BPH Migration a Possible Threat to Food Security in India

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RICE BROWN PLANTHOPPER MIGRATION- A POSSIBLE THREAT TO

FOOD SECURITY IN INDIA

N.V.Krishnaiah*, V.Jhansi Lakshmi and G.R.KattiDirectorate of Rice Research, Rajendranagar, Hyderabad-500030, INDIA.

Email: [email protected]

AbstractRice brown planthopper, Nilaparvata lugens (Stal) has become a threat to

sustainability to rice production and productivity in all major rice growing countries in

south, south-east and east Asian countries. Long range migration of this insect fromChina to Japan and Korea stretching about 2000 km in bai-u season during april-may is

well known for the past 40 years. In India the insect used to be confined to southern

states of Tamil Nadu, Karnataka, Kerala and A.P. prior to 1975. It later spread to

Orissa, West Bengal, Aassam, by 1995, and to Chattisgarh, Bihar, Jarkhand, and U.P. by 2000. By 2005, BPH became an important pest of rice in U.P., Haryana and Punjab

also. In view of extremely low winter temperatures in Punjab, Haryana, U.P. and Bihar

and absence of rice crop, the only known host plant of BPH, the insect can not survive

during winters in these states. There fore migration of the insect from nearest easternstates of west Bengal, and Orissa in June-July along with the southwest monsoon winds

to Punjab and Haryana appeared to be the most likely possibility. However, the abovehypothesis needs to be confirmed through national level planning and experimentation.

BPH prevalent in Indian subcontinent including, India, Bangladesh and Sri Lanka is

distinctly different from the biotype prevalent in southeast and East Asian countries.

As it has been observed in Bangladesh, boro rice in west Bengal, Bihar and Assammight be harbouring BPH towards harvest and there by aiding in long range migration

of the insect from these states to Punjab and Haryana.

As the contribution of Punjab and Haryana to central rice pool is nearly 45-50%,the importance of new threat posed by BPH to rice crop in these states and

consequently to food security of India, hardly needs elaboration.In India, rice is the most important staple food crop and source of calories for 65% of the population. It is grown in 45 million hectares and produces about 105- 110

million tones of rice. Rice is grown mainly during kharif season (June to December)

throughout India, followed by Rabi season (January to April-May) mainly in southernand eastern parts of the country. For the last 15 years, another season called “boro”

(November-December to March-April) has also emerged as the most important in

parts of West Bengal, Assam, Bihar, Jarkhand, U.P. and Uttaranchal where assured

irrigation particularly under tube wells is possible. The area under “boro” is increasingyear after year due to high productivity and also encouragement by respective

governments.

Rice planthoppers, brown planthopper, Nilaparvata lugens (Stal) (BPH) andwhitebacked planthopper, Sogatella furcifera (Horvath) (WBPH) are the most

economically important insect pests attacking rice crop. Both the nymphs and adults of

these hoppers suck the sap from phloem and xylem resulting in wilting and drying upof the rice plant. Under field conditions, the damage by BPH and WBPH spreads in a

circular fashion and is technically termed as “hopper-burn”. If timely control measures

are not taken up, the entire field could be hopper burnt by the planthoppers in a span

of 15-20 days. Between the two hoppers, BPH is far more important economically as

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the area damaged every year as well as the intensity of damage are very high

compared to WBPH.

Biology and Morpho- forms in planthoppers:

These hoppers are small insects. The adults measure about 4-6 mm in length and

3-4 mm in width. Females insert microscopic eggs into leaf sheaths of rice plants,

which hatch into about 1mm nymphs. They moult 5 times, each time increasing in sizeand finally become adults. The egg period is 5-7 days while total nymphal period is

13-18 days depending on temperature. The nymphs and adults damage the crop by

sucking the plant sap.In both the hoppers, two types of morphological forms are present. 1.Those with

long or fully developed wings or macropterous adults 2. Those with short or half

developed wings are technically called brachypterous adults. Both the forms are

present in males as well as in females. Macropterous adults are capable of flying over long distances some times extending to hundreds or few thousands of kilometers.

These are capable of withstanding starvation during the flight until they reach a

suitable habitat, which is usually a freshly planted rice crop. However, the

macropterous adults can lay substantially low number of eggs per female, usually inthe range of 70-100. Thus, macropterous forms have evolved to withstand the harsh

conditions for migration from fields or areas where the crop is harvested to new andmore favourable areas. Majority of the nymphs emerging from the eggs laid by

macropterous adults in the new habitat become brachypterous or short winged forms.

