Pathogens and Parasitoids of Forest Pest Insects in the Region of the Forest Protection Station on Plovdiv (Bulgaria), during the period 1990-2017

Abstract

During the period 1990-2017, a survey of the entomopathogens and parasitoids of several pest insects was conducted, including the lepidopterans Lymantria dispar, Euproctis chrysorrhoea, Leucoma salicis, Malacosoma neustria, Orthosia cerasi, Aporia crataegi, Operophtera brumata, Eilema complana, Tortix viridana, Archips xylosteana, Paranthrene tabaniformis, Gypsonoma aceriana, Thaumetopoea pityocampa, T. solitaria, Phyllocnistis unipunctella, the coleopterans Saperda populnea, Ips typographus, I. acuminatus, I. sexdentatus, Pityogenes chalcographus, Dryocoetes autographus, Hylurgops palliatus, Phyllobius sp. and the hymenopterans Diprion pini, Neodiprion sertifer, Gilpinia sp. and Tremex fuscicornis. As a result of these studies 5 viruses, 1 protozoan species, 7 microsporidian species, 5 species of entomopathogenic fungi and 46 parasitoid species have been documented in 27 host insects collected in the region of the Forest Protection Station Plovdiv. The first successful introduction in Bulgaria of the entomopathogenic fungus Entomophaga maimaiga in populations of L. dispar was conducted in 1999 in the region of the Forest Protection Station at Plovdiv (in the village of Gorni Domlyan, Karlovо Forestry) and 7 subsequent introductions were later performed in the region of the station. As a result, L. dispar density has been maintained at low levels in that area and only 60 hectares were sprayed with insecticides for L. dispar control in the last 18 years. Another success was the first field release in Europe and Bulgaria of the entomopathogenic fungus Entomophaga aulicae in a healthy population of the brown tail moth, Euproctis chrysorrhoea, in 2016 in the village of Zhenda (Kardzhali Forestry). Investigations in 2017 showed that 19% of E. chrysorrhoea larvae sampled from release sites had died due to infection by E. aulicae.

Full text

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Silva Balcanica, 19(3)/2018 DOI: 10.6084/m9.gshare.8198294
PATHOGENS AND PARASITOIDS OF FOREST PEST INSECTS
IN THE REGION OF FOREST PROTECTION STATION PLOVDIV
DURING THE PERIOD 1990 – 2017
Daniela Pilarska1,2, Georgi Georgiev3, Maria Dobreva4, Danail Takov2, Plamen Mirchev3,
Danail Doychev5, Margarita Georgieva5, Rumen Nachev4, Pencho Dermendzhiev4,
Slavimira Draganova6, Andreas Linde7, Ann E. Hajek8
1New Bulgarian University – Soa, Department of Natural Sciences
2Institute of Biodiversity and Ecosystem Research – Soa, Bulgarian Academy of
Sciences 3Forest Research Institute – Soa, Bulgarian Academy of Sciences,
4Forest Protection Station Plovdiv
5Forestry University – Soa
6Institute of Soil Science, Agrotechnology and Plant Protection
‘Nikola Poushkarov’ – Soa
7 Eberswalde University for Sustainable Development – Eberswalde
8 Department of Entomology, Cornell University, Ithaca – New York
Abstract
During the period 1990-2017, a survey of the entomopathogens and parasitoids of several pest
insects was conducted, including the lepidopterans Lymantria dispar, Euproctis chrysorrhoea, Leucoma salicis,
Malacosoma neustria, Orthosia cerasi, Aporia crataegi, Operophtera brumata, Eilema complana, Tortix viridana,
Archips xylosteana, Paranthrene tabaniformis, Gypsonoma aceriana, aumetopoea pityocampa, T. solitaria,
Phyllocnistis unipunctella, the coleopterans Saperda populnea, Ips typographus, I. acuminatus, I. sexdentatus,
Pityogenes chalcographus, Dryocoetes autographus, Hylurgops palliatus, Phyllobius sp. and the hymenopterans
Diprion pini, Neodiprion sertifer, Gilpinia sp. and Tremex fuscicornis. As a result of these studies 5 viruses, 1
protozoan species, 7 microsporidian species, 5 species of entomopathogenic fungi and 46 parasitoid species
have been documented in 27 host insects collected in the region of the Forest Protection Station Plovdiv.
