Biologicals - Wiley

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1BiologicalsGreen Alternatives for Plant DiseaseManagement

Neeta SharmaDepartment of Botany, Lucknow University, Lucknow, India

1.1 Introduction

Worms have destroyed half the wheat, hippopotami have eaten the rest; thereare swarms of locusts alight; the rats roam in the field, the cattle devour, the littlebirds pilfer and if the farmer loses sight for an instant of what remains on theground, it is carried off by the robbers. (Anonymous)

Man’s dependence on plants for sustenance and survival has always been ofparamount importance. The origins of civilization can be traced back to man’sdiscovery and assurance of an available, accessible and affordable food supply.The maintenance of an adequate supply of food is essential for the existenceand prosperity of a nation.

Today, we produce about four billion metric tons of food per annum.However, there are claims that food production has increased at the sametime that there are counter-claims that report on the depletion of our naturalresources. To ensure sufficient food for every inhabitant of the Earth, bothin quantity and in quality, native ecosystems are rapidly being converted forhuman use, destroying forests, soil and native plants and animals. However,pressure is growing on finite resources of land, energy and water. Such aprojection presents mankind with wide-ranging social, economic, environ-mental and political issues that need to be addressed today in order toensure a sustainable future tomorrow. One key issue is the production ofsufficient food for everyone in a world of finite resources. At the close of the

Biological Controls for Preventing Food Deterioration: Strategies for Pre- and Postharvest Management,First Edition. Edited by Neeta Sharma.© 2014 John Wiley & Sons, Ltd. Published 2014 by John Wiley & Sons, Ltd.

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2 CH1 BIOLOGICALS

twentieth century, astonishing advances in agricultural productivity andhuman ingenuity have not yet been translated into a world free of hungerand malnutrition. To produce sufficient food, commercial and subsistencefarming systems must be highly productive, but sustainable and nonpolluting(Sharma, Sharma and Prabha, 2012).

1.2 Food supply on a collision courseWhile advances in science and technology have greatly increased food avail-ability, we are definitely facing a potential food production crisis. The Interna-tional Food Policy Research Institute (IFPRI) projects that global demand forcereals between 1993 and 2020 will increase by 41% to 2490 million metric tonsand for roots and tubers to increase by 40% to 855 million tons. Loss of foodarguably poses greatest vulnerability to food security worldwide. Approxi-mately half of the population in the Third World does not have access toadequate food supplies. Diseases caused by various biotic factors, a generalphenomenon, is a matter of grave concern at the field level as well as after har-vest resulting in food losses. Due to poor practices in harvesting, storage andtransportation, coupled with market and consumer wastage, it is estimatedthat 30–50% (nearly 1.2–2 billion tonnes) of all food produced never reachesa human stomach. In developed countries, losses and wastage of food havebeen estimated to be between 10–60%. In developing countries these lossescan run to over 50%. It has been estimated that a minimum of 47 000 000metric tons of durable crops and 60 000 000 metric tons of perishable cropsbecome victims of various pathogens.

The average minimum losses reported for roots and tubers and fruits andvegetables were 16% and 21% respectively; many more ‘qualitative’ refer-ences, not included here, indicate estimates of 40–50% and above. CurrentFAO (Food and Agricultural Organization) projections in food demandsuggest that cereal demand will increase by almost 50% towards 2050. It isprojected that the current scenario of losses and constraints due to climaticconditions, soil fertility, and availability of water, arable land, and low-costenergy, suggests that production increase could fall to 0.87% towards 2030and to 0.5%, by 2030–2050. The world will struggle to produce food in theface of rising populations, limited energy supplies, and the degradation of oursoil and fresh water. Furthermore, this figure does not reflect the fact thatlarge amounts of land, energy, fertilizers and water have also been lost in theproduction of foodstuffs which simply end up as waste. This level of wastageis a tragedy that cannot continue if we are to succeed in the challenge ofsustainably meeting our future food demands.

In addition, a production short of demand, a greater geographical inequityin production and demand, combined with possibly more challenging weather


1.3 THE ENORMITY OF THE PROBLEM 3

and subsequent speculation in food markets, could leave us in an even worsecondition than that seen in the current crisis, if appropriate options forincreasing food supply and security are not considered and implemented.

1.3 The enormity of the problem1.3.1 OverpopulationThe world today is characterized by an exponential growth in population.The prospects are that the world population will increase to 8.3 billion in2025. The United Nations’ mid-range projection for global population growthpredicts that by 2075, the world population will be at about 9.5 billion people.With an expected 40% population increase and an average annual incomegrowth rate of 4.3%, developing countries are projected to account for mostof the increase in global demand for cereals and meat products. This meansthat there could be an extra three billion mouths to feed by the end of thecentury, a period when substantial changes are anticipated in the wealth,calorific intake and dietary preferences of people in developing countriesacross the world. Rising populations combined with improved nutritionstandards and shifting dietary preferences will exert pressure for increases inthe global food supply. If this trend continues unchanged, there is almost aunanimous consensus that the limits to growth on this planet will be reachedsome time within the next one hundred years. This tendency to overpopula-tion is responsible for many difficulties and problems that harass the modernworld, especially in nations with restricted land area meant for growingfood crops.

1.3.2 Effective land usageOver the past five decades, improved farming techniques and technologieshave helped to significantly increase crop yields, along with a 12% expansionof farmed land use. However, with global food production already utilizingabout 4.9 Gha of the 10 Gha usable land surface available, a further increase infarming area without impacting unfavourably on what remains of the world’snatural ecosystems appears unlikely. The challenge is that an increase inanimal-based production will require greater land and resources, as livestockfarming demands extensive land use. One hectare of land can, for example,produce rice or potatoes for 19–22 people per annum. Considerable tensionsare likely to emerge, as the need for food competes with demands for ecosys-tem preservation and biomass production as a renewable energy source.On top of this, nearly one-third of the world’s cropland (115 billion hectares)has been abandoned due to soil erosion and loss of fertility.


4 CH1 BIOLOGICALS

1.3.3 Water useOver the past century, fresh water abstraction for human use has increased atmore than double the rate of population growth. Currently about 3.8 trillionm3 of water is used by humans per annum. The drilling of millions of irrigationwells has pushed water withdrawal in many countries beyond recharge ratesfrom rainfall, leading to groundwater mining. As a result, water tables arenow falling in countries that contain half the world’s people, including thebig three grain producers: China, India and the United States. About 70%of this is consumed by the global agricultural sector, and the level of use willcontinue to rise over the coming decades. Of all the environmental trends thatare reducing the world’s food supplies, the most immediate is water shortages.Indeed, depending on how food is produced and the validity of forecasts fordemographic trends, the demand for water in food production could reach10–13 trillion m3 annually by mid-century. This is 2.5–3.5 times greater thanthe total human use of fresh water today.