These are robust and capable of laying 400- 600 eggs /female. Majority of the nymphs

from these eggs also become brachypterous adults enabling very rapid increase in population. At the time of first settling of macropterous forms, the insects are very

sparsely populated, usually 1-2 insects/10- 100 hills. Within 2-3 generations, the

populations will raise to 40–100 insects /hill which is far above the economicthreshold level of 10-20 insects /hill and can cause “hopper burn” if no control

measures are adopted.History and distribution of planthoppers in different states:

Large-scale field damage of BPH was reported for the first time in India during

1972 from Kuttanad area of Kerala, although it was known as an insect associated

with rice almost since 1900. From 1973 onwards, its occurrence and damage in vastareas in farmers’ fields was reported from Krishna-Godavari delta of A.P., Kaveri

delta of Tamil Nadu, Tungabhadra delta of Karnataka, Mahanadi delta of Orissa and

vast areas in west Bengal particularly Chinsurah region. Almost during the same

period, WBPH was noticed in northwestern parts of the country, mainly Punjab,Haryana and western U.P. although the areas of occurrence and intensity of damage

was low compared to BPH. The same situation continued almost for a decade or more.

Meanwhile, efforts were intensified to evolve varieties resistant to BPH and werereleased for large-scale cultivation in endemic regions. These varieties were found

favor with farmers initially and adopted in some endemic regions. This probably

resulted in reduction of BPH damage in almost all endemic deltas. But simultaneously,WBPH started appearing along with BPH in all endemic areas of A.P., Karnataka,

Tamil Nadu, Kerala, Orissa and West Bengal. WBPH however, continued to be

important in Punjab, Haryana and western UP. This situation continued up to the year

2002-03. From 2005-06, there were sporadic but large-scale occurrence of BPH in

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Bihar, Jarkhand, U.P., Haryana and Punjab. From 2007 -08 onwards, BPH has attained

number one pest status in the entire Indo-Gangetic belt stretching from West Bengal,

Bihar, Jarkhand, U.P., Haryana and Punjab although WBPH was present in lownumbers.

Microclimate in rice crop ecosystem a determining factor for BPH multiplication

in India after 1972:The microclimate like optimum temperature (22 ± 30 C), very high humidity

(≥90%), and very low wind movement, together with favorable succulent food plant

favored rapid multiplication of BPH settled in young crop in Japan. Japonica varietiescultivated there from the beginning of 20th century created the microclimate described

above and this microclimate appeared to be the major factor responsible for BPH

multiplication and damage there. Absence of such favorable ecological factors in case

of tall indicas, which were solely under cultivation in India, before green revolutionera appeared to have kept BPH under check. However, the microclimate at basal

portion of rice plant in currently cultivated dwarf indicas similar to the one that existed

in japonicas since 1920s in Japan appeared to be responsible for rapid spread,

multiplication and damage of BPH in India since 1972.POSSIBLE REASONS FOR DISTINCTNESS OF INDIAN BPH:

BPH present in Indian subcontinent including Sri Lanka is quite distinct fromEast Asian biotype present in China, Japan, Korea, The Philippines, Vietnam and

Malaysia. The rice varieties viz., IR26 with Bph1 gene and IR36 with bph 2 gene

released by IRRI for general cultivation in the Philippines and in several East Asian

and South-East Asian countries were found to be resistant and promising in the entireEast Asian region but was found to be susceptible in India.

1. As already pointed out, BPH was present in Indian subcontinent ever since rice

cultivation was in vough in this country. i.e. possibly more than thousands of yearsago. But BPH became notorious only after green revolution or cultivation of short

statured, high N responsive, high tillering varieties providing suitable microclimateand consequent BPH flare-up. Therefore, the distinctness of Indian BPH must haveits genetic origin much before green revolution era.

2. BPH in India must have undergone parallel evolution along with tropical indica

rice in hot humid tropical climate present in South India, the region to which mostof the Indian rice cultivation was confined. During these possible few thousands of

years, the insect did not have any genetic interchange with the BPH present in East

Asia and South East Asia. Therefore, it preserved its genetically controlled

virulence to some resistant genes.3. Many of the tall indicas cultivated in India appeared to have possessed genes with

moderate to high level of resistance to BPH. This might be responsible for keeping

BPH under “silent suppression” for such a long time until the onset of greenrevolution. These resistant cultivars might have possibly exerted pressure on the

insect to preserve its high virulence. During this process, the insect must have

acquired virulence to Bph1 and bph2 genes and also consolidated the virulence.4. The main southwest monsoon and less important northeast monsoons prevalent in

Indian subcontinent can never cross Himalayas and move further north to China.

