Jammu and Kashmir Academy of Art, Culture and Languages
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Effect of Some Alien Invasive Plant Species on Soil Microbial Structure and Function
Get PDFkey driver of global environmental change is the invasion of
ecosystems by alien species, many of which attain sufficiently high
abundance to alter ecosystem structure and function (D‘Antonio and
Vitousek, 1992; Ogle et al., 2003; Meffin et al., 2010). Biological invasions affect
virtually all ecosystems on earth, but the extent of invasion of different regions
and biomes, and the quality of information emanating from them varies greatly
(Foxcroft et al., 2010). The invasions by alien species are also known to impact
ecosystem services (Charles and Dukes, 2008) and human well-being (Pejchar and
Mooney, 2009; Vilà et al., 2011). Invasive alien plants, because of their ability to
alter ecological processes, such as carbon and nitrogen cycling (Liao et al., 2008;
Ehrenfeld, 2010), hydrological cycles (Calder and Dye, 2001), frequency and/or
intensity of fire (Brooks et al., 2004) and alteration of the normal disturbance
regimes in the native communities (D‗Antonio and Meyerson, 2002; Werner et al.,
2010), have transformed many ecosystems by out competing native species
(Lankau, 2010) and thus, are rightly regarded as one of the most substantial threats
to biodiversity on earth (Cronk and Fuller, 1995; Chapin et al., 2000; Kowarik,
2003; Werner et al., 2010).
Invasive species are known to directly compete for resources with native
species (Werner et al., 2010), disrupt inherent co-evolved interactions among
long-associated native species (Callaway and Aschehoug, 2000; Callaway et al.,
2008; Werner et al., 2010; Zhang et al., 2010), like pollination (Butz Huryn, 1997;
Simberloff and Von Holle, 1999; Chittka and Schürkens, 2001; Aizen et al., 2008)
and seed dispersal (Knight, 1986; Riera et al., 2002; Traveset and Riera, 2005;
Cavallero and Raffaele, 2010) and result in modification of interspecific
interactions, community structure, and ecosystem processes in the native
communities (Vitousek et al., 1997; Lonsdale, 1999; Richardson et al., 2000;
Ehrenfeld et al., 2001; Le Maitre et al., 2002; Karl et al., 2005; Traveset and
Richardson, 2006; Emer and Fonseca, 2011). Recent global meta-analysis of 199
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research studies dealing with 1041 field studies involving 135 alien plant taxa
revealed that abundance and diversity of resident species decreased in invaded
sites, whereas primary production and several other ecosystem processes were
enhanced (Vilà et al., 2011).
But most of the studies exploring the effects of plant invasions have
focused on aboveground flora and fauna (Levine et al., 2003), although soil
organisms play important roles in regulating ecosystem-level processes (Wardle et
al., 2004), and soils contain much of the biodiversity of terrestrial ecosystems
(Torsvik et al., 1990; Vandenkoornhuyse et al., 2002), because aboveground
communities are relatively easy to observe and quantify (Belnap and Phillips,
2001) and also because there are methodological limitations in studying
belowground diversity. As a result, few studies to date have considered the effects
of invasive organisms on the abundance, composition and activity of the soil biota.
However, the advent of tools and techniques that exploit presence of signature
biomolecules, such as Phospholipid Fatty Acids (PLFA), Denaturing Gradient Gel
Electrophoresis (DGGE), Terminal Restriction Fragment Length Polymorphism
(T-RFLP) etc. has revolutionized the field of soil microbial ecology. These
techniques have been used to monitor changes in microbial communities in many
plant invasion studies (Meyer, 1994; Kourtev et al., 2002a, 2003; Angeloni et al.,
2006; Batten et al., 2006; Li et al., 2006; Kulmatiski and Beard, 2008; Zhang et
al., 2010), and the results have revealed that invasive alien plants may suppress
harmful rhizosphere soil microbes (Bais et al., 2004a; Lorenzo et al., 2010) and
enrich beneficial ones thereby establishing positive feedback which could
contribute to their proliferation (Klironomos, 2002; Batten et al., 2006; Kulmatiski
and Beard, 2008; Sanon et al., 2011) to the detriment of native biodiversity
(Callaway et al., 2004a; Lorenzo et al., 2010). On the other hand, several studies
have also revealed negative effect of invasive plants on soil fungi due to invasion
by Bromus tectorum (Belnap et al., 2005), arbuscular mycorrhizal fungi in
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response to dominance of non-mycorrhizal Alliaria petiolata in North American
forests (Roberts and Anderson, 2001; Wolfe and Klironomos, 2005; Stinson et al.,
2006; Callaway et al., 2008; Wolfe et al., 2008; Pringle et al., 2009; Vogelsang
and Bever, 2009), microbial biomass C and ratio of fungi to bacteria due to
Falcataria moluccana (Allison et al., 2006), both soil fungi as well as bacteria
due to Acacia dealbata invasion (Lorenzo et al., 2010).
