Fungal entomopathogens: a systematic review
←
→
Page content transcription
If your browser does not render page correctly, please read the page content below
Sharma and Sharma Egyptian Journal of Biological Pest Control
https://doi.org/10.1186/s41938-021-00404-7
(2021) 31:57
Egyptian Journal of
Biological Pest Control
REVIEW ARTICLE Open Access
Fungal entomopathogens: a systematic
review
Rajat Sharma1* and Priyanka Sharma2
Abstract
Background: Apprehensions about the safety and the environment regarding the insecticidal application against
insect infestations have directed our attention toward advancement of biological mediators so that they are
assimilated into the concept of integrated pest management stratagems to develop a more practical approach for
the management of insect pests. Management of insect pests by making use of biological approaches (such as
fungal entomopathogens (EPF) or others which are antagonistic to insect population) provides a substitute
approach which reduces the continuous use of chemical amalgams against insect pests.
Main body: The present review provides a framework of the present status of information on EPF as it identifies
with their current use as biological control of pest infestations. To utilize a variety of biological control
methodologies against insect hosts, it is essential to improve our comprehension of the ecology of EPF and also
their role in nature. This article may assist us with understanding the virulence and the virulence factors related
with EPF and present the latest developments and accomplishments in the significant field. We focus on recent
instances of studies that show the overall patterns in interactions among insect pests and EPF prompting the
advancement of epizootics. Also, we sum up the topical discoveries on current status of mycoinsecticides and
propose future research needs.
Conclusions: As the current mechanism of fungal pathogenesis on insects is moderately slow and needs
improvement, there is likewise the requirement for additional comprehension of the interactions among
entomopathogens and insect pests so as to grow soundly planned procedures by identifying potential targets and
via the improvement of fungal strains for improving the adequacy of these organisms in field applications.
Keywords: Entomopathogenic fungi, Biological control agents, Infection process, Enzymes, Pathogenesis, Host
defense, Epizootiology, Mycoinsecticides
Background suppressing the insect pest infestations due to their ab-
Insect pests are regarded as major deterrents which have stemiously minimal application effort, high usefulness
accounted for an estimated 10.80% crop losses on global and expediency (Sharma 2019), but concentrated appli-
scale in the era of post green revolution (Dhaliwal et al. cation of chemicals has brought about the advancement
2015). Also, an estimated loss of global annual crop pro- of resistance to either one or even more classes of insec-
duction corresponding to 18-26% valued at $470 billion ticides in as much as 500 species of pests (Kumar and
has been observed recently (Mantzoukas and Eliopoulos Kalita 2017).
2020). To reduce these losses, insecticides are employed As a result, the microbial agents (entomopathogens)
and, as a result, have become an essential method for are viewed as regulatory operators of pest infestations
and represent the different species of fungi, viruses,
* Correspondence: sharmarajat.ysp@gmail.com
protozoa, and bacteria. Initial studies in reference to
1
Department of Plant Pathology, Dr. YS Parmar University of Horticulture and entomopathogens were carried out by Agostino Bassi
Forestry, Nauni, Solan, Himachal Pradesh 173230, India who established that the infectious agent, instigating the
Full list of author information is available at the end of the article
© The Author(s). 2021 Open Access This article is licensed under a Creative Commons Attribution 4.0 International License,
which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give
appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if
changes were made. The images or other third party material in this article are included in the article's Creative Commons
licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons
licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain
permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.Sharma and Sharma Egyptian Journal of Biological Pest Control (2021) 31:57 Page 2 of 13 occurrence of muscardine disease in case of silkworms thus, the life cycle of entomopathogenic fungi is contin- was Beauveria bassiana Bals. (Hypocreales: Cordycipita- ued on new hosts. ceae). Entomopathogens which befall naturally are sig- EPF also play an important role as either colonizer in nificant controlling factors against insect populace (Roy rhizosphere (Pava-Ripoll et al. 2011) or plant growth and Cottrell 2008). Tanzini et al. (2001) used the term promoters (Jaber and Enkerli 2017). EPF account for the entomopathogenic for the micro-organisms which regu- principal number of taxa as in the diverse group of late the population of insect pests to the levels wherein fungi, there are more than 100 genera of EPF comprising no economic damage to crop plants is observed. Delgado of 750-1000 (St Leger and Wang 2010). The multi- and Murcia (2011) defined the term in relation to the layered jobs played by EPF could likewise be utilized in a microbial populace which is proficient in attacking in- roundabout way as biofertilizers (Jaber and Enkerli sect pests by incorporating them into their own life cycle 2017), and microbial control specialists in contradiction and by utilizing them as hosts and also classified these of both pests and plant infections (Mantzoukas and micro-organisms as either facultative or obligate para- Grammatikopoulos 2019). sites attacking insect pests, having high potential for survival. Main text Use of microbial population as control agents is not Biological control of insects only effective against insect pests but this approach is Biological control of insect pests with EPF is one of the also environmentally safe and sound for humans (re- most desirable and effectual practice involving uses of duced pesticide residues) as well as the non-target or- natural microorganisms, which hinder their activity and ganisms. The provocation for the impression of using can be used as an alternative to the chemical insecti- microbial insect pathogens against insect pests re- cides. There have been some genera of EPF, which are sulted from close examination of the disease of silk- antagonistic toward field, greenhouse, forest, storage, worm (Audoin 1837). Afterward, the recommendation and household pests. These can be incorporated as EPF, to assign microbial insect pathogens against insects for instance Beauveria, Metarhizium, Isaria, Lecanicil- came from LeConte (1874) and Pasteur (1874). The lium, and Hirsutella. The different species belonging to first efficacious mass-produced microbial control ap- these genera are target specific and cause infection in plication on large scale was carried out by Kras- many insects. EPF have several biological attributes, such silstschik (1888) against Bothynoderes punctiventris as target-specificity, high reproductively, short gener- (Germar) (Coleoptera: Curculionidae) (sugar beet wee- ation time, and long survival, which play significant roles vil) by making use of the antagonistic nature of the in biocontrol of insect pest. conidiospores of Metarhizium anisopliae (Metchni- EPF species are mostly isolated from the soil, which koff) (Hypocreales: Clavipitaceae) in Russia. The protects them from the damaging solar radiation (Mey- credit for examining infectious nature of M. aniso- ling and Eilenberg 2007). It has been noted that certain pliae must be attributed to Elie Metchnikoff, who ini- species of Beauveria and Metarhizium can infect and kill tially identified the microbial agent as Entomopthora insects in soil and also EPF interact with roots of plant anisopliae against wheat cockchafer, Anisoplia aus- for their growth and survival which predominately relies triaca (Herbst) (Coleoptera: Scarabaeidae). on insects for carbon and not on soil (Inglis et al. 2001). Out of all the other microbial control agent, EPF are Endophytic EPF evolve inside the above ground plant the most imperative due to accumulation of various fac- tissues and do not produce any perceptible symptoms of tors, such as easy distribution, easy manufacturing tech- infection. Their usage provides numerous advantages niques, availability of large number of already identified consisting of high yield, cost-effectiveness, preservation strains, and over-expression of exogenous toxins and en- of