Lakhasly

INTRODUCTION The Aleppo pine (Pinus haleppensis) is the most common tree in Algeria and it has a very important place in the balance of Mediterranean ecosystems.Among the individuals collected, T. destruens and O. erosus were the only species found in living trees, demonstrating that O. erosus is also capable of attacking stressed trees while it is usually considered as a secondary beetle.The vegetation is composed of Aleppo pine (Pinus halepensis Mill.), Atlas cedra (Cedrus allantica Manetti), holm oak (Quercus ilex L.), narrow?leaved mock privet (Phillyrea angustifolia L. Rouy), turpentine tree (Pistacia terebinthus L.), lentisk (Pistacia lentiscus L.), Phoenicean juniper (Juniperus phoenicea L.), cade juniper (Juniperus oxycedrus L.), rosemary (Salvia jordanii J.B.Walker), globe daisies (Globularia alypum L.) and hairy thyme (Thymus munbyanus subsp.It is in the middle of three provinces Setif, Bordj Bou Arreridj and M'sila (35?48'36.3"N 5?08'58.5"E, 700- 1500 m asl.). The annual rainfall is 396 mm and the mean annual temperature is 14.17?C. The majority of the massif is made of hard dolomitic limestones and marls. The most widespread forest formations in the area are composed of Aleppo pine, holm oak, Atlas cedra, Phoenicean juniper, cade juniper, globe daisies, narrow-leaved mock privet, oriental hawthorn (Crataegus laciniata), and Eucalyptus tree (Eucalyptus sp.). The Ouannougha forest (17671 ha) is a part of the mountain range of Bibans, it is located in the province of Bordj Bou Arreridj (36?09'35.2"N, 4?12'16.8"E, 900-1280 m asl.), 420 mm of precipitation falls annually with a mean annual temperature of 15.6 ?C.Orthotomicus), procoxae contiguous, intercoxal piece longitudinally emarginate to absent, never complete; elytra moderately sulcate to elaborately excavated, with lateral margin usually armed by tubercles or spines; pronotum more strongly declivous on anterior third, asperities usually larger; worldwide (Wood 1986) Orthomicus erosus Wollaston, 1857 (Mediterranean pine beetle) Close to the genus Ips, from which it is distinguished by the straightness of its declivity whose apical edge is not explained backward.MATERIALS AND METHODS Study area The study was carried out in a semi-arid region located in the Hodna and the Bibans Mountains, in North-Eastern Algeria, between 35?41'05.2" and 36?11'34.0" latitude (N) and 4 and 5? longitude (E), and at an altitude of 900-1300 m. The three forests of Boutaleb, Ouled Tebben and Ouenougha were selected for sampling, taking into account the forest dieback, the surface area of the forests and their ecological importance in the region (Figure 1). The study area is part of the semi-arid bioclimatic domain. Twenty?three, 25 and 30 sites were investigated in the Boutaleb, Ouled Tebben and Ouenougha forests, respectively (Figure 1). The Boutaleb forest (28427 ha) is located between the high Setifian plains to the north and the Hodna basin to the south (35?44'21.1"N 5?19'47.9"E, 950-1886 m asl.).Scolytinae subfamily Tibiae armed on apical and/or lateral margins either by spines or socketed denticles, apical mucro formed by mesal element (compared to Protohijlastes structure); male spiculum gastrale present, antennal club variable, with or without sutures, head narrower than pronotum; pronotum almost never with constriction near middle, pronotum edged on the sides and back.For example, with the aggressive Mediterranean species Tomicus destruens, the bored galleries damage the vascular system (xylem or phloem) and the cambium, resulting in various physiological imbalances (Chakali 2007; Lieutier et al. 2017).The trees composing this forest are Aleppo pine, holm oak, Atlas cedra, Phoenician juniper, and cade junie Bark beetles collection and identification Bark beetles were collected from Pinus helepensis trees in the three forests.Crypturgini tribe LeConte, 1876 Small size species, antennal funicle 2-or 3-segmented, club with sutures on posterior face about equal to those on anterior face; pronotum feebly declivous on anterior half and unarmed, punctuated, reticulate in many species (Balachowsky 1949; Wood 1986).Collected insects were observed under a stereomicroscope and grouped in morphotypes for the identification with keys according to their taxonomic characteristics ( Balachowsky 1949; Gil and Pajares 1986; Wood 1986; Alonso-Zarazaga 1988; Pfeffer 1995; Alonso?Zarazaga and Lyal 2009).The tunnel is about 8 to 10 cm long and 3 to 4 mm wide, the larval galleries develop in the bark thickness without affecting sapwood Discussion This study investigated the diversity of bark beetle species in the North-Eastern region of Algeria for the first time.Breeding in the bark of the trunk and branches of decaying pines previously infested by more aggressive species such Orthomicus, egg galleries forming a confused system partially bored into the bark thickness. Attacks by these two bark beetle species in coniferous forests rely on two complementary factors: the existence of trees weakened by stress and a certain level of pest population (Lieutier and Levieux 1985).Global warming and its consequences like repeated heatwaves and drought have a significant impact on trees and their predators, resulting in an increased mortality and