Major contributions in my professional career
1981-1985
During the period I was working as a Research Assistant. The main areas in which I was working is the Thrips-Weed-Crop
Interaction with particular emphasis on the role of the weeds as collateral weeds for important thrips pests on ground nut, castor etc. I also worked on the thrips as the pollinators of important solanaceous
plants like brinjal etc.
My Ph.D. studies were on the Bioecology of two important thrips species, Retithrips
syriacus and Rhipiphorothrips cruentatus with particular reference to the Insect
–Host plant interactions. The biology of these pests as influenced by host plants was studied along with the nature
of damage, histopathology of damage and the role of physico chemical characteristic of the plants on the biology of the these
thrips species.
1985-1989- (ICAR RESEARCH COMPLEX FOR NORTH EASTERN HILLS REGION-NAGALAND
CENTRE).
During this period I was working as Scientist on the Pest management of major insects of several crops like Rice, maize,
vegetables and fruit crops.
1989-1991- (NATIONAL RESEARCH CENTRE FOR CASHEW-PUTTUR)
During this period I was working on the Integrated
Pest management of cashew pests, especially cashew stem and root borers Plocaederus spp. and tea mosquito bug Helopeltis antonii.
The major emphasis was to
manage these pests through prophylactic and biological control methods.
1991-1994 (PROJECT DIRECTORATE OF BIOLOGICAL CONTROL-BANGALORE)
Genetic improvement and Pilot plant production of Trichogrammatids
and Chrysopids.
I was working on the selection of suitable strain of chrysopids for different crop pests at different ecosystems. I
was also engaged in developing a suitable strain of Chrysoperla carnea resistant to monocrotophos and the synthetic pyrethroids.
1994- till date (PROJECT DIRECTORATE OF BIOLOGICAL CONTROL-BANGALORE)
Assigned the duty of establishing the Entomophagus Insect Behaviour Laboratory . The laboratory was established with
the sophisticated instruments like Insect Activity meter, leaf area analyser, Electro antennogram, Gas chromatography-mass
selective detector, Amino acid analyser, water purification system, b scintillation counter,
vacuum concentrator , wind tunnels, olfactometers, and other miscellaneous equipments .
USE
OF SEMIOCHEMICALS TO INCREASE THE EFFICIENCY OF PREDATORS.:
1.
Kairomones for the adults of Chrysoperla
carnea
Several
wind tunnels/ oflcatometers were developed and tested theier efficicncey for
the larvae and adults of chrysopids.
Starving
period was studied and found that the adults starved for 24 hours responded well to the kairomones.
Insect
activity meter studies revealed that the adults showed arrestant behaviour on contact with the kairomones.
Electro
antennogram studies also revealed that the adults showed positive response to the kairomones.
Olfactometer
studies/ multiple choice experiments revealed that the adults responded to the 50% honey, 0.33% and 0.66% l-tryptophan three
to 15 days after hydrolysis.
Field
cage and field studies confirmed that the adults oviposited more on the cotton plants treated with 3 day old L-tryptophan.
Kairomones
were also used to induce oviposition on the tomato plants, the less preferred host plants of C.carnea. However no oviposition was observed.
As the L-tryptophan –valine was found to the
fraction repsponsible for the attraction of chrysopoids studies were inirated using this combination as valine is very much
cheapter than the tryptophan.laboratory and field cage experiments were conducted to find out the potential of the valine-tryptophan combination.However L tryptophan alone was found to be better
than others.
Field cage experiments were conducted to find out
the utility potential of the valine-tryptophan combination.L tryptophan alone was found to be better than others.
2.Kairomones for the larvae
of Chrysoperla carnea
The preliminary trials indicated among the larvae, the early third
instar larvae showed higher response to the kairomoes. Also 4 hour starvation was found
ideal for the behavioural studies.
Insect
activity meter studies revealed that the larvae did not show any behavioural
response on contact with the kairomones. A three dimensional stucutre was found
necessary to evoke any behaviural response.
Y’
tube olfactometer studies indicated that the larvae responded well to the scale extracts of H.armigera and other kairomonal substances.
