Assam Agricultural University

Jorhat, Assam

History of whitegrub project in Assam:

The center started functioning in August 2004 for research on agriculturally important soil arthropods of North-East hill region of India. Very little work on biology, bionomics, behaviour, seasonal incidence, population dynamics, crop losses and integrated management of whitegrubs and other soil arthropods have so far been carried out in this part of the country. Therefore, one of the major mandates is to explore and investigate the aforesaid aspects of whitegrubs and other soil arthropods. Except tea, most of the crops grown in this region are generally free from pesticidal umbrella. Therefore, a wide array of soil dwelling natural enemies of different crop pests and other useful soil micro arthropods is available in N,.E. India. There is a huge scope to investigate and search for new soil borne entomogenous fungi and their subsequent utilization in crop pest management. The research on the role of soil micro and meso fauna in the formation of humus, break down of organic m atter and nutrient cycling is still to get its momentum in this region.

Scientists associated with the Project:

SNo Name of the Scientist Photo Designation Contact Date of Joining in the Project
1. Dr. Badal Bhattacharyya Sr. Scientist & Principal Investigator

AINP on Soil Arthropod Pests

Department of Entomology
Assam Agricultural University
Jorhat (Assam), PIN: 785013

Phone: +91-9465648957

Fax: 0376-2310037

E-mail: badalassam@gmail.com
05.11.04
2. Mr. Himangshu Mishra Technical Assistant

AINP on Soil Arthropod Pests

Department of Entomology
Assam Agricultural University
Jorhat (Assam), PIN: 785013

Phone: +91-8721025421

Fax: 0376-2310037

E-mail: himansuu.misra@gmail.com
 
3. Ms. Dhanalakhi Gogoi Technical Assistant

AINP on Soil Arthropod Pests

Department of Entomology
Assam Agricultural University
Jorhat (Assam), PIN: 785013

Phone: +91-9706261687

Fax: 0376-2310037

E-mail: dhanalakhi.gogoi@gmail.com
 

Important species of Soil Arthropods in Assam:

The important soil arthropods infesting various crops in Assam are as follows:

Whitegrub: Holotrichia sp, H. consanguinea Blanchard, H. longipennis Blanchard, H. sikkimensis Blanchard, Apogonia sp., A. aerea Blanchard, Adoretus sp, A. ferruginea Fabricius, A. aerial Arrow, Adoretus pallens Blanchard, Anomala sp., A. chlorosoma Arrow, A. chloropus Arrow, Anomala dorsalis Fabricius, Lepidiota mansueta Burm

Cut worm: Agrotis ipsilon Hufnagel

Termite: Odontotermes obesus (Ramb.) and Microtermes obesi (Holgren)

Red ant: Dorylus orientalis Westwood

Burrowing cricket: Brachytrupes portentosus Licht

Mole cricket: Grylotalpa africana P de B

[1]. WHITEGRUBS: Survey and surveillance revealed wide array of scarab beetles including several new records from Assam. The scarabaeid fauna of Assam alone comprised of 43 species representing 21 genera and 6 subfamilies. Out of 43 species, 41 species have been reported for the first time from North East India. The major species recorded are Lepidiota mansueta, Sophrops irridipennis, Apogonia ferruginea, Anomala chlorosoma, Anomala chloropus, Heteronychus sp, Holotrichia serrata, Adoretus sp. and Adoretus aerial.

Scarab beetles recorded from Assam





[2]. CUT WORMS: Cut worm or greasy surface caterpillar viz, Agrotis ipsilon Hufnagel is an important polyphagous soil pest of cole crops like cauliflower, cabbage and knolkhol and other vegetable like potato, cucurbits, pea, okra etc. It also attacks rapeseed and mustard. Cut worm infestation in vegetables may go up to 35-40 per cent in potato; especially in TPS transplanted crop. The seedling mortality in potato crop may be as high as 25-30 per cent due to cut worm within 10-20 days of germination. The tuber infestation varies from 2.91 to 12.21 per cent. Of late, cut worms have become a major cause of seedling loss in vegetables grown in plastic green houses.





[3]. TERMITES: Termite is a perennial problem in many tea growing areas in the state. However, in field crops the attack of Odontotermes obesus (Ramb.) and Microtermes obesi (Holgren) are noticed in sugarcane, wheat and maize. Sugarcane setts (preserved and planted) as well as standing crops are very often attacked by the termites. Sett infestation may be up to 90 per cent while infestation in standing crop may vary from 10-20 per cent. Termite infestation in wheat and maize ranges from 5-10 per cent.