forest decline (Morcillo et al. 2019).Global warming and its effects cause stress and weaken the defense of fragile trees, which facilitates the development of species already existing in the territory and potentially the introduction of new species of bark beetles (Suarez-Vidal et al. 2019).Ipini tribe Bedel, 1888 Eye shallowly sinuate with lower half narrower than above; protibia with 3-4 socketed teeth; antennal club rarely obliquely truncate (Pityokteines.This species which has long been confused with the neighboring species Tomicus piniperda, is responsible for the dieback of Aleppo pine forests in the semi-arid regions of Algeria (Guit et al. 2016).It is clear that the colonization of Aleppo pines is initiated by T. destruens, a more aggressive primary species, followed by O. erosus which is considered a secondary species (Lopez et al. 2007; Sanguesa-Barreda et al. 2015; Lieutier et al. 2016).The main objective of our study was to investigate the distribution of bark beetle species responsible for the decline of the Aleppo pine in the Central-Est semi-arid region of Algeria.Antenna funiculus is composed of 2 short segments, with an oval-shaped club provided with a fine and incomplete digitula, diffuse sutures rejected at the end.Pronotum longer than wide with parallel sides beyond the middle, with dense and tight punctuation, devoid of short bristle brushes at the apex of the elytra replaced with scattered silks denser than on the rest of the elytra. These two species are common on Pinus throughout the Mediterranean basin including the semi-arid regions in Algeria (Balachowsky 1949; Chakali 2004; Lopez et al. 2007; Lieutier et al. 2016).Species such as O. erosus, H. ligniperda, and C. micklitzi use aggregation pheromones to attract other individuals and thus massively attack the trees (Lieutier et al. 2016). Species of the genus Crypturgus are secondary bark beetles that occupy biotypes previously colonized by other species and do not affect healthy trees (Lieutier et al. 2016).In Algeria, 17 coniferous bark beetle species are monitored (Lieutier et al. 2016), but the bark beetle fauna of Algeria was not reviewed recently, and most of the existing records are old. Other scientific names: Crypturgus abbreviatus Eggers, Crypturgus barbeyi Strohmeyer, Crypturgus brevipennis Reitter Crypturgus mediterraneus Eichhoff, 1889 Has a size of 1,1-1,5 mm. Longer, slender shape (Figure 4). Mesal surface of elytra at suture with interlocking groove and flange continued to base without a series of nodules or cavities immediately behind scutellum (Balachowsky 1949; Wood 1986). Taking advantage of the entrances to the galleries of other species, the galleries of C. numidicus are bored irregularly throughout the thickness of the Aleppo pine bark, and these galleries are abandoned as soon as the bark dries out (Balachowsky 1949).However, trees can withstand the stresses and avoid dieback when favorable conditions return, but biotic factors such as pests can aggravate the stress and lead to their death (Anderegg et al. 2015).The attack occurs at different levels of plant vitality; some species develop on healthy plants, but many select hosts that are physiologically stressed or injured.The Boutaleb massif is exclusively made up of sedimentary rocks (marl, limestone, dolomite and clays with a lesser extension).Galleries: forming a marbled network that penetrates the thickness of the bark, rapidly reducing it to a spongy mass that is abandoned as soon as it dries out.This species is multiplying rapidly due to the physiological stress of Aleppo pines caused by climate change (Chakali 2004; Guit et al. 2016).In a recent survey in Europe, O. erosus was the most commonly found species in Portugal, Spain, France, Greece, Italy and Hungary (Faccoli et al. 2020).Several authors have reported the presence of these species in Algeria (Balachowsky 1949; Pfeffer 1995), and for instance, Nichane (2013) reported the presence of H. ligniperda in the region of Tlemcen.This poorly known species were abundantly found under the trunk bark of Aleppo pines in the Boutaleb forest, with galleries dug into the sapwood of dead trees.Other bark beetle species attack recently dead trees and introduce symbiotic fungi (Ambrosia), and the hatched larvae then feed on the mycelium of these fungi.Some of the bark beetles are known for their association with xylophagous fungi, which can aggravate the mechanical damage caused by the insects leading to dieback.The Ouled Tebben forest or Righa Dahra (14932 ha) is located in the east of the Boutaleb forest between the high Setifian plains to the north and the Hodna basin to the south.At least five colonized trees were chosen randomly in every sampling day, based on direct observation of the bark (trunk, branches) and the presence of boring dust or pitch tubes as indicators of bark beetle infestation.Pronotum coarsely and uniformly punctuated over its entire surface by large closely spaced dots of irregular diameter and not very deep.Crypturgus numidicus was the most abundant species in the three forests, followed by Orthomicus erosus and Tomicus destruens.When reaching a high population density, O. erosus can overwhelm the host defenses, thus causing tree mortality (Faccoli