e rst successful introduction in Bulgaria of the entomopathogenic fungus Entomophaga maimaiga in
populations of L. dispar was conducted in 1999 in the region of the Forest Protection Station at Plovdiv
(in the village of Gorni Domlyan, Karlovо Forestry) and 7 subsequent introductions were later performed
in the region of the station. As a result, L. dispar density has been maintained at low levels in that area and
only 60 hectares were sprayed with insecticides for L. dispar control in the last 18 years. Another success
was the rst eld release in Europe and Bulgaria of the entomopathogenic fungus Entomophaga aulicae in a
healthy population of the brown tail moth, Euproctis chrysorrhoea, in 2016 in the village of Zhenda (Kardzhali
Forestry). Investigations in 2017 showed that 19% of E. chrysorrhoea larvae sampled from release sites had
died due to infection by E. aulicae.
Key words: insect pests, pathogens, parasitoids, Entomophaga maimaiga, biological control
Forest pest insects are a major cause of economic and aesthetic loss in forestry
systems and are of particular concern as forest habitats become more fragmented, land
use pressures increase, and climate change impacts forest ecosystems.
Many insects in Bulgaria attained pest status when plantation forestry increased in
importance and created monocultures that favour pest outbreaks. e most signicant

42
pests of Bulgarian forests are species in the orders Coleoptera and Lepidoptera. In the
coniferous forests bark beetles (Coleoptera: Curculionidae) and the processionary moth,
aumetopoea pityocampa (Denis & Schiermüller) (Lepidoptera: Notodontidae) are
of greatest concern. Important pests of broadleaf forests include moths in the families
Erebidae [Lymantria dispar (Linnaeus), Euproctis chrysorrhoea (Linnaeus), Leucoma salicis
(Linnaeus)], Tortricidae [Archips xylosteana (Linnaeus), Tortrix viridana Linnaeus] and
Geometridae [(Operophtera brumata (Linnaeus), Erannis defoliaria (Clerck), Alsophila
aescularia (Denis et Schiermüller), Alsophila aceraria (Denis et Schiermüller)]. ese
pests can cause signicant damage and each year huge areas of forests are aected. Forestry
administrations are committed to reducing the use of pesticides in the environment and
to emphasizing the use of biological control agents.
Pathogens and parasitoids as natural enemies are such control agents that play
important roles in regulating population densities of forest pest insects.
In the region of Plovdiv Forest Protection Station the main pests during the last
twenty years are the lepidopterans T. pityocampa, L. dispar, E. chrysorrhoea, A. xylosteana,
T. viridana, E. defoliaria, O. brumata and the bark beetles Ips typographus (Linnaeus), Ips
acuminatus (Gyllenhal), Ips sexdentatus (Börner) and Pityogenes chalcographus (Linnaeus).
In order to set the stage for practical application of conservation practices and
control measures for the biological protection of our forest ecosystems, a survey of
entomopathogens and parasitoids of several pest insects was conducted in the region of
the Forest Protection Station Plovdiv.
In this paper we present results of investigations on pathogens and parasitoids of
pest lepidopterans, coleopterans and hymenopterans.
As a result of our studies 5 viruses, 1 protozoan species, 7 microsporidian species,
5 species of entomopathogenic fungi, and 46 parasitoid species have been documented
in 27 insect species collected in the region of the Forest Protection Station Plovdiv during
the years 1990 – 2017.
Viruses
Five viruses were detected in the lepidopterans L. dispar, T. pityocampa, L. salicis,
the bark beetle I. typographus and the hymenopteran Neodiprion sertifer (Georoy).
e rst virus was the L. dispar nuclear polyhedrosis virus (LdNPV; Baculoviridae).
LdNPV infects all tissues and develops in the nuclei of infected cells. It was detected
in 1999 in 2.3% of the gypsy moth larvae collected in Gorni Domlyan village,
Karlovo State Forestry, where in the same year the rst successful introduction of the
fungus Entomophaga maimaiga Humber, Shimazu & Soper (Entomophthoromycota,
Entomophthorales) was conducted (Pilarska et al., 2000). e same virus was detected
in 2003 in 85.2% in larvae collected in the region of Chekeritsa State Game Enterprise
(Annual Report of Forest Protection Station Plovdiv, 2003) .