1.3.4 Energy useEnergy is an essential resource across the entire food production cycle, withestimates showing an average of 7–10 calories of input being required in theproduction of 1 calorie of food. Since much of this energy comes from the uti-lization of fossil fuels, wastage of food potentially contributes to unnecessaryglobal warming as well as inefficient resource utilization. In the modern indus-trialized agricultural process – which developing nations are moving towardsin order to increase future yields – energy use in the making and applica-tion of agrochemicals such as fertilizers and pesticides represents the singlebiggest component. Indeed, on a global scale, fertilizer manufacturing con-sumes about 3–5% of the world’s annual natural gas supply. With productionanticipated to increase by 25% between now and 2030, sustainable energysourcing will become an increasingly major issue. Energy to power machinery,both on the farm and in the storage and processing facilities, together with thedirect use of fuel in field mechanization and produce transportation, adds tothe energy total, which currently represents about 3.1% of the annual globalenergy consumption.

1.4 Preventing food lossesWorldwide, approximately 9000 species of insects and mites, 50 000 species ofplant pathogens, and 8000 species of weeds damage crops. Insect pests causean estimated 14% of loss, plant pathogens cause a 13% loss, and weeds a 13%loss. Although considerable attention has been drawn to the enormity of foodlosses and waste due to food spoilage, a limited number of resources have


1.5 HAZARDS FROM SYNTHETIC PESTICIDES 5

been devoted to its solution. Promoting food security through loss reductionis the most feasible and sustainable method of increasing food production.This area, which has long been ignored, has only recently been acknowledgedby the international agencies monitoring world food resources.

Chemical pesticides became indispensable in agricultural production(Zhang, Li and Liu, 2011). Application of fertilizers and pesticides to cropsbecame the norm. Crop loss from pests declines to 35% from 42% whenpesticides are used, however, without pesticide application, the loss of fruits,vegetables and cereals from pest injury would reach 78%, 54% and 32%,respectively (Cai, 2008). Over the 1990s, global pesticide sales remainedrelatively constant, between US$270–300 billion, of which 47% were herbi-cides, 79% were insecticides, 19% were fungicides/bactericides and 5% theothers. Over the period 2007–2008, herbicides ranked the first in the threemajor categories of pesticides (insecticides, fungicides/bactericides, herbi-cides). Fungicides/bactericides increased rapidly and ranked second. About23 million kg of fungicides are applied to fruits and vegetables annually, andit is generally accepted that production and marketing of these perishableproducts would not be possible without their use. Europe is now the largestpesticide consumer in the world, with Asia in second place. As for countries,China, the United States, France, Brazil and Japan are the largest pesticideproducers, consumers or traders in the world. Despite the advances made inagriculture and large-scale pesticide use during recent decades, the destruc-tion of food at every level by diseases is still beyond control. Wasting foodmeans losing not only life-supporting nutrition but also precious resources,including land, water and energy.

1.5 Hazards from synthetic pesticidesThe history of pesticide development has been instructive in terms of benefitsderived as well as the hazards which accompany indiscriminate use of thesechemicals. The era of the ‘Green Revolution’ was dominated by ‘the Grey’(Sharma and Bhandari, 2014). Whether due to shortsightedness or theunidirectional approach, lack of adequate planning and mismanagement inthe pre- and postharvest environment, the inputs directed towards increasingproductivity could not generate the desired results and instill a sense of foodsecurity in the masses. The world became so obsessed with the idea of increas-ing crop productivity that it completely forgot that the produce should besafe for human consumption and the environment. According to a report byWHO and UNEP, there are more than 26 million human pesticide poisoningswith about 220 000 deaths per year worldwide (Richter, 2002). The problemsassociated with using pesticides include failure of pest control and damageto human health. These hazardous chemicals contaminate the environment,enter the food chain, destroy native insect pests, build residual toxicity in


6 CH1 BIOLOGICALS

plant and animal tissues and introduce health hazards to humans such ascancers, hormonal imbalances and respiratory troubles, targeting non-targetmicroorganisms and increasing the incidence of pest resurgence due to thedevelopment of resistance in pests towards these chemicals. The aim is notonly to prevent losses but also to go ‘Green’ in order to recover and reapthe benefits of the ‘stolen harvest’. Hence, the need for safe and effectivenonchemical methods to prevent the bio-deterioration of food grains wasbrought to the forefront.

1.6 A way out of this crisisGlobally, food safety has emerged as a key element in decay control pro-grammes. Understandably, alternatives to chemical pesticides or productsthat allow reduced use in terms of fewer or reduced rates of application arebeginning to appear on the market. A part of the solution to this problem iscontrol through the use of biopesticides, the foundation on which sustainable,nonpolluting pest control for tomorrow’s farms must be built.

There is no formally agreed definition of a biopesticide. ‘Biologicals’ or‘biopesticides’ are certain types of mass-produced agents derived from aliving microorganism or a natural product and sold for the control of plantpests. In a much simpler way, we can say that these are pest managementtools that are based on beneficial microorganisms (bacteria, viruses, fungiand protozoa), beneficial nematodes or other safe, biologically based activeingredients. The use of these materials is widespread with applications tofoliage, turf, soil or other environments of target insect pests.

1.7 Types of biopesticidesBiopesticides fall into three different types according to the active substancecontained: (1) microorganisms; (2) biochemicals; and (3) semiochemicals.The US Environmental Protection Agency also classifies some transgenes asbiopesticides.

1.7.1 Microbial pesticidesNaturally occurring or genetically controlled bacteria, fungi, viruses and pro-tozoa are all being used as the active ingredient for the biological control ofpestiferous insects, plant pathogens, weeds, microorganisms (e.g. a virus bac-terium, fungus, nematode or protozoan). These pesticides can control manydifferent kinds of pests, though each separate active ingredient is relativelyspecific for its target pests. Microbial pesticides need to be continuously mon-itored to ensure they do not become capable of harming non-target organisms,including humans.