Invasive alien plants also significantly influence catabolic diversity of the
soil microbial communities through their impact on the activity of soil enzymes,
which represent a link between litter decomposition, microbial activity, and
nutrient availability (Sinsabaugh et al., 2000; Elk, 2010). The influence of exotic
plants on the activity of soil enzymes has been reported by several workers
(Kourtev et al., 2002b; Allison et al., 2006; Chapuis-Lardy et al., 2006; Li et al.,
2006; Fan et al., 2010).
It is clear from the growing number of studies that invasive alien species
can alter ecosystem processes through a wide variety of mechanisms, over a
variety of spatial and temporal scales (Ehrenfeld, 2010). Indeed, multiple
mechanisms have been indentified that interact and reinforce each other in
bringing about ecosystem change. Thus, it is necessary to search for mechanisms
of impact of invasive alien species through documentation of interacting
mechanisms, rather than to focus on single causative pathways as a ―holy grail‘ of
universal explanation (Simberloff, 2010).
The need for studies that explore the impact of invasive alien species has
assumed urgency in India and Kashmir in view of reported occurrence of 1,599
species, belonging to 842 genera in 161 families in India representing 8.5% of the
total Indian vascular flora (Khuroo et al., 2011). Likewise, total alien flora of the
Kashmir Himalaya is represented by 571 plant species, belonging to 352 genera
and 104 families. Of the 787 and 436 species that have either escaped from
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intentional cultivation, or spread after unintentional introduction in India and
Kashmir, respectively, 225 species are invasive in India (Khuroo et al., 2011) and
77 species are invasive in Kashmir (Khuroo et al., 2008).
While studies related to demography phenotypic plasticity (Allaie et al.,
2005), allelopathy (Allaie et al., 2006), mycorrhizal mutualism (Shah and Reshi,
2007; Shah et al., 2008a and b), herbivore induced over-compensatory growth
(Rashid et al., 2006) and seed germination (Rashid et al., 2007) have been carried
out on various invasive plant species in Kashmir, very few studies have
documented the impact of alien species (Shah et al., 2008a; Khuroo et. al., 2010)
in the Kashmir Valley. It is because of these lacunae that broad quantitative
syntheses of how impacts vary in response to the attributes of recipient ecosystems
and of the invaders themselves (Levine et al., 2003) are not available. This
absence of a broad-scale assessment limits the ability to generalize and predict
when and where impacts might be most deleterious (Vilà et al., 2011). Besides,
there are many studies in which the same invasive alien species causes quite
different impacts on ecosystem processes at different sites or at different times.
This variability in effect emphasizes the importance of ecological context in
understanding and anticipating impact on ecosystems.
It is in this context that the present study was carried out to evaluate the
impact of three invasive alien plant species, namely Conyza canadensis (L.)
Cronq. Sambucus wightiana Wall. ex Wt. and Arn. and Anthemis cotula L. on soil
microbial structure and function. While S. wightiana (Adoxaceae) invades the
understory of coniferous forests in the Kashmir Valley, A. cotula and C.
canadensis (both belonging to Asteraceae) are dominant elements of vegetation in
ruderal habitats. The specific questions addressed during the present study were
A study of personality characteristics & academic achievement of children of working & non working mothers
Get PDFThere is a great impact of working mothers on thin children‟s in terms of their school performance, social adjustment and other personality characteristics.
In view of the studies it is evident that there is great effect of working mothers on personality characteristics of their children. The parental attitude towards children, their love, affections and care play a critical role in the personality development. It has been also realized that research work should be carried on to find out the influence of employed mother on personality characteristics especially for the children for the age group 6 to 12 because there is very less research work done on this age group. Thus the researcher
has got interest to find out the difference, if any among children of working and non working mothers in terms of their personality characteristics and educational achievement.