beneficial organisms, safe to humans, no harmful ef- dogenous proteins (St Leger and Wang 2010). EPF legit- fect on environment, and varied biodiversity (Mantzou- imately influence plants more than the most compound kas and Eliopoulos 2020). The most commonly applied pesticides. For instance, endophytic EPF have been ar- and naturally occurring EPF endophyte species are chived in many plants, for example, soybeans, wheat, to- Beauveria bassiana, Isaria fumosorosea Wize (Hypo- matoes, and bananas (Jaber 2015). As per the action creales: Clavicipitaceae), and Metarhizium anisopliae mechanism of EPF is concerned, they release spores (Akutse et al. 2013). The endophytic EPF gives protec- thereby infecting the body of the insect host. The fungal tion against numerous pests to host plant and aids to spores initially propagate on the exterior of host body ameliorate plant response through production of com- and later penetrate the host. As a result, death of the in- pounds and inducing systemic resistance in the host sect is inevitable within 4-7 days (conditional on the plant. The endophytic EPF and host plant upon quantity of spores). Cadaver of the insect serves as the colonization secrete several types of chemicals such as origin of new spores, which further disseminate, and secondary metabolites and enzymes. The secondary
Sharma and Sharma Egyptian Journal of Biological Pest Control (2021) 31:57 Page 3 of 13
plant metabolites (alkaloids, flavonoids, phenolics, etc.) and Pell 2003). The gypsy moth, Lymantria dispar
are produced by the host plant as defense against fungal Linnaeus (Lepidoptera: Erebidae), accidentally intro-
pathogens, and endophytic EPF produce secondary plant duced in the USA during the 1860s, and E. mai-
metabolites (benzopyranones, phenolic acids, quinones, maiga introduced from Japan in the 1900s by
and steroids) and enzymes (β-1,3-glucanases, chitinases, placing infected cadavers onto tree trunks and able
amylases, laccases, and cellulases) which helps in the to control larvae of Gypsy moth which feed on the
interaction between endophyte and plant host (Zaynab leaves of many trees (Hajek et al. 2004). The fungal
et al. 2018). movement of E. maimaiga can take place through
Historical evidences show the application and efficacy air-borne conidia (Shah and Pell 2003). Z. radicans
of EPF have been many as the EPF M. anisopliae var were imported from Israel to release in Australia
acridum has been applied as spray suspension in Africa during 1970 to control spotted alfalfa aphid, Ther-
to control the locusts (Langewald and Kooyman 2007). ioaphis trifolii f. maculata (Buckton) (Hemiptera:
Spray preparation of hydrophobic conidia was articu- Aphididae), a serious pest of legume plants.
lated in oil or as wettable agent, and hydrophilic blasto- ii. Augmentation. The biological control agents of
pores were formulated as wettable powders. The solar insect-pests are present in their indigenous pest
radiation affects the persistence of fungal propagules and populations in various circumstances. The natural
their effectiveness can be improved by solar blockers enemies are either few or active late to restrict the
(Inglis et al. 2001). Conidia of M. anisopliae were used crop damage. There are two strategies of augmenta-
on seeds of corn before planting to reduce the damage tion: Inoculation biological control and inundation
of wireworms and this increased fresh weight and dens- biological control (Shah and Pell 2003).
ity of corn (Kabaluk and Ericsson 2007).
Pest control by EPF (approaches)
Biological control is regarded as a pleasing technique for a. Inoculation biological control. The intentional
regulating insects, due to its insignificant environmental release of a minute amount of fungal biological
impact and inhibiting the development of resistance in control agents so that it will multiply and control
vectors. EPF can be employed under three broad bio- the pest for an extended period and sustain the pest
logical control approaches, i.e., classical biological con- population below the economic threshold level. The
trol, augmentation, and conservation, by making use of natural enemies are inoculated in small to moderate
living organisms to suppress the insect population and amounts in the early season of the crop, increase
making it less abundant or less damaging (Hajek 2004). the number of biological control agents, and spread
over a period of time before the insect-pest popula-
i. Classical biological control. Classical biological tion reaches the maximum potential. The natural
control has been a notable approach that includes enemies are not able to control the pest population
the use of a biological control agent to manage the permanently at a high population density. After a
insect pest population. The introduction of an regular interval of time, the new inoculations must
exotic biological control agent for the permanent be made for reestablishment because the control is
establishment and long-term sustainable and eco- not achieved from released natural enemies (Abdel-
nomical pest control in the new location. The intro- ghany 2018). Soil can be inoculated with mycor-
duction of the Vidalia beetle, Rodolia cardinalis rhiza to intensify growth and to advance up a
(Mulsant) (Coleoptera: Coccinellidae), from natural process. Beauveria brongniartii inoculated
Australia to California in the late 1880s to control on Barley seeds to produce mycelium and aerial co-
the scale insect, Icerya purchase Maskell (Hemip- nidia for the control of European cockchafer, Melo-
tera: Margarodidae), is the successful example of lontha melolontha Linnaeus (Coleoptera:
classical biological control and this approach cannot Scarabaeidae) in Central Europe (Keller et al. 1999).
be better understood without this historical dimen- The consolidated use of Zoophthora radicans Batko
sion (Abdelghany 2018). The classical biological (Entomophthorales: Entomophthoraceae) and semio-
control needs strong, regional co-ordination of the chemicals for the control of Diamondback moth,
efforts for the successful management of insect- Plutella xylostella Linnaeus (Lepidoptera: Plutelli-
pests. There are few examples of classical biological dae) which is a significant pest of Brassica (Furlong
control with EPF such as Entomophthora maimaiga and Pell 2001).
Humber, Shimazu and Soper (Entomophthorales: b. Inundation biological control. Inundation
Entomophthoraceae), and Zoophthora radicans (Bre- biological control includes fungal biological control
feld) (Entomophthorales: Entomophthoraceae) (Shah agent to control the population density of a nastySharma and Sharma Egyptian Journal of Biological Pest Control (2021) 31:57 Page 4 of 13
pest. Inundative augmentation involves the release examination of their digestive systems (e.g., production
of a massive amount of natural enemy for of toxins and enzymes and utilization of nutrients) and
accelerated short-term control of the insect-pest utilizing genomic analysis (e.g., mtDNA restriction
population (Liu and Li 2004). The control of the length polymorphism, karyotyping, and rRNA sequences
pest population is accomplished by the released nat- (Khachatourians 1991).
ural enemies themselves. The pest population is Fungi (true) are presently positioned in four legitimate
controlled immediately, and the population of both phyla (Basidiomycota, Ascomycota, Zygomycota, and
pest and natural enemies diminishes with time. The Chytridiomycota). An artificial phylum, Deuteromycota
fungus is employed as a chemical pesticide and dif- is also documented comprising of filamentous fungi
ferent terms are used, i.e., mycopesticide, mycoin- which exist in anamorphic forms (asexual). It is alleged
secticide, and biopesticide have been associated that the affiliates of this phylum are in fact either basid-
with inundation biological control (Abdelghany iomycetes or ascomycetes which have lost their ability to
2018). Verticillium lecanii (Zimmerman) (Hypo- multiply sexually or their sexual structures are not yet
creales: Cordycipitaceae) is adopted to control described (Alexopoulos et al. 1996). In addition, teleo-
aphids, whiteflies, and thrips inside the glasshouses morphs for various genera of deuteromycete (entomo-
in Europe. The mycoinsecticide “Vertalec” is applied pathogenic) have along these lines been recognized, and
against aphids and “Mycotal” against whiteflies and a portion of these teleomorphs can likewise be in fact
thrips. Beauveria bassiana “Mycotrol” as a commer- entomopathogenic (e.g., Cordyceps and Torrubiella spp.
cial mycoinsecticide by Mycotech used against a are identified teleomorphs of Paecilomyces spp. (Samson
wide range of insect pests in North America. et al. 1988)).
