The loss of
cotton crop due to insect pests on an overall basis has been
reported to be 16%. Among various species, the sucking insect pests
i.e. whitefly (Bemisia tabaci), jassids (Amrasca devastans)
and thrips (Thrips tabaci) and bollworms (American, spotted,
spiny and pink) are serious pests, polyphagous, and cosmopolitan in
nature. Over the last few years, they have attained a special
attention in Pakistan. To control these notorious pests there has
been a complete reliance on pesticides. These insecticides of
different nature and worth Rs. 12 billion per annum are being
imported in Pakistan. Out of these about 70% are used only in cotton
crop. The continuous and indiscriminate use of synthetic
insecticides has created resistance in insects, problems of health
hazards not only to human and animal life but also aided to pollute
environment in many parts of the world. In this era of pesticides,
Integrated Pest Management (IPM) has got increasing attention as a
potential means of ameliorating crop losses while reducing reliance
on chemical pest control, thereby enhancing the long term
sustainability of agro-ecosystem. This approach utilizes multiple
strategies to reduce or prevent pest problems. Research on host
plant resistance, biological control, chemical control and
insecticide resistance management, the most important components of
IPM, is in progress. [top]
Host Plant Resistance
morphological characters of plant impart resistance against major
insect pests of cotton. These plant attributes have been used to
complement chemical control. This method is also compatible to
cultural practices. Studies were initiated during 1973-74 that gave
very fruitful results in the form of nectaried and nectariless insect
resistant varieties. Screening and evaluation of cotton germplasm for
their resistance against major insect pests and ecological studies of
bollworm complex in cotton through pheromone baited traps are in
Biological control is the most effective method when used
with other compatible pest control practices in IPM programme. These
practices include cultural control, planting insect resistant
varieties, sterile insect technique (SIT), male/female annihilation
technique through pheromones and using selective insecticides when
other practices fail to keep pest numbers below the economic
threshold. Biological control is neither hazardous to the human health
nor to the environment. There is no chance for the pest to develop
resistance against natural enemies that commonly occurs with
insecticides. NIAB has started R&D work on mass scale on bio-control
management of insect pests of agricultural crops especially those of
cotton and sugarcane assisting the farmers by providing them the
beneficial insects Trichogramma, Chrysoperla and Bracon
for field releases.
recommended in crisis, chemical control still remains the major method
of pest control under field conditions. Efficacy trials of
insecticides, especially on new chemistry insecticides are a regular
feature at NIAB. The objective is to guide farmers on the most
effective options available for the management of major pests of
For the last
three decades, there has been an extensive use of pesticides for
controlling economic pests and hence increasing the productivity of
our crops. This led to the development of insecticide resistance in
the major crop pests resulting in control failures by insecticides.
Insecticide resistance is a genetic phenomenon with serious economic
repercussions. A laboratory for Insecticide Resistance Management is
being established at NIAB to detect insecticide resistance in major
pests, determine its mechanisms and devise insecticide resistance
One of the major constraints to chickpea production in
is blight caused by a fungus Ascochyta rabiei. This disease
can destroy the crop in days when appears in epidemics under
favourable environmental conditions.
Disease samples are collected from major chickpea growing
areas and research stations. The isolates obtained from this
material are studied in order to categorize according to their
pathogenicity and are used for screening of germplasm to evaluate
resistance potential of host varieties/lines against this disease.
Biological pathotyping of isolates using host differential set is
conducted for determining their pathogenicity level. Genetic
variability of isolates is also being studied through genotyping
using molecular marker techniques such as RAPDs. Work on Induced
Systemic Resistance in chickpea and rice against diseases by
treating the plants with simple chemicals and its biochemistry is in
important disease of chickpea is wilt which is soil borne and caused
by Fusarium oxysporum f.sp. ciceris. Field and lab.
screening of varieties against wilt which has almost wiped out
chickpea cultivation in irrigated belt of Pakistan is in progress.
have spread at an alarming pace in the cultivated crops during the
last two decades. These diseases include: cotton leaf curl, tomato
leaf curl, shoestring of tomato, sesame leaf curl, sesame phyllody
and chickpea stunt disease etc. Other important diseases are
bacterial leaf blight (BLB) and brown spot of rice, and quick
decline of mango, shisham and citrus.
resistant varieties is a solution to the problems. For a successful
breeding programme a reliable disease screening technique is
necessary to identify genetic resources. In the absence of a uniform
technique, no meaningful results could be drawn. Phytopathology
group is helping breeders to identify resistant sources against
important viral and phytoplasma diseases of cotton, tomato, sesame,
and chickpea through the use of artificial inoculations (grafting,
sap inoculation etc.) and under natural field conditions
|Research Programme |
Host Plant Resistance against cotton
Ecological studies of bollworm
complex through pheromone baited traps in cotton.