et al. 2020).Aphanommata filum live in conifer trunks, it has already been observed in Algeria (Folwaczny 1973; Alonso-Zarazaga 1988).This is consistent with the findings of H. Jordal (Jordal 2014), which showed that Rhyncolini species live in the wood and under the bark of dead trees, adults lay eggs in excavated tunnels, and show similar behavior as Scolytidae.Common pests are the pine processionary caterpillars and bark beetles (Lieutier et al. 2016; Bao et al. 2020).They are represented worldwide by 6,000 species grouped in 29 tribes (Alonso-Zarazaga and Lyal 2009).The Boutaleb forest was the most affected with a total number of individuals collected of 666 followed by the Ouenougha and Ouled Tebben forests with 547 and 416 individuals, respectively (Figures 2, 3, and Table 3).Crypturgus numidicus Ferrari, 1867 The genus Crypturgus comprises the smallest species within Scolytidae (0.8-1.5 mm).Crypturgus species exhibit a narrow-shaped and cylindrical elongated body (Figure 4), and a brown or black colour with shiny or matt reflections.It has a convex and smooth elytral declivity, without a denticular processes, bristles of the interstries at least twice as long as the stries.Anterolateral areas of pronotum unarmed; precoxal costa on prothorax absent.The mother gallery measures 10-16 cm, the larval galleries are numerous, irregular, long and intertwined (Balachowsky 1949).Tomicus destruens has been reported on Aleppo pines in the Djelfa region (Chakali 2004).Very few studies have focused on this species, which is common throughout Algeria and the most common bark beetle in the forests studied here.This confirms that this species nests in the bark of trunks and branches of dying Pine trees attacked by other bark beetles (Balachowsky 1949).Crypturgus mediterraneus is poorly spread and was detected here only in the forests of Boutaleb and Ouled Tebben.C. mediterraneus has been sampled in the thick bark of the trunks of trees colonized by O. erosus, where it uses the gallery systems of other species to penetrate and lay eggs.These last insects develop in lignified stems and feed on vascular tissues, from the shoots to the tree trunk.Most species develop on decaying trees or dead wood but some species can also colonize stressed living trees (Paine et al. 1997).Saproxylophagous insects that only develop in deadwood, are not considered as pests (Sauvion et al. 2013).The bark was removed to access the galleries and collect in situ all present insects, placed in sterile microtubes and then stored at 4?C.Dorsally the head is not visible, the anterior of the pronotum has transverse spicule bands.Stocky, broad, robust species, especially in the female, whose apical brushes of the elytra are very dense.Host plants: Pinus halepensis, P. pinaster, P. nigra, P. brutia (Pfeffer 1995).Hylurgini tribe Gistel, 1848 Pronotum, elytra and abdomen fully free of scales.Hylurgus ligniperda Fabricius, 1787 Elongated and cylindrical in appearance, with a size of 4.5-5.8 mm. General color of the body is black-brown with reddish antennae (Figure 4).Striations formed by a row of large, regularly spaced, shallow circular dots.Another differential character, from H. ligniperda, is the length of the lateral silks of the pronotum, which are the same size as the elytrals, while they are longer in H. ligniperda.Shiny black and finely dotted pronotum inclined forwards in relation to the elytra.On the other hand, Tomicus destruens is attracted by terpenes emitted from wounds in trees attacked by pioneer bark beetles.All these bark beetle species are associated with xylophagous fungi which probably play a role in the colonization of the host trees.Females of T. destruens preferentially seek for the northern slopes of the relief and the southern side of the tree to make their maternal gallery.In the region of Zaragoza in Spain, galleries of O. erosus occupy a large area of the attacked trees compared to T. destruens.The density of galleries of O. erosus on attacked Aleppo pine trees was higher than that of T. destruens (Sanguesa-Barreda et al. 2015).In Algeria, O. erosus can also colonize Atlas cedar trees (Talbi and Bouhraoua 2015).In the three forests studied, C. numidicus was sampled from the bark of trees colonized by O. erosus.In conclusion, 6 bark beetle species and one Cossoninae species were recorded for the first time in the center of the East region of Algeria.Therefore, the geographical distribution of bark beetle species in Algeria remains to be further clarified.There are no studies that focus on bark beetles in the study region despite the recent forest decline phenomenon.A total of 7 species were identified, 6 belonging to the Scolytinae subfamily and one to the Cossoninae subfamily (Table 2).Antennae mace sutures are procurved upwards in their middle in an arc shape.The margin of the elytral declivity is concave with 4 teeth on each side, the second ones are the largest and fused to the base of the third one.Galeries: Irregular star-shaped gallery with 2 or 3 arms, 4 to 8 cm long, sub-cortical in decaying trees.Has a size of 1.5-1.6 mm, antenna funiculus composed of 2 segments, antenna head formed by a single segment.Light colored, pronotum and underside of body more or less dark brown, elytra