Metarhizium anisopliae var. acridum commercial The oomycetes, once positioned in Mastigomycotina,
product “Green Muscle” effective against locust and have now been set in the kingdom of Stramenopila,
grasshopper pests in Africa (Shah and Pell 2003). phylum Oomycota (Barr, 1992). Individuals from this
kingdom offer different highlights of monophyletic ori-
gin, including a comparative flagellum hair structure and
incorporate labyrinthulids, diatoms, and algae (Patterson
iii. Conservation biological control. Conservation 1989). The phylogenetic connection among the four
biological control concerns with the modification of phyla of fungi has been proposed, in view of on ultra-
the environment or farming practices to defend and structural and morphological highlights, and to a great
intensify specific entomopathogens to lessen the extent affirmed by resulting analyses of DNA sequence
effect of pests. This approach accommodates to (Alexopoulos et al. 1996) as stated earlier.
distinguish effective indigenous biological control Chytridiomycetes might be well-thought-out as the
agents and the selection of practices to conserve most “crude” organisms since the predecessor of this
and raise their population. The practices which group diverged primarily and retained flagella and cen-
prefer fungal biological control agent may include trioles (Barr, 1992). The zygomycetes diverged before
irrigation and reduction in pesticide usage. The EPF the occurrence of a dikaryotic stage and consistently
increase in population size and their effective septate mycelium, which are normal for the basidiomy-
results in a low pest population. Natural enemies cetes and ascomycetes and the flagella was lost eventu-
include all types of biological regulation: macro-and ally. After the progenitors of basidiomycetes and
microorganisms controlling invertebrates, weeds, ascomycetes veered, the basidiomycetes’ predecessor de-
and plant diseases, including the antagonistic micro- veloped basidiospores (meiospores ordinarily delivered
organisms responsible for suppressive soils. The four for each basidium), in addition to clamp connec-
conservation biological control approach is corre- tions and dolipore septa (barrel shaped) and the ascomy-
lated to the chief principle of organic farming, cetes’ progenitors developed ascospores (i.e., meiospores
which has the protection of the present natural en- for the most part delivered eight for every ascus). The
emies (Shah and Pell 2003 and Abdelghany 2018). scientific classification of the Ascomycota is all the more
plainly characterized and contains two significant orders:
Classification of entomopathogenic fungi Laboulbeniales (Class: Laboulbeniomycetes) and Hypo-
The classification of fungal organisms has generally re- creales (Class: Sordariomycetes; subclass: Hypocreomy-
lied on their respective ultrastructure (e.g., structure of cetidae) (Hibbett et al. 2007).
septum and that of the cell wall) and their morphology Hibbett et al. (2007) suggested an arrangement of
(e.g., mechanism of conidiogenesis) as essential stan- characterization for all fungal groups dependent on mo-
dards. The more exact arrangement of EPF into charac- lecular phylogenetic investigations. As stated in the
terized scientific taxa has been accomplished by the background section, there are 750-1000 EPF, these canSharma and Sharma Egyptian Journal of Biological Pest Control (2021) 31:57 Page 5 of 13
be found primarily placed in two fundamental groups: and dispersal under preponderating environmental cir-
phylum Zygomycota, subphylum Entomophthoromyco- cumstances (Roy et al. 2006).
tina, order Entomophthorales, and phylum Ascomycota Metarhizium spp. and Beauveria spp. belonging to the
(subkingdom Dikarya). Nonetheless, the Zygomycota is order Hypocreales are opportunistic hemibiotrophic in
not an acknowledged phylum inside the re-examined nature while fungi belonging to the order Ento-
classification. Hence, the Entomophthorales have not mophthorales are biotrophic. Metarhizium spp. and
been allotted a phylum in the current arrangement. Beauveria spp. are entomophagous that infect living in-
Most of EPF recognized to date have been positioned in sects and saprophagous that invade dead insect corpse.
the following classes: Zygomycetes (phylum Zygomy- Entomophthorales exterminate their host by the
cota), Hyphomycetes (phylum Deuteromycota), and Pyr- colonization of tissues (Freimoser et al. 2003). Time be-
enomycetes and Laboulbeniales (phylum Ascomycota) tween application of entomopathogens and revelation to
(Samson et al. 1988). the activity of various parasitoids is vital for the contin-
ued existence of the respective parasitoids (Oreste et al.
Infection process 2015). The application of EPF in context of the time of
EPF face numerous host challenges in each generation application has been found to affect the rate of
to produce adequate fresh infectious spores to sustain vi- parasitization by a parasitoid. For instance, the treat-
able populations. The prosperous transmission usually ments of entomopathogens M. anisopliae and B. bassi-
needs the discharge of massive spore numbers and glu- ana and time of fungal treatment influenced the rate of
tinous spore surfaces that enhance adhesion (Vega et al. parasitization by Encarsia formosa Gahan (Hymenoptera:
2012). The spores germinate and directly invade through Aphelinidae) against Trialeurodes vaporariorum (West-
the hard exoskeleton of the host insect (Vega et al. wood) (Hemiptera: Aleyrodidae) (Oreste et al. 2015).
2012). The fungi do not necessitate to be ingested. The
EPF commonly invade through the mouthparts or spira- Fungal invasion
cles because of non-sclerotized integument, and smooth The process of pathogenesis is initiated by the adhesion
penetration (Clarkson and Charnley 1996). The penetra- of conidia to the insect cuticle. The attachment of fungal
tion of the epicuticle is directly by germ tubes or infec- propagules to the host exoskeleton is the first and fore-
tion pegs originated from the underneath of appressoria most step of the infection process (Sevim et al. 2015).
(Zacharuk 1981). The fungal cells propagate inside the Fungi are heterotrophic organisms that consume the
hemocoel, tissues, and muscles of the host’s body so that non-chemical compounds provided by different organ-
it dies (Vega et al. 2012). The EPF can infect non- isms as their chief source of energy. The non-specific ad-
feeding stages such as eggs and pupae. The fungal hesion mechanisms involved in binding are controlled
germlings are steadily crossing distinct environments by the hydrophobic attributes of the conidial cell wall
and counter to the variations invoking biochemical pro- (Boucias et al. 1988). This process includes interaction
cesses and cellular differentiation to form particular among the conidial proteins and the hydrophobic exo-
morphological structures. The fungal germlings conform skeleton surface of the susceptive insects (Fang et al.