1.7 TYPES OF BIOPESTICIDES 7

Baculoviruses These target-specific viruses, belonging to the family Bac-uloviridae, include two genera of occluded viruses, nuclear polyhedroviruses(NPVs) and granuloviruses (GVs), and one group of non-occluded viruses(NOVs) which can infect and destroy a number of important plant pests(Table 1.1). In spite of their limitations in use that include slow speed of kill, anarrow spectrum of biological activity, short residual effect and photostability,they have the major advantages of being highly specific to a limited number ofinsects, having no demonstrated toxicity to any other living forms, includinghumans, and leave no toxic residues in crops. Their large-scale productionposes certain difficulties, so their use has been limited to small areas. All prod-ucts produced and processed as concentrated powders can be formulated asliquids, suspension concentrates (SC) or wettable powders (WP). The roleof natural baculoviruses in agriculture might be enhanced if the length oftime required to kill the target pest insect population is shortened and theirsynergistic or potentiating interaction with chemical insecticides could beexploited, resulting in a reduction of the rate of application of the latter andthereby reducing the chemical load in the environment.

Bacteria Several bacterial species have been developed as biopesti-cides, prominent among these are based on various sub-species of Bacillusthuringiensis Berliner (Bt) (Choudhary and Johri, 2009). The primary marketsfor sprayable Bt products are in vegetable and horticultural crops with a smallshare going to control forest pests and insects of public health importance.

Table 1.1 Baculoviruses as biopesticides.

Baculovirus Trade name Target pests Crops

1. Spodoptera exigua NPV SPOD-X Beet army worm, S exigua(Hübner)

Glasshouses in theNetherlands

2. S littoralis NPV Spodopterin Egyptian cotton leafworm, S littoralis(Boisd)

Cotton

3. Anagrapha falcifera(Kirby) NPV Celerylooper

AfNPV Broad-spectrum control oflepidopterous larvae

Many

4. Helicoverpa zea Disparvirus Gypsy moth larvae, Ldispar (L)

Forests

5. Lymantria dispar NPV Gemstar Cotton bollworm H zeaTobacco budworm,Heliothis virescensFabricius

Corn, cotton

6. Anticarsia gemmatalisNPV

Polygen Multigen Velvet bean caterpillarAnticarsia gemmatalis(Hübner)

Soybean


8 CH1 BIOLOGICALS

The worldwide market for Bt products is still very small, estimated atUS$100 million, approximately 1.5% of the total insecticide market world-wide. These control products contain the endotoxins plus live bacterial cells.Currently, 26 Bt-based products are registered by the US EPA and mar-keted worldwide. Of these, 15 are derived from naturally occurring strains,e.g. Able, Bactospeine, Dipel, Javelin, Thuricide and Xentari. Three productsare derived from plasmid conjugation, resulting in cry gene exchangesproducing new toxin arrays. Examples of these products are: Condor, Design,Foil, and Cutlass. Further improvements in efficacy and a broader spectrum ofactivity were achieved via a recombination of cry proteins. The recombinantBt technology has already resulted in several improved Bt products, includingCrymax, Lepinox and Raven. The K84 strain of Agrobacterium radiobacter isused to control crown gall (Agrobacterium tumefaciens), while specific strainsof Bacillus subtilis, Pseudomonas fluorescens and Pseudomonas aureofaciensare being used against a range of plant pathogens including damping-off andsoft rots.

Fungi Fungal biopesticides (Table 1.2) sold as dry powder or liquid formula-tions and used against Rhizoctonia, Pythium, Fusarium and other soil-borne

Table 1.2 Fungi as bioagents.

Fungi Product

Ampelomyces quisqualis Ces AQ(10)Beauveria bassiana Ostrinil, Naturalis-L, Naturalis-O and

Naturalis-T (Troy), and BotaniGard,Mycotrol and Corn Guard

B. brongniartii microgranule Betel, and Engerlingspilz

Candida oleophila AspireChondrostereum purpureum BiochonColletotrichum gloeosporioides (Penz) Sacc f sp

aeschynomeneCollego

Coniothyrium minitans Campbell ContansGliocladium catenulatum Gilman & Abbott granular (GR) formulation, PrimastopMetarhizium anisopliae Sorok BioBlast

Metarhizium avoviride Green MuscleMyrothecium verrucaria DiTera

Paecilomyces fumosoroseus PreFeRal

Phytophthora palmivora (Butl) DeVineTrichoderma harzianum Tul, variety TH11

(Harzan), strain T-39 Trichoderma harzianumTul, variety TH11 (Harzan), strain T-39

SoilGard, Trigard, Trichodex, Harzan andformulated as a microgranule

Verticillium lecanii (Zimmerman) Viegas Mycotal and Vertalec


1.7 TYPES OF BIOPESTICIDES 9

pathogens including Trichoderma harzianum. Coniothyrium minitans is amycoparasite applied against Sclerotinia sclerotiorum, an important diseaseof many agricultural and horticultural crops. Microbial antagonists, includingyeasts and filamentous fungi, are also used as control agents of postharvestdiseases, mainly against Botrytis and Penicillium in fruits and vegetables.

At least 170 different biopesticide products based on entomopathogenicfungi Beauveria bassiana or Metarhizium anisopliae have been developed foruse against at least five insect and acarine orders in glasshouse crops, fruitand field vegetables as well as broad-acre crops. The largest single countryof use is Brazil, where commercial biopesticides based on M. anisopliae areused against spittlebugs on around 750000 ha of sugarcane and 250 000 haof grassland annually. The fungus has also been developed for the control oflocust and grasshopper pests in Africa and Australia and is recommendedby the Food and Agriculture Organization of the United Nations (FAO) forlocust management.

1.7.2 Plant-derived productsThe use of locally available plants for the control of pests and pathogens is anage-old technology in many parts of the world. Farmers in their traditionalwisdom have identified and used a variety of plant products and extracts forpest control, especially in storage. As many as 2121 plant species are reportedto possess pest management properties, 1005 species of plants exhibitinginsecticide properties, 384 with antifeedant properties, 297 with repellantproperties, 27 with attractant properties and 31with growth-inhabiting prop-erties have been identified. The efficacy of essential oils and vegetable oils inpreventing the infestation of stored product pests such as bruchids, rice andmaize weevils has been well documented. Root extracts of Tagetes or Aspara-gus as nematicide and Chenopodium and Bougainvillea as antivirus have alsobeen reported. Currently, 30 mating-disruption pheromone-based productsare registered by the US EPA for the control of 11 lepidopterous pest speciesincluding: pink bollworm (PBW) (Pectinophora gossypiella (Saunders)),codling moth (CM) (Laspeyresia pomonella (L)), oriental fruit moth (OFM)(Grapholitha molesta (Busck)), gypsy moth (GM) (Lymantria dispar (L)),and peach tree-borer (PTB) (Anarsia lineatella (Zeller)) among others.