are much lighter and yellowish.Galleries: forming an irregular network that penetrates the thickness of the bark.Galleries: The female bore a longitudinal uniramous gallery in the middle-upper part of stem and large branches, sapwood is little affected.Another study showed the presence of T. destruens in the Tlemcen region in the extreme east of Algeria (Nichane et al. 2013).According to Chakali (2007), Mediterranean pine forests have been confronted with T. destruens over the last two decades.In our study, O. erosus was found on living trees in Boutaleb forest, suggesting that it can be a serious pest in semi-arid regions.The larval galleries are highly branched and start from the galleries of other species (Lieutier et al. 2016).This species colonizes the middle or upper part of the trunks of Aleppo pines (Markalas 1997).Hylurgus species are secondary bark beetles, attacking only weak or dead trees.The diversity of bark beetles in the studied region is low compared to other countries.The females dig a gallery under the bark to deposit their eggs into the cambium (Davi et al. 2020).Reference individuals for each species were stored in ethanol.RESULTS AND DISCUSSION Identification In this study, 1629 specimens were collected and identified from 76 Aleppo pine trees.When visible, scutellum usually flushes with elytral surface, often flattened (Wood 1986).Elytra with deep and regular striae, smooth or punctuated interstriae with long intervals.Nests in the bark of the trunk and branches of dying pine trees attacked by more aggressive species.Dotted and hairy pronotum, with a smooth longitudinal midline.Lateral pronotum hairiness are less abundant but longer than the sides of elytra hairiness.Hylurgus micklitzi Wachtl, 1881 Has a size of 3.2-4.4 mm. Differs from H. ligniperda by its smaller size (Figure 4).Galleries: At the base of the trunk of which it nests, driving its oblique galleries into the thickness of the bark.Interstries with a row of granules, except in the second interstrie of the elytral declivity, where the granules disappear.Seven species were identified, unevenly distributed between the three forests.All Mediterranean bark beetles that are able to colonize living trees use the host exhaustion strategy.Although O. erosus is considered an important pest in many regions of the Mediterranean basin, many consider it a secondary pest.For instance, very often trees colonized by O. erosus or T. destruens are later colonized by Crypturgus numidicus.This species which has been little studied, is often misidentified as C. numidicus (Balachowsky 1949).Hylurgus micklitzi was present in all of the studied forests, but it was found only in decayed trees.Bark beetles or Scolytinae belong to Curculionidae.In addition, bark of the same trees was put in plastic bags and examined in the laboratory to collect the insects.The total number of beetles collected for each sampling site was estimated.The antennae is composed of 5 segments, the second one is shorter than the first.The teeth are more reduced in the females, presenting 3 small denticles, since the third pair is small.Long and narrow elytra, evenly rounded declivity.Silks of interstries shorter and more regular than in C. numidicus, arranged in a single row.Nests in the bark of the trunk of dying pine trees attacked by more aggressive species.Antennal funicle composed of 5 to 7 segments.Antennae funiculus formed by 6 segments.Orthomicus erosus and T. destruens were the only species found on living trees.It was reported for the first time in the Babors massif (Peyerimhoff 1919).Females settle in the basal part of the trunk and exposed roots of dead or weakened trees.Geographic coordinates were noted for every tree.Pilosity is present all over the body (Balachowsky 1949; Wood 1986; Lopez et al. 2007).Limited to the Mediterranean region.Antenna is composed of 6 segments.Elytra with irregular hairiness.Tomicus destruens Wollaston, 1865 Adults are 3.0-5.3 in size.By contrast, H. ligniperda was present only in Ouennougha forest.The strategy of mass attack is used to overwhelm the defenses of the host.The annual rainfall is 468 mm and the mean annual temperature is 13.3?C.ciliatus Desf).The sampling began in May 2017 and was carried out every 15 days for each forest until September 2017 (Table 1).Adults are 3 to 3.8 mm in size, orange or yellowish when young and black at maturity.Reflections slightly shiny.Pronotum totally dotted.Head extended forward in form of short rostrum.Pronotum and elytra are dark brown in color.Posterior edge of pronotum is straight.Wide but rough interstries.Can also grow on large bare roots.Brown elytra in mature adults (Figure 4).Secondary

INTRODUCTION
The Aleppo pine (Pinus haleppensis) is the most
common tree in Algeria and it has a very important place in
the balance of Mediterranean ecosystems. Global warming
and its consequences like repeated heatwaves and drought
have a significant impact on trees and their predators,
resulting in an increased mortality and forest decline
(Morcillo et al. 2019). However, trees can withstand the
stresses and avoid dieback when favorable conditions
return, but biotic factors such as pests can aggravate the
stress and lead to their death (Anderegg et al. 2015).