to colonize insect tissue and neutralize potential host re- 2005). This process happens in three consecutive stages:
sponses. Infection structures reasonably emerge as a 1.Adsorption of the spores to the insect exoskeleton
mechanism to surmount host barriers (St Leger and 2.Adhesion of pre-germinated spores to the host
Wang, 2010). The process of infection can be restrained cuticle
by low humidity conditions because fungus requires high 3.Germination and development till appressoria for-
humid conditions for germination and maturity of fungal mation (Tellez-Jurado et al. 2009)
structures. The cuticle is a significant impediment to fungal inva-
The perception of a susceptive host can involve chem- sion. The insect epicuticle is differentiated into multi-
ical and topographical signals. The cuticle of tobacco layers; the outer epicuticle is mechanically fragile while
hornworm, Manduca sexta Linnaeus (Lepidoptera: the inner epicuticle designates toughness, although the
Sphingidae), has been used to study the impact of sur- enzymes produced by EPF conquer this obstruction
face topography on appressorium formation. The ap- (Charnley and St Leger, 1991). The outer epicuticle may
pressoria developed after extensive germination across be penetrated by an inadequate force and prevent the
the micro folds of the exoskeleton of 1-day fifth-instar passage of cuticle-degrading fungal enzymes. Once the
larvae. The fungus does not get induction signals from epicuticle is passed, penetrant structures may expand
the exoskeleton due to micro folds. Contrastingly, the laterally propagating penetrant plates. The lateral expan-
appressoria germinate close to conidium on 5-day fifth- sions promote penetration by inducing fractures in the
instar larvae (St Leger and Wang, 2010). The entomo- insect cuticle (Brey et al. 1986) and expedite dispersal of
pathogen uses the host cadaver for spore production the pathogen cuticle-degrading enzymes (Goettel et al.Sharma and Sharma Egyptian Journal of Biological Pest Control (2021) 31:57 Page 6 of 13 1989). In addition, insect epicuticular lipids play import- proteases, lipases, and chitinases synthesis help to de- ant role in binding fungus to the host cuticle (Ferron grade the cuticle and release nutrients for fungus ger- 1978). The procuticle is impermeable to pathogen secre- mination (Franco et al. 2011). tions; the degree of resistance depends on cuticle thick- M. anisopliae and B. bassiana spores are hydrophobic ness and hardening. Insects having heavily sclerotized in nature so they bind to insect cuticle (Holder and Key- body segments and cuticular melanisation induced by hani 2005). The conidia of M. anisopliae have cuticle- physical damage or β-1,3 glucans on the fungal cell wall degrading catalysts and the potential to modify the sur- (Charnley 1989), is common (Butt et al. 1988). Melanisa- face of the integument for the attachment. During pre- tion support to prevent fast-growing pathogens (St Leger germination development as the conidium dilates, excre- 1991), but evaluating these responses in disease resist- tion of adhesive mucus takes place which improves the ance is challenging because of inadequate understanding initial hydrophobic interactions among the conidium of the amounts of melanin expected to influence infec- and cuticular surface (Boucias and Pendland 1991). M. tion and how melanin reactions might prevent fungal anisopliae strains are more precise toward the scarabid germination. The inhibitory compounds on the exoskel- beetles. The cuticle of scarabids has antifungal com- eton such as phenols, quinones, and lipids lead to the pounds such as short-chain fatty acids. The EPF must failure of fungal invasion (Kerwin 1984). have the capability to endure antifungal compounds for The Beauveria, Metarhizium, and Isaria belonging to the successful invasion (Boucias and Pendland 1991). order Hypocreales have hydrophobic conidia due to The germ tubes of M. anisopliae develop appressoria at hydrophobins (cysteine-rich proteins) in the cell wall the surface of the cuticle, infection peg in epicuticle, while Verticillium lecanii has hydrophilic conidia (Inglis penetrant hyphae in procuticle, and yeast-like hyphal et al. 2001). The conidia of the order Entomophthorales bodies in the hemocoel. The infection structures are large and originate from sporangia. The conidia at- emerged as a mechanism to overwhelm host barriers. tach themselves to the cuticle and support the adhesion M. anisopliae var acridum is specific for the locusts. process (Papierok and Hajek 1997). In addition, Neozy- The conidia may be produced in internal air spaces gites and Zoophthora spp. exhibit elongated capillioconi- as the corpse shrivels out under unpropitious cir- dia and adhere to the exoskeleton through an adhesive cumstances (Wang and St Leger, 2005). Once the droplet (Glare et al. 1985). EPF invades the cuticle comprised of a polysacchar- The process of adhesion among the spore and the in- ide network and enters into the hemocoel, this in- sect cuticle is mediated by the presence of molecules duced biophysical or biochemical interruption in the synthesized by the fungus, called adhesins. In M. aniso- insect which leads to death of the host insect pliae, MAD1 adhesin-like protein is present on the co- (Charnley 2003). The fungus will burst out through nidial surface to attach to the host surface, but for the exoskeleton of the host insect, producing aerial adhesion to plant surfaces MAD2 is present (Pava-Ripoll spores following high relative humidity conditions. et al. 2011). MAD1 adhesin affects germination and blas- The unrestricted germination of the fungus may tospore formation, significantly reducing fungus viru- happen on the corpse of the host insect. The life lence (Wang and St Leger, 2007). The conidium cycle of the EPF gets completed if sporulated on the develops and produces penetration structures under cadaver of the host (Samson et al. 1988 and Charn- promising conditions of temperature, relative humidity, ley 2003). Under adverse environmental conditions, nutritional, and physical requirements in the cuticle. resting spores produced within the dead insect may The penetration structures such as appressoria or germ facilitate the fungus to persist for long periods (Sam- tubes penetrate the host insect through infection peg son et al. 1988). (Shah and Pell 2003). Conidiobolus obscurus (Hall & Dunn), Pandora neoa- Host response phidis (Remaud & Hennebert), Entomophthora plan- After a successful invasion, the EPF proliferate inside the choniana Cornu, and Batkoa apiculata (Thaxt.) host insect and septicemia occurs. The fungus combats (Entomophthorales: Entomophthoraceae) belong to the host-induced restrictions and poisonous compounds order Entomophthorales. These can penetrate the cu- additionally; the infection depends on the genetic poten- ticle directly from the germ tube without the forma- tial of the pathogen. Structural features such as tion of appressoria (Hajek and Delalibera 2010). B. sclerotization hinder penetration while enzyme inhibi- bassiana requires carbon and fatty acids for the ger- tors and tyrosinases generate antimicrobial melanins mination of conidia. In addition, insect epicuticular comprise the frontline defense toward weak pathogens lipids may help in the germination of conidia by pro- (Gillespie et al. 2000). The protease inhibitors are also viding energy sources and have antifungal properties present in the hemolymph of infected insects to limit le- (Ferron 1978). The hydrolytic enzymes such as thal infections. Moreover, the distinct behaviors of the
Sharma and Sharma Egyptian Journal of Biological Pest Control (2021) 31:57 Page 7 of 13
host insect can defend. Mycosis provokes physiological (Valadares-Inglis and Peberdy 1997). Bbchit1 encoding
symptoms of abnormalities in the insect-like lack of co- gene was present in the B. bassiana genome and its
ordination, altered behavior, and paralysis. Death results amino acid sequence is similar to endochitinase of Strep-
from a succession of effects that involve the physical de- tomyces avermitilis Kim and Goodfellow, S. coelicolor,
terioration of tissues, toxicity, and dehydration of cells and T. harzianum (Fang et al. 2005). The epicuticular
by loss of fluids, and consumption of nutrients (Bustillo layer of the insect is made up of non-polar lipids which
2001). The grasshopper Camnula pellucida (Scudder) would be barriers to entomopathogenic fungi without
(Orthoptera: Acrididae) retrieved from the infection of the action of lipases and lipoxygenases (Khachatourians
Entomophaga grylii (Fresenius) (Entomophthorales: and Qazi, 2008). The growth of EPF is also inhibited by
Entomophthoraceae) by raising internal body the presence of saturated fatty acid chains. The cuticular
temperature (Carruthers et al. 1992). The prominent lipids affect the conidial germination of B. bassiana and
virulence constituent in M. anisopliae is PR1 protease, P. fumosoroseus. Also, the nymphs of silver leaf whitefly,
which reduces the time of death by 25% in Manduca B. argentifolii, produce a thick coating of long-chain wax
sexta (St Leger et al. 1996). Spores can germinate swiftly esters affecting spore germination (Lord et al. 2002).