The problem, selected for the purpose of the present investigation reads as:
“A study of personality characteristics & Academic achievement of children of working & non working mothers.
The present study was undertaken with the objectives of identifying the children of working & non working mothers & comparing differentiating them on personality characteristics & academic achievement.
200 students of the 5th & 6th grade, of which 100 students (50 boys & 50 girls) of working mothers & 100 students (50 boys & 50 girls) of non working mothers served as sample for the present study.
The data was collected with the help of
(1) Porter & Cattell children personality Questionnaire (CPQ).
The CPQ measures 14 primary traits useful in understanding & evaluating the course of personal, social & academic development, Plus traits related to creativity. Traits measured by CPQ include emotional stability, self concept level, excitability & apprehension, scores for extraversion, anxiety & other broad trait patters & also obtained as combination of the primary scales. It is meant for age groups between 8-12 years. Each form has 140 items. Time required is 30 to 60 minutes per form. Min reading level s 4th standard.
(2) Academic achievement which was measured on the basis of scores scurried by the subjects in their previous examination i.e, 4th & 5th class.
Statistical Analysis:-
The data collected was subjected to statistical treatment. For testing the hypothesis formulated for the present study, mean, S.D & t-Test was employed
Some Aspects of Mathematical Programming in Statictics
Get PDFThe Almighty has created the Universe and things present in it with an
order and proper positions and the creation looks unique and perfect. No one
can even think much better or imagine to optimize these further. People
inspired by these optimum results started thinking about usage of
optimization techniques for solving their real life problems. The concept of
constraint optimization came into being after World War II and its use
spread vastly in all fields. However, in this process, still lots of efforts are
needed to uncover the mysteries and unanswered questions, one of the
questions always remains live that whether there can be a single method that
can solve all types of nonlinear programming problems like Simplex
Method solves linear programming problems. In the present thesis, we have
tried to proceed in this direction and provided some contributions towards
this area.
The present thesis has been divided into five chapters, chapter wise
summary is given below:
Chapter-1 is an introductory one and provides genesis of the
Mathematical Programming Problems and its use in Statistics.
Relationship of mathematical programming with other statistical
measures are also reviewed. Definitions and other pre-requisites are
also presented in this chapter. The relevant literature on the topic has
been surveyed.
Chapter-2 deals with the two dimensional non-linear programming
problems. We develop a method that can solve approximately all type
of two dimensional nonlinear programming problems of certain class.
The method has been illustrated with numerical examples.
Chapter-3 is devoted to the study of n-dimensional non-linear
programming problems of certain types. We provide a new method
based on regression analysis and statistical distributions. The method
can solve n-dimensional non-linear programming problems making
use of regression analysis/co-efficient of determination.
In chapter-4 we introduce a filtration method of mathematical
programming. This method divides the constraints into active and non
active and try to eliminate the less important constraints (non-active
constraints) and solve the problem with only active constraints. This
helps to find solution in less iterations and less in time while retaining
optimality of the solution.
The final chapter-5 deals with an interesting relationship between
linear and nonlinear programming problems. Using this relationship,
we can solve linear programming problems with the help of non-linear
programming problems. This relationship also helps to find a better
alternate solutions to the linear programming problems.
In the end, a complete bibliography is provided
Myth in Wole Soyinka’s A Dance of the Forests and The Bacchae of Euripides
Get PDFEssentially a playwright, Soyinka is also recognized as a prolific essayist, poet, novelist and theatre director. He is also one of the continent‘s most imaginative advocates of native culture and of the humane social order it embodies. He writes mainly in English. His works are distinguished by their exploration of the African world view, and are steeped in Yoruba mythology, imagery and dramatic idioms. His satiric pen, directed at the leadership iniquities on his continent and inhuman conduct among people, has also produced powerful works.
As a human rights activist who declares that human liberty is his abiding religion, Soyinka has endured incarceration at the hands of repressive regimes. He has been placed on trial on trumped-up charges of treason and has undergone spells of political exile. In the midst of several violent and repressive African regimes, Soyinka was awarded the Nobel Prize for Literature in 1986 to become the first African Laureate.
