Parasitoids of Ips typographus (Coleoptera: Scolytidae) - Journal of ...

Volume 16(1), 171-173, 2012
JOURNAL of Horticulture, Forestry and Biotechnology
www.journal-hfb.usab-tm.ro
Predators of Pityogenes chalcographus (Coleoptera:
Scolytidae) in Natural Park Apuseni
Fora, C.G. 1* , Lauer, K.F. 2 , Berar, C. 1 , Ştefan, C. 1 , Silivăşan, M. 1 , Lalescu, D. 1
1 Banat University of Agricultural Sciences and Veterinary Medicine from Timisoara; 2 University of Applied
Sciences Weihenstephan-Triesdorf
* Corresponding author. Email: foraciprian@yahoo.com
Abstract Alongside the European spruce bark beetle, in the Natural Park
Apuseni, the small spruce bark beetle Pityogenes chalcographus encountered
favourable mass reproduction conditions. Thus, massive attacks at the trees’
feet were observed in different arboreta. This phenomenon will largely spread
unless urgent measures for eradicating the pest hole are undertaken. This is
why we have decided to investigate the parasitoid populations for Pityogenes
chalcographus in the protected environment. In 2011 the most numerous
species were: Nemosoma elongatum, Rhizophagus cribratus, Rhizophagus
depressus, Thanasimus formicarius, Quedius plagiatus, Quedius lateralis,
Quedius cruentus, Quedius xanthopus.
The Natural Park Apuseni, 75.784 ha in surface, is
situated in the Bihor Mountains of the Western
Romanian Carpathians.
The construction of the natural park took place in
2004, in order to protect the karstic values of the area,
the tradition and the flora and fauna biodiversity, listed
as V IUCN category - Protected areas. In the protected
area two zones were created. The first one is a
conservation zone, occupying approximately 18% of
the total park surface, and the second one, a buffer
zone, occupying the rest of the surface, approximately
82%.
In the natural park, wood vegetation is dominant
and it covers approximately 75% of its total surface.
Wood species are mainly represented by spruce (70%),
beech (27%), fir (2%). Other resinferous species are
represented, like the scots pine and the larch or
deciduous species like the ash, the holm, the sycamore
maple, the birch and the elm, which get mixed up with
the dominant species. The spruce either forms pure
arboreta or it mixes with the ash and the fir forming
valuable arboreta.
Together with Ips typographus, due to its size and
to the fact that it predominantly attacks the crown of
the host trees, Pityogenes chalcographus is in its turn
one of the most important predators of the spruce in
Romania. That is why we have to examine it most
carefully. We are motivated by the fact that, initially,
the Pityogenes chalcographus attacks thin parts of the
Key words
Pityogenes chalcographus,
predators, Natural Park
Apuseni
spruce’s crown, contributing thus to their
supplementary destabilization and creating favourable
conditions for the installation of the Ips typographus
species, which undertakes the final blow leading to the
desiccation and death of the attacked trees. The only
chance of stopping the mass reproduction of the Ips
typographus species as well as of the Pityogenes
chalcographus pest is to transport the infested wood
outside the arboreta (Feicht, 2004). Unless immediate
measures are undertaken in order to stop such attacks,
the effects upon natural or planted forests will be
catastrophic on large surfaces (Niemeyer et al., 1995;
Dengler, 1995; Weslien and Schroeder, 1996). As a
general rule, the predators of the studied species are not
taken into account, since it is estimated that they do not
have a major influence on the abundance in number of
the pest species. The hypothesis that parasitoids have a
decisive influence in the reduction of pest populations
is not yet fully verified.
Material and Method
Study area
The sampling areas were set in the special
conservation zone of the Natural Park Apuseni, were
wood material infested by the bark beetle was
identified. Thus, three areas were chosen in Poiana
Ponor, Valea Someşului Cald and Cheile Ordâncuşii
(table 1).
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Table 1
Characteristics of the plots in the Natural Park Apuseni
Location
Arboretum
composition
Average
age
Consistency Litter Altitude Array Declivity Tree
no.
Sample
no.
Poiana Ponor 10MO 100 0.7 4 1160 SV 21 2 8
Valea Someşului
Cald
10MO 120 0.7 3 1175 S 20 2 8
Cheile Ordâncuşii 6MO 4FA 70 0.8 3 868 SE 36 2 8
Sampling method
The sampling trees were chosen from those
infested, and the sampling took place in two takes. The
total tree number and the samples taken are presented
in table 1. The first take of peaks and branches was
sampled after flight I (10 June) and the second take
after flight II (27 July). From each tree 4 samples were
taken, thin parts of the crown (peaks and branches)
infested by bugs. Each sample measured 1m in length
6-12 cm in diameter, since it is a well know fact that
Pityogenes chalcographus predominanatly attacks
bodies less than 15 cm in diameter (Stolina, 1969).