In 2004, after an outbreak of the satin moth, L. salicis, in the region of Plovdiv
State Forestry, an epizootic caused by an undetermined nuclear polyhedrosis virus was
observed. As a result, 69% of the collected larvae died with symptoms of NPV (Annual
Report of Forest Protection Station Plovdiv, 2004).

43
In 2008, a granulosis virus, TpGV (Baculoviridae), was detected in dead larvae of
the pine processionary moth, T.pityocampa, collected from the village of Banya, Karlovo
State Forestry. Viral infections caused 100% mortality of pine processionary moth larvae
(Annual Report of Forest Protection Station Plovdiv, 2008).
During the period 2003 and 2011, an entomopox virus, ItEPV Wegensteiner &
Weiser (Entomopoxviridae) was observed in spruce bark beetles, I. typographus, collected
in Beglika, Batak State Forestry and Borino, Borino State Forestry. ItEPV spheroids were
detected in midgut epithelial cells. Prevalence of this virus in the beetles collected in Beglika
in 2005 was 16.6 and the virus caused 4.7% infection in 2011. In Borino the virus was
detected in 2003 in 3.8% of the investigated individuals (Takov et al., 2006, 2007).
e fth virus documented in the region of Forest Protection Station Plovdiv
was the nuclear polyhedrosis virus of the satin moth Neodiprion sertifer (Georoy). It
was detected in the region of Karlovo State Forestry in 2016, where 1.8 ha of pine trees
were infested with the satin moth. is virus caused 50% mortality of the sawy larvae
(Annual Report of Forest Protection Station Plovdiv, 2016).
Protozoa
Protozoa of the genus Gregarina (Apicomplexa, Eugregarinoida) were detected
in three bark beetle species: I. typographus, I. acuminatus and I. sexdentatus. Gregarina
typographi Fuchs was detected in I. typographus collected in three sites: Beglika, Borino
and Yundola from 2003 to 2011 (Takov et al., 2006, 2007, 2012). is gregarine was
observed in the midgut lumen of beetles collected in Beglika in 2005 and 2011, with a
prevalence of 16.6% and 31.7%, respectively. In Borino, 7.3% of all investigated beetles
were infected with G. typographi in 2003 and 5.9% in 2005. e pathogen was also
found in 5.1% of individuals collected in Yundola in 2009. Gregarina spp. were also
found in I. acuminatus (prevalence of 7.2% in Borino in 2005) (Takov et al., 2007)
and in I. sexdentatus (prevalence of 11.1% in Slaveyno State Forestry in 2017) (Annual
Report of Forest Protection Station Plovdiv, 2017).
Microsporidia
In total, seven microsporidian species (Microsporidia) were detected in the gypsy
moth L.dispar, E. chrysorrhoea, tortricids and I. typographus.
e rst microsporidian documented in the study period was Endoreticulatus
schubergi (Zwolfer) Cali et Garhy in L. dispar in 1996 and 1997, near Asenovgrad
(Asenovgrad State Forestry). It infects the gut epithelium and is transmitted horizontally
by oral uptake of spores. e prevalence of E. schubergi in the host population increased
with the growth of the host larvae as the season progressed. e prevalence of E. schubergi
in 1996 varied from 2.0 to 11.5% (average 6.1%) and in 1997 varied from 27.0 to
56.0% (average 3.2%) (Pilarska et al., 1998).
In the same host, a second microsporidian species, Nosema lymantriae Weiser was
detected in two sites (Chekeritsa State Game Enterprise and Gorni Domlyan, Karlovo
State Forestry) in 2009 and 2010. is microsporidium infects the fat body, silk glands,
Malpighian tubules and gonads. It is transmitted horizontally and transovarially. e

44
prevalence in Chekeritsa was 13.9% (2009) and 1.9% in Gorni Domlyan (2010) (D.P.,
unpublished).
In 2000, 72 brown tail moth, E. chrysorrhoea, populations in Balkan, Sredna
Gora, Sakar and Rodope Mountains were screened for microsporidian infections. In 13
populations collected in Sakar and Rodope Mountains, a Nosema sp. was detected, and
in 8 populations in Balkan, Sredna Gora and Sakar Mountains an Endoreticulatus sp.
was observed (Pilarska et al., 2001a). e prevalence of Nosema sp. was 37.9% (Rodope
Mt.) and 21.4% (Sakar Mt.), and the prevalence of Endoreticulatus sp. in Balkan and
Sredna Gora Mountains was 11.1% and 10.0%, respectively (Annual Report of Forest
Protection Station Plovdiv, 2000).