Nigeria gained independence in 1960 and Soyinka has always been critical of its dictators ever since. In 1967, in what became one of his most contentious essays, ―The Writer in a Modern African State‖, he questioned the Negritude movement. Soyinka sees that negritude affirms one of the central Eurocentric prejudices against Africans, namely the dichotomy between European rationalism and African emotionalism. In his essay ―Reparations, Truth and Reconciliation‖ (1999), Soyinka defended the idea that the West should pay reparations for crimes committed against African people.
Soyinka‘s representation of Postcolonial African identity will be examined in the light of his two plays, The Bacchae of Euripides and A Dance of the Forests to show how this writer‘s idiom of cultural authenticity both embraces hybridity and defines itself as specific and particular. His works conceptualize identity in ways that modify colonial perception of ‗Africaness‘. Soyinka has been one of the most outspoken critics of the concept of negritude,
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which has been associated with Leopold Senghor, the writer and former President of Senegal. Soyinka sees that negritude encourages into self-absorption and affirms one of the central Eurocentric prejudices against Africans. Soyinka negates the inferiority of Africans by saying― A Tiger does not show his tigritude but acts‖
Response of Fodder Oats to Fertility Levels and Cutting Management at Different Sowing Dates
No full textA field experiment was conducted at the Experimental Farm of Division of Agronomy, Sher-e-Kashmir University of Agricultural Sciences & Technology of Kashmir, Shalimar, Srinagar during Rabi 2009-10 and 2010-11 on silty clay loam soil low in available nitrogen, medium in available phosphorus and potassium and sufficient in available calcium with neutral pH. The experiment was laid out in randomized block design replicated thrice with three sowing dates (September, 20, September, 30 and October, 10), three fertility levels (150 : 70 : 40, 125 : 60 : 30 and 100 : 50 : 20 kg N:P2O5:K2O ha-1) and two cutting levels (single cut and double cut). The study revealed that the crop sown on September, 20 recorded significantly higher plant height, number of tillers m-2, leaf area index and dry matter production upto 120 DAS. However, at harvest September, 30 and October, 10 sown crops at par with one another recorded significantly higher plant height, number of tillers m-2, leaf area index and dry matter production than September, 20 sown crop. October, 10 sown crop recorded significantly higher leaf stem ratio upto 150 DAS, however, at 180 DAS and at harvest leaf stem ratio remained similar under different sowing dates. Both total green and dry fodder yields (1st + 2nd cut) recorded with September, 30 and September, 20 sown crops were at par but significantly higher than October, 10 sown crop. Similar trend was also noticed in case of pooled data over two years. At first cutting September, 30 sown crop recorded higher nitrogen, phosphorus, potassium and calcium uptake whereas at second cutting October, 10 sown crop at par with September, 30 sown crop recorded significantly higher nitrogen, phosphorus and potassium uptake. Crude protein content was higher and crude fibre and ash content were lower in October, 10 sown crop compared to other sowing dates. The results also indicate that the plant height, number of tillers m-2, leaf area index, dry matter production, leaf stem ratio were significantly higher with fertility level 150 : 70 : 40 kg N:P2O5:K2O ha-1. The said treatment also recorded significantly higher total green and dry fodder yield (1st + 2nd cut) than other fertility levels. The fertility level 150 : 70 : 40 kg N:P2O5:K2O ha-1 recorded significantly higher nitrogen, phosphorus and potassium uptake while calcium uptake was significantly higher with fertility level 125 : 60 : 30 kg N:P2O5:K2O ha-1. Crude protein and ash content remained significantly higher at highest fertility level whereas crude fibre content was not significantly affected. The results also indicate that the single cut crop recorded significantly higher plant height, number of tillers m-2, leaf area index and dry matter production than double cut (excluding 1st cut) crop at different growth intervals, however, leaf stem ratio at 90, 120 and 150 DAS was significantly higher in double cut crop. The double cut crop recorded significantly higher total green and dry fodder yield (1st + 2nd cut) than single cut crop. Nitrogen, phosphorus, potassium and calcium uptake recorded under single cut crop was significantly higher than double cut crop (excluding 1st cut). The double cut crop recorded higher crude protein content but significantly lower crude fibre and ash content than single cut crop. The study revealed that the oats crop sown on September, 30 fertilized with 150 : 70 : 40 kg N:P2O5:K2O ha-1 and cut twice viz., December, 15 and 50 per cent flowering proved to be most economic in terms of benefit cost ratio, net and gross returns
Cultural Retrieval as a Dramatic Strategy: A Study of Girish Karnad’s Tughlaq, Tale-Danda and Bali-The Sacrifice
Get PDFThe Indian English literature has developed as an important, vibrant and versatile body of writing and has drawn attention of the global audiences. It has made a substantial progress by encapsulating various issues that India has been facing from time to time. It has grappled with the onslaughts of colonialism, globalization, and Indian socio-political and cultural issues. It drew its impetus from Indian sensibility, philosophy, sociology, psychology, history, myths and religious beliefs and attracted attention of the people across the boundaries.