Field testing of new chemistry
insecticides for their efficacy against sucking insect. pests and
Biological control of major insect
pests of crops, fruits and vegetables.
Insecticide resistance, its
mechanisms and management. [top]
b. Plant Pathology<![if !supportLists]>
Survey of major chickpea and rice
growing areas of Punjab and NWFP for assessment of incidence of
Isolation, purification and
virulence studies of Ascochyta rabiei, Fusarium oxysporum f.sp.
ciceris (FOC) and Xanthomonas oryzae oryzae (Xoo)
Screening of promising chickpea
germplasm for resistance against blight and Fusarium wilt
Genetic characterization of
Ascochyta rabiei, FOC and Xoo isolates using DNA
molecular marker techniques.
Induction of systemic disease
resistance to chickpea and rice against diseases by simple and
Studies on host specificity of
toxins, virulence, pathogenicity, effect on host plants and other
Biological factors for mechanism of resistance and susceptibility.
Screening of cotton, rice, tomato
and sesame germplasm against certain biotic and abiotic diseases
and disorders under field, screen house and laboratory conditions.
resistance studies have resulted in evolution of three insect pest
tolerant varieties of cotton. The first variety NIAB-86 was evolved in
1990. It is nectaried and hairy, tolerant to sucking insect pests with
good fibre characters having yield potential upto 6800 kg ha-1.
The second variety NIAB-26N was evolved in 1992. It is nectariless
hairy with large bolls and attractive opening: relatively resistant
to insect pests especially pink bollworm and jassid. Another
breakthrough was evolution of NIAB-Karishma variety in 1996. The
variety is nectariless and hairy, tolerant to sucking insect pests and
bollworms, heat and virus, possesses the best combination of fiber
characters i.e. GOT 37.4% staple length 28.6 mm, fineness 4.9 Mv and
strength 93 ppsi with the maximum record yield potential upto 7400 kg
ha-1. The variety covered 14 to 21 % area under cotton in
Punjab. In addition, more than 300 advanced strains and varieties of
cotton have been screened and evaluated for their resistance against
sucking insect pests and bollworm complex.
experiments showed that egg parasitoids, Trichogramma spp. and
effective and useful for the control of major insect pests of cotton
i.e. American, Pink and spotted bollworms and borers and Pyrilla of
sugarcane. Large field trials against these pests covering hundreds of
acres of different farmers have been conducted. Farmers have reduced
the number of insecticide applications and saved the considerable cost
of insecticide inputs.|
laboratory rearing of American and Pink bollworms,
and Bracon species low cost artificial diets have been
formulated that are very favourable for the development and
vigour of these insects. Many insecticides, host plants, Bt
toxins and beneficial insects have been screened and tested
under bioassay studies.
have been tested for their efficacy against sucking insect pest i.e.
jassid, whitefly, aphid, thrips and mite, and bollworm complex i.e.
American, Spotted, Spiny, Pink and Army bollworm. It has been found
that Imidachloprid and Actachloprid gave better results in
controlling the sucking insect pests whereas, Emamectin, Indoxcarb,
Spinosad and Abamectin are effective against bollworm complex.
The application of insecticides by drip irrigation has been
compared with conventional spray method to control the insect pests of
cotton. The results showed that chemigation with drip irrigation did
not provide adequate control of whitefly, jassid and thrips. However,
it was successful in controlling termites in cotton.
management of cotton mealy bug, its susceptibility was
assessed to endosulfan, six pyrethroids, five
organophosphates, three carbamates and three neonicotinoids
using a leaf dip bioassay. Bifenthrin and profenofos exhibited
the lowest LC50s, followed by lambdacyhalothrin,
deltamethrin, chlorpyrifos, methidathion and carbosulfan.
These insecticides were therefore recommended to the farmers
through the provincial extension department for the chemical
control of cotton mealy bug.
genetic diversity has been established in selected isolates of
Ascochyta rabiei collected from different chickpea growing areas
of Pakistan through biological pathotyping and genotyping.
on their aggressiveness, isolates have been classified into various
categories such as least aggressive, medium aggressive and highly
aggressive isolates and highly virulent isolates.
collection of about 200 isolates originating from different chickpea
growing areas is being maintained.
geographical map of chickpea growing areas of Pakistan has been
constructed to mark the prevalence distribution of these isolates,
in different chickpea growing areas.
and facilities for screening of chickpea germplasm against blight
and wilt diseases in the field and under controlled environment
through direct inoculations, using culture filtrates/toxins,
electrolytic leakage and water culture method have been developed.
bioautography technique for detecting antifungal compounds on TLC
(thin layer chorography) plate has established and standardize.
