First records of Sirococcus conigenus causing shoot blight on Pinus peuce in Bulgaria

Macedonian pine (Pinus peuce) is a southern Balkan Peninsula endemic, growing in high mountains of Bulgaria, between 1400 and 2100 m a.s.l. Stands of P. peuce form the upper tree line forest areas. During a survey in 2020-2022 on Macedonian pine natural stands and plantations in Bulgaria, symptoms of shoot blight were observed in the Pirin Mts, the Rila Mts and Mt Vitosha. The fungal pathogen Sirococcus conigenus was identified as the causal agent of the disease that appeared for the first time on Pinus peuce in Bulgaria and Balkan Peninsula. Incidence of blighted shoots on individual trees varied, but was as high as 70-80% in the Rila Mts and Mt Vitosha

New parasitoid (Hymenoptera, Chalcidoidea) records of bark beetles (Coleoptera, Curculionidae, Scolytinae) in pine plantations in Bulgaria

In 2020 and 2021, chalcidoid parasitoids (Hymenoptera, Chalcidoidea) of bark beetles in pine (Pinus spp.) plantations were studied in Bulgaria. Samples (cuttings of stems and branches) of pine trees infested by bark beetles were collected from seven plantations of Pinus sylvestris and P. nigra in Bulgaria. From each sampling plot, five cuttings were collected and placed in photoeclectors in laboratory conditions (18-22ºC). Emerged bark beetles and parasitoids were regularly gathered and fixed in ethanol.Six parasitoid species - Dinotiscus colon, Metacolus azureus, M. unifasciatus, Rhopalicus quadratus, R. tutela (Chalcidoidea: Pteromalidae) and Heydenia pretiosa (Chalcidoidea, Heydeniidae) were reared from five bark beetle hosts (Ips acuminatus, Pityogenes bistridentatus, Pityophthorus pityographus, Tomicus piniperda and T. minor). Amongst them, three species (H. pretiosa, M. azureus and R. quadratus) are recorded as new for Bulgarian fauna

A checklist and areography of the longhorn beetles (Coleoptera, Cerambycidae) of Pirin Mountains, Bulgaria

The longhorn beetles fauna of Pirin Mountains, Bulgaria, was studied, based on literature data and original material. As a result, 100 taxa from five subfamilies are listed for the area, as follows: Prioninae (7 taxa), Lepturinae (31 taxa), Spondylidinae (9 taxa), Cerambycinae (28 taxa) and Lamiinae (25 taxa).This study presents two new records for Pirin Mts. (Oxymirus cursor and Tetropium fuscum fuscum) and new localities or additional information for 13 cerambycid taxa (species and subspecies). The 100 longhorn beetle taxa belong to 17 zoogeographical categories and eight complexes. The European complex occupies a dominant position (34%), followed by those from Palaearctic (17%), Eurosiberian (15%), Mediterranean (15%), European-Iranoturanian (9%), Balkan endemic (5%) and Holarctic (4%) complexes

Monitoring of the health status of Castanea sativa in the Belasitsa mountain, southwest Bulgaria

In the period 2017-2023, a survey for the assessment of the phytosanitary condition of sweet chestnut (Castanea sativa) was conducted in a permanent sample plot (PSP) Belasitsa, which is part of the European large-scale network for monitoring the health status of forest ecosystems under the International Co-operative Program ‘Forests’. The PSP is set in a natural chestnut stand in Belasitsa mountain at an altitude of 643 m. Data collected from the first years of the monitoring determined a slight deterioration in the health status of the chestnut trees caused by an infection with the fungal pathogen Cryphonectria parasitica. An improvement in trees’ vitality and lack of active necrosis were observed in 2022-2023. On the wounds, initiation of callus along the wounded edges was reported. Currently, the introduction of new and dangerous invasive insect pests Dryocosmus kuriphilus, Corythucha arcuata, etc., has not been detected. Attacks of both pests could further deteriorate the health status of the sweet chestnut in Belasitsa