An undetermined Nosema isolate was discovered in the fat body tissues and silk
glands of larvae of Orthosia cerasi (Fabricius) from Gorni Domlyan in 2010, with a
prevalence of 20.0% (Pilarska et al., 2017).
In 2011, during an investigation of newly hatched tortricid larvae from the
region of Rakitovo and Alabak Forestry Stations, another Nosema sp. was detected. Its
prevalence was 12.5% in the larvae from Rakitovo and 5.0% in the larvae from Alabak
(Annual Report of Forest Protection Station Plovdiv, 2011).
Chytridiopsis typographi Weiser was found in the bark beetle I. typographus,
collected in 2003 in Borino and in 2011 in Beglika. Spores were observed in the cells of
the midgut epithelium, enclosed in sporophorous vesicles or without such enclosures.
Prevalence was 1-6% in beetles from Beglika and 3.8% in beetles from Borino (Takov et
al., 2006, 2012).
Fungi
In total, ve species of entomopathogenic fungi were detected in the lepidopterans
L. salicis, E. chrysorrhoea, L. dispar, E. defoliaria, aumetopoea solitaria (Freyer),
T.pityocampa, Malacosoma neustria (Linnaeus), Aporia crataegi (Linnaeus), T. viridana,
in the bark beetles Dryocoetes autographus (Ratzeburg), Hylurgops palliatus (Gyllenhal),
and in the weevil Phyllobius sp.
e rst fungal entomopathogen discovered was Entomophaga aulicae (E. Reichardt)
Humber (Entomophthoromycotina, Entomophthorales) in 16 outbreak populations of
brown tail moth, E. chrysorrhoea, in Balkan, Sakar, Sredna Gora and Rodope Mountains
in 2000. e fungus was identied as the cause of high larval mortality with the result of
a reduced population density of this moth (Pilarska et al., 2001b).
In 2016, mortality of brown tail moth larvae was also observed in the region of
Asenovgrad State Forestry. Microscopic analyses showed that mortality was also caused
by E. aulicae. In order to preserve inoculum of the fungus, dead brown tail moth larvae
were collected and stored in the soil humus layer (Pilarska et al., 2016a).
e third fungal pathogen identied was the hypocrealean fungus Beauveria
bassiana (Balsamo) Vuillemin (Ascomycota, Hypocreales), found in dead larvae of
L. salicis (Markova, Georgiev, 1992), T. solitaria (Mirchev et al., 2012), L. dispar, A.
crataegi, E. defoliaria, T.pityocampa, M. neustria, T. viridana, D. autographus, H. palliatus
and Phyllobius sp., collected from 20 sites (Draganova et al., 2013).

45
Aspergillus niger van Tieghem (Ascomycota, Eurotiales) was found in E. defoliaria,
another Aspergillus sp. was detected in T. pityocampa, L. dispar and T. viridana, and in
T. pityocampa, M. neustria and T. viridana an entomopathogenic fungus belonging to
the genus Fusarium Link was discovered (Ascomycota, Hypocreales) (Draganova et al.,
2013).
Introduction and release of entomopathogenic fungi
e rst successful introduction of the entomopathogenic fungus Entomophaga
maimaiga into populations of L. dispar in Bulgaria was conducted in 1999 in the region
of the Forest Protection Station at Plovdiv, in the village of Gorni Domlyan (Karlovо
Forestry) (Pilarska et al., 2000). In the period 2000-2004 the prevalence of E. maimaiga
in local populations of L. dispar ranged from 6.1% (2000) to 15.9% (2004). However,
the fungus persisted in the introduction site and in 2005, massive epizootics caused by
this fungus were recorded in State Forestry Haskovo and State Forestry Kirkovo (Pilarska
et al., 2007). In 2012 fungal epizootics were reported from the regions of State Forestry
Haskovo and Harmanli with larval mortality of 100%. In the period 2005-2013, seven
subsequent introductions were performed in the region of the Forest Protection Station
Plovdiv (Georgiev et al., 2013; Pilarska et al., 2016b). As a result, the L. dispar density
has remained at low levels in that area and only 60 hectares had to be sprayed with
insecticides for L. dispar control during the last 18 years.