in the digestive tract of the insect where the relative hu- The destructive effects of these virulence enzymes on
midity is high but digestive fluids degrade germinating cuticle can be attributed to the structure and enzyme ac-
hyphae (Charnley 2003). cessibility of protein polymers in the cuticle. The ma-
nipulation of pathogen enzymes helps to understand the
Virulence enzymes associated with EPF best cuticle structure and its natural degradation. The
The process of pathogenesis is mediated by mechanical characterization of enzyme regulation will enable ma-
force and the enzymatic process. The EPF require viru- nipulation of enzyme levels with the help of chemical
lence enzymes like proteases, peptidases, chitinases, and and biotechnological procedure for insect control (Kra-
lipases for entry and successful growth (Khachatourians mer et al. 1988).
and Qazi 2008). The proteases and peptidases help in
the degradation of the insect cuticle because insect cu- Epizootiology of fungal diseases in insects
ticle is composed of chitin and protein. These also aid in An epizootic of insect fungal diseases is a large number
the degradation of saprophytic fungi and activate pro- of cases of a disease in a host population. The diseased
phenoloxidase in the hemolymph. The fungi B. bassiana, hosts are usually very abundant during epizootics. Epizo-
B. brongniartii, Lagenidium giganteum (Schenk) (Oomy- otiology of fungal diseases involves the natural history of
cota: Lagenidiales), Nomuraea rileyi (Farl.) Samson the disease, phenology of both pathogen and host, im-
(Hypocreales: Clavicipitaceae), M. anisopliae, and V. pact of the pathogen on host populations, and associ-
lecanii have been identified with protein degrading en- ation of epizootics with weather conditions. The disease
zymes (Sheng et al. 2006). B. bassiana has subtilisin-like development and spread are affected by the host and
serine endoprotease (Pr1 and Pr1B) and M. anisopliae pathogen populations, the environment, and the impact
has chymotrypsin (CHY1) (Screen et al. 2001). St Leger of human activities. The pathogen having different char-
et al. (1996) constructed an engineered mycoinsecticides acteristics includes virulence, dispersal, survival, and in-
based on M. anisopliae by over-expressing the Pr1 toxic oculum density. The disease incidence depends on the
protease from M. anisopliae genome. This was engi- insect age and position in the tree canopy. Abiotic fac-
neered to enhance the killing speed of M. anisopliae. tors such as moisture, temperature, and sunlight may
The Pr1 over-expression activates the phenoloxidase sys- determine whether infection can occur. The moisture
tem in the hemolymph of Manduca sexta which causes helps in the germination and sporulation, and
a 25% reduction in the time of death. The EPF M. aniso- temperature is a limiting factor for disease development.
pliae, B. bassiana, and V. Iecanii have grown in culture The primary interactions within host-pathogen systems
containing cuticle of locust produce various hydrolytic increase, appreciation of community-level influences
enzymes which are active against insect cuticle. may aid in understanding, and predicting the develop-
The chitinases (endo and exo-chitinases) play import- ment of epizootics. The low-density host populations
ant roles in the cleavage of N-acetylglucosamine. The have less infection, resulting in a host increase (preepi-
enzyme helps to break the insect cuticle polymer into zootic phase). Host populations reach high densities, and
monomers. The chitinolytic enzymes were present in M. disease epizootics cause population decline (epizootic
anisopliae, M. flavoviride, and B. bassiana culture sup- phase). The reduced host populations have a high infec-
plemented with insect cuticles (St Leger et al. 1996). The tion, owing to abundant fungi in the environment (post-
enzymatically produced protoplast and cell of M. aniso- epizootic phase) (Goettel et al. 2005).
pliae have chitinolytic enzymes. These enzyme activities The epizootiology of insect pathogenic fungi on insects in-
were cell-bound and located in the membrane fraction cludes Entomophthora muscae (Cohn) (Entomophthorales:Sharma and Sharma Egyptian Journal of Biological Pest Control (2021) 31:57 Page 8 of 13 Entomophthoraceae) infection on the onion fly, Delia an- increased, resulting in greater infection of A. pisum tique Meigen (Diptera: Anthomyiidae), and N. rileyi on (Pickering and Gutierrez 1991). The pathogens and nat- Anticarsia gematalis Hubner (Lepidoptera: Noctuidae) in ural enemies’ interactions could potentially impact host soybean (Carruthers and Haynes 1986). The EPF Erynia and pathogen populations. Diatraea saccharalis (Fabri- radicans and Entomophaga aulicae Batko (Entomophthor- cius) (Lepidoptera: Crambidae) parasitized for 1-6 days ales: Entomophthoraceae) produce the highest mortality in were inoculated with M. anisopliae; the fungus was not spruce budworm, Choristoneura fumiferana (Clemens) harmful to three species of parasitoids (Folegatti and (Lepidoptera: Tortricidae), which is a major defoliator in bal- Alves 1987). The fungal infection of hosts in more ad- sam and spruce trees (Perry and Whitfield, 1984). E. grylli vanced stages of parasitization impaired fungal develop- causes high mortality in C. pellucida and Melanoplus bivit- ment. As the primary interactions increases, the tatus Say (Orthoptera: Acrididae) (Pickford and Riegert appreciation of community-level influences may help in 1963). Soil is a complex habitat that harbors flora and fauna. predicting and understanding the development of M. anisopliae is the most frequent mycopathogens of soil in- epizootics. sects, particularly of beetles (Keller and Zimmermann 1989). M. anisopliae and B. bassiana are isolated from temperate Role of EPF in nature soils and have a broad host range. B. brongniartii is primarily EPF play important role as plant disease antagonists, a pathogen of cockchafers, Melolontha spp., and other Scar- rhizosphere colonizers, biocontrol agent of insect-pests, abidae (Zimmermann 1992). Epizootics have been found on plant growth promoting fungi, and fungal endophytes. wireworms, Agrotis spp., and larvae of Amphimallon solsti- The use of natural or modified fungi or bacteria that are tialis Linnaeus (Coleoptera: Scarabaeidae). On the other antagonists of plant pathogens is considered as biological hand, under in vitro conditions, various native parasitoids control. The survival or disease-causing activity of a such as Leptopilina heterotoma Thomson (Hymenoptera: pathogen is reduced by the production of various metab- Figitidae), Pachycrepoideus vindemiae Rondani (Hymenop- olites, such as antibiotics, bioactive volatile compounds tera: Pteromalidae), and Trichopria drosophilae Perkins (Hy- (e.g., ammonia, hydrogen cyanide, alkyl pyrones, alco- menoptera: Diapriidae), have been reported to distinguish hols, acids, esters, ketones and lipids) and enzymes. and parasitize invasive pest, Drosophila suzukii (Matsumura) Some other mechanisms are also involved like