When one goes through the history of Indian English literature, one comes to know that the Indian English Drama (hereafter, IED) has made a little progress than the Indian English Novel and Poetry. Diachronically speaking, the IED made its debut before the rest of the two afore-mentioned genres but failed to keep pace with them because of some reasons which will be discussed in detail in Chapter III. Unlike Novel and Poetry, Drama cannot be restricted to reading only. It is a genre which needs a theatre for its enactment. This lack of theatricality in India has proved detrimental for the IED as well as dramatists. The second problem that this genre faced was that of the English language. English being a foreign language did not cater to the needs of Indian people who knew very little of the language. The dialogues in English from Indian characters seemed unconvincing because they lacked in Indian flavour,
temperament and sensibility. Despite this failure of Indian English, the IED has attracted the attention of various writers who contributed a lot to this genre and infused life in it. Contemporary Playwrights like Vijay Tendulkar, Mahesh Dattani, Mohan Rakesh and Girish Karnad have done a commendable job in this field and it is worthwhile to explore its various dimensions and features
Studies on needle blight disease of Blue pine (Pinus wallichiana Jack.) in Kashmir
No full textStudies were conducted on the etiology, epidemiology and management of needle blight of Blue pine (Pinus wallichiana) seedlings during 2008-2009 at Shalimar campus, Srinagar, Kashmir. The disease was prevalent in all the three surveyed districts of Kashmir viz. Anantnag, Baramulla and Srinagar with disease incidence of 31.11 and 28.83 per cent in nurseries and 42.85 and 35.84 per cent in plantations during 2008 and 2009, respectively. The average disease intensity in respective years in nurseries and plantations was 19.93 and 14.51 and 27.44 and 23.92 per cent, respectively. Lophodermium needle blight disease was characterized by the appearance of chlorotic patches which turned reddish brown with straw coloured centre surrounded by yellow halo. Infection at needle tip resulted in dieback. Severe infections caused the death of entire needle and premature defoliation. Characteristic black stromatic zone lines across the needle surface appeared in June-July. Fungal fructifications (pycnidia and hysterothecia) appeared on the infected intact and fallen needles during July to October. The hysterothecia with prominent longitudinal slits were usually formed on abaxial surface of needles. The Leptrostroma state (anamorph of Lophodermium pinastri) isolated in culture was unable to cause pathogenecity on both attached and detached Blue pine needles. The fungus proved pathogenic only when ascospore suspension was inoculated on Blue pine seedlings and detached needles. The pathogen associated with the disease on morphological characters was identified as Lophodermium pinastri Chiv. The pathogen exhibited maximum radial mycelial growth and pycnidial formation on PDA, Richards and Malt extract media. The host range of Lophodermium pinastri in various conifer plants revealed that all the conifer species (Pinus wallichiana, P.halepensis, Abies pindrow, Cedrus deodara, Cuprussus torulosa, Picea smithiana and including one Cryptomeria species) reacted positively except Thuga orientalis. The ascospore release and germination of Lophodermium pinastri under in vitro conditions varied significantly at different test temperatures with highest ascospore release and germination at 25°C. The ascospore release occurred in relative humidity regimes of 60 to 100 per cent only with highest ascospore release and germination at 100 per cent RH. The disease appeared in February and reached maximum by the end of October. During the study period maximum logrithemic infection rate of 0.0618 and 0.0285 unit/day was recorded during the first fortnight of April in 2008 and 2009, respectively. Weather factors viz. temperature and relative humidity were positively correlated with disease intensity (62.1 per cent contribution). However, except temperature all other weather factors were positively correlated with the disease development