Higher plants are the source of a wide spectrum of secondary metabolitessuch as alkaloids, essential oils, flavonoids, phenolics, quinines, saponins,sterols and tannins, which offer resistance to pathogens and some of thesecan be used as biopesticides. They include, for example, pyrethrins, which arefast-acting insecticidal compounds produced by Chrysanthemum cinerariaefolium. They have low mammalian toxicity but degrade rapidly after applica-tion. This short persistence prompted the development of synthetic pyrethrins(pyrethroids). The most widely used botanical compound is neem oil, aninsecticidal chemical extracted from seeds of Azadirachta indica. Two highly


10 CH1 BIOLOGICALS

active pesticides are available based on secondary metabolites synthesizedby soil actinomycetes. Spinosad, a mixture of two macrolide compoundsfrom Saccharopolyspora spinosa, has a very low mammalian toxicity andresidues degrade rapidly in the field. Farmers and growers used it widelyfollowing its introduction in 1997 but resistance has already developed insome important pests such as western flower thrips. Abamectin, a macrocycliclactone compound produced by Streptomyces avermitilis, is active against arange of pest species but resistance has developed in tetranychid mites to italso, though they fall within the definition of a biopesticide but they havebeen evaluated by regulatory authorities as synthetic chemical pesticides.A wide range of predatory animals use insect-specific toxins to kill their prey.These toxins can be introduced into crops to render them resistant to insectattack and some work is underway to incorporate them into baculoviruses toincrease the speed of kill.

Microorganism-derived natural products currently used as biopesticidesagainst various plant diseases and pathogens have been summarized inTable 1.3.

1.7.3 SemiochemicalsA semiochemical is a chemical signal produced by one organism that causesa behavioural change in an individual of the same or a different species.The most widely used semiochemicals for crop protection include insectsex pheromones, some of which can now be synthesized and are used formonitoring or pest control by mass trapping, lure-and-kill systems and matingdisruption. Man-made pheromones are used to disrupt insect mating bycreating confusion during the search for mates, or can be used to attractmale insects to traps. The most commonly used plants are neem (Azadirachtaindica), pongamia (Pongamia glabra) and mahua (Madhuca indica). Some2–5% neem or mahua seed kernel extract has been found effective againstrice cutworm, tobacco caterpillar, rice green leafhopper and several speciesof aphids and mites.

1.8 Strategies of biological controlThere are four strategies for biological control: classical, inoculation, inun-dation and conservation biological control. Classical biological control is theintentional introduction of an exotic, usually co-evolved, biological controlagent for permanent establishment and long-term pest control. In the caseof microorganisms, widely distributed in nature, the term exotic means theuse of a particular strain or biotype, which is not native to the area wherethe pest is controlled. Introduced species to induce long-term effect have toacclimatize to the area under certain climatic conditions, multiply and spread.


1.8 STRATEGIES OF BIOLOGICAL CONTROL 11Ta

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12 CH1 BIOLOGICALS

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and

P.la

chry

man

sCa

rsne

r

Wet

tabl

epo

wde

r(W

P)an

dliq

uid

conc

entr

ate

Agri

myc

in17

and

AS-5

0(N

ovar

tis)

,Pl

anto

myc

in(A

ries

Agro

-Vet

Indu

strie

s)an

dPa

usha

myc

in(P

aush

ak).

8.Va

lidam

ycin

(Str

epto

myc

eshy

gros

copi

cus)

give

exce

llent

cont

rolo

fR

sola

niin

rice,

pota

toes

,ve

geta

bles

,st

raw

berr

ies,

toba

cco,

ging

er,

cott

on,

suga

rbe

etan

dse

vera

loth

ercr

ops

Disp

ersi

ble

pow

der

(DP)

,so

lubl

eco

ncen

trat

e(S

L),

pow

der

seed

trea

tmen

t(D

S)an

dliq

uid

form

ulat

ions

Valid

acin

,Va

limun

(Tak

eda)

,So

laco

l(Ta

keda

and

Aven

tis)

,M

ycin

(San

onda

)an

dVi

vada

my

(Vie

tnam

Pest

icid

e)9.

Aver

mec

tins

(Str

epto

myc

esav

erm

itili

s)Ag

ains

tth

ene

mat

ode

Nem

atos

piro

ides

dubi

usem

ulsi

fiabl

eco

ncen

trat

es(E

C)an

dre

ady-

for-

use

bait

s(R

B)Dy

nam

ec,

Avid

,Ze

phyr

and

Agri

-Mek

(Nov

arti

s)an

dAb

acid

e(M

auge

t)10

.Em

amec

tin

(Str

epto

myc

esav

erm

itili

s)Ca

terp

illar

cont

roli

ncr

ops

such

asve

geta

bles

,co

rn,

tea,

cott

on,

pean

uts

and

soyb

eans

atra

tes

Benz

oate

asem

ulsi

fiabl

eco

ncen

trat

e(E

C)an

dso

lubl

egr

anul

e(S

G)fo

rmul

atio

ns

Proc

laim

and

Affir

m


1.8 STRATEGIES OF BIOLOGICAL CONTROL 1311

.M

ilbem

ecti

n(S

trep

tom

yces

hygr

osco

picu

s)Ag

ains

tm

ites

Emul

sifia

ble

conc

entr

ate

(EC)

form

ulat

ion

Milb

ekn

ock

(San

kyo)

12.

Baci

llus

thur

ingi

ensi

sd-

endo

toxi

ns(B

acill

usth

urin

gien

sis

Berli

ner

(Bt)

Inse

ctic

idal

tola

rvae

ofth

eor

der

Lepi

dopt

era,

tobo

thla

rvae

and

adul

tsof

afe

wCo

leop

tera

nsan

dto

the

larv

aeof

som

eDi

pter

ans,

also

agai

nst

nem

atod

es

Form

ulat

ions

are

sold

wit

hliv

esp

ores

Able

(The

rmo

Trilo

gy),

Bact

ospe

ine

(Val

ent

BioS

cien

ces)

,Di

pel(

Vale

ntBi

oSci

ence

s),

Jave

lin(T

herm

oTr

ilogy

),Th

uric

ide

(The

rmo

Trilo

gy)

and

Xent

ari(

Vale

ntBi

oSci

ence

s).

13.

Spin

osad

(Sac

char

opol

yspo

rasp

inos

a)Ta

rget

phyt

opha

gous

inse

cts

such

asca

terp

illar

s,le

afm

iner

s,th

rips

and

folia

ge-f

eedi

ngbe

etle

s

Wat

er-b

ased

susp

ensi

onco

ncen

trat

e(S

C)fo

rmul

atio

nTr

acer

,Co

nser

ve,

Succ

ess

and

Spin

Tor

(Dow

Agro

Scie

nces

)14

.Po

lyna

ctin

s(S

trep

tom

yces

aure

us)

Spid

erm

ites

unde

rw

etco

ndit

ions

emul

sifia

ble

Emul

sifia

ble

conc

entr

ates

(EC)

Mit

ecid

in(p

lus

feno

buca

rb)

and

Mit

edow

n(p

lus

fenb

utat

inox

ide)

(Eik

ouKa

sei)

15.

