the posterior side. The posterior hole remains covered by a round trap door or operculum through which adult males emerge. 

Feeding Ground for Lac Insects: 

To get good quality lac through cultivation, it is necessary to ensure proper type of feeding ground to the lac insects. The insects need to be provided with succulent shoots, as it cannot drive its slender proboscis through thick bark. For getting a good number of requisite succulent shoots, the most important method is pruning. 

Pruning: 

Pruning means cutting away old, weak and diseased twigs from the host plants. It is done in January or June. It is very important for cultivation as it induces the host plants to throw out new succulent twigs. Pruning should be done with a sharp instrument to give a short and neat cut. If trees are old and have lost their capacity to produce vigorous shoots of new flush, heavier pruning is carried out to produce the new wood at the expense of the old. Such operation will bring the tree to a better shape, so that subsequent pruning will give the desired flush. Proper pruning should result in a good shape and give plenty of chances for the development of new shoots. 

Enemies of lac insect: 

Vertebrate enemies of lac insects: 

The important vertebrate enemies are squirrels and rats. The damage caused by these enemies as 50% of brood sticks. Squirrels are active during the daytime and the damage by them is more common under forest conditions. Rats are active at night-time and the damage usually occurs near about the villages. Besides squirrels and rats, monkeys also cause some damage to lac encrustations and to the newly developing shoots from pruned host trees by breaking them. 

Control: 

It is difficult to control the squirrels and rats under the open field conditions where lac is cultivated. However, scaring away of these animals or poisoning them may be adopted to keep the rodents under attack. 

Insect enemies of lac insect: 

It has been estimated that on an average, up to 30-40% of the lac cells are destroyed by insect enemies of lac crop. At times, the enemy attack can be so serious as to result in total crop failure. 

There are two kinds of enemy insects: 

(i) Parasites, and (ii) Predators. 

(i) Parasites: 

All parasites causing damage to lac insect belong to the Order Hymenoptera of class Insecta.  

Predators: 

The predators, on the other hand, are more serious and may cause damage up to 30-35 per cent to the cells in a crop. The important predators of lac insects are Eublemma amabilis and Pseudohypatopa pulverea are the most destructive to lac insects and are in regular occurrence but their incidence may vary from season to season, place to place and crop to crop. 

Prevention and Control of Insect Enemies: 

Preventive measures: 

  1. Parasite- and predator- free brood lac should be used for inoculation. 

  2. Self-inoculation of lac crops should be avoided as far as possible. 

  3. Inoculated brood bundles should be kept on the host tree for a minimum period only. 

  4. Phunki (empty brood lac sticks) should be removed from the inoculated trees in 2-3 weeks time. 

  5. All lac cut from the tree and all phunki brood lac (after use as brood lac) not required for brood purpose should be scraped or fumigated at once. 

  6. Cultivation of Kusmi strain of lac should be avoided in predominantly Rangeeni area and vice versa. 

Mechanical control: 

Set of 60 mesh synthetic netting (brood bag) to enclose brood lac for inoculation purposes can reduce infestation of enemy insects of lac. The emerging lac larvae easily crawl out from the minute pores of the net and settle on the twigs of the lac host plants, whereas the emerging adult predator enemies cannot move out of the brood bags and get entrapped within the net. This can check the egg laying by the predator moths on the new crop. 


Chemical control: 

Application of 0.05% endosulfan at 30-35 days stage of crop has been identified as the most effective dose of insecticide without any adverse effect on the economic attributes of the lac insect. 


Microbial control: 

Use of bio-pesticide, Thuricide (Bacillus thuringiensis) at 30-35 days stage of crop is the effective microbial control measure for important enemy insects of lac in field condition. 

Biological control: 

Two ant predators, viz. Camponotus compresus and solenopsis geminate rufa, are the most important and promising for biological control of predator enemies of lac in field condition. Egg parasitoids, viz. Trichogramma pretiosum, T. chilonis, T. poliae, Trichogrammatoidea bactrae and Telenomus remits, have been found to be effective in management of many lac predators like P. pulverea. Again, hyperparasitism is found to happen in some lac cultivation areas where parasites of lac insects could also be controlled biologically by hyperparasitic insects, viz., Aprostocetus (Tetrastichus) purpureus is secondary parasite of Coccophaqus tchirchii and Eupelmus tachardiae is a secondary parasite of Eublemma amabilis. 





