A willow sawfly, Nematus salicis (Linnaeus) (Hymenoptera: Tenthredinidae), a new record and new pest of Salix spp. in Turkey

2006·3.3 MB·

by  Önder Calmasur

PROC. ENTOMOL. SOC. WASH.
108(1), 2006, pp. 139-144
A WILLOW SAWELY, NEMATUS SALICIS (LINNAEUS)
(HYMENOPTERA: TENTHREDINIDAE), A NEW RECORD AND NEW PEST
OF SALIX SPP. IN TURKEY
ONDER CALMASUR AND HIKMET OZBEK
Atatiirk University, Agricultural Faculty, Department of Plant Protection, 25240 Erzu-
rum, Turkey (e-mail: [email protected]; hoz@ abtaueni.ekdu.t r)
Abstract.4A willow sawfly, Nematus salicis (Linnaeus, 1758) (Hymenoptera: Tenthre-
dinidae), is a new record for the Turkish fauna and a new pest of willow (Salix spp.) in
Turkey. Its developmental stages, biology, damage, and parasitoids were studied in Er-
zurum during 2002 and 2003. Adults appear during the last three weeks of August, and
females insert eggs in groups under the cuticle of the lower surface of willow leaves
starting at the leaf apex. Larvae are leaf-edge feeders and consume the entire leaf leaving
only the midrib. Nematus salicis is univoltine and overwinters as prepupae in cocoons in
the soil. One larval parasitoid was reared, Hyperbatus segmentator (Holmgren) (Hyme-
noptera: Ichneumonidae), which is new record for Turkey. One species of egg parasitoid,
Tetrastichus sp. (Hymenoptera: Eulophidae) also was reared. The percentage of larval
parasitism is low, but egg parasitism averages 32.8%.
Key Words: Nematus salicis, Tenthredinidae, Hymenoptera, willow pest, Salix
Willow (Salix spp., Salicaceae) species (Gauld and Bolton 1988, Fritz et al.1986,
are grown predominantly along rivers and Roininen 1991).
streams, especially in the eastern and cen- Larvae of Nematus salicis (Linnaeus) are
tral regions of Turkey. Most species are free feeding and are important willow pests.
valuable and popular because of their rapid Although the species is widespread in
growth and have been the trees chosen for northern and central Europe and Caucasia
plantations where a quick return on the in- (Lacourt 1999), this is the first record of the
vestment was desired by villagers. They species from Turkey.
have been used as firewood and timber, and, There have been very few studies of the
to a lesser extent, as conservation and or- tenthredinid pests of willow in Turkey.
namental plantings. Salix species are also Croesus septentrionalis (Linnaeus) and Tri-
important for erosion control in the country. chiocampus viminalis (Fallén) were recog-
Sawflies are one of the most common nized for the first time as willow and poplar
and diverse groups of insects found on wil- pests in Turkey by Acatay (1943) and Er-
lows (Benson 1950, Kontuniemi 1960). Ne- dem (1962), respectively. Bas (1973) added
matus Panzer is the one of the largest gen- some data on the damage and biology of
era of Tenthredinidae associated with wil- these species. Recently, Calmasur and Oz-
lows. Of the willow sawflies, many species bek (2004a, b) recorded additional tenthre-
induce leaf and stem galls and some make dinid species feeding on willow leaves, in-
leaf rolls, but most species are free-feeding cluding the larvae of Rhogogaster chloro-
and important defoliators or skeletonizers soma Benson, Allantus togatus (Panzer),
140 PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON
Table 1. Rain, temperature, and humidity in 2002 and 2003 in Erzurum (Meteorology District Directorship).
