Techniques Developed

[1]. Mass rearing of whitegrubs in the laboratory:

  Collect the beetles at night by jerking the host trees.

  Confine the beetles in wire gauge cages, the bottom of which should be provided with 10 cm. layer of
     moist soil to serve as ovipositor substrate.

     

  Keep the soil moist by sprinkling water periodically whenever needed.

  Leafy branches of host tree are placed in the cages as food of beetles.

  Provide fresh leafy branches daily and keep cage soil moist.

  Sieve the cage soil every morning with 5 mesh sieves and separate the eggs.

       

  Handle the eggs with the help of paper/paper tag.

     

  Put the eggs in earthen (5 to 7 cm.dia.) crucibles containing moist soil. 10-15 eggs can bee placed in
     a crucible at 0.5 cm depth.

     

  Cover the crucible with another inverted crucible of the same size.

     

  Keep several such covered egg crucible in a big shallow ear then bowl (about 40-50 cm.dia.)
     containing moist soil.

       

  Cover the big bowl with same sized inverted bowl.

     

  Periodically examine the eggs.

  When eggs hatch, transfer the first instar grubs carefully with the help of paper tags in another
     earthen bowl containing 1:1 sand and well rotten organic manure.

     

  Keep the soil mixture properly moistened.

  After 3-4 days transfer the grubs into earthen pots /bowls already sown with any crop of your area.
     Such pots should be sown in a relay fashion at internal of few days as to provide living roots regularly.

       

  Keep watering the pots as and when required.

  After few days as the grubs become older, change them to other pots/bowls containing the growing
     crops. Also reduce the number of grubs/pot as they become bigger to avoid canabolism.

       

  The grubs will grow on the living roots and after completing 3 instars, will be transformed in to pupae.

  Make a pupal camber in the crucible by pressing the inverted index finger in the soil.

       

  Transfer each pupa signally in a small earthen crucible (5 cm. dia) containing moist soil.
     Don't put any soil on the pupa; cover it with another inverted crucible of same size.

       

  Several such pupae containing earthen crucibles can be placed in a bigger earthen bowl (50 cm. dia.)
     containing moist soil. Cover the bowl with same sized inverted bowl.

     

  Examine the pupae periodically

  After completion of the pupal period the freshly emerged beetles may be allowed to stay in the earthen crucible for 24 hours as they could be very delicate; when their elytra got hardened after 24 hours, they could be transferred to glass desiccators filled with moist soil, cover the desiccators with lid lightly to avoid loss of moisture.

  Open the lid of the desiccators at fortnightly interval to check the moisture, if the moisture goes low; add water to the soil of the desiccators.

  The beetles remain in inactive state till the next monsoon season.


[2]. The Pheromone Technology for Beetle Management:

The adults of Holotrichia consanguinea emerge from soil with first good shower (premonsoon or monsoon) and congregate on preferred hosts. These beetles can be killed conveniently by spraying of imidacloprid 17.8 SL (0.027%) or monocrotophos 36 WSC (0.05%) or quinalphos 25EC (0.05%) or carbaryl 50 WP (0.2%) during day time just after the first shower of the season. In any case the spraying operation should be completed within three days of the showers with the objective to kill the adults before they are able to lay eggs in the soil. This technique is very effective, but at some places, where the population of host trees per unit area is very high, spraying of all the host trees within a very short period is a problem, consuming more time, labour and insecticide and also pollutes the environment.

To over come these problems, Durgapura centre of All India Network Project on Soil Arthropod Pests has generated whitegrub management technology using pheromone.

The pheromone (methoxy benzene), isolated from the abdominal glands of calling female adults of H. consanguinea have a unique property of acting as aggregating pheromone, attracting both the sexes from a distance of 15 meters. Use of this pheromone has made beetle control operation easier, economical and less hazardous as only one tree within a radius of 15 meters is required to be sprayed with insecticide and loaded with "Pheromone Dispensers".