Kairomones
based on the scales of C.cephalonica fortified with the n-tricsoane was found to
increase the predatory efficiency of the larvae of C.carnea on cotton. The formulations
based on the cyclohexane were less phytotoxic than hexane.
The
kairomones when used as the mass priming agent increased the predatory potential of C.carnea
when the larvae were exposed to the kairomones based on the scales of H.armigera.
Kairomones
were also used to increase the predatory potential of the C.carnea on the non host
plants. The predatory potential of C.carnea
was found to be increased on the sunflower plants with less phytoxicity however the predatory potential was not increased
on tomato with no phytotoxiciy.
3. Kairomones for the coccinellids.
The
larvae of Cheilomenes sexmaculata did not show any response to the kairomones in
y tubes.
The
adults of Coccinella septumpunctata showed higher response to the kairomones than C.sexmaculata.
Efforts
were made to induce oviposition by C.sexmacualta
using kairomones without the natural diet. However, no oviposition could be noticed.
Chemical
analysis of kairomonal substances like scales of H.armigera etc revealed that the
primay compounds are tircosane, pentacosane etc which vary in their composition.
The body , larval, pupal and egg was of Helicoverpa armigera were also analysed for its volatile component. Heptadecane was found to be the major component
of all the extracts. While pentacosane was found in high concentration in the body wash, limonene was found only in pupal
wash. Plant related volatile like alpha-caryophyllene and alpha-terpinene were found in feeding larval stages. Heneicosane
was found in large quantity in egg wash.
DBT SPONSORED PROJECT USE OF SEMIOCHEMICAL
TO INCREASE THE BIOCONTROL POTENTIAL OF SOME IMPORTANT PREDATORS AND PARASITOIDS.
The Kairomones were also tested as “mass priming agents” to increase the searching
efficiency of the egg parasitoids Trichogramma chilonis.
The fraction containing L-tryptophan and valine was found to evoke more behavioural response in the earlier studies.
Therefore to find out the exact combination of L-tryptophan and L valine which is highly efficient, the solutions containing
L-tryptophan and L valine at concentrations 0.66 : 0.11 , 0.66:0.22, 0.66: 0.33, 0.66: 0.44 , 0.66: 0.55 and 0.66 : 0.66 (tryptophan : valine in grams per 100 ml) were used in the multiple choice tests. The 0.66
: 0.11 and 0.66 : 0.22 combination of tryptophan-valine were found to evoke better
oviposition . However L-tryptophan alone continued to evoke better response than other combinations.
The hydrolysis of L-tryptophan is time consuming, besides the hazards of using the strong acids for hydrolysis. Therefore,
quick oxidisers derived from the venom of snakes and slow oxidisers like hydrogen peroxide were used to oxidize the L-tryptophan instead of hydrolysis. The quick oxidisers did not reduce the oxidation period, the
solution after 3 days of oxidation was found to be better than the 1 or 2 days oxidized tryptophan. The efficiency of the
tryptophan oxidised with quick oxidisers was on par with the hydrogen peroxide oxidized L-tryptophan . The hydrolyzed L-tryptophan
was still found to be better than the oxidized tryptophan in wind tunnel and multiple choice methods.
The ultimate breakdown product of the L-tryptophan was identified as the indole acetaldehyde which was found responsible for the attraction of the chrysopids to the L-tryptophan. The indole acetaldehyde is not available in India and has to be imported
at an exorbitant cost. Hence a simple procedure to convert the indole acetic acid to indole acetaldehyde was found out and
studies were conducted to find out the optimum concentration of indole acetaldehyde for using as ovipositional attractant
for Chrysoperla carnea. Preliminary
results have indicated that the particular concentration of indole acetaldehyde has recorded more number of eggs than the hydrolyzed L-tryptophan in multiple choice
tests.
Formulations of kairomones based on tricosane, pentacosane, heneicosane and hexatriacontane were prepared and tested
for their efficiency on the egg parasitoids, Trichogramma chilonis in Y tube tests
and cage tests. The formulation based on tricosane was found to attract more
adults than control.