Therefore, Himalayas appeared to have acted as a natural barrier for preventing

Indian BPH populations from moving to China.

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5. Only for the last 5-10 years, there appears to be long distance migration of BPH

either from Maharashtra side or from Orissa-west Bengal side towards Bihar,

Jarkhand, U.P., Haryana and Punjab. Although the exact reason for this is not veryclear, it is probably an exploratory exercise as a part of innate nature of this insect

to move even to very far off places in search of food when ever weather conditions

are favorable. Secondly cultivation of huge acreage under “boro” rice might also be aiding in exploiting the migratory nature of the insect.

Major thrust on “boro” and large scale BPH epidemics in Indo-Gangetic belt.

As already explained “boro” or summer rice is the broad term given for rice seasonfrom November-December to April-May in Assam, West Bengal, Bihar, Jarkhand and

parts of Eastern U.P. under assured irrigation, particularly by taking advantage of

ground water with tube wells. Low temperatures characterize this season during early

stage of the crop followed by rapid rise in temperatures after winter. So cold toleranceduring early stages of crop growth followed by ability to tolerate warm summer

weather in later stages or at the maturity are the essential features required for varieties

to perform well during “boro” season. As this “boro” season is characterized by very

high productivity some times upto 8 tonnes /ha and also almost free from pests anddiseases, barring blast in winter months, governments have encouraged the farmers to

go in for rice in a large scale in these areas and harvesting rich dividends. In fact“boro” has become very important for boosting average rice productivity of the nation

as a whole and become synonymous with rice security or food security.

At the same time if we observe the pest situation, rice crop in “boro” is almost

insect pest free during early period or up to 35-40 days after transplanting (DAT)during the cold period. Later, stem borer and leaf folders started damaging in late 90s

and early part of this century. However, BPH has also become an important pest for

the past 7-8 years as it occurred in Bangladesh. Very high levels of fertilizer doses, particularly of nitrogen and continuous standing water in the field, favorable

microclimate with low wind velocity, together with mild temperatures (20-25

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C)appeared to be the factors responsible for high BPH multiplication and consequentdamage to the crop.

Migration as a possible reason for spread of BPH to Punjab and Haryana:

BPH is present almost throughout the year in Tamil Nadu, Kerala, Karnataka,A.P., Orissa. and parts of West Bengal. The pest however, can not survive the severe

winters present in Punjab, Haryana, U.P., Bihar, Jarkhand and northern parts of west

Bengal from November to February as the temperatures are near freezing point or at

times towards negative figures. BPH cannot over-winter in egg stage. Further, thereare no alternate hosts for BPH where it can survive and complete its life cycle.

Therefore, BPH must be migrating from southern or eastern parts of India during the

months of May-June immediately after the harvest of rabi crop in these states.Southwest monsoon must be helping BPH migration:

Southwest monsoon also starts almost during the same period i.e. beginning of

June every year. However, it takes about a month or so for the full monsoon winds to be active throughout the country. The progress of south-west monsoon is all along the

west coast from Kerala to Konkan region of Maharashtra, followed by Tamil Nadu

and Karnataka, then A.P. and Orissa, but can not cross the Vindhya and Sathpura

mountain ranges present in M.P. Simultaneously South-west monsoon also starts in

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Bay of Bengal and moves from coastal areas of West Bengal and Bangladesh and

proceeds in north-westerly direction due to its inability to cross Himalayas. Both the

halves of southwest monsoon meet somewhere in areas of Chattisgarh-Jarkhand-Bihar borders and moves in northwesterly direction. Thus, the movement of southwest

monsoon winds is northwesterly in direction from west Bengal through Jarkhand,

Bihar, U.P. and then finally reaching Haryana and Punjab.From 1972 upto early 90s, WBPH was the major problem in Punjab and Haryana

probably because the macropterous adults of WBPH could move along the first

southwest monsoon winds moving from west Bengal towards Punjab and Haryana in anorthwesterly direction. It is well known that when compared to BPH, WBPH is more

migratory and does not settle even if suitable host plant viz., rice crop is available. It

easily moves forward along the winds even with slight macro-climatic disturbance due

to winds. WBPH rarely settles to the extent that it can multiply to the population levelsthat can cause economic damage to rice crop. Hence, it could settle early in Punjab

and Haryana, which are the final destination points of southwestern monsoon. Further,

the quantum of damage to rice crop per insect due to WBPH is very less compared to

BPH due to lower level of sap intake. That is why WBPH could not become a seriousthreat to rice production in Punjab and Haryana although it is present since 1972.