Common pests are the pine processionary caterpillars and
bark beetles (Lieutier et al. 2016; Bao et al. 2020). These
last insects develop in lignified stems and feed on vascular
tissues, from the shoots to the tree trunk. Most species
develop on decaying trees or dead wood but some species
can also colonize stressed living trees (Paine et al. 1997).
The females dig a gallery under the bark to deposit their
eggs into the cambium (Davi et al. 2020).
Global warming and its effects cause stress and weaken
the defense of fragile trees, which facilitates the
development of species already existing in the territory and
potentially the introduction of new species of bark beetles
(Suárez-Vidal et al. 2019). The attack occurs at different
levels of plant vitality; some species develop on healthy
plants, but many select hosts that are physiologically
stressed or injured. The strategy of mass attack is used to
overwhelm the defenses of the host. For example, with the
aggressive Mediterranean species Tomicus destruens, the
bored galleries damage the vascular system (xylem or
phloem) and the cambium, resulting in various
physiological imbalances (Chakali 2007; Lieutier et al.
2017). Other bark beetle species attack recently dead trees
and introduce symbiotic fungi (Ambrosia), and the hatched
larvae then feed on the mycelium of these fungi. Some of
the bark beetles are known for their association with
xylophagous fungi, which can aggravate the mechanical
damage caused by the insects leading to dieback.
Saproxylophagous insects that only develop in deadwood,
are not considered as pests (Sauvion et al. 2013).
Bark beetles or Scolytinae belong to Curculionidae.
They are represented worldwide by 6,000 species grouped
in 29 tribes (Alonso-Zarazaga and Lyal 2009). In Algeria,
17 coniferous bark beetle species are monitored (Lieutier et
al. 2016), but the bark beetle fauna of Algeria was not
reviewed recently, and most of the existing records are old.
Therefore, the geographical distribution of bark beetle
species in Algeria remains to be further clarified. There are
no studies that focus on bark beetles in the study region
despite the recent forest decline phenomenon.
The main objective of our study was to investigate the
distribution of bark beetle species responsible for the
decline of the Aleppo pine in the Central-Est semi-arid
region of Algeria.
MATERIALS AND METHODS
Study area
The study was carried out in a semi-arid region located
in the Hodna and the Bibans Mountains, in North-Eastern
Algeria, between 35°41'05.2" and 36°11'34.0" latitude (N)
and 4 and 5° longitude (E), and at an altitude of 900-1300 m.
The three forests of Boutaleb, Ouled Tebben and
Ouenougha were selected for sampling, taking into account
the forest dieback, the surface area of the forests and their
ecological importance in the region (Figure 1). The study
area is part of the semi-arid bioclimatic domain. Twenty￾three, 25 and 30 sites were investigated in the Boutaleb,
Ouled Tebben and Ouenougha forests, respectively (Figure 1).
The Boutaleb forest (28427 ha) is located between the
high Setifian plains to the north and the Hodna basin to the
south (35°44'21.1"N 5°19'47.9"E, 950-1886 m asl.). The
annual rainfall is 468 mm and the mean annual temperature
is 13.3°C. The Boutaleb massif is exclusively made up of
sedimentary rocks (marl, limestone, dolomite and clays
with a lesser extension). The vegetation is composed of
Aleppo pine (Pinus halepensis Mill.), Atlas cedra (Cedrus
allantica Manetti), holm oak (Quercus ilex L.), narrow￾leaved mock privet (Phillyrea angustifolia L. Rouy),
turpentine tree (Pistacia terebinthus L.), lentisk (Pistacia
lentiscus L.), Phoenicean juniper (Juniperus phoenicea L.),
cade juniper (Juniperus oxycedrus L.), rosemary (Salvia
jordanii J.B.Walker), globe daisies (Globularia alypum L.)
and hairy thyme (Thymus munbyanus subsp. ciliatus Desf).
The Ouled Tebben forest or Righa Dahra (14932 ha) is
located in the east of the Boutaleb forest between the high
Setifian plains to the north and the Hodna basin to the
south. It is in the middle of three provinces Setif, Bordj
Bou Arréridj and M’sila (35°48'36.3"N 5°08'58.5"E, 700-
1500 m asl.). The annual rainfall is 396 mm and the mean
annual temperature is 14.17°C. The majority of the massif
is made of hard dolomitic limestones and marls. The most
widespread forest formations in the area are composed of
Aleppo pine, holm oak, Atlas cedra, Phoenicean juniper,
cade juniper, globe daisies, narrow-leaved mock privet,
oriental hawthorn (Crataegus laciniata), and Eucalyptus
tree (Eucalyptus sp.).
