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