Total Rain/mm Average Temperature (C°) Average Humidity (%)
Months 2002 2003 2002 2003 2002 2003
May 73.1 29.9 9.8 11.6 55.8 52.0
June 74.0 45.7 14.3 14.5 57.0 50.6
July 32),1 18.5 18.3 18.9 53.0 49.3
August 54.6 Sel 16.6 20.0 53.6 42.7
September 18.1 19.3 13.6 SES S229 46.3
and Tenthredo livida Linnaeus. Canakciog- the willows at 3 or 4 day intervals. The
lu (1993) listed Salix caprea as the host larva were reared in cages (30 X 30 X 50
plant of Eriocampa ovata (Linnaeus). cm) and provided with shoots of willows
The purpose of this study is to record the inserted in glass containers with water. Lar-
habits and biology of this new pest in the vae were transferred to the leaves. Egg mas-
ecological conditions of Erzurum, Turkey. ses with leaves were placed in 90 mm Petri
dishes in the laboratory and emerging par-
MATERIAL AND METHODS
asitoids were collected with an aspirator.
This study was conducted in 2002 and Twenty larvae, cocoons, and adults were
2003 on the campus of Atatiirk University measured for body length and head capsule
in Erzurum, which is located near the base dimensions.
of Paland6ken Mountain (over 3,000 m) in
eastern Turkey (39°549005'N and RESULTS
41°41'184"E, at an altitude of 1,85041,900 Description.4Adult (Fig. 2d): General
m). Erzurum has cold and snowy winters, body color yellow, only compound eyes,
rainy springs, and dry summers, with an av- vertex, ocellar area, mesonotum, and sheath
erage temperature of 5.3°C and relative hu- black. Head from above transverse, broader
midity of 64.2% in 1950-2002. The aver- than long in female with black areas on ver-
age temperature was 5.1°C in 2002 and tex narrower than those of the male. Anten-
2003. The average temperature of May, na dark brown on dorsal surface, light
June, July, August, and September in 2002 brown on ventral surface; 9-segmented,
and 2003 are given in Table 1. with 3# antennal segment approximately
Over 30 species of Salix occur in Turkey, equal to longest ocular diameter; antenna
but only three species are present as orna- almost equal to body length in male, slight-
mental plants on the Atatiirk University ly longer than half body length in female.
campus, Salix babylonica L., S. nigricans Wings uniformly lightly infuscated, costa
Smith, and S. grandifolia Seringe. Salix ba- and stigma black, other veins brownish;
bylonica is the most abundant. body length 6.0411.5 mm.
Study of Nematus salicis began after Egg (Fig. 2a): Bean shaped, dirty white;
damage by sawfly larvae were observed on dimensions 0.640.7 mm and 1.3541.56 mm.
the leaves of Salix on the campus in 2001. Larva (Fig. 2b): Head black, thorax and
Adults were reared from these larvae and last abdominal segments yellow, first 8 ab-
identified as Nematus salicis. Starting in the dominal segments greenish blue, each body
early summers of 2002 and 2003, willow segment marked with 5 black spots which
trees on the campus were checked at sev- form stripes along the body. Thoracic legs
eral-day intervals, and the biology and blackish blue, prolegs translucent, present
damage of N. salicis were recorded. Addi- on abdominal segment 247 and 10. Late in-
tionally, in order to obtain parasitoids, lar- star larva 2.043.3 cm long (Fig. 2b). Larval
vae and eggs were collected randomly from dimensions (average lengths): Ist instar: 0.4
VOLUME 108, NUMBER 1 141
June Jisty August September October
2003
Overnantenng
Seplember October
Fig. 1. Duration of biological stages of Nematus salicis in Erzurum in 2002 (top) and 2003 (bottom).