The Ouannougha forest (17671 ha) is a part of the
mountain range of Bibans, it is located in the province of
Bordj Bou Arréridj (36°09'35.2"N, 4°12'16.8"E, 900-1280
m asl.), 420 mm of precipitation falls annually with a mean
annual temperature of 15.6 °C. The trees composing this
forest are Aleppo pine, holm oak, Atlas cedra, Phoenician
juniper, and cade junie
Bark beetles collection and identification
Bark beetles were collected from Pinus helepensis trees
in the three forests. The sampling began in May 2017 and
was carried out every 15 days for each forest until
September 2017 (Table 1).
At least five colonized trees were chosen randomly in
every sampling day, based on direct observation of the bark
(trunk, branches) and the presence of boring dust or pitch
tubes as indicators of bark beetle infestation. Geographic
coordinates were noted for every tree. The bark was
removed to access the galleries and collect in situ all
present insects, placed in sterile microtubes and then stored
at 4°C. In addition, bark of the same trees was put in plastic
bags and examined in the laboratory to collect the insects.
The total number of beetles collected for each sampling site
was estimated.
Collected insects were observed under a
stereomicroscope and grouped in morphotypes for the
identification with keys according to their taxonomic
characteristics ( Balachowsky 1949; Gil and Pajares 1986;
Wood 1986; Alonso-Zarazaga 1988; Pfeffer 1995; Alonso￾Zarazaga and Lyal 2009).
Reference individuals for each species were stored in
ethanol.
RESULTS AND DISCUSSION
Identification
In this study, 1629 specimens were collected and
identified from 76 Aleppo pine trees. The Boutaleb forest
was the most affected with a total number of individuals
collected of 666 followed by the Ouenougha and Ouled
Tebben forests with 547 and 416 individuals, respectively
(Figures 2, 3, and Table 3). A total of 7 species were
identified, 6 belonging to the Scolytinae subfamily and one
to the Cossoninae subfamily (Table 2).
Scolytinae subfamily
Tibiae armed on apical and/or lateral margins either by
spines or socketed denticles, apical mucro formed by mesal
element (compared to Protohijlastes structure); male
spiculum gastrale present, antennal club variable, with or
without sutures, head narrower than pronotum; pronotum
almost never with constriction near middle, pronotum
edged on the sides and back. When visible, scutellum
usually flushes with elytral surface, often flattened (Wood
1986).
Ipini tribe Bedel, 1888
Eye shallowly sinuate with lower half narrower than
above; protibia with 3-4 socketed teeth; antennal club
rarely obliquely truncate (Pityokteines. Orthotomicus),
procoxae contiguous, intercoxal piece longitudinally
emarginate to absent, never complete; elytra moderately
sulcate to elaborately excavated, with lateral margin
usually armed by tubercles or spines; pronotum more
strongly declivous on anterior third, asperities usually
larger; worldwide (Wood 1986)
Orthomicus erosus Wollaston, 1857 (Mediterranean pine
beetle)
Close to the genus Ips, from which it is distinguished by
the straightness of its declivity whose apical edge is not
explained backward.

Adults are 3 to 3.8 mm in size, orange or yellowish
when young and black at maturity. Dorsally the head is not
visible, the anterior of the pronotum has transverse spicule
bands. The antennae is composed of 5 segments, the
second one is shorter than the first. Antennae mace sutures
are procurved upwards in their middle in an arc shape. The
margin of the elytral declivity is concave with 4 teeth on
each side, the second ones are the largest and fused to the
base of the third one. The teeth are more reduced in the
females, presenting 3 small denticles, since the third pair is
small. Elytra with deep and regular striae, smooth or
punctuated interstriae with long intervals. Pilosity is
present all over the body (Balachowsky 1949; Wood 1986;
Lopez et al. 2007).
Galeries: Irregular star-shaped gallery with 2 or 3 arms,
4 to 8 cm long, sub-cortical in decaying trees.
Crypturgini tribe LeConte, 1876
Small size species, antennal funicle 2-or 3-segmented,
club with sutures on posterior face about equal to those on
anterior face; pronotum feebly declivous on anterior half
and unarmed, punctuated, reticulate in many species
(Balachowsky 1949; Wood 1986).
Crypturgus numidicus Ferrari, 1867
The genus Crypturgus comprises the smallest species
within Scolytidae (0.8-1.5 mm). Crypturgus species exhibit
a narrow-shaped and cylindrical elongated body (Figure 4),
and a brown or black colour with shiny or matt reflections.
Antenna funiculus is composed of 2 short segments, with
an oval-shaped club provided with a fine and incomplete
digitula, diffuse sutures rejected at the end. Long and
narrow elytra, evenly rounded declivity. Breeding in the
bark of the trunk and branches of decaying pines
previously infested by more aggressive species such
Orthomicus, egg galleries forming a confused system
partially bored into the bark thickness.
Has a size of 1.5-1.6 mm, antenna funiculus composed
of 2 segments, antenna head formed by a single segment.
Light colored, pronotum and underside of body more or
less dark brown, elytra are much lighter and yellowish.