competi- (Diptera: Drosophilidae) at varying degrees of adequacy tion, antibiosis, hypovirulence, parasitism, and induced (Ibouh et al. 2019). systemic resistance (Ownley and Windham 2007). The Soil is a complex habitat that harbors flora and fauna. EPF like B. bassiana, Lecanicillium spp., are antagonistic M. anisopliae is the most frequent mycopathogens of toward insects but also antagonistic to plant pathogens soil insects, particularly of beetles (Keller and Zimmer- (Kim et al. 2008). B. bassiana utilizes different antagon- mann 1989). M. anisopliae and B. bassiana are isolated ism mechanism like antibiosis, competition, and induced from temperate soils and have a broad host range. Beau- systemic resistance (Benhamou and Brodeur 2001). veria brongniartii is primarily a pathogen of cockchafers, EPF in the Hypocreales are ubiquitous members of the Melolontha spp., and other Scarabidae (Zimmermann soil microbiota. The EPF Beauveria, Isaria, and Metarhi- 1992). Epizootics have been found on wireworms, Agro- zium are isolated from soil. The soil not only protects tis spp., and larvae of Amphimallon solstitialis Linnaeus EPF from damaging solar radiation but also from the ex- (Coleoptera: Scarabaeidae). Soil is a reservoir for fungi tremes of temperature (Inglis et al. 2001). The plant that infect insects present on aerial parts of plants. EPF rhizosphere has free carbon in abundant amount and persist in the soil as mycelium or pseudosclerotia. The exploited by saprotrophic microorganisms (Whipps spores of N. rileyi pathogenic to lepidopteran insects ad- 2001). EPF interact with plant roots for growth or sur- here to the leaves of the plant (Ignoffo et al. 1977). vival (St Leger and Wang, 2010). The ability of EPF has Cordyceps mycoflora is rich in humid and tropical for- impaired through the antimicrobial metabolites secreted ests and this EPF play a significant role in regulating in- by microbes present in the soil. The B. bassiana applied sect population because of the stable microclimates to control Colorado potato beetle, Leptinotarsa decemli- (Evans 1982). The interactions between virulent and neata (Say) (Coleoptera: Chrysomelidae), but there is avirulent isolates were complex and are the outcome of low mortality due to increased soil fungistasis levels dual infection in the leaf-cutting ant, Acromymex echin- (Groden and Lockwood 1991). M. anisopliae applied as tior Forel (Hymenoptera: Formicidae) (Hughes and conidia to corn seeds before planting to reduce damage Boomsma, 2004). The virulent Aspergillus flavus Link from wireworms, and increased stand density and fresh (Eurotiales: Trichocomaceae) dominated when inocu- weight of field corn (Kabaluk and Ericsson 2007). The lated with M. anisopliae. P. neoaphidis infects the sym- fungus which infect internal tissues of above ground patric aphids, kills few Acyrthosiphon kondoi Shinji plant parts without causing symptoms are known as fun- (Hemiptera: Aphididae), and pathogen density is gal endophytes (Arnold and Lutzoni 2007). The sum of
Sharma and Sharma Egyptian Journal of Biological Pest Control (2021) 31:57 Page 9 of 13
fungal endophytes protects host plants against insect Thus, the market is presently directed by small to
pests (Rudgers et al. 2007). Acremonium, Beauveria, Cla- medium-sized organizations.
dosporium, Clonostachys, and Isaria are some of the EPF Another explanation behind the small share of the
(Vega et al. 2008). overall industry of the fungi as mycoinsecticides is its
EPF are also employed in integrated pest management moderately slow killing rate and an expansion in share
programs as one of the natural enemies against arthro- of the market value legitimately corresponds to the kill-
pods including insect pests. Nowadays, the usage of fun- ing speed (St Leger and Wang 2010). In spite of the fact
gal pathogens is drawing special attention as a biological that these products have the upside of a confined host
control agent of many insect pests and this approach is range, this particularity is likewise one of the restricting
reliable, cost-effective, and environmentally safe elements for their commercial use (Ownley et al. 2004).
(Wraight et al. 2001). EPF possesses several attributes In this manner, a mycopesticide with a more extensive
that make them a potential candidate to be utilized in host extend however with next to zero impact on other
the IPM program. Some of the fungi including Beau- natural enemies of useful organisms may have an im-
veria, Metarhizium, Isaria, Lecanicillium, Hirsutella, and portant commercial advantage in the event that it all the
Entomophthorales are used as entomopathogens. The B. while controls different insect pests and additionally
bassiana is effective against lepidopteran, coleopteran, plant infections (Wraight and Carruthers 1999).
and hemipteran pests. B. bassiana has also been found However, since the advent of worries over the effect of
to be pathogenic in opposition to the larvae of Capnodis synthetic compounds, cost of enlisting synthetic concoc-
tenebrionis (Linnaeus) (Coleoptera: Buprestidae) in la- tions for high value crop plants, development of insecti-
boratory assays as reported by El Khoury et al. (2020) cide resistance, and the developing enthusiasm for
wherein the mortality/transience of C. tenebrionis ran “organic/natural” food has now guaranteed a business
between 26 and 76%. opportunity for biological agents of pest control, thereby
Metarhizium anisopliae is effective against scarab bee- incorporating formulations dependent on EPF. EPF have
tle grubs, weevils, termites, and cutworms. L. lecanii used generally been utilized more broadly on forest pests than
against insects belong to order Hemiptera and Thysanop- on pests of crops (Feng 2003).
tera. Paecilomyces lilacinus is used against nematodes Mycopesticide formulations depend on a confined
(Root-knot, cyst, lesion burrowing) (Skinner et al. 2014). number of fungal species, fundamentally Beauveria
These fungal-based products are harmful to specific insect bassiana, B. brongniartii, Lecanicillium muscarium, L.
pests (host-specific) and relatively safe to beneficial in- longisporum, M. anisopliae, Paecilomyces fumosoroseus,
sects, non-target organisms, and ecosystems. There is no and Verticillium lecanii. About 33.9% of the mycoinsec-
problem of toxic residues on crops as agrochemicals ticidal formulations are based on B. bassiana, trailed by
(Laird et al. 1990). The EPF has been developed or is being M. anisopliae (33.9%), I. fumosorosea (5.8%), and B.
evaluated as an integral and essential component of IPM brongniartii (4.1%) (Faria and Wraight 2007). However,
or IDM. Parasitoids have likewise been accounted for to to build the share of the overall industry of EPF, the kill-
go about as vectors of EPF to the hosts during instances of ing speed which is the significant deterrent restricting
foraging, as reported by Oreste et al. (2016), wherein their utilization as mycoinsecticides ought to be en-
Encarsia formosa acted as a passive vector to transfer the hanced (St Leger and Wang 2010).