Bila

nafo

s(S

trep

tom

yces

hygr

osco

picu

s,S.

virid

ochr

omeo

gene

s

Cont

rolo

fan

nual

wee

dsan

dat

high

erra

tes

for

cont

rolo

fpe

renn

ialw

eeds

Solu

ble

pow

der

(SP)

and

liqui

dfo

rmul

atio

nsM

eiji

Her

biac

e(s

odiu

msa

lt)

(Mei

jiSe

ika)

16.

Azad

irach

tin

(Aza

dira

chta

indi

caA

Juss

)Se

vera

leff

ects

onph

ytop

hago

usin

sect

s,dr

amat

ican

tife

edan

t/re

pelle

ntef

fect

,po

wde

rym

ildew

s

Crud

eex

trac

t,em

ulsi

fiabl

eco

ncen

trat

es(E

C)Ne

emix

90,

Neem

azid

,Tr

ilogy

90(N

eem

oilf

ordi

seas

eco

ntro

l),

Tria

ct90

(Nee

moi

lfor

dise

ase

cont

rol)

,Bi

o-ne

em,

Mar

gosa

n-O,

Azat

in,

Alig

n,Tu

rple

xan

d

(Con

tinue

dov

erle

af)


14 CH1 BIOLOGICALS

Tabl

e1.

3(C

ontin

ued)

S.no

Prod

uct

(sou

rce)

Dise

ases

Form

ulat

ion

base

Trad

ena

me

Bollw

hip

(all

Ther

mo

Trilo

gy),

Fort

une

Aza

and

Fort

une

Biot

ech

(For

tune

),Az

atin

(Agr

idyn

e),

Neem

Sura

ksha

,Pr

onee

m,

Neem

Wav

ean

dAz

aTe

chni

cal

(all

Kara

pur

Agro

),Ne

emAz

al(T

rifo

lio-M

),Ka

ynee

m(K

rish

iRas

ayan

),Ne

emol

in(R

allis

),Su

reFi

rean

dNe

emac

htin

(Con

sep)

and

Nim

beci

dine

(TSt

anes

)17

.Ni

coti

ne(N

icot

iana

rust

ica

L)Co

ntro

lof

man

ysu

ckin

gin

sect

sDi

sper

sibl

epo

wde

r(D

P),

solu

ble

conc

entr

ate

(SL)

oras

fum

igan

tfo

rmul

atio

ns

Nico

Soap

(Uni

ted

Phos

phor

usLt

d),

No-F

id(H

orti

chem

),XL

-Al

lNi

coti

ne(V

itax

)an

dNi

coti

ne40

%Sh

reds

(Dow

Agro

Scie

nces

)18

.Pl

ant

pela

rgon

ican

dre

late

dfa

tty

acid

sCo

ntro

lof

man

ydi

ffer

ent

inse

ctsp

ecie

sin

vege

tabl

es,

frui

tan

dor

nam

enta

ls;

fung

icid

alus

esin

clud

edi

seas

eco

ntro

lin

grap

es,

rose

san

dot

her

crop

san

dhe

rbic

ide

uses

incl

ude

tota

lwee

dco

ntro

land

mos

sco

ntro

lin

law

ns

Liqu

idco

ncen

trat

e(S

L)fo

rmul

atio

nsTh

inex

and

Scyt

he(M

ycog

en)

and

Gran

tico

(Jap

anTo

bacc

o).


1.8 STRATEGIES OF BIOLOGICAL CONTROL 1519

.Py

reth

rins

(Chr

ysan

them

umci

nera

riaef

oliu

m)

Asin

sect

icid

es,

fung

icid

es,

tota

lhe

rbic

ides

oras

mos

ski

llers

Aero

sold

ispe

nser

s(A

E),

disp

ersi

ble

pow

ders

(DP)

,em

ulsi

fiabl

eco

ncen

trat

es(E

C),fo

ggin

gco

ncen

trat

es,

wet

tabl

epo

wde

rs(W

P)an

dul

tral

ow-v

olum

eliq

uids

(UL)

Alfa

dex

(Nov

arti

s),Py

roci

dean

dEv

ergr

een

(MGK

),Py

rony

l(m

ixtu

re),

Exci

teR

and

Pren

tox

Pyre

thru

mEx

trac

t(a

llPr

enti

ss),

Milo

n(D

elic

ia),

Pyco

n(f

orco

ncen

trat

edm

ixtu

rew

ith

pipe

rony

lbut

oxid

e),

(Agr

opha

rm)

and

Chec

kOut

(Con

sep)

20.

Rote

none

(Der

ris,Lo

ncho

carp

usan

dTe

phro

sia

spec

ies)

Inse

ctic

ide

Disp

ersi

ble

pow

der

(DP)

,em

ulsi

fiabl

eco

ncen

trat

e(E

C)an

dw

etta

ble

pow

der

(WP)

form

ulat

ions

Chem

Sect

,Cu

beRo

otan

dRo

teno

neEx

trac

t(a

llTi

fa),

Noxfi

rean

dRo

teno

neFK

-11

(Agr

Evo

Envi

ronm

enta

lHea

lth)

and

Pren

fish

(mix

ture

),Pr

enti

ss,Sy

npre

nFi

sh(m

ixtu

re)

and

Pren

tox

(all

Pren

tiss

)21

.Ry

ania

extr

acts

Cont

rolo

fbo

ring

inse

cts

Wet

tabl

epo

wde

r(W

P)Na

tur-

Gro

R-50

and

Natu

r-Gr

oTr

iple

Plus

(Agr

iSys

tem

sIn

tern

atio

nal)

and

Ryan

50(D

unhi

llCh

emic

al)

22.