On the contrary, BPH is more sedentary and does not move forward unless thesituation demands in terms of exhaustion of food sources by way of harvest of the

crop. Hence, BPH was confined only to eastern parts of India apart from its southern

strong hold. However, with the large-scale cultivation of rice in boro season in the

states of West Bengal, Bihar, Jarkhand and Eastern U.P., rice crop is available to BPHin these areas up to April- May. More favorable climate exists in these states for the

multiplication of BPH from February to May. Hence, BPH might have become one of

the pests for boro rice in these areas similar to Bangladesh. Further, boro rice in thesestates might be serving as a temporary shelter for BPH migrating from Orissa and

coastal areas of west Bengal until up to the harvest of rice in April-May. Immediatelyafter harvest of boro rice the time is also ripe for southwest monsoon, which can takeBPH up to Punjab and Haryana quite early in the kharif season i.e. in June, or early

parts of July. This allows sufficient time for completion of 2 or even 3 generations for

BPH before the kharif rice is harvested in October end or first fortnight of November.Thus, boro rice might be helping for wide spread occurrence and damage by BPH in

Punjab, Haryana and western U.P.

PROCESS OF BPH LONG DISTANCE MIGRATION:

BPH can usually move few meters in the same field when disturbed. The insectscan fly few hundreds of meters to few kilometers from one rice crop area nearing

harvest to another area where young rice crop is available. This small distance

movement or short range migration or technically termed as trivial migration involvesthe following steps.

a.) The movement of BPH (macropterous males and females) from plant base to the

tip of crop canopy either at dawn or at dusk when the wind speed is low (< 5m/second)

b) Taking off into the blowing wind upto a few metres height (usually 5-15mts)

c) Movement along the wind direction at this height for few meters to few kilometers

d) Landing to the fresh sites by downward movement.

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e) Establishing the population at the new site.

However, long-range migration of BPH, which involves the movement of insects

for few hundreds of kilometers up to even 2000 kilometers, is entirely different. Inthis case there will be mass movement of BPH usually in groups ranging few

thousands to few lakhs at a time. The insects move to the tip of crop canopy either

during dawn or dusk. The favorable time is again dependant on temperature. Fromcanopy the insects make a slow upward movement until the insects reach up to a

height of 750 to 2000 metres above ground level. Then BPH will be above the cloud-

forming zone of atmosphere or troposphere. At this height, the insects are carried byforward movement of frontal-zones of hot humid winds in southwest monsoon. The

movement will occur at a wind speed of 5m-20m /sec. In this manner BPH can move

for about 25 – 45 hours to reach a destination, which is about 800 to 2000 km away.

What environmental, physiological and behavioral factors determine the exact landingof the migrating insects is not very clearly understood even today. The physiological

factors like exhaustion of reserve body energy, or behavioral factors like oriented

downward movement due to some environmental stimulus like humidity gradient or

light source on the surface of the earth might be playing a role.CONSEQUENCE OF BPH MIGRATION ON ITS MANAGEMENT:

From the above discussion, it is likely that the BPH populations present insouthern states viz., Kerala, Karnataka, Tamil Nadu and A.P. and those present in

eastern states like Orissa, Chatthisgarh and West Bengal might be migrating to U.P.,

Punjab and Haryana. Consequently there is every likelihood for genetic mixing of

BPH populations present through out the Indian subcontinent including Bangladeshand Pakistan. This has tremendous implications on the management of BPH through

out Indian subcontinent.