[4]. RED ANT (Dorylus orientalis Westwood): Red ant is a serious problem in all the potato growing areas of Assam. Tuber infestation in severe cases may be as high as 51.77-61.50 per cent. .Red ants have recently emerged as a sporadic pest of French bean in some places of Assam.



[5]. BURROWING CRICKET (Brachytrupes portentosus Licht): It attacks rabi and summer vegetables and wheat during the seedling stage. The extent of damage in vegetables may be up to 25 per cent.

[6]. MOLE CRICKET (Grylotalpa africana P de B): Mole cricket (G. africana) also attacks wheat crop and the seedlings of winter vegetables in Assam. It is also an occasional pest of potato responsible for 18.07-38.97 per cent tuber damage.

Major crops infested by Soil Arthropods in Assam:

The important soil arthropods infesting various crops in Assam are as follows:

1. Whitegrub: Green gram, Black gram, French bean, Rose, Potato, Sugarcane& Colocasia

2. Cut worm: cauliflower, cabbage and knolkhol and other vegetable like potato, cucurbits, pea, okra

3. Termite: sugarcane, wheat and maize. Sugarcane setts (preserved and planted) as well as standing crops

4. Red ant: French bean

5. Burrowing cricket: rabi and summer vegetables

6. Mole cricket: wheat crop and the seedlings of winter vegetables, Potato

Salient research achievements:

1. Survey and surveillance revealed wide array of scarab beetles including several new records from Assam. The scarabaeid fauna of Assam alone comprised of 43 species representing 21 genera and 6 subfamilies. Out of 43 species, 41 species have been reported for the first time from North East India. The major species recorded are Lepidiota mansueta, Sophrops irridipennis, Apogonia ferruginea, Anomala chlorosoma, Anomala chloropus, Heteronychus sp, Holotrichia serrata, Adoretus sp. and Adoretus aerial.

2. The seasonal life cycle and biology of a white grub beetle, Lepidiota mansueta was studied on Majuli river island and in the laboratory during 2005-2012. Of late, this species of white grub has appeared as a severe key pest of many field crops in Majuli, the largest mid-river deltaic island of the world. The most severely affected crops were potato, sugarcane, Colocasia and green gram and the extent of damage was found to vary from 42-48, 15-20, 35-40 and 30-35 per cent, respectively. L. mansueta has a biennial life cycle, which is first of its kind from North East India and the duration of egg, grub and pupal stages varied from 12-17, 635-671 and 28-35 days, respectively. Third instar grubs caused heavy damage to the crops and showed a prolonged developmental period which varied from 545 to 563 days. L. mansueta can be regarded as a rare species, because it spends its entire life cycle under the ground except for a short period during which adults come out of the ground for mating. Both sexes of adults were observed not to feed on any plants in the field and hence this species has got the unique distinction of first Indian phytophagous white grub species with nonfeeding adults. The possible effect of changes in activities of migratory predatory birds of L. mansueta might have strong bearing on the sudden large scale appearance of this pest in Majuli.



3. The key morphological character of 3rd instar grub was identified i.e., the presence of distichous palidim in raster, which will be of great help in identifying the grubs at farmers' level. The distributions of scales in the elytra of adults have been studied.

4. While studying the sexual dimorphism of L. mansueta based on pupal character, it was observed that the pupae which had a prominent protrusion on the ventral surface towards the posterior of the abdominal segment were males and those with flat abdominal segments were females.

5. The Stereo zoom and Scanning Electron Microscopy (SEM) of spiracular system of L. mansueta grubs indicates that they possess peripneustic tracheal arrangement. It shows absence of a conventional spiraclular opening, but presence of a convex projecting central bulla in place of the opening and sclerotized and smooth sieve plate with ultramicroscopic (< 3 micron wide) aeropyles, which provide protection against entry of water into the tracheoles but allowing only gaseous exchange for respiration. This study was undertaken to investigate the survival of grubs of L. mansueta under flooded condition since Majuli, being a river island is inundated by flood during rainy season.

6. Scanning Electron Microscopy (SEM) study of lamellate antennal lobes of both the sexes of L. mansueta adults exhibited a wide variation in respect of distribution of sensillae. The females showed seven types of sensillae whereas the males exhibited only three types of sensillae, which clearly indicates the role of pheromonal compounds in chemical communication between the two sexes.