e release of the entomopathogenic fungus Entomophaga aulicae using the
methodology for introduction of E. maimaiga was an attempt to conduct biological
control against one of the most important insect pests – the brown tail moth. erefore, in
2016, we conducted the rst controlled eld release of E. aulicae in Bulgaria, in a healthy
population of E.chrysorrhoea in the village of Zhenda (Kardzhali State Forestry) (Pilarska
et al., 2017b). e release of E. aulicae was performed in the beginning of November
2016 using the inoculum from an outbreak site of E. chrysorrhoea in Asenovgrad. Our
investigations in 2017 showed that the introduction was successful, with 19% of E.
chrysorrhoea larvae sampled from the release sites dying due to infections caused by E.
aulicae (Annual Report of Forest Protection Station Plovdiv, 2017).
Parasitoids
In total, 46 parasitoid species were detected in 11 insect hosts: the small poplar
longhorn beetle Saperda populnea (Linnaeus), the lepidopterans Phyllocnistis unipunctella
(Stephens) (syn. Phyllocnistis suusella Z.), Gypsonoma aceriana (Duponchel), Paranthrene
tabaniformis (Rottemburg), L. salicis, T. pityocampa, T. solitaria, the sawies Diprion pini
(Linnaeus), N. sertifer, Gilpinia sp., and the tremex wasp Tremex fuscicornis (Fabricius).
In S. populnea larvae, 5 hymenopteran and dipteran parasitoids were found in
Plovdiv, Ognyanovo, Simeonovgrad, Manole, and Klisura regions: Iphiaulax impostor
(Scopoli) (Hymenoptera: Braconidae), Dolichomitus populneus (Ratzeburg), Xylophrurus
lancifer (Gravenhorst), Gelis ornatulus (omson) (Hymenoptera: Ichneumonidae) and
Billaea irrorata (Meigen) (Diptera: Tachinidae) (Georgiev, 2001a; Georgiev et al., 2004).
G. ornatulus was found as a hyperparasitoid.

46
In P. unipunctella larvae, 10 primary and secondary hymenopteran parasitoids
were found in the Pazardzhik region: Chrysocharis nephereus (Walker), Chrysocharis sp.
1, Chrysocharis sp. 2, Cirrospilus elegantissimus Westwood, Cirrospilus lyncus Walker,
Cirrospilus pictus (Nees), Kratoisma usticrus (Erdös), Sympiesis sericeicornis (Nees),
Sympiesis sp. and Tetrastichus sp. (Hymenoptera: Eulophidae) (Georgiev, Pelov, 1996;
Georgiev, 2005). e hyperparasitoid Tetrastichus sp. was detected in K. usticrus, C.
nephereus, S. gyori, S. sericeicornis and Sympiesis sp. e host mortality caused by all
parasitoid species reached up 77.6%, and K.usticrus had the strongest impact on the host
population (Georgiev, 2005).
In G. aceriana larvae, 6 hymenopteran parasitoids were found in the Pazardzhik
region: Bracon variator Nees, Macrocentrus marginator (Nees), Orgilus obscurator (Nees),
Apanteles erevanicus Tobias (Hymenoptera: Braconidae), Pristomerus ruabdominalis
Ucida and Pristomerus vulnerator (Panzer) (Hymenoptera: Ichneumonidae) (Georgiev,
1995). e total mortality of G. aceriana larvae caused by parasitoids ranged between
5.9 and 28.6% in the rst host generation and between 35.8-44.4% in the second host
generation (Georgiev, Samuelian, 1999). A. erevanicus was the most common parasitoid,
causing host mortality of up to 27.5%.
In larvae of P. tabaniformis, 5 parasitoids were found in the Pazardzhik region:
Apanteles evonymellae (Bouché), Bracon intercessor Nees (Hymenoptera: Braconidae),
Eriborus terebrans (Gravenhorst), Pristomerus vulnerator (Panzer) and Dolichomitus
populneus (Ratzeburg) (Hymenoptera: Ichneumonidae) (Georgiev, Tsankov, 1995;
Georgiev et al., 2001). Host mortality caused by all parasitoid species was 27.6%, and A.
evonymellae was the most common parasitoid, causing host mortality of 18.6%.