Plan

t-de

rive

dfa

tty

acid

sIn

sect

icid

alac

tivi

tyLi

quid

conc

entr

ate

Thin

exan

dSc

ythe

(Myc

ogen

)an

dGr

anti

co(J

apan

Toba

cco)


16 CH1 BIOLOGICALS

So it is important to understand the biology of the ‘exotic’ species and thetarget species, as well as have the ability to monitor its presence in the area.Inoculation biological control is also the intentional release of a living organ-ism as a biological control agent with the expectation that it will multiply andcontrol the pest for an extended period, but not permanently. Inoculationinvolves releasing small numbers of natural enemies at prescribed intervalsthroughout the pest period, starting when the density of pest is low. The natu-ral enemies are expected to reproduce themselves to provide more long-termcontrol. Inundation biological control is the use of living organisms to controlpests when control is achieved exclusively by the released organisms them-selves. They suppress pests by:

1. producing a toxin specific to the pest;2. causing a disease;3. preventing the establishment of other microorganisms through competi-

tion; or4. other modes of action.

1.9 Biopesticides: advantages and limitationsBiopesticides are selective, produce little or no toxic residue and developmentcosts are significantly lower than those of conventional synthetic chemicalpesticides (Figure 1.1). Biopesticides generally affect only the target pest and

• Ease of utilisation

• Effectiveness

• Controlled industrial

production

vs

• Polluting (air, ground water,

soil)

• Toxicity (wide spectrum of

action)

• Resistance phenomenon

• GMO

• Natural compounds

• Microoraganisms

Biopesticides Chemical pesticides

PESTICIDES

• Less polluting (active at low concentration)

• Less toxic (targeted action, biodegradable)

• Multiplicity of mode of action (lowering the

emergence of resistance phenomenon)

• More complex utilisation

• Effectiveness depending on biotic/abiotic factor

• Complex industrail production

vs

Figure 1.1 Pesticides versus biopesticides: a critical view.


1.10 MAJOR CONSTRAINTS 17

closely related organisms, in contrast to broad spectrum, conventional pes-ticides that may affect organisms as different as birds, insects, and mammals.Biopesticides often are effective in very small quantities and often decomposequickly, thereby resulting in lower exposures and largely avoiding the pollu-tion problems caused by conventional pesticides. Biopesticides can be appliedwith farmers’ existing spray equipment and many are suitable for local-scaleproduction. When used as a fundamental component of integrated pest man-agement (IPM) programmes, biopesticides can greatly decrease the use ofconventional pesticides, while crop yields remain high.

The disadvantages of biopesticides include a slower rate of kill comparedwith conventional chemical pesticides, shorter persistence in the environmentand susceptibility to unfavourable environmental conditions. Because mostbiopesticides are not as efficacious as conventional chemical pesticides, theyare not suited for use as stand-alone treatments. However, their selectivity andsafety mean that they can contribute meaningfully to incremental improve-ments in pest control.

1.10 Major constraintsAlthough substantial progress has been made in selection and developmentof biopesticides, there are many such issues which need to be addressed andresolved. The following agronomic, commercial, social and technical issuesrequire immediate attention (Butt, Jackson and Magan, 2001).

1.10.1 Agronomic aspectsSome of the agronomic issues are as follows.

Development of crop protection strategies Crops are grown under diversifiedenvironmental and geographic conditions. The conditions such as tempera-ture, rainfall, soil types, crop varieties and even pathogens differ from oneplace to another. In such circumstances it becomes the duty of the producerof these bioagents to convince the user about the efficacy and robustness ofthe product.

Compatibility with other agrochemicals and bioagents This needs thoroughinvestigations so that the grower is aware which agent can be used in the sametank mix. Industry must work closely with researchers and extension servicesbefore the product reaches the market. For instance, fungicides used for dis-ease control may kill entomogenous fungi.

Organic farming Recent emphasis in policy towards more environmentally-friendly farming practices and the importance of simpler reduction have led


18 CH1 BIOLOGICALS

to more attention being paid to organic farming and the establishment ofspecific policy provisions. But there exists an urgent need for projects thatintegrate agronomic practices used by organic growers with natural agents forincreased productivity.

1.10.2 The commercial perspectiveThe key to the commercial success of biopesticides depends upon theirfavourable market research. This is essential because markets for biologicalsare smaller and generally require more input than markets for chemicals.Companies must take a very precise look at their markets and know who willbuy and use their products. Experience in agrochemicals is not sufficient noris in cognizance with socio-economic trends (e.g. the expansion of the organicfarming sector and public sensitivity to health risks and environmentalpollution). There are many reasons for this restricted adoption of biologicalcontrol agents (BCAs) in crop protection:

• There are no strong incentives to develop these agents and/or discouragechemical pesticides. The supermarket code of practice and the possibleintroduction of pesticide taxes may be key drivers for BCA use.

• Newly introduced chemical pesticides have good environmental profileswith few side effects and low persistence.

• There is no universally acceptable registration procedure.• The use of exotic BCAs is restricted.• Field performance is unreliable and unpredictable. In part, this can be

attributed to insufficient information for growers and poor storage anddistribution conditions.

• The infrastructure which facilitates transfer of new technologies andresearch knowledge to the ‘end user’ (i.e. the grower) is either absent orhas broken down.

• Product introduction is also slow because the main producers are oftensmall to medium-sized enterprises (SMEs) with limited resources foreffective development and marketing.

• Many biopesticides have high levels of selectivity. For example, bioinsecti-cides based on baculoviruses, such as the CpGV are selective for just oneor a few species of insect. This is of great benefit in terms of not harm-ing other natural enemies and wildlife, but it means that biopesticides areniche market products with low profit potential. To quote Gelernter: ‘Thefeatures that made most Biological Control Products so attractive fromthe standpoint of environmental and human safety also acted to limit thenumber of markets in which they were effective.’

• Low production costs remain the key to cost-effective products yetthey attract neither research money nor speculative investment. Cost-competitive products will succeed, sometimes even where control isimperfect.



• Corporate commitment is a must as good companies can generate funds toensure that a good, cost-effective product will reach the market, i.e. they donot enter the scene half-heartedly. The commitment is not limited to onlysale of the products but also encompasses the follow-through to ensurethat end users feel comfortable in using BCAs.

• Good management is also important to ensure that the company remainsfocused and does not diffuse its resources (i.e. spread the risk).

Figure 1.2 shows the commercial characteristics for an ideal biopesticide.

1.10.3 Public anxiety over BCAsSafety is a major concern for all crop protection products and in-depth knowl-edge is required to evaluate the risks involved in the use of BCAs. The desireto release biological control agents into the ecosystem generates some anxi-ety in the general public. This apprehension revolves around the conceivablenegative effects on human health and ecosystem stability. Many fungi producebiologically active secondary metabolites, some of which are very toxic andthis is a major concern with all fungal BCAs as their presence would representa health risk. Techniques must be developed to identify toxin producers andto select strains that are good crop protection agents but not toxin producers.The methodologies and tools developed would help detect toxins in foodstuffsand the environment (target and non-target hosts, plants, soil and water).