Coconut caterpillar Opisina arenosella is a dreaded pest . Four parasitoids
viz. larval parasitoid Goniozus nephantidis, prepupal parasitoid Elasmus nephantidis and pupal parasitoids, Brachymeria nephantidis
and B.nosatoi were recommended against this pests. Attempts were made to increase
the efficiency of these parasitoids using kairomones. Y tube olfactometer and multiple choice tests were conducted to select
the best kairomone source for the larval parasitoid, Goniozus nephantidis . The washings from the Opisina infested galleries
were found to attract more adults of Goniozus nephantidis than the other kairomones
like larval washings. More adult emergence of G.nephantidis was noticed in kairomone
treated larvae than untreated control. Experiments conducted with Y tube olfactometer
to see the effect of kairomone compounds on the
behaviour of Trichogramma chilonis revealed that dodecane , tricosane and hexadecane
were effective attractant for T.chilonis.
The pupal parasitoids like Brachymeria nephantidis and B. nosatoi were reared on the pupa of Opisina arenosella , the culturing of which is laborious. The larvae of Opisina arenosella were reared on the coconut palms and parasitoids were reared on these larvae. Attempts were
made to rear these parasitoids on the pupae of the common laboratory hosts, Corcyra
cephalonica using kairomones from gallery washings. Brachymeria nephantidis
was able to parasitize more number of kairomone treated pupae of C. cephalonica
compared to untreated pupae. More number of adults were obtained from the kairomone treated pupae than untreated pupae.
Electro antennogram tests were done to screen the best kairomones for the Chrysoperla
carnea. The adults of C.carnea responded to the various concentrations of tryptophan
- valine combinations. The combination of tryptophan -valine 0.66:0.11 was found to evoke good response among the concentrations
tested. Another EAG study revealed that indole acetaldehyde also evoked antennal response like other kairomones.
Mass priming experiments were conducted to study the
effect of kairomones on the parasitising efficiency of T. chilonis under semi- field conditions. The parasitoids exposed
to compounds like dodecane and hexacosane were able to parasitise more eggs successfully than untreated control .
Pot studies were also conducted using kairomones as formulations on cotton, sprayed prior to release of parasitoid.
Dodecane was found to enhance the parasitisation by T. chilonis. Test with other
compounds are under progress.
Multiple choice tests using wax dummies sprayed with different concentrations and different combinations of kairomones
from gallery wash and pupal wash were tested on Brachymeria nephantidis, pupal parasitoid of Opisina arenosella. The combination of 75 mg of gallery wash and 2 pupal wash extract was found to be most effective
in attracting B. nephantidis and it
was also noted that the parasitoid attempted several times to parasitise wax dummies by sitting on them. This concentration
of kairomone was then used as kairomonal mask to study the parasitisation of B. nephantidis
on Corcyra cephalonica pupa. The
studies are still in progress.
Chemical analysis of gallery wash , larval, prepupal and pupal wash of O. arenosella
was done using GC-MS. It was noted that 13-tetradecanal and myristic
acid exclusively present in gallery wash can be accounted for its major attraction to the parasitoids. Hexadecane was found
to be the major compound in all the four extracts. While, larval wash contained additional compounds like alpha-terpinene
and alpha-humulene, pupal wash had a very high composition of pentadecane and an exclusive compound-tetracosane, which can
be the factor responsible for attracting Brachymeria
nephantidis.
In order to develop kairomones for Cotesia
flavipes, the larval parasitoids of Chilo
partellus, preliminary studies were conducted using electroantennogram (EAG) to find out behaviour of adults to kairomones.
Higher EAG response was noticed from extracts of frass derived from C. partellus feeding on the host plant maize than frass
from artificial diet. Further studies under progress.
Multiple choice oviositional studies are being conducted in the laboratory
to find
out ovipositional behaviour of Chrysoperla carnea to Indole acetaldehyde. These
experiment is in progress .
Field
studies are conducted to find out the ovipositional response of Chrysopids and Coccinellids to acid hydrolysed and oxidised
L- tryptophan. The experiment is in progress.
Field studies are conducted to find out the efficacy of kairomone formulations in increasing the
parasitisng efficiency of Trichogramma
chilonis on cotton. The experiment is in progress.