Thus, in take I 12 infested assays were gathered and in
take II other 12 assays. The samples thus constituted
were numbered, introduced in collectors and set in
three locations near the sampling areas (Padiş, Doda
Pilii, Casa de Piatră).
Collectors
The collectors (figura 1) are made from PE type
transparent pipes, with 30 cm in diameter and 1 m in
length, placed vertically. At their inferior end the
collectors have a broad cone which at its base unloads
in an insect collecting recipient.
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Fig. 1. Collectors for insects (Natural Park
Apuseni/Padiş)
On their superior side, the collectors have a cloth
which allows inside ventilation but does not allow the
insects to exit. Once in 7 days the insects are collected
in plastic recipients, they are numbered and dated. The
last verifications were carried out in 19.09.
Species identification
The samples were analysed in the Forest
Entomology laboratory of the Faculty for Horticulture
and Forestry of Timişoara, from the point of view of
the species composition as well as from a quantitative
point of view.
Results and Discussions
During the 3 months observation period, 8 main
predator species for the Pityogenes chalcographus
beetle could be identified (figura 2), as follows:
Nemosoma elongatum (Coleoptera: Trogositidae),
Rhizophagus cribratus (Coleoptera: Monotomidae),
Rhizophagus depressus (Coleoptera: Monotomidae),
Thanasimus formicarius (Coleoptera: Cleridae),
Quedius plagiatus (Coleoptera: Staphylinidae),
Quedius lateralis (Coleoptera: Staphylinidae), Quedius
cruentus (Coleoptera: Staphylinidae), Quedius
xanthopus (Coleoptera: Staphylinidae).
The first three species represented 90.74% (figure
2) of the total captured predator number: Nemosoma
elongatum, Rhizophagus cribratus şi Rhizophagus
depressus. Less represented were the species
Thanasimus formicarius, Quedius plagiatus, Quedius
lateralis, Quedius cruentus and Quedius xanthopus. On
all three locations Nemosoma elongatum was the
dominant species of main importance. Not the same
can be said about the other 7 species which, together,
represented less than 24% of the total captures. The
Nemosoma elongatum species was encountered in
every wood sample from the collectors of both take I
and II, thus accounting for the greatest frequency. Next
in line was the predator Rhizophagus cribratus which
represented 25% of the take I samples and 67% of the
take II samples. Rhizophagus depressus was present in
42% of the take I samples and in 50% of the take II
samples. Thanasimus formicarius came up in 25% of
the take I samples and in 25% of the take II samples.
Quedius plagiatus was present in 20% of the take I
samples and in 20% of the take II samples. Quedius
cruentus came up in 17% of the take I samples and in
20% of the take II samples. Quedius lateralis and
Quedius xanthopus were in 8% of the take I samples
and in 17% of the take II samples.

100%
80%
60%
40%
20%
0%
17.6. 21.6. 28.6. 5.7. 12.7. 19.7. 26.7. 1.8. 8.8. 15.8. 22.8. 29.8. 5.9. 12.9. 19.9. Total
Nemosoma elongatum Rhizophagus cribratus Rhizophagus depressus Quedius plagiatus
Quedius lateralis Quedius cruentus Quedius xanthopus Thanasimus formicarius
Fig. 2. Specific relative abundance of predators in Poiana Ponor, Valea Someşului Cald and Cheile Ordâncuşii
Although 8 predator species were identified in the
wood samples in all three locations of the natural park,
we can not say whether they largely influenced the
Pityogenes chalcographus populations. Still, their
presence indicates the fact that there is a connection
between the predators and their pray in the studied
perimeter.
Conclusions
The research carried out on the predators of the
spruce bark beetle Pityogenes chalcographus, in 2011,
on 3 locations from the Natural Park Apuseni (Poiana
Ponor, Valea Someşului Cald and Cheile Ordâncuşii)
led to the following conclusions:
1. From the 8 main predator species
identified, Nemosoma elongatum,
Rhizophagus cribratus and Rhizophagus
depressus were the best represented.
Thanasimus formicarius, Quedius
plagiatus, Quedius lateralis, Quedius
cruentus and Quedius xanthopus
represented less than 24% of the total
captures.
2. The frequency of the predators’ appearance
in the 24 studied samples was of 100% for
the Nemosoma elongatum species, 46% for
Rhizophagus cribratus and Rhizophagus
depressus, 25% for Thanasimus
formicarius, 20% for Quedius plagiatus,
18.5% for Quedius cruentus and 12.5% for
Quedius lateralis and Quedius xanthopus.
Acknowledgements
This study was financed by the project “Postdoctoral
School in Agriculture and Veterinary Medicine”,
POSDRU/89/1.5/S/6237, co-financed by the European
Social Fund, through the Sectorial Operational
Programme for Human Resources Development 2007-
2013. We would like to thank the administration of
Natural Park Apuseni for technical support and general
permission. Also, our thanks to Mister Mircu Adrian
from the Institute for Research and Forest Facilities of
Timişoara, who helped determine the species.
References
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