Effectiveness against

a wide range of

pathogens

Non production of

deleterious secondary

metabolites

Viability at 4%

cell-water

content

Resistance to

standard

fungicides

Fast

growth rate

Genetically

stable

Stress

tolerant

IDEAL

BIOPESTICIDE

Figure 1.2 Commercial characteristics of an ideal biopesticide.


20 CH1 BIOLOGICALS

1.10.4 Technical issuesThe key technical issues that need to be dealt with in the development of effi-cacious BCAs include the following.

Ecological fitness Mostly the bioagents perform well under controlled con-ditions but are unable to operate to their fullest once applied to test plants inthe field. This is probably attributed to the physiological and ecological con-straints that limit the efficacy of bioagents. Thus, BCA strains must tolerate awide range of climatic (fluctuating temperatures, humidity, UV light), edaphic(soil types) and biotic (antagonists) factors. To overcome this problem, geneticengineering and other molecular tools can offer a new possibility for improv-ing the selection and characterization of bio-control agents. Various methodsthat can contribute to increasing the efficacy of bio-agents include mutationor protoplasm fusion utilizing poly ethylene glycol.

1.10.5 Virulence and efficacyOne major criticism of BCAs is that they act slowly and often lose their vir-ulence, therefore, they give only limited protection to crops. Clearly, moreaggressive strains of BCAs, i.e. those that work more quickly and requirelower inoculums can be sought. Factors that determine pathogen virulence(virulence determinants) should be identified and used in strain selection andquality control. It also becomes necessary to identify cultural conditions whichcan retain virulence without increasing the production costs. At present, lim-ited progress has been made in this direction partly because the underlyingmechanisms for attenuation have not been elucidated.

Production There is also an urgent need to mass-produce the bioagents,understand their mechanism of action and to evaluate the environmentalfactors that favour the rapid growth of biocontrol agents. Production costsmust be reduced so the end product competes with conventional pesticideson cost grounds (it is true that in countries such as the USA registration ofbiologicals is a shorter, less expensive process, allowing the economic devel-opment of an effective product for use in a small niche market), productsmust be easy to handle and packaged products must have a shelf-life that isacceptable to the user.

Formulation and application Formulation and application methods are alsokey issues influencing the efficacy of commercial products and research onthese topics should be focused on specific environmental applications.

An efficient formulation is essential for any crop protection agent, totranslate laboratory activity into adequate field performance. Little progresshas been made in this direction despite the fact that formulations will improve



the field efficacy of BCAs and expand their market opportunities beyondhigh value niche markets. New, more effective formulation componentse.g. UV protectants, humectants and carriers, virulence-enhancing factorsand binders must be sought. For example, in the case of formulation, onepossibility is the addition of molecules that favour the adhesion of thebacteria to fruit or leaves when used as a spray. Another option could be tocombine the strain with a substrate like chitin which may stimulate biocontrolactivity (Zhang, Li and Liu, 2011). In all cases, it is essential that theseformulates be compatible with other BCAs (viruses, bacteria and ento-mophilic nematodes). Biologically-based inputs such as pheromone trapsand microbial pesticides can be used to interfere with pest activities. GreenMuscle (Metarhizium anisopliae var acridium) formulated in oil and appliedat very low volumes is a good example of a fungal BCA that uses innovativeformulation characteristics to enhance its effectiveness against locusts.An antagonist formulation with essential oil also promotes plant health andmanages soil-borne diseases (Tripathi and Sharma, 2013).

Successful application of biological controls requires more knowledge-intensive management. BCA products should be capable of applicationthrough standard hydraulic nozzles or application equipment with fewspecial application requirements. Growers will not readily invest in new sprayequipment to apply a BCA, nor will they accept a very different spray regimeor more frequent applications than is normal practice. To this end, extensionpersonnel and growers must also be fully aware of the costs and benefits thatbiopesticides can provide. Understanding when and where biological controlof plant pathogens can be profitable requires an appreciation of its placewithin integrated pest management systems.

Registration For BCAs there is the requirement of a registration package,generally including toxicology and efficacy data for each individual organismand formulated product, in every intended country (Whipps and Lumsden,1998). The high cost associated with this process has consequently stifledcommercial development of bioagents for niche markets (Chandler et al.,2011). Unfortunately without the rigours of a registration package involvingtoxicological and efficacy data, safe use cannot be assured. As an answerto this, numerous products have appeared on the market which actuallywork by checking the growth of the pests and pathogens but purport tobe plant growth promoters, soil conditioners, biofertilizers and biologicalactivators.

Regulatory authorities are now aware of this anomaly and are attemptingto encourage legal registration and use in variety of ways. The EnvironmentalProtection Agency (EPA) in the USA has implemented faster and cheaperregistration processes for biological pesticides in comparison with chemicalpesticide. Regulatory authorities in member countries in the European Com-munity have started implementing the Plant Protection Product Directive


22 CH1 BIOLOGICALS

91/414/EEC, which paves the way for rapid pan-European registration onceit has been obtained from one of the member states.

Packaging and storage Both farmer and distributor will be deterred fromusing a novel BCA if the shelf-life, storage requirements and packaging aredifferent from those of conventional chemicals. Some BCAs have a specificneed for refrigeration, but very few distributors have such facilities and evenfewer would be prepared to invest in them, though some specialist distribu-tors for certain macro-organism biocontrol agents (predators and parasites)already have such refrigerated storage and distribution facilities worldwide.

Improved targeting Cost-effective control of pests, weeds and diseasesdemands efficient targeting of the BCA. Recently it has been shown thathoney bee-mediated delivery of the insect pathogen, Metarhizium anisopliaeincreased pollen beetle control (Meligethes spp.) in oilseed rape (Butt et al.,1998). The bees were more efficient than conventional sprayers in deliveringthe inoculum to the pest-infested flowers. There is also evidence that theuse of systems that attract insects to a trap that contains a fungal ento-mopathogen where they are contaminated, allowing them to take the BCAto other members of the species is also showing promise, particularly forcommunal insects. ‘Push–pull’ pest control strategies entail insect pests beingdriven out of the cash crop with the application of feeding deterrents andbeing drawn into a trap crop where they are controlled by inundation withpathogens or other benign control agents. To encourage pests into the trapcrop, lures such as favoured plant varieties (i.e. those more attractive than thecrop) and chemical attractants (sex pheromones and gustatory stimulants)would be used. Feeding attractants incorporated into formulations may beuseful to encourage insects to feed on BCAs. As yet, very few inexpensivebut effective lures and deterrents have been developed for commercial use.