fungal propagules from tainted to uninfected populaces As the natural strains of these EPF are deficient in terms
due to the virtue of its oviposition and host handling. of adequate levels of virulence (Rangel et al. 2005), there-
fore, manipulation at genetic level is important to improve
Mycoinsecticides: present scenario their viability and ecological wellness (Fang et al. 2005)
The market of chemical pesticides represents as much as Also, dual infection by different entomopathogens does
98% of the worldwide market of crop protection and not affect the mortality of insects. For instance, according
consequently, the portion of biopesticides is just 2%. to Tarasco et al. (2011) when contrasted with the values
(Anon 2005). A more profound investigation of the which were noted when the two entomopathogens (ento-
share of the overall industry of biopesticides has uncov- mopathogenic nematode Steinernema ichnusae (Nema-
ered that mycoinsecticides have contributed for an ex- toda: Steinernematidae) and EPF B. bassiana) were
ceptionally little division of the market of biopesticide, inoculated individually against Galleria mellonella Fabri-
on the grounds that a large share has been accounted by cius (Lepidoptera: Pyralidae), concurrent infection showed
formulations which are based on the bacterium Bacillus neither synergistic nor additive effects.
thuringiensis. The development of biopesticides for pest
control was at first upheld and contributed by multi- Future prospects
national agrochemical organizations yet a large portion Future investigations on EPF should zero in on attempt-
of them have opted out since 1980s (Charnley 2003). ing to comprehend the ecosystem of the fungal growthsSharma and Sharma Egyptian Journal of Biological Pest Control (2021) 31:57 Page 10 of 13 in a setting that centers on their role as antagonists of et al. 1988) and the staggering interest has been investi- plant diseases. Most intriguing future prospect in terms gating the potential for B. bassiana and M. anisopliae. A of EPF is the possibility to devise stratagems for strain few instances of late examinations are the investigations improvement. Attributes which could be tended to in- on the rice water weevil, a pest of rice in North and clude expanded killing power (reduced LD50), capacity South America (Chen et al. 2005), the Sunn pest, Eury- to start disease at low humidity conditions, upgraded gaster integriceps Puton (Hemiptera: Scutelleridae), a timeframe of realistic usability, and environmental major insect pest of wheat and barley in West and Cen- steadiness (for example, temperature tolerance, and re- tral Asia (Parker et al. 2003), and thrips (Ekesi and Man- sistance against UV), augmented kill (reduced LT50), im- iania 2003). proved sporulation during large-scale manufacturing and Investigations into the strain improvement and poten- extension of the host. Lane et al. (1991) suggested that tial targets for mycoinsecticides will give insights into culture conditions impact the attributes of contagious enhanced disposition of mycoinsecticides for the best fungal spores and can be controlled to increment pest control and improved development of formulations, mycoinsecticide effectiveness. For instance, Blastospores detailing to upgrade their adequacy so utilization of the of B. bassiana from carbon-restricted cultures had lower EPF can turn into an essential share of agricultural groupings of starch and lipid and were fundamentally frameworks as well as the integrated pest management less harmful toward the rice green leafhopper than were stratagems. the blastospores from nitrogen-restricted cultures. Direct manipulation at genetic level would give Conclusion upgraded targeting for single genes or clusters of genes, In the present review, an attempt is made to sum up the for example, epizootic capability of Beauveria spp. and utilization of fungal organisms as biopesticides, the au- Metarhizium spp. was enhanced by genetic manipula- thors endeavor and gather the information about the tion, thereby enhancing their saprophytic potential by EPF as biocontrol operators. We gather knowledge on Wang and St Leger (2005). ESTs and cDNA microarrays the past and present researches about EPF to investigate were utilized to investigate gene expression during de- approaches to improve their capacities. The action velopment on a plant root exudate. Genetic manipula- mechanism of infection by the EPF is not only complex tion needs the foundation of cloning and transformation but specialized as well. Therefore, there is a need to ac- frameworks, which have been accomplished for P. fumo- quire the knowledge of insect-fungus interaction as the soroseus, B. bassiana, and M. anisopliae (Lima et al. host-pathogen interactions are basic determinants of 2006). pathogenicity and epizootic turn of events. Molecular Keeping the agro-ecosystems aside, EPF are also find- and biochemical examinations of host-pathogen interac- ing the exploit of their activity against the human and tions are characterizing those properties yielding ex- animal pests, for example, work on mosquitoes (Blanford panded pathogenicity and are focused on the et al. 2005) and tsetse flies (Maniania et al. 2003). Inves- management of explicit fungal processes. Examinations tigations on Brassica root flies (Delia floralis (Fallen) at the level of an organism include investigations of the (Diptera: Anthomyiidae) and Delia radicum Linnaeus turn of events and activity of different phases of host (Diptera: Anthomyiidae)) (Eilenberg and Meadow 2003), and pathogen, which are regularly in association with fire ants (Brinkman and Gardner 2004), and mound variations in natural conditions of the ecosystem. The building termites (Milner 2003) show the assortment of utilization of EPF in agro-ecosystems has expanded as of expected targets for mycoinsecticides. Other potential late because of the extraordinary potential they have in targets researched for utilization of mycoinsecticides in- the field of pest management, speaking to a productive corporate bee parasite Varroa destructor Anderson & option in contrast to the utilization of synthetic chemical Trueman (Arachnida: Varroidae) (Shaw et al. 2002), compounds, which are viewed as exceptionally hurtful to blowflies (Wright et al. 2004), parasitic mites (Smith the soundness of man and environment alike. Under- et al. 2000), reduviid bugs such as Triatoma (Lazzarini standing the components engaged with the process of et al. 2006) and ticks (Samish et al. 2004). infection, will permit the development of new organic/ On the other hand, EPF have potential for control of a biological formulations that are compelling for field use certain number of insect pests, and it is imperative to and securing the beneficial species of insects. Be that as distinguish potential targets for mycoinsecticide develop- it may, there are various limitations on the utilization of ment and advancement. For instance, beetles and larval EPF as an insecticide, for instance, the potential out- pests are every now and again host to fungal diseases comes of contamination with mycotoxins such as, citri- however seem to have similarly not many viral and bac- nin, zearalenone, aflatoxins, fumonisins, and terial pathogens. Subsequently, fungi are frequently the trichothecenes delivered by various saprophytic fungi as microbes of choice for beetle and bug pests (Samson environmental toxins cannot be precluded. Other
Sharma and Sharma Egyptian Journal of Biological Pest Control (2021) 31:57 Page 11 of 13
limitations include the facts that not only the application Audoin V (1837) Nouvelles expe´riences sur la nature de la maladie contagieuse
of EPF must coincide with high relative humidity condi- qui attaque les Vers a` soie, et qu’on de´signe sous le nom de Muscardine.