chile Sanstar: fl 1.em,.3# instar: 1:9;em,j4" renchyma tissue for a short period, then
instar: 2.5 cm. Head capsule length and continued feeding on the edges of the
width: (0.7540.65 mm), (1.4841.38 mm), leaves, usually consuming the entire leaf
(2.0241.97 mm), (2.742.45 mm) first, sec- leaving only the midrib. The larvae pass
ond, third, and fourth instars respectively. through four instars. Mature larvae fell to
Biology (Fig. 1).4Adults first emerged the ground under the trees on which they
on August 9 in 2002 and August 11 in developed and burrowed into the soil for a
2003. The emergence period lasted about 2 distance of 2-10 cm. Here they constructed
weeks. Females started to oviposit on Au- a brown cylindrical cocoon with soil parti-
gust 14 and August 18 in 2002 and 2003, cles fastened on its surface, 4.046.3 cm
respectively. Eggs were inserted in groups long and 1.642.7cm wide (Fig. 2c). Over-
under the cuticle of the lower leaf surface, wintering was as a prepupa in a cocoon. In
Starting at the tips of the leaves (Fig. 2a). both years, larvae entered soil the first week
Groups of eggs reached from the tip to the of October. However, we observed low
middle of the leaves when females depos- numbers of larvae feeding on the leaves un-
ited the highest numbers of eggs. Numbers til October 20 in 2003. There is only one
of eggs were 8464 per group (mean = 44, generation a year under the ecological con-
SE = + 4.3, n-= 20 groups). Oviposition ditions at Erzurum during the two years ob-
lasted until mid-September. Eclosion first served.
occurred on August 19 and August 26 in An epidemic of N. salicis on willow oc-
2002 and 2003, respectively, and lasted curred in the summer of 2002 on the uni-
about 10 days. Young larvae fed on the pa- versity campus, and the larval population
142 PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON
Fig. 2. Damage and biological stages of Nematus salicis. a, Egg. b, Larva and damage. c, Cocoon and
prepupa. d, Adult. e, Damage. f, Hyperbatus segmentator ovipositing in the larva of N. salicis.
was much higher than in 2003. Larvae con- (Hymenoptera: Ichneumonidae: Ctenopel-
sumed all leaves and defoliated the trees of matinae) (Fig. 2f) and one egg parasitoid,
Salix babylonica (Fig. 2e). Because of their Tetrastichus (Hymenoptera: Eulophidae)
high density and lack of preferred food, lar- were reared. The percentage of larval par-
vae left the trees after defoliation to find a asitism was low, but egg parasitism aver-
new food sources. The ground was almost aged 32.8% (SE = 2.4, n = 19). Hyper-
covered with larvae. We counted more than batus segmentator is also a new record for
100 larvae searching for food plants in 1m/?. the Turkish fauna.
We observed that N. salicis preferred S. ba-
bylonica as food plant rather than S. nigri- DISCUSSION
cans and S. grandifolia. However, since The occurrence of Nematus salicis in
most of the S. babylonica trees on the cam- Turkey is not unexpected since it is known
pus were defoliated (Fig. 2e) there was se- form Europe and Caucasus. According to
rious damage also on other Salix species. In the classification of the Turkish fauna re-
spite of an outbreak of N. salicis on the cently proposed by Vigna-Taglianti et al.
campus in 2002, there was negligible larval (1999), we place N. salicis in the European
feeding on the leaves of Populus tremula chorotype, which includes species that oc-
Linnaeus and P. nigra Linnaeus although cur in Europe, Caucasus, and Turkey.
we found some egg masses on the leaves Our observations showed that N. salicis
of both poplar species. is an important pest of Salix species, partic-
In the laboratory, one larval parasitoid, ularly Salix babylonica in Erzurum Prov-
Hyperbatus segmentator Holmgren, 1857 ince. The epidemic of N. salicis on willows
VOLUME 108, NUMBER 1 143
in the summer of 2002 on the university ment of Agriculture, Washington, DC, for
campus could be related to more precipi- determination of the sawfly and making
tation in 2002 than 2003 (Table 1.). comments on the first version of manu-
Our study compares favorably with stud- script. We also thank to Dimitriy R. Kas-
ies by Martinek (1958) on Nematus salicis paryan, Zoological Institute, Russian Acad-
from the former Czechoslovakia and by emy of Sciences, St. Petersburg, Russia, for
Lacroix (1928) from France. Martinek identification of the ichneumonid. We are
(1958) studied populations on Salix alba L. grateful to M. Doganlar, M. Kemal Univer-
and S. fragilis L. and Lacroix (1928) on Sa- sity, Hatay, for determination of the egg
lix spp. In our studies, Salix babylonica was parasitoid.
the preferred host species. Also, we found
only one generation a year in the ecological LITERATURE CITED
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ACKNOWLEDGMENTS
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144 PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON
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