7. The pheromonal compounds of L. mansueta were investigated in collaboration with NIAS, Japan and NBAII, Bangalore. GCMS-EAD analysis revealed that both male and female adult antennas showed significant responses in FID-GC peaks which clearly showed there is a presence of a probable aggregation pheromone in males while female abdominal extract showed good responses towards the male antenna indicating the presence of a sex pheromone.

8. Nine species of avian predators with encouraging predatory activities were identified.

9. While evaluating insecticides against white grubs (L. mansueta) in potato, quinalphos 25EC @ 400 gm a.i. /ha recorded lowest tuber damage (10.22 %) and highest tuber yield (86.72 ql/ha) with B:C ratio of 10.11:1. The pesticide residue analysis did not showed any detectable amount of quinalphos in potato samples collected at harvest. This technology has been recommended by the "Annual Technical Committee Meeting, 2011" of Assam Agril. University, Jorhat.

10. Soil application of imidacloprid @ 200 SL (48 g a.i./ha) at the time of sowing + one spray of NSKE 5ml/lit at 15 days after sowing (DAS) + gram bait 1st at 25 DAS and 2nd at 55 DAS to reduce the infestation of cutworm, Agrotis ipsilon in potato. This technology has been recommended by Technical Committee Meeting for Rabi, 2012 as OFT.

11. Soil drenching of furrows with chlorpyriphos 25 EC @ 0.06 per cent before sowing of potato tubers to reduce the infestation of red ant, Dorylus orientalis. This technology has been recommended by Technical Committee Meeting for Rabi, 2012 as OFT.

12. The maximum number of soil arthropods (5241.90/sq.m) was extracted by Tullgren funnel by using 40 watt electric bulbs in high light intensity up to 72 hours of exposure as compared to 60 and 100 Watt Tungsten bulbs. This was the maiden attempt to standardize the Tullgren Funnel to extract soil arthropods from soil samples.

13. Among the three ecosystems selected for determining the quantitative distribution of soil arthropods, the highest population of soil arthropods was recorded in forest ecosystem (13150.10/sq. m) followed by fallow land (7817.40/sq. m) and agroecosystem (4787.40/sq. m). Among the various soil arthropods extracted, collembolans and soil mites were recorded in large proportion during the course of investigation.

14. Mass campaigning against L. mansueta: Mass campaigning for the collection & destruction of L. mansueta beetles were conducted through " Farmers Participatory Approach" by involving 25 numbers of "Krishak Gut" from 25 numbers of Lepidiota endemic villages of Majuli during Feb-May,2012. This massive campaigning was exceedingly successful and about 43000 beetles were collected by both light trap and scouting by the farmers of Majuli. In 2013, the collection of the beetles was demonstrated by using Solar LED light traps which were supplied by Dr. Seiji Tanaka, National Institute of Agrobiological Sciences (NIAS), Tsukuba, Japan. The light trap collection and scouting was started from 1st April, 2013 and continued up to the 1st week of May. This massive campaigning was exceedingly successful and about 37000 beetles were collected by both light trap and scouting from both cultivated and non cultivated areas of endemic pockets by the farmers of Majuli. This success story has been highlighted by almost all local newspapers and electronic media of North East India.

Important recommendations:

The following technology has been recommended and included in the Package of Practices of Rabi Crops of Assam:

"Three budded sugarcane setts may be dipped in solution of chlorpyriphos 20EC @ 2ml/lit for 30 minutes before preserving the setts in "deep trench trash cover" method".

Ongoing Research Projects:

[1]. Multilocation Trials:

Expt. No.1: Monitoring Of Soil Arthropods

A. Species profiling of soil arthropods through light trap:

B. Monitoring of natural enemies of soil arthropods:

C. Scouting:

Expt. No.2: Management of Whitegrubs Through Chemicals

A. Field evaluation of insecticides as soil application

B. Field evaluation of Insecticides as post-sown soil application in standing crop: (20-22 days after mass beetle emerged)

Expt. No.3: Microbial Control of White Grubs

A. Field evaluation of entomopathogenic fungi, Beauveria brongniartii and Metarhizium anisopliae and against white grub

Expt. No.4: Management of cutworm

Expt. No.5: Preparation of inventory of soil Arthropods (GroupWise classification) under different Agro Ecosystem by Tullgren Funnel Method (TFM).

[2]. Location Specific Trial:

Expt. No.6: Management of termites in preserved setts of sugarcane

Under the aegis of this project, training programmes on various aspects of soil insect pests and their management have been conducted through various agencies including KVKs of Assam