in terms of infection rate (units/day) (25.7 per cent contribution). The pathogen perpetuated in the form of pycnidia and hysterothecia on fallen diseased needles. The fungal fructifications (pycnidia and hysterothecia) and their viability decreased with increase in the depth of placement in forest litter. Maximum fructifications on pine needles were observed at ground surface (0 cm depth). The diseased needles kept at 0 cm litter depth exhibited maximum hysterothecial formation and ascospore production and greater viability. Conidiomatal formation and conidial production of L. pinastri occurred in the 2nd fortnight of August and in 1st fortnight of September in the year 2008-2009 and 2009-2010, respectively. However, hysterothecial formation, ascospores production and their viability decreased significantly with increase in burial depth in forest litter. Non-systemic fungitoxicants, tested at various concentrations significantly inhibited the mycelial growth and ascospore germination of the pathogen by 52.31 to 76.34 and 60.50 to 82.21 per cent, respectively. Hexaconazole 5 EC proved superior over all other systemic fungitoxicants tested followed by flusilazole 40 EC and carbendazim 50 WP. The studies on in vivo evaluation of most effective fungitoxicants under mist- and poly-chamber conditions at three relative humidity regimes revealed that disease incidence and intensity were comparatively higher in mist- than in poly-chamber. In both, mist- and poly-chambers the Blue pine seedlings treated with hexaconazole 5EC (@ 0.03%) or carbendazim 50WP (@ 0.1%) treated seedlings had significantly less disease incidence and intensity. Increase in humidity regime from 60 to 100 per cent significantly enhanced needle blight disease incidence and intensity. All the fungitoxicants used as either single spray or protectant followed by systemic fungitoxicant spray significantly reduced the disease incidence and intensity as compared to check. The mean disease intensity in fungitoxicant treated Blue pine plants varied from 3.68 to 11.70 per cent as compared to 26.66 per cent in check. Among the fungitoxicants tested mancozeb 75 WP (@0.3%) followed by 2nd spray with carbendazim 50 WP (@0.1%) or hexaconazole 5EC (@0.03%) proved superior in reducing the disease incidence and intensity on Blue pine plantations or spraying with chlorothalonil 75WP (@0.3%) followed by 2nd spray with carbendazim 50 WP (@0.1%) or hexaconazole 5EC (@0.03%) was effective in minimizing disease incidence and intensity. Two-spray treatments exhibited lesser disease intensity (3.68-5.71%) and no defoliation as compared to mono-sprayed treatments which exhibited disease intensity of 8.64 to 11.70 per cent and defoliation of 1 to 10 per cent. Electrolytic leakage in infected blue pine needles was monitored by measuring the conductivity change in pine needles affected by Lophodermium needle blight disease. Highest electrolytic leakage of 345.33 µmoh/cm was noticed in pine needles having > 81 per cent of disease severity in comparison to unaffected check (181.33 µmoh/cm)
Effect of some heavy metals on haematology of fish –cyprinus carpio
Get PDFIncreased industrilisation, urbanisation, population growth and over all man’s greed to over exploit mother nature has created a serious threat to all kinds of life both in aquatic and terrestrial environment. This has now become a global problem and the aquatic systems are greatly affected as large amount of wastes from industries,pesticides
and other organochemicals and fertilizers being used in agricultural fields make their way easily into water bodies through run off and result in pollution of water. Among all the types of pollution, aquatic pollution is of greater concern as each and every kind of life depends on water. And among all the types of aquatic pollutants,heavy metals extensively contaminate the natural ecosystems and are released into the water bodies from industrial and other man made activities (Velez and Montoro, 1998;
Conacher et al, 1993). Among these sources, industrial wastes constitute the major source of metal pollution in natural waters (Livingstone, 2001)
Effects of the Food Plants on the Bionomics of Cabbage aphids, Brevicoryne brassicae (L.)
