Distribution of Entomopathogenic Nematodes from the

Distribution of Entomopathogenic Nematodes from
the Eastern Black Sea Region of Turkey
Huseyin YILMAZ1,2, Lieven WAEYENBERGE3, Ismail DEMIR2,
Zihni DEMIRBAG2 & Maurice MOENS3*
1 Department of Biology, Faculty of Arts and Sciences, Giresun University, 28049, Giresun, Turkey
2 Department of Biology, Faculty of Arts and Sciences, Karadeniz Technical University, 61080 Trabzon, Turkey
3 Institute for Agricultural and Fisheries Research (ILVO), Burg. Van Gansberghelaan 96, 9820 Merelbeke, Belgium
* Corresponding author, email: [email protected]
Introduction
Entomopathogenic nematodes (EPNs) of the genera Steinernema Travassos and Heterorhabditis Poinar are obligate pathogens that infect a wide range of soil insects.
Currently, there are about 69 valid EPN species belonging to Steinernematidae (56) and Heterorhabditidae (13) families. When screening EPN species or strains for
controlling a specific insect pest, the better adapted an EPN is to local environmental conditions and the targeted pest, the higher the level of efficacy likely to be achieved.
Therefore, it is important to survey for and preserve indigenous EPN species or strains.
Turkey, a country of 784560 km2, is located between Europe and Asia as a bridge. A few EPN surveys have been conducted and demonstrated the presence of S. affine, S.
carpocapsae, S. feltiae, S. weiseri, S. anatoliense (an endemic species) and H. bacteriophora (Hazir et al., 2003). We report the preliminary results of a detailed survey study
on the distribution of EPNs in the North-Eastern part of Turkey in view of their use against economically important insect pests in this area.
Materials and Methods
Soil samples were collected in the period May 2006 to November 2007 from different localities,
habitats (viz. hazelnut and tea plantation areas, spruce forests, vegetables fields, grasslands etc.)
and altitudes in the North-Eastern part of Turkey (Fig. 1). Soil samples were baited with Galleria
mellonella (L.) larvae. Dead larvae were placed into White traps (White, 1927) and infective
juveniles were used to reinfect G. mellonella larvae.
For light microscopy investigations, nematodes were fixed in hot 4% formalin (60-80°C). Fixed
nematodes were transferred to anhydrous glycerine. All measurements were made using an
Olympus BX50 light microscope.
DNA extraction and PCR amplification of ITS regions of rRNA were performed as described by
Spiridonov and Moens (1999). PCR products were cloned to pGEMT vector, transformed to E.coli
JM109 cells and sequenced. Multiple sequence alignments were performed by ClustalX 1.81 and
arranged manually by GeneDoc.
Figure 1. EPN sampling sites map in the Eastern Black Sea Region: Steinernema
ssp. (dark circles) , Heterorhabditis ssp. (stars), no nematodes (light circles).
Results
Entomopathogenic nematodes were recovered from 9 of 224 soil samples (4%) taken 62 sampling sites (Fig. 1) from different habitats (Table 1). Out of the 9 positive
samples, 5 steinernematids (55%) and 4 heterorhabditids (45%) were detected. Using their morphology and morphometrics, the isolates were identified as Steinernema
carpocapsae (3), S. affine, S. feltiae, Heterorhabditis bacteriophora (3) and H. megidis (Table 2). The sequences of the ITS and D2-D3 region of rDNA confirmed this
identification.
Table 2. Locality, soil type, habitat and altitute of entomopathogenic nematodes isolated from the Eastern Black Sea Region of Turkey.
Table 1. Localities of EPN-positive soil samples.
Sampling area
No. of soil
No. of
% of with
samples
with EPNs
EPNs
Hazelnut field
70
3
4,2
Vegetable field
53
3
5,6
36
1
3,7
25
1
4
(Tea, Maize, Bean, Cabbage, Potato)
Forest
(Picea, Alnus, Populus, Quercus etc.)
Grassland
Roadside edge
16
0
0
Others
24
1
4,1
Total
224
9
4
Species & isolate name
Locality
Soil Type
Habitat
Altitute (m)
Sampling date
S. carpocapsae S1
Surmene, Trabzon
Sandy-clay-loam
Hazelnut field
20
Apr, 2006
S. carpocapsae B122
Balaban, Trabzon
Sandy-loam
Vegetable field
950
Aug, 2006
S. carpocapsae G14
Kumbet, Giresun
Clay
Mixed spruce forest
1160
Apr, 2006
S. feltiae B1
Bulancak, Giresun
Sandy-loam
Vegetable field
25
Mar, 2007
S. affine U36
Unye, Ordu
Sandy-clay-loam
Hazelnut field
70
Mar, 2007
H. bacteriophora M3
Yomra, Trabzon
Sandy-loam
Hazelnut field
100
Sep, 2006
H. bacteriophora D51
Duzkoy, Trabzon
Sandy-clay-loam
Grassland
220
Mar,2007
H. bacteriophora D52
Duzkoy, Trabzon
Loam
Vegetable field
250
Mar, 2007
H. megidis P69
Pazar, Rize
Sandy-clay-loam
Bank of a small river
5
Jul, 2006
Conclusions
H. megidis is recorded for the first time from Turkey. Here, we report the occurrence of S. affine in Asia for the second time. The habitats from which the entomopathogenic
nematodes were isolated were broadly classified as disturbed (66.6%), which included agricultural fields and hazelnut planted areas, and undisturbed (33.3%), which
included spruce forest and grassland. In view of the results of this and previous survey it may be concluded that EPNs are quite diverse in Turkey, but distributed at a low
frequency. Further research will be directed to determine the insecticidal effects of these isolates against the soil-borne insect pests in this region.
References
•Hazır, S., Keskin, N., Stock, P. S., Kaya, HK. & Özcan, S. (2003). Diversity and distribution of entomopathogenic nematodes in Turkey. Biodiversity and Conservation 12: 375-386.
•Spiridonov, S. E. & Moens, M. (1999). Two previously unreported species of steinernematids from woodlands in Belgium. Russian Journal of Nematology 7: 39-42.
•White, G. F. (1927). A method for obtining infective nematode from cultures. Sciences 66: 302-303.