Lac Cultivation:

Cultivation of lac involves proper care of host plants, regular pruning of host plant, infection or inoculation, crop-reaping, control of insect pests, and forecast of swarming, collection and processing of lac. The first and most important prerequisite for lac cultivation is the proper care of the host plant. It is the host plants on which lac insects depend for their food, shelter and for completion of their life cycle. There are two ways for the cultivation of host plants. One is that plants should be allowed to grow in their natural way and the function of lac-culturist is only to protect and care for the proper growth of plants. Another way is that a particular piece of land is taken for the purpose and systematic plantation of host plant is made there. Regular watch is necessary in this case by providing artificial manures, irrigation facilities, ploughing and protecting the plants from cattle and human beings for which the land should be fenced. The larvae of lac insects are inoculated on host plants only after the host plants have reached a proper height. The lac larvae feed on the cell sap by inserting their proboscis in the tender twigs. The proboscis can only be inserted in the tender young off-shoots. For this before inoculation, pruning of lac host plants is necessary. The branches less than an inch in diameter are selected for pruning. Branches half inch of less in diameter should be cut from the very base of their origin. But the branches more than half inch diameter should be cut at a distance of 1 ½ inch from the base. 

Inoculation:

The method by which the lac insects are introduced to the new lac host plant is known as inoculation. This may be of two types, namely “Natural infection” and “Artificial infection”. When infection from one plant to other occurs by natural movements of insect, it is called natural infection. This may be due to overcrowding of insect population and nonavailability of tender shoots on a particular tree. Artificial infection takes places through the agencies other than those of nature. Prior to about two weeks of hatching, lac bearing sticks are cut to the size of six inches. They are called “Brood lac”. Brood lacs are then kept for about two weeks in some cool place. 

When the larvae start emerging from this brood lac, they are supposed to be ready for inoculation. Strings сan be used for tieding the brood lac with the host plant may be of different types in longitudinal infection the brood lac is tied in close contact with host branches. In lateral infection the brood lac is tied across the gaps between two branches. In interlaced method, brood lac is tied among the branches of several new shoots. 

Lac Crop:

The lac insects repeat its life cycle twice in a year. There are actually four lac crops since the lac insects behave in two ways either they develop on Kusum plants or devlop on plants other than Kusum. The lac which grows on Non-Kusum plants is called as “Ranjeem lac,” and which grows on Kusum plant is called as “Kusumi lac. Four lac crops have been named after four Hindi months in which they are cut from the tree. They are as follows: 

Ranjeeni Crop:

(i) Katki: 

Lac larvae are inoculated in June-July. Male insect emerges m August-September. Female give rise to swarming larvae in October-November and the crop is reaped in Kartik (October and November). 

(ii) Baisakhi: 

Larvae produced by Katki crop are inoculated in October-November, male insects emerges in February-March, females give rise to swarming larvae m June-July, the crop is reaped in Baisakh (April-May). 

Kusumi Crop: 

(i) Aghani: 

Lac larvae are inoculated in June-July, male insect emerges m September, female give rise to swarming larvae in January-February and crop is reaped in Aghan (December-January). 

(ii) Jethoi: 

The larvae produced by Aghani crop is inoculated in the month of January- February, male emerges in March-April, female give rise to swarming larvae in June- July and the crop is reaped in the month of Jeath (June-July). 

The time of infection with swarming larvae, the time of emergence of male insects, the time of reaping the crop, and the time of producing swarming larvae by female etc., are shown m tabular form below 


Scraping and Processing of lac:

Lac cut from the host plant is called as “stick lac”. Lac can be scraped from the twigs before or after the emergence of larvae. If it is used for manufacturing before the emergence of larvae, the type of lac produced is called as “Ari lac” and if it is used for manufacturing purpose after swarming of larvae has occurred, the lac is said to be Phunki lac”. The scraping of lac from twig is done by knife, after which they should not be exposed to sun. The scraped lac is grinded in hard stone mills. The unnecessary materials are sorted out In order to remove the finer particles of dirt and colour, this lac is washed repeatedly with cold water. Now at this stage it is called as “Seed lac” and is exposed to sun for drying. Seed lac is now subjected to the melting process. The melted lac is sieved through cloth and is given the final shape by molding. The final form of lac is called “Shellac”. Colour or different chemicals may be mixed during melting process for particular need.



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