Gallic acid, a phenolic compound has been identified as a
biochemical marker from chickpea plants resistant to Ascochyta
rabiei, which could be used for screening of chickpea germplasm
against Ascochyta blight under laboratory conditions.
Systemic resistance in chickpea against Ascochyta blight and
Fusarium wilt can be increased by treating the plants with
chemicals, such as Salicylic acid, K2HPO4 and
Bion (benzothiazone). Reduction in both of the diseases were
observed in different experiments conducted with these chemicals.
Protection against Ascochyta blight was observed 27-80% with
different concentrations of Bion (0.2, 0.3, 0.4 mM), 45-60% with
Salicylic acid (1.0, 1.5 mM) and 30-60% with K2HPO4
(30, 50, 70 mM)
Protection against Fusarium wilt was observed 50-73% with different
concentrations of Bion (0.3, 0.4 mM), 47-70% with Salicylic acid
(1.0, 1.5mM) and 22- 60% K2HPO4
(30, 50 mM) in different experiments conducted under control
environmental conditions. Work on induced systemic resistance (ISR)
is being continued with these chemicals and neem leaves extract for
final recommendation to farmers.
The discolouration of vascular bundles
in plants is reported to be directly related to susceptibility to
Fusarium oxysporum. However, research work at NIAB showed that
quantification of Fusarium oxysporum f.sp. ciceris (FOC)
at seedling stage in chickpea is more reliable approach for
determining resistance than vascular discolouration.
Incidence of BLB is increasing in Pakistan in recent years
especially in Kaller belt, which is famous for high quality
rice producing area. Screening of rice germplasm against three
important and prevalent diseases (BLB, blast and brown spot)
is being conducted to help the rice breeders to develop
disease resistant varieties. 264 Entries/Varieties from Rice
Research Station, Kala Shah Kaku, NIAB, and PARC Islamabad
have been checked for BLB resistance. No line/variety was
found resistant. KSK-11 from RRI, Kala-Shah-Kaku, PARC-261
from PARC and P-52-9-2 from NIAB were found moderately
resistant. 229 lines/varieties have been screened against
Blast disease. Three were found highly resistant (IR-6,
KS-282, KSK-10) and 27 were found resistant including a dwarf
mutant, DM-15-1-95 developed at NIAB. 139 varieties/entries
were screened against Brown spot disease and NIAB-1 and
PK-3699-43, a non-aromatic entry from PARC were found
resistant. Characterization of different plant pathogens by
biological pathotyping and genotyping using molecular marker
technique is also being done to find the prevalence of various
pathogens in different geographical regions. These studies
will help in the screening of rice germplasm against different
pathogens and different pathotypes for attaining durable
resistance. So far six pathotypes have been identified in the
collection of indigenous isolates collected from various rice
growing areas of Punjab. Work on sheath blight, sheath rot and
stack burn is included in our future programme.
Identified a number
of highly resistant mutant lines against cotton leaf curl disease-Multan
(CLCuD-Multan) through artificial inoculation (grafting) and by
exposing them to high inoculum pressure by planting in natural
hotspots. NIAB-999 and NIAB-111, approved cotton varieties are among
the germplasm identified as resistant against CLCuD-Multan. However
recent graft inoculation studies showed that all the cotton germplasm
is susceptible to CLCuD-Burewala.
Group is also
providing expertise and facilities to the breeders for the screening
of cotton germplasm against cotton mosaic, bacterial blight, stunting,
and boll rots etc.
exotic tomato germplasm (representing more than one hundred
varieties), planted in field, tunnel and screen house were observed
against certain diseases to generate basic information for setting
research priorities in order to develop resistant varieties for the
integral disease management programme. Several biotic and abiotic
diseases were found at NIAB. Among biotic diseases early blight caused
by Alternaria solani, late blight by Phytopthora infestance,
bacterial leaf spots, various fruit rots (Alternaria alternata,
Geotrichum candidum, Aspergillus niger, A. flavus, Rhizopus stolonofer)
were found pathogenic and their causes were isolated on artificial
medium for varietal screening programme. Tomato plants were also found
to be infected with cucumber mosaic virus (CMV) and tomato leaf curl
virus. One new disease Alternaria leaf blight by Alternaria
alternata was also recorded. All the germplasm under study showed
the varying responses to all the biotic factors. Among abiotic
disorders sunscald, zippering, blossom end rot, catfacing were
observed in varying degree of responses.|
More than 100
sesame genotypes were evaluated against sesame phyllody and leaf
curl diseases in the field, out of which only six showed minor
infection of phyllody where as five genotypes showed minor leaf curl
disease and the remaining material was free from both diseases..