Interested parties must co-operate even more The successful deployment offungal BCAs depends on close co-operation between all interested parties.This includes researchers developing BCAs, manufacturers who will producethe agent, growers who wish to use the BCAs and government agencies whooften fund the research. The latter undoubtedly are central to the success offungal BCAs. The other players believe governments could do the following:

• strengthen extension services to accelerate ‘technology transfer’ fromresearch institutes/industry to the grower;

• streamline or refine policies and/or procedures to reduce product devel-opment time and/or costs, e.g. reform registration procedures;

• support research which bridges theory and practice so that more and moreSMEs start taking the lead in reaching out to ‘end users’. Several SMEsare working closely to reduce the time and cost to develop new BCAs, to


1.11 CONCLUSION AND FUTURE PROSPECTS 23

increase market size and to reduce distribution costs. Besides providingtechnical support to growers, they are using all channels of communica-tion, e.g. providing information on product use via websites, publishingliterature on BCAs and through specialists.

1.11 Conclusion and future prospectsOver the past one hundred years, research has repeatedly demonstrated thatphylogenetically diverse microorganisms can act as natural antagonists of var-ious plant pathogens. Indeed, a variety of pathogenic and non-pathogenicmicroorganisms can induce plant defences and may be useful as biocontrolagents. There is a growing demand for sound, biologically-based pest man-agement practices. Recent surveys of both conventional and organic growersindicate an interest in using biocontrol products, suggesting that the marketpotential of biocontrol products will increase in the coming years. Funding forbasic and applied research in this direction ensures that innovations in bio-logical control research will continue. An upswing in commercial interests hasalso developed in the past few years, and the prospects for increased growthare positive. Clearly, the future success of the biological control industry willdepend on innovative business management, product marketing, extensioneducation, and research (Strasser, 2009). Increased demand for organic pro-duce and participation in home gardening activities by pesticide-wary urbanpopulations have enlarged the market for biocontrol products. The field ofplant pathology will contribute substantially to making the coming century theage of biotechnology by the development of innovative biocontrol strategies.

There are conventional opportunities based on the chemistry and mode ofaction of a natural product as well as the opportunity associated with thediscovery of a new protein (and its gene) that may be used to transform atarget crop. It was observed in 1992, that plants resist the attack of bacterialpathogens by the formation of harpin, a protein that is now being used to acti-vate crop defences prior to pathogen attack (Khokhani et al., 2013). Researchon the mechanisms of biocontrol employed by effective bacterial strains hasrevealed a variety of natural products that can be exploited for the develop-ment of chemical control measures. One well-known example is pyrrolnitrin,a natural product produced by some Pseudomonas spp. That compound pro-vided the chemical model for development of fludioxonil, a broad-spectrumfungicide used as seed treatment, foliar spray, or soil drench (Park, 2011).The effects of organic amendments suggest that both chemical and biologicalcomponents of compost-amended soils can contribute to disease suppression.Such discoveries point to the substantial potential of diverse programmes inbasic research to lead to improvements in various biological control strate-gies. Such opportunities will continue to persuade companies to seek newnatural products and new producers. This activity will be complemented by


24 CH1 BIOLOGICALS

smaller organizations with expertise in the culture of organisms, the isolationof natural products or the formulation of living crop protection agents. It isunlikely that biopesticides will replace chemical crop protection within thenext 20 years, but it is certain that the number and quality of products willincrease and the costs will fall. These developments will guarantee an increas-ing place in the market for biopesticides for the foreseeable future.

With people becoming more health-conscious, biological control seemsto be the best alternative to disease suppression. Bioagents effect diseasesuppression with no environmental hazards. Research has proved that thebio-agents trigger the growth of plants. Bioagents themselves, because theyare non-pathogenic to plants, need to be formulated in a way that favoursthe activity and survival of the microbes they contain. Moreover the novelconcept of biocontrol needs a space outside the laboratory to see its fruits inpresent production systems. More and more farmers are coming to realize theshort-term benefits and long-term positive effects of the use of bioagents andother ecologically safe methods to tackle pests. It is heartening to observethe growing awareness among farmers and policy-makers of ecologicallysustainable methods of pest management.

A variety of research questions still remain to be fully answered aboutthe nature of biological control and the means to most effectively manageit under production conditions. Advanced molecular techniques are nowbeing used to characterize the diversity, abundance and activities of microbesthat live in and around plants, including those that significantly impact planthealth (McSpadden, Gardener and Weller, 2001). However, much remainsto be learned about the microbial ecology of both plant pathogens and theirmicrobial antagonists in different agricultural systems. Fundamental workremains to be done in characterizing the different mechanisms by whichorganic amendments reduce plant disease. More studies on the practicalaspects of mass-production and formulation need to be undertaken to makenew biocontrol products stable, effective, safer and more cost-effective.

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ated infection of pollen beetle (Meligethes spp.) by the insect pathogenic fungus,Metarhizium anisopliae. Bio. Sci. Tech., 8, 533–538.

Butt, T.M., Jackson, C.W. and Magan, N. (eds) (2001) Fungi as Biocontrol Agents:Progress, Problems and Potential. CABI Publishing, Wallingford, UK.

Cai, D.W. (2008) Understanding the role of chemical pesticides and prevent misuse ofpesticides. Bull. Agric. Sci. Tech., 1, 36–38.

Chandler, D., Bailey, A.S., Tatchou, G.M., et al. (2011) The development, regula-tion and use of biopesticides for integrated pest management. Phil. Tran. R. Soc.Biological Sciences, 366(1573), 1987–1998.

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Khokhani, D., Zhang, C., Li, Y., et al. (2013) Discovery of plant phenolic com-pounds that act as Type III secretion system inhibitors or inducers of the fire blightpathogen, Erwinia amylovora. Appl. Envron. Microbiol., 79(18), 5424–5436.

McSpadden, P., Gardener, B. and Weller, D.M. (2001) Changes in populations ofrhizosphere bacteria associated with take-all disease of wheat. Appl. Environ.Microbiol., 67, 4414–4425.

Park, J.Y. (2011) Production of antifungal compounds phenazine and pyrollnitrin.Letters in Applied Microbiology, 52(5), 532–537.

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Sharma, N., Sharma, S. and Prabha, B. (2012) Postharvest biocontrol: new conceptsand applications, in Crop Stress and its Management: Perspective and Strategies (edsB. Venkateswarlu et al.), Springer Science and Business Media, Bern, Switzerland,pp. 471–495.

Strasser, H. (2009) Concepts and visions to overcome problems with microbial bio-control agent registration. IOBC WPRS Bulletin, 45, 41–46.

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