Ann sci Nat 8:257–270
tions but also there is a need for a period where no Barr DJS (1992) Evolution and kingdoms of organisms from the perspective of a
chemical fungicide application has taken place. More- mycologist. Mycologia 84:1–11
over, the inoculum has short timeframe of realistic us- Benhamou N, Brodeur J (2001) Pre-inoculation of Ri T-DNA transformed
cucumber roots with the mycoparasite, Verticillium lecanii, induces host
ability and the formulation requires 2–3 weeks to kill defense reactions against Pythium ultimum infection. Physiol Mol Plant
the insects. Along these lines, novel thoughts and specu- Pathol 58:133–146
lation need to rise which will further assist in building Blanford S, Chan BHK, Jenkins N, Sim D, Turner RJ, Read AF, Thomas MB (2005)
Fungal pathogen reduces potential for malaria transmission. Science 308:
up the fungi’s abilities as biocontrol specialists. 1638–1641
Boucias DG, Pendland JC (1991) Attachment of mycopathogens to cuticle: the
Abbreviations
initial event of mycosis in arthropod hosts. In: Cole GT, Hoch HC (eds) The
mtDNA: Mitochondrial deoxyribonucleic acid; rRNA: Ribosomal ribonucleic
Fungal Spore and Disease Initiation in Plants and Animals. Plenum Press,
acid; PR1: Pathogenesis related protein-1; IPM: Integrated pest management;
New York, pp 101–128
IDM: Integrated disease management; LD: Lethal dose; LT: Lethal time;
Boucias DG, Pendland JC, Latge JP (1988) Nonspecific factors involved in
EST: Expressed sequence tag; cDNA: Complementary deoxyribonucleic acid
attachment of entomopathogenic Deuteromycetes to host insect cuticle.
Appl Environ Microbiol 54:1795–1805
Acknowledgements
Brey PT, Latge JP, Prevost MC (1986) Integumental penetration of the pea aphid,
Not applicable
Acyrthosiphon pisum, by Conidiobolus obscurus. J Invertebr Pathol 48:34–41
Brinkman MA, Gardner WA (2004) Red imported fire ant (Hymenoptera:
Authors’ contributions
Formicidae) control in nursery pots treated with Beauveria bassiana and
Both RS and PS researched and reviewed the existing literature on the topic
bifenthrin. J Entomol Sci 39:75–187
at hand. RS worked on the “Background,” “Classification of
Bustillo A (2001) Hongos en insectos y poszibilidades de uso en el control
Entomopathogenic Fungi,” “Mycoinsecticides: Present Scenario,” “Future
biológico de plagas en Colombia. In: Seminario Uso de entomopatógenos
prospects,” and “Conclusion” sections of the manuscript. PS worked on
en Colombia. Sociedad Colombiana de Entomología, Bogotá, pp 30–53
sections titled “Biological Control of Insects,” “Pest Control by EPF
Butt TM, Wraight SP, Galaini-Wraight S, Humber RA, Roberts DW, Soper RS (1988)
(Approaches),” “Infection process,” “Virulence enzymes associated with EPF,”
“Epizootiology of fungal diseases in insects,” and “Role of EPF in Nature.” RS Humoral encapsulation of the fungus Erynia radicalls (Entomophthorales) by
contributed to the critical review and editing of the manuscript. Both the potato leafhopper Empoasca fabae (Homoptera: Cicadellidae). J Vertebr
authors read and approved the final manuscript. Pathol 52:49–56
Carruthers RI, Haynes DL (1986) Temperature, moisture, and habitat effects on
Funding Entomophthora muscae (Entomophthorales, Entomophthoraceae) conidial
Not applicable germination and survival in the onion agroecosystem. Environ Entomol 15:
1154–1160
Availability of data and materials Carruthers RI, Larkin TS, Firstencel H, Feng Z (1992) Influence of thermal ecology
Not applicable on the mycosis of a range land grasshopper. Ecology 73:190–204
Charnley AK (1989) Mechanisms of fungal pathogenesis in insects. In: Whipps JM,
Declarations Lumsden RD (eds) The biotechnology of fungi for improving plant growth.
Cambridge Univ. Press, London, pp 85–125
Ethics approval and consent to participate Charnley AK (2003) Fungal pathogens of insects: cuticle degrading enzymes and
Not applicable toxins. Adv Bot Res 40:241–321
Charnley AK, St Leger RJ (1991) The role of cuticle degrading enzymes in fungal
Consent for publication pathogenesis in insects. In: Cole GT, Hoch HC (eds) The fungal spore and
Not applicable disease initiation in plant and animals. Plenum Press, New York, pp 267–286
Chen H, Chen ZM, Zhou YS (2005) Rice water weevil (Coleoptera: Curculionidae)
Competing interests in mainland China: invasion, spread and control. Crop Protect 24:695–702
The authors declare that they have no competing interests. Clarkson JM, Charnley AK (1996) New insights into the mechanisms of fungal
pathogenesis in insects. Trends Microbiol 4:197–203
Author details Delgado PAM, Murcia OP (2011) Hongos entomopatógenos: Uma alternativa
1
Department of Plant Pathology, Dr. YS Parmar University of Horticulture and para la obtención de Biopesticidas. Ambi-Agua 6:77–90
Forestry, Nauni, Solan, Himachal Pradesh 173230, India. 2Department of Dhaliwal GS, Jindal V, Mohindru B (2015) Crop losses due to insect pests: global
Entomology, Dr. YS Parmar University of Horticulture and Forestry, Nauni, and Indian scenario. Indian J Entomol 77:165–168
Solan, Himachal Pradesh 173230, India. Eilenberg J, Meadow R (2003) Fungi for biological control of Brassica root flies,
Delia radicum, and Delia floralis. In: Upadhyay RK (ed) Advances in microbial
Received: 8 January 2021 Accepted: 15 March 2021 control of insect pests. Kluwer, New York, pp 181–192
Ekesi S, Maniania NK (2003) Metarhizium anisopliae: an effective biological control
agent for the management of thrips in horti-and floriculture in Africa. In:
References Upadhyay RK (ed) Advances in microbial control of insect pests. Kluwer, New
Abdelghany TH (ed) (2018) Entomopathogenic fungi and their role in biological York, pp 165–180
control. OMICS International, USA, pp 3–27 El Khoury Y, Noujeim E, Ravlic J, Oreste M, Addante R, Nemer N, Tarasco E (2020)
Akutse KS, Maniania NK, Fiaboe KKM, Van den Berg J, Ekesi S (2013) Endophytic The effect of entomopathogenic nematode and fungi against four
colonization of Vicia faba and Phaseolus vulgaris (Fabaceae) by fungal xylophagous pests. Biocontrol Sci Technol 30(9):983–995
pathogens and their effects on the life-history parameters of Liriomyza Evans HC (1982) Entomogenous fungi in tropical forest ecosystems: an appraisal.
huidobrensis (Diptera: Agromyzidae). Fungal Ecol 6:293–301 Ecol Entomol 7:47–60
Alexopoulos CJ, Mims CW, Blackwell M (1996) Introductory mycology, 4th edn. Fang W, Leng B, Xiao Y, Jin K, Ma J, Fan Y, Feng J, Yang X, Zhang Y, Pei Y (2005)
Wiley, New York, p 880 Cloning of Beauveria bassiana chitinase gene Bbchit1 and its application to
Anonymous (2005) Spotlight on biopesticides. Crop Protection 184. (http://www. improve fungal strain virulence. Appl Environ Microbiol 71:363–370
cropprotection-monthly.co.uk). Accessed 18 November 2020. Faria MR, Wraight SP (2007) Mycoinsecticides and Mycoacaricides: a
Arnold AE, Lutzoni F (2007) Diversity and host range of foliar fungal endophytes: comprehensive list with worldwide coverage and international classification
are tropical leaves biodiversity hotspots? Ecology 88:541–549 of formulation types. Biol Control 43:237–256You can also read