Get PDFphids, commonly known as „Plant lice‟ are soft bodied insects which damage different types of plants including valuable fruit & vegetable crops. Among aphids, the cabbage aphid Brevicoryne brassicae (L.) is one of the most important pests of cruciferous crops like cabbage, cauliflower, knol-khol, kale, turnip etc. It is a small blue grey coloured aphid with short cornicles (tube like structures at the end of abdomen) & body covered with waxy secretions. The cabbage aphids feed on the underside of leaves in large clusters, in the center of cabbage heads, flowers, flower-stalks & on the youngest leaves. Cabbage aphid damages leaves & flowers of plants directly by sucking sap & indirectly by secreting honey dew which attracts sooty mould. The aphid is also a vector of 11 non-persistent, 5 semi-persistent & 4 persistent plant viruses (Ulusoy & Bayhan, 2006). A thorough understanding of pest biology is essential for developing a reliable pest population prediction system & more environmental friendly management strategies. Though much work has been carried out in the country on the pests of cruciferous crops but no systematic work seems to have attempted in the valley in this regard particularly on the crops like cauliflower, cabbage, kale, turnip & knol-khol.
A
In order to have an idea about the previous work done on the said topic, an attempt was made to review the available literature on the subject. Early workers like Daiber (1970) studied the influence of temperature on the biology of three species of aphids- Brevicoryne brassicae (L.), Lipaphis erysimi Kalt. & Myzus persicae Sulz. infesting cabbage. Chua (1977) studied the population of Brevicoryne brassicae (L.) & its parasites & Hyperparasites in England on Brussel-sprouts. Amin et al. (1980, 1982), Muhammad et al. (1989), Kashyap & Sharma (1994), Paula et al. (1995), Opender (1998), Vasicek et al. (1999), Cividanes (2002), Debraj & Singh (2003), Rossa et al. (2003), Vasicele et al.(2003), Satar (2005) & Ulusoy et al. (2006) studied the biology of Brevicoryne brassicae on different Brassica species under different temperature regimes. Amjad et al. (1999), Liu & yiu (2001), Rana (2005) studied the biology of turnip aphid (Homoptera: Aphididae) on various Brassica species under varied temperature zones.
In order to fulfill the aims and objectives of the present research, the methodology covering different aspects was divided into different sections. First of all the desired host plants of Brevicoryne brassicae viz. cabbage, cauliflower, kale, knol-khol & turnip were cultivated in nursery beds in the month of Feb-March 2010.This was done to ensure the availability of the stock all round the year for experimentation. The plants were transplanted into pots containing loam soil & rotten manure in the
ratio of 1:1. After cultivating the crops second step involves the rearing of cabbage aphids, Brevicoryne brassicae (L.). In order to study the biological parameters of the cabbage aphids, equal number of apterous viviparous females was transferred individually to each potted host plant. The individual leaves were covered with cone shaped transparencies in order to restrict the movement of aphids. All the plants were covered with a fine net in order to prevent the attack of cabbage aphids by parasites & predators. The potted plants were kept under ambient temperature & humidity conditions in the laboratory until each experiment was concluded.
To observe the effect of different host plants on the biology of Brevicoryne brassicae a set of five experiments were conducted. After noting down the different parameters in the life-cycle of Brevicoryne brassicae, the data generated was statistically analyzed for drawing inferences.
The results indicate that there is a negative correlation between the average monthly temperature & nymphal period of cabbage aphid on kale. Similarly negative correlation was observed between temperature and other biological parameters like reproductive period, adult longevity and total longevity of the cabbage aphid. The different developmental times on different plants, from first instar to adult cabbage aphids can be
attributed to differences in the levels of sensitivity & resistance of the host plants.
Robert (1987) stated that the chemical structure, quality of nutriment, and colour of leaf affect development time, life-span, survival rate & fecundity of aphids. The difference in the developmental period, total longevity & adult longevity of cabbage aphid on cauliflower, turnip, cabbage & knol-khol can be attributed to the structural difference in the leaves of the said crops, besides the differences in the chemical composition of their leaves. The differences in the different biological parameters of B.brassicae observed on kale in different months of the year may be attributed to the changing temperature‟s in different months of the year. Besides these factors, the age of plant & sinigrin accumulation in the leaves of the crop can also effect the biological parameters of the cabbage aphid (Brevicoryne brassicae).
Thus the present work reveals that this biological work is the first of its kind in the valley. The overall life cycle of the pest was found to be longest on cauliflower (29.16 days) & shortest on turnip (15.48 days) which can be attributed to the morphological structure of turnip leaves and high resistance shown by the crop for the pest