For varied and obvious reasons, insecticides are extensively used for BPHmanagement throughout India as well as in other Asian countries where this pest is a

major menace. In India, organophosphates like monocrotophos, acephate andcarbamates like carbaryl and BPMC as sprays and carbofuran as granules have beenrecommended and extensively used ever since BPH became a major pest in 1972 till

1995. Later, other insecticides like ethofenprox (ether derivative) and neo-nicotinoids

like imidacloprid, thiamethoxam, clothianidin became very popular due to their extremely high effectiveness, low rate of active ingredient per hectare, relative safety

to humans and lesser cost per treating unit area. Therefore, neo-nicotinoids became

very popular in almost all BPH endemic rice tracts starting from Kaveri delta of Tamil

Nadu, Kuttanad area of Kerala, Tungabhadra delta of Karnataka, Krishna-Godavarizone of A.P. and Mahanadi delta of Orissa as well as Chinsurah region of west

Bengal. There are already reports that BPH and to some extent WBPH in all these

areas have developed resistance to neo-nicotinoids particularly, imidacloprid even tothe extent of 35-40 fold. The information from A.P. has already been published and

similar reports from other regions are in the offing.

Now, we can very clearly understand that once there is extensive genetic mixing of BPH from zones where there is already high level of neonicotinoid resistance with the

populations in other zones, this becomes the problem for the whole country. Then, we

have to search for other groups like buprofezin (an insect growth regulator cum chitin

synthesis inhibitor), which is of course currently showing promise against neo-

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nicotinoid resistant populations. But we cannot depend on a single molecule for a long

time and sooner or later BPH may become resistant to buprofezin also. This finally

leads to catastrophe of BPH menace throughout India.

IMPORTANCE OF BPH MIGRATION FOR FOOD SECURITY OF INDIA.

1. Enhancing rice production and productivity in India for years to come is vital for

sustaining food and nutritional security for teaming millions in the country, where65% of the population still depend on rice for calories and nutrition.

2. For increasing average rice productivity of the nation, enhancing the area under

“boro” rice in West Bengal, Bihar, Jarkhand, U.P. apart from Orissa and Assam isvery important in view of already realized high productivity of ” boro” as well as

scope for further enhancement through varietal and management technologies.

3. BPH has become an important pest of rice in India and spread to non-traditional

areas like Punjab and Haryana, which are major sources of central rice pool in thecountry. These two states alone contribute about 50% of rice to the central rice pool.

4. BPH cannot survive the winter temperatures in Punjab and Haryana that too in

the absence of its only host plant rice. Thus, migration of BPH to Punjab and Haryana

is a major factor for attaining an important pest status for BPH in these two states in particular, apart from other states.

5. “Boro” rice, on which average Indian rice productivity is dependant might beaiding BPH migration to Punjab and Haryana, which warrants a thorough

investigation. This emphasizes the need for devising suitable long-term BPH

management practices through out the country. Integrated pest management (IPM)

based on varietal resistance, cultural practices, enhancing natural enemy activity andneed based suitable insecticide application with least damage to rice ecosystem hardly

needs any emphasis.

BPH migration from China to Japan a guideline for Indian rice entomologists:

Although BPH is relatively a new pest to India, it was a major threat to rice

production in Japan since 1920s. Many epidemics have occurred there sometimesresulting in heavy damage. Similar to our northwestern parts of Punjab and Haryanarice is grown only during one season in Japan. Therefore, it was thought for a long

time that BPH might be over wintering in egg stage during colder months in Japan.

But it was never proved. Later, many experiments conducted at International RiceResearch Institute (IRRI), Philippines, India, and China have shown that BPH cannot

develop at temperatures lower than 50 C. And also, BPH cannot complete its life cycle

on any other alternate host plants once rice is harvested.

During 1969, large number of BPH, WBPH and other similar small insects wereobserved at lights in the ships boarded in East China Sea at southwestern tip of Japan.

Later a general survey was conducted through out Japan, which confirmed that large-

scale migration of BPH and WBPH along with another similar species smaller brown planthopper (SBPH), Laodelphax striatellus occurs every year from main land China

to Japan.

LONG RANGE MIGRATION IN EAST ASIAN & SOUTH-EAST ASIAN BPH

BIOTYPE:

BPH in South East Asian countries like Malayan peninsula, Vietnam and The

Philippines can breed and multiply through out the year as the temperatures are

congenial and rice crops are grown through out the year. During the period from mid

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April to early May, BPH from these countries can migrate to southern China province

of Guangxi or Hainan islands, where rice crop is available through out the year and

temperatures are also favorable for year round multiplication of BPH. In Guangxi,BPH can multiply for one or two generations. Then the insects move towards north or

northeasterly direction and reach to central and eastern China provinces like Zhejiang,

Nanjing, Anhui etc. and multiply there up to middle of June. From there some populations of BPH migrate to Korea via northern China, while some other

populations can move to Japan. These migrations are carried by bai-u or southwest

monsoon winds and approximate time is from early June to first half of July. Rice cropis available during June to Sept-Oct in Korea as well as in Japan. The insect completes

2-3 generations, multiply and causes very high damage if no control measures are

taken up. Once, rice crop is harvested in October in Japan and Korea, the reverse

autumn migration of BPH starts. The BPH migrate first. to central and eastern Chinacarried by northeasterly winds. Later the insects are carried to southern tip of China or

Guangxi province, their favorable habitat for year round multiplication.