Reflections slightly shiny. Stocky, broad, robust species,
especially in the female, whose apical brushes of the elytra
are very dense. Pronotum totally dotted. It has a convex
and smooth elytral declivity, without a denticular
processes, bristles of the interstries at least twice as long as
the stries. Limited to the Mediterranean region.
Galleries: forming a marbled network that penetrates
the thickness of the bark, rapidly reducing it to a spongy
mass that is abandoned as soon as it dries out.
Nests in the bark of the trunk and branches of dying
pine trees attacked by more aggressive species.
Other scientific names: Crypturgus abbreviatus Eggers,
Crypturgus barbeyi Strohmeyer, Crypturgus brevipennis
Reitter
Crypturgus mediterraneus Eichhoff, 1889
Has a size of 1,1-1,5 mm. Longer, slender shape (Figure
4). Silks of interstries shorter and more regular than in C.
numidicus, arranged in a single row. Pronotum longer than
wide with parallel sides beyond the middle, with dense and
tight punctuation, devoid of short bristle brushes at the
apex of the elytra replaced with scattered silks denser than
on the rest of the elytra.
Galleries: forming an irregular network that penetrates
the thickness of the bark. Nests in the bark of the trunk of
dying pine trees attacked by more aggressive species.
Host plants: Pinus halepensis, P. pinaster, P. nigra, P.
brutia (Pfeffer 1995).
Hylurgini tribe Gistel, 1848
Pronotum, elytra and abdomen fully free of scales.
Anterolateral areas of pronotum unarmed; precoxal costa
on prothorax absent. Antennal funicle composed of 5 to 7
segments. Head extended forward in form of short rostrum.
Mesal surface of elytra at suture with interlocking groove
and flange continued to base without a series of nodules or
cavities immediately behind scutellum (Balachowsky 1949;
Wood 1986).
Hylurgus ligniperda Fabricius, 1787
Elongated and cylindrical in appearance, with a size of
4.5-5.8 mm. General color of the body is black-brown with
reddish antennae (Figure 4). Pronotum and elytra are dark
brown in color. Dotted and hairy pronotum, with a smooth
longitudinal midline. Pronotum coarsely and uniformly
punctuated over its entire surface by large closely spaced
dots of irregular diameter and not very deep. Posterior edge
of pronotum is straight. Lateral pronotum hairiness are less
abundant but longer than the sides of elytra hairiness.
Antenna is composed of 6 segments. Elytra with irregular
hairiness. Striations formed by a row of large, regularly
spaced, shallow circular dots. Wide but rough interstries.
Hylurgus micklitzi Wachtl, 1881
Has a size of 3.2-4.4 mm. Differs from H. ligniperda by
its smaller size (Figure 4). Another differential character,
from H. ligniperda, is the length of the lateral silks of the
pronotum, which are the same size as the elytrals, while
they are longer in H. ligniperda.
Galleries: At the base of the trunk of which it nests,
driving its oblique galleries into the thickness of the bark.
Can also grow on large bare roots. The mother gallery
measures 10-16 cm, the larval galleries are numerous,
irregular, long and intertwined (Balachowsky 1949).
Tomicus destruens Wollaston, 1865
Adults are 3.0-5.3 in size. Antennae funiculus formed
by 6 segments. Shiny black and finely dotted pronotum
inclined forwards in relation to the elytra. Brown elytra in
mature adults (Figure 4). Interstries with a row of granules,
except in the second interstrie of the elytral declivity,
where the granules disappear.
Galleries: The female bore a longitudinal uniramous
gallery in the middle-upper part of stem and large branches,
sapwood is little affected. The tunnel is about 8 to 10 cm
long and 3 to 4 mm wide, the larval galleries develop in the
bark thickness without affecting sapwood
Discussion
This study investigated the diversity of bark beetle
species in the North-Eastern region of Algeria for the first
time. Seven species were identified, unevenly distributed
between the three forests. Crypturgus numidicus was the
most abundant species in the three forests, followed by
Orthomicus erosus and Tomicus destruens.
Orthomicus erosus and T. destruens were the only
species found on living trees. These two species are
common on Pinus throughout the Mediterranean basin
including the semi-arid regions in Algeria (Balachowsky
1949; Chakali 2004; Lopez et al. 2007; Lieutier et al.
2016). All Mediterranean bark beetles that are able to
colonize living trees use the host exhaustion strategy.
Species such as O. erosus, H. ligniperda, and C. micklitzi
use aggregation pheromones to attract other individuals and
thus massively attack the trees (Lieutier et al. 2016). On the
other hand, Tomicus destruens is attracted by terpenes
emitted from wounds in trees attacked by pioneer bark
beetles. All these bark beetle species are associated with
xylophagous fungi which probably play a role in the
colonization of the host trees.