In L. salicis larvae and pupae, 9 parasitoid species were found in the Pazardhik region:
eronia atalantae (Poda) (Hymenoptera: Ichneumonidae), Brachymeria intermedia
(Nees), Brachymeria minuta (Linnaeus) (Hymenoptera: Chalcididae), Monodontomerus
aereus Walker (Hymenoptera: Torymidae), Compsilura concinnata (Meigen), Exorista
larvarum (Linnaeus), Pales pavida (Meigen) (Diptera: Tachinidae), Agria mamillata
(Pandelle) (Diptera: Sarcophagidae) and Megaselia sp. (Diptera: Phoridae) (Georgiev,
1996a). Six species (B. intermedia, M. aereus, C. concinnata, E. larvarum, P. pavida and
A. mamillata) were conrmed as primary parasitoids. One species (T. atalantae) was both
a primary and secondary parasitoid, and two species (B. minuta and Megaselia sp.) as
hyperparasitoids on P.mamillata. e parasitoids reduced the pest population by 36.7%,
and A. mamillata and B. intermedia had the strongest impacts.
In T. pityocampa, 7 egg parasitoids were found in Kurtovo, Banya, Yanino, Kardzhali,
Ivaylovgrad, Rozino, and Klisura regions: Baryscapus servadeii (Domenichini), Baryscapus
transversalis Graham, Pediobius bruchicida Rondani (Hymenoptera: Eulophidae),
Anastatus bifasciatus (Georoy), Eupelmus vesicularis (Retzius) (Hymenoptera:
Eupelmidae), Ooencyrtus pitiocampae Mercet (Hymenoptera: Encyrtidae) and
Trichogramma embryophagum Hartig (Hymenoptera: Trichogrammatidae) (Tsankov et
al., 1996a, 1996b; Mirchev et al, 1998; Mirchev, Tsankov, 2001; Mirchev, 2005; Mirchev
et al., 2011). Six of these species are primary parasitoids, and one (B. transversalis) is a
hyperparasitoid of B. servadeii and O.pitiocampae.

47
Four species were found as egg parasitoids of T. solitaria in the regions of
Ivaylovgrad and Madzharovo for the rst time: Anastatus bifasciatus (Hymenoptea:
Eupelmidae), Ooencyrtus pityocampae Mercet, Ooencyrtus masii (Mercet) and Ooencyrtus
sp. (close to O. indenitus Myartseva) (Hymenoptea: Encyrtidae) (Mirchev et al., 2014;
Boyadzhiev et al., 2017).
In D. pini pupae in Topolovgrad region, 4 hymenopteran and dipteran parasitoid
species were found: Agrothereutes adustus (Gravenhorst), Exenterus amictorius (Panzer),
Olesicampe sp. (Hymenoptera: Ichneumonidae) and Drino inconspicua (Meigen)
(Diptera: Tachinidae) (Georgiev, Bochev, 1996). Parasitoids caused mortality rates of
31.6% in D. pini and A. adustus had the strongest impact on the host population
In Ognyanovo region, 3 parasitoids of N. sertifer were detected. Two species,
Dipriocampe diprioni (Ferriére) (Hymenoptera: Tetracampidae) and Baryscapus oophagus
(Otten) (Hymenoptera: Eulophidae), were reared from host eggs (Georgiev, 2001b), and
Agrothereutes adustus from host pupae (Georgiev, Kolarov, 1999). D. diprioni was found
as a primary parasitoid, and B. oophagus as a hyperparasitoid.
Two parasitoids were detected and reported for rst time in Bulgaria: Diplostichus
janithrix (Hartig) (Diptera: Tachinidae) in Gilpinia sp. in the Ognyanovo region
(Georgiev, 1996b), and Ibalia leucospoides (Holchenwarth) (Hymenoptera: Ibaliidae) in
Tremex fuscicornis in the Manole region (Ljubomirov et al., 2006).
We conclude that the pathogens and parasitoids found in the region of the Forest
Protection Station Plovdiv form an extensive natural enemy complex, maintaining the
population densities of insect pest species at lower levels. is is particularly important for
species that potentially increase to outbreak densities and whose populations then cause
economic losses in forest ecosystems or severe allergies to humans and animals (L. dispar,
E. chrysorrhoea, E. defoliaria, T. pityocampa, L. salicis, T. solitaria, etc.). Some fungal
pathogens (E. maimaiga, E. aulicae, B. bassiana) are already used in forest protection as
classical or augmentation biological agents.
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E-mail: dpilarska@yahoo.com