Simultaneously, some populations of BPH from eastern& central China move towards

Vietnam, Malaya and The Philippines. Thus after 40 years of hard labor of riceentomologists, it is well established by now that BPH present in the entire Southeast

Asian and East Asian countries is a single intermingling population.We can use many techniques for ground observations like light traps, yellow

pan water traps, sticky traps, sweep nets, field monitoring by visual counting, toe-nets

(1metre diameter and 2.5 meter deep) arranged at different heights like 5m, 10mts,

15mts and 20mts etc. The number of BPH actually observed in the above mentionedground tools at different periods could be correlated with the weather charts obtained

from meteorological department. Computer simulation models can then developed by

using either two-way trajectory analysis or three dimensional trajectory models toenable to track back the actual source of BPH. Radar observations to track the mass

migration of planthoppers can also be helpful. Air sucking machinery can be usedwhile travelling by aeroplanes at a height of 1500 –2000 mts to practically see the presence of BPH / WBPH at that height.

Simultaneously some basic studies need to be conducted on biological features

and abilities of BPH before and after migration. These include 1) factors that favor thedevelopment of macropters in BPH populations. 2) The starvation tolerance of

macropterous BPH. 3) Mating behavior of macropterous BPH. 4) Establishing the

basic processes in long-range migration like a) initial take off. b) Mass migration for

long distance. c) Landing etc. 5) Weather parameters required for all these processes.6) Genetics of macropterous character in BPH. 7) Correlating the BPH population

characteristics at the site after migration to those at the possible source site with regard

to the spectrum of insecticide resistance to a set of insecticides prevalent in BPH siteafter migration to those prevalent in BPH present in possible site of migration source.

Summary:

Rice brown planthopper Nilaparvata lugens (Stal) a notorious sucking pest of

rice in India, Bangla Desh, Sri Lanka, China, Japan, Korea, Indonesia, Malaysia,

Vietnam, The Philippines and other south and Southeast Asian countries. In India the

insect used to be confined to four southern states viz., Tamil Nadu, Karnataka, Kerala

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and A.P. prior to 1975. It later spread to Orissa, west Bengal, Assam, by 1995, and to

Chattisgarh, Bihar, Jarkhand, and U.P. by 2000. By 2005, BPH became an important

pest of rice in U.P. Delhi, Haryana and Punjab also.In view of extremely low winter temperatures in Punjab, Haryana, U.P. and

Bihar and absence of rice crop, the only known host plant of BPH, the insect can not

survive during winters in these states. There fore migration of the insect from nearesteastern states of west Bengal, and Orissa or even Maharashtra in June July along with

the southwest monsoon winds to Punjab and Haryana appeared to be the most likely

possibility.Long-range migration of BPH from China to Japan and Korea stretching about

2000 km is well-established phenomenon for the last 40 years. Therefore, the above

hypothesis is put forward. How ever this needs to be confirmed through national level

planning and experimentation.From the point of view of host-plant resistance, BPH prevalent in Indian

subcontinent including, India, Bangladesh and Sri Lanka is distinctly different from

the biotype prevalent in southeast and East Asian countries. The main reason could be

geographically isolated evolution of the insect.As it has been observed in Bangladesh, boro rice in west Bengal, Bihar and

Assam might be harbouring BPH towards harvest and there by aiding in long rangemigration of the insect from these states to Punjab and Haryana.

As the contribution of Punjab and Haryana to central rice pool is nearly 45-50%,

the importance of new threat posed by BPH to rice crop in these states and

consequently to food security of India, hardly needs further elaboration.

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BPH OCCURRENCE IN INDIA IN 1975

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BPH OCCURRENCE IN INDIA IN 2005 & LATER

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BPH Migration a Possible Threat to Food Security in India

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