Field cage experiments were conducted to find out
the possibility of reducing the dosage of Trichogramma chilonis on cotton with
the use of kairomone formulations. The experiment is in progress.
Multiple choice tests are being conducted to select
best kairomonal formulation for parasitoids of coconut pest, Opisina arenosella.
The experiment is in progress.
Quantitative analysis of the kairomone
compounds in the scales, egg washings, abdomen tip is being done so as to create synthetic kairomone compounds with the specific
active kairomone compounds. The experiment is in progress.
ICAR
CESS- IMPLICATIONS OF TRITROPHIC INTERACTIONS ON THE INTEGRATED PEST MANAGEMENT OF
SOME IMPORTANT CROP PESTS
This project was initiated in March 1999 with Dr.
S.P.Singh as the PI.
The Electro antennogarm response of the pest Helicoverpa armigera and the predator Chrysoperla
carnea to the volatile of the cotton, sunflower, chickpea and pigeon pea was studied. The adults of H.armigera showed higher response to the volatile of the chickpea and pigeon pea while C.carnea showed least response. However the response of C.carnea to
the volatile of cotton and sunflower is very high.
The EAG response of the H.armigera and C.carnea to the volatile of the different varieties
of cotton and sunflower was studied. Some varieties like MCU 7 and savitha evoked higher behavioural response.
The ovipositional response of the H.armigera and C.carnea to the different leaf, bolls/heads of different
varieties of cotton and sunflower was studied in the laboratory. Some varieties recorded higher oviposition.
The predatory potential of the larvae of C.carnea to different varieties of cotton and sunflower was studied in the semi field conditions. In some varieties
the predatory potential was very high.
The EAG and ovipositional behaviour of the adults
of H.armigera and C.carnea to the volatile
compounds of the cotton plants was tested. The response to the hexenol and pentanol
is very high in both the species.
Physical characterisation of the varieties of cotton
and sunflower was done by counting the number of trichomes in the leaves.
The varietal difference in the volatile was analysed by extraction and head space
analysis using GCMS. There is a significant variation in the volatile composition of monoterpenes between the different varieties
of cotton.
EXTENSION
ALL INDIA CO ORDINATED PROJECT ON NATIONAL DEMONSTRATION.
As the incharge of the All India Co‑ordinated Research Project on National Demonstration,
conducted several demonstrations on yield potential of HYV rice varieties, crop rotation
patterns including all agronomic, plant protection measures.
The yield potential of paddy (variety IR 8)ranged from 3.5
to 4.2 tones. Among the several crop rotations demonstrated Paddy‑potato resulted in higher income (Rs 3954+ Rs21940
per hectare), compared to other crop rotations. Several field days were arranged in which several farmers participated.
RESEARCH CUM DEMONSTRATION PLOTS ON CASHEW.
Engaged in the establishment of cashew trees with particular
reference to the plant protection measures in the demonstration plots at farmer's field .
TRAINING
I have taken part in the training programs conducted to State
Department Officials/ farmers on various cultivation packages of maize, paddy, pulses and oilseeds by Trainers Training
Centre and Krishi Vigyan Kendra of Nagaland Centre.
I have also delivered several lectures on the pest Management
practices against cashew pests conducted at National Research Centre for Cashew, Puttur conducted for the Development Officials
from different states.
I have delivered several lectures on the production and utilisation of Chrysopids in the regular training programmes
conducted for extension workers.
KNOWLEDGE OF HANDLING SOPHISTICATED INSTRUMENTS
I have been handling the following sophisticated instruments for synthesising
Kairomones and kairomone related research.
1. Insect Activity Meter- (VIDEOMEX V)
2. Leaf area analyser (Skye Instrument)
3. Electron Antennogram (SYNTECH)
4. Amino acid Analyser (Shimadzu)
5. Gas Chromatography-Mass Selective Detector (Hewlwtt Packard)
6. Speed vac Concentrator (Savant)
7. uv-vis Spectrophotometer (Shimadzu)
8. Scan Electron microscope (Hitachi)
9. Ultra centrifuge (Beckman)
10. Image Analysis
system (leica)
11. Miscellaneous instruments like pH meters, shakers, water bath shakers, orbital shakers etc.