Tomicus destruens has been reported on Aleppo pines
in the Djelfa region (Chakali 2004). Another study showed
the presence of T. destruens in the Tlemcen region in the
extreme east of Algeria (Nichane et al. 2013). Females of
T. destruens preferentially seek for the northern slopes of
the relief and the southern side of the tree to make their
maternal gallery. According to Chakali (2007),
Mediterranean pine forests have been confronted with T.
destruens over the last two decades. This species is
multiplying rapidly due to the physiological stress of
Aleppo pines caused by climate change (Chakali 2004;
Guit et al. 2016). This species which has long been
confused with the neighboring species Tomicus piniperda,
is responsible for the dieback of Aleppo pine forests in the
semi-arid regions of Algeria (Guit et al. 2016).
It is clear that the colonization of Aleppo pines is
initiated by T. destruens, a more aggressive primary
species, followed by O. erosus which is considered a
secondary species (Lopez et al. 2007; Sangüesa-Barreda et
al. 2015; Lieutier et al. 2016). Attacks by these two bark
beetle species in coniferous forests rely on two
complementary factors: the existence of trees weakened by
stress and a certain level of pest population (Lieutier and
Levieux 1985).
In the region of Zaragoza in Spain, galleries of O.
erosus occupy a large area of the attacked trees compared
to T. destruens. The density of galleries of O. erosus on
attacked Aleppo pine trees was higher than that of T.
destruens (Sangüesa-Barreda et al. 2015). In Algeria, O.
erosus can also colonize Atlas cedar trees (Talbi and
Bouhraoua 2015). In a recent survey in Europe, O. erosus
was the most commonly found species in Portugal, Spain,
France, Greece, Italy and Hungary (Faccoli et al. 2020).
When reaching a high population density, O. erosus can
overwhelm the host defenses, thus causing tree mortality
(Faccoli et al. 2020).
Although O. erosus is considered an important pest in
many regions of the Mediterranean basin, many consider it
a secondary pest. In our study, O. erosus was found on
living trees in Boutaleb forest, suggesting that it can be a
serious pest in semi-arid regions.
Species of the genus Crypturgus are secondary bark
beetles that occupy biotypes previously colonized by other
species and do not affect healthy trees (Lieutier et al.
2016). For instance, very often trees colonized by O. erosus
or T. destruens are later colonized by Crypturgus
numidicus. Very few studies have focused on this species,
which is common throughout Algeria and the most
common bark beetle in the forests studied here. It was
reported for the first time in the Babors massif
(Peyerimhoff 1919). In the three forests studied, C.
numidicus was sampled from the bark of trees colonized by
O. erosus. This confirms that this species nests in the bark
of trunks and branches of dying Pine trees attacked by
other bark beetles (Balachowsky 1949). Taking advantage
of the entrances to the galleries of other species, the
galleries of C. numidicus are bored irregularly throughout
the thickness of the Aleppo pine bark, and these galleries
are abandoned as soon as the bark dries out (Balachowsky
1949). Crypturgus mediterraneus is poorly spread and was
detected here only in the forests of Boutaleb and Ouled
Tebben. This species which has been little studied, is often
misidentified as C. numidicus (Balachowsky 1949). C.
mediterraneus has been sampled in the thick bark of the
trunks of trees colonized by O. erosus, where it uses the
gallery systems of other species to penetrate and lay eggs.
The larval galleries are highly branched and start from the
galleries of other species (Lieutier et al. 2016). This species
colonizes the middle or upper part of the trunks of Aleppo
pines (Markalas 1997).
Hylurgus species are secondary bark beetles, attacking
only weak or dead trees. Hylurgus micklitzi was present in
all of the studied forests, but it was found only in decayed
trees. By contrast, H. ligniperda was present only in
Ouennougha forest. Females settle in the basal part of the
trunk and exposed roots of dead or weakened trees. Several
authors have reported the presence of these species in
Algeria (Balachowsky 1949; Pfeffer 1995), and for
instance, Nichane (2013) reported the presence of H.
ligniperda in the region of Tlemcen.
Aphanommata filum live in conifer trunks, it has
already been observed in Algeria (Folwaczny 1973;
Alonso-Zarazaga 1988). This poorly known species were
abundantly found under the trunk bark of Aleppo pines in
the Boutaleb forest, with galleries dug into the sapwood of
dead trees. This is consistent with the findings of H. Jordal
(Jordal 2014), which showed that Rhyncolini species live
in the wood and under the bark of dead trees, adults lay
eggs in excavated tunnels, and show similar behavior as
Scolytidae.
In conclusion, 6 bark beetle species and one Cossoninae
species were recorded for the first time in the center of the
East region of Algeria. The diversity of bark beetles in the
studied region is low compared to other countries. Among
the individuals collected, T. destruens and O. erosus were
the only species found in living trees, demonstrating that O.
erosus is also capable of attacking stressed trees while it is
usually considered as a secondary beetle. Secondary