For the purpose, a single tree from a group of host trees within a radius of 15 meters could be selected and sprayed with imidacloprid 17.8 SL (0.027%) or monocrotophos 36 WSC (0.05%) or quinalphos 25 EC(0.05%) or carbaryl 50WP(0.2%), during day time. "Pheromone Dispensers" be placed (3-4 dispensers/tree) on this host tree in the evening, continuously for three evenings at the time of beetle emergence. No time gap should be given between onset of rain, spraying and pheromone loading. This should be done for 3-4 days after first emergence of beetles.

The beetles which are attracted by pheromone, settle and feed on the sprayed host trees and get killed soon by contact as well as stomach action of the insecticide and thus, not able to return to soil next morning for egg laying.

By pheromone loading, number of trees to be sprayed is drastically reduced, which make the beetle control operation more effective, economical and less time consuming.

How a farmer can prepare the "Pheromone Dispenser" himself:

Materials:

1. Wire: 30-40 cm long

2. Sponge: 10 cm2

3. Pheromone: 3 ml

4. Stone: About 50 g

 

Methods:

Tie the sponge piece with one end and stone with another end of the wire. Pour the pheromone on the sponge drop by drop and throw it on the tree (3-4/tree/night).



[3]. Technology for Grub Management:

(A). Seed Treatment Technology

To protect groundnut crop from grub, Seed treatment with clothianidin 50 WDG (Dantotsu) at 2g per kg seed or Imidacloprid 600 FS at 6.5 ml / kg seed or quinalphos 25 EC at 25 ml/kg seed or imidacloprid 200 Sl at 3 ml/kg seed is quit effective. For this, a known quantity of seed should be placed in a seed treatment drum and the required quantity of insecticide added to it. The drum should then be swirled gently to provide uniform coat of the insecticide. Vigorous shaking should be avoided. The seed thus coated should be spread on a cement floor or plastic sheet under shade so that the insecticidal coat gets dried. This seed should be sown in furrows. The interval between coating and sowing should be short. The seed treatment is effective only for regular monsoon sown crop. Pre-monsoon sown crop or early sown crop may not be protected by seed treatment.

 

(B). Soil Treatment Technology

Presowing soil treatment with chlorpyriphos 10 G at 20 kg/ha or qunialphos 5 g at 25 kg/ha effectively protects the crop. The insecticides should be placed in seed furrows and not broadcasted. Soil treatment is suggested as an alternative to seed treatment.



(C). Standing Crop Treatment Technology

For advance sown crop, seed treatment or soil treatment should not be done as these will become ineffective by the time beetles emerge, lay eggs and grubs develop. For such crop, application of imidacloprid 17.8 SL at 300 ml / ha or quinalphos 25 EC or chlorpyriphos 20 EC at 4 l/ha with irrigation water be done. 3-4 weeks after onset of monsoon (mass emergence of beetles). Insecticidal application in standing crop could be done in the following ways :

1. Required amount of insecticide be applied at the point from which the water enters into the plot. This can be accomplished by putting the insecticide in an earthen pitcher having a hole in the bottom. A cotton wick should be placed in the hole for controlling the drops. The drops should be so calibrated with the movement of wick that the required amount of insecticide is applied uniformly with irrigation. The pitcher can be placed on a tripod.

2. Soil collected from the field (approx. 80-100 kg/ha) be treated with required amount of insecticide and the insecticide impregnated soil should be uniformly applied in standing crop near root zone in furrows. The application should be followed by light irrigation so that the insecticide percolates downwards. Insecticide impregnated soil can also be used against whitegrub in rainfed crop provide it rains soon after the application.

3. Insecticide sufficiently diluted with water could be taken in a rose can and be applied at the entry point of the irrigation water as described in method no.1. Farmer should ensure how much of diluted insecticide shall be needed for the plot to apply the recommended dose. Alternatively, insecticide could be applied with the rose can in the plant root zone in furrows, followed by light irrigation. It is suggested that higher dilution of insecticide in the later method will facilitate uniform application of insecticide.