Damage caused by singing cicadas (Hemiptera: Cicadidae) in the field protective forest belts in South Dobrudzha, Bulgaria

During the period 2020-2023, strong damage caused by singing cicadas (Hemiptera: Cicadidae) were registered on ash trees (Fraxinus spp.) in the field protective forest belts (FPFBs) in South Dobrudzha, northeastern Bulgaria. Bioacoustic studies have shown that the sounds are of Cicada orni. Many exuvia of the species were also found on the trunks and branches of ash trees. On the upper shoots and petioles, numerous oviposition holes were observed, which lead to leaf fall and drying of branch tips. In different FPFBs, tree crown damage ranges from a moderate (25-60% defoliation) to a severe (over 60% defoliation) degree. The attacks were stronger on Fraxinus excelsior and F. americana compared to F. angustifolia. The cicadas affect both old trees and young ash saplings. In young plantations, other tree species (Sophora japonica, Gleditsia triacanthos) were also affected. Imaginal activity of Cicada orni was recorded in July and August, and the peak of egg hatching occurred from early August to mid-September. The high number of Cicada orni necessitates the development of measures to control the pest in the FPFBs

New braconid parasitoids (Hymenoptera: Braconidae) on bark beetles in Ihtimanska Sredna Gora Mountain, Bulgaria

In 2020, two braconid species (Hymenoptera: Braconidae) were found as parasitoids of bark beetles in Pinus sylvestris plantations in Ihtimanska Sredna Gora Mt. Coeloides bostrichorum Giraud was reared from stem samples attacked by Tomicus piniperda and Tomicus minor in the region of Krushovitsa vill. (State Forestry Enterprise Elin Pelin), and Dendrosoter middendorffi (Ratzeburg) – by Ips acuminatus, Pityophthorus pityographus and Pityogenes bistridentatus in the region of Krushovitsa vill. and Golema Rakovitsa vill. (State Game Enterprise Aramliets). Coeloides bostrichorum caused 7.4% mortality of T. piniperda and T. minor, and Dendrosoter middendorffi – 5.6-12.5% of Ips acuminatus, 5.6% of P. bistridentatus, and 2.8% of I. acuminatus, P. pityographus and P. bistridentatus. In the total braconid parasitoid complex, D. middendorffi was the dominant species with a relative share of 87.5%

New braconid parasitoids (Hymenoptera: Braconidae) on bark beetles in Ihtimanska Sredna Gora Mountain, Bulgaria

In 2020, two braconid species (Hymenoptera: Braconidae) were found as parasitoids of bark beetles in Pinus sylvestris plantations in Ihtimanska Sredna Gora Mt. Coeloides bostrichorum Giraud was reared from stem samples attacked by Tomicus piniperda and Tomicus minor in the region of Krushovitsa vill. (State Forestry Enterprise Elin Pelin), and Dendrosoter middendorffi (Ratzeburg) – by Ips acuminatus, Pityophthorus pityographus and Pityogenes bistridentatus in the region of Krushovitsa vill. and Golema Rakovitsa vill. (State Game Enterprise Aramliets). Coeloides bostrichorum caused 7.4% mortality of T. piniperda and T. minor, and Dendrosoter middendorffi – 5.6-12.5% of Ips acuminatus, 5.6% of P. bistridentatus, and 2.8% of I. acuminatus, P. pityographus and P. bistridentatus. In the total braconid parasitoid complex, D. middendorffi was the dominant species with a relative share of 87.5%

Three species of bark beetles (Coleoptera: Curculionidae, Scolytinae) on Pinus peuce in Pirin Mountains in Bulgaria

In 2020 and 2021, three species of bark beetles (Coleoptera: Curculionidae, Scolytinae) were established on Macedonian pine (Pinus peuce) in the region of Vihren hut in Pirin Mts. Branches, damaged by snow were collected and studied in laboratory conditions. As a result, 24 specimens of Ips amitinus were reared in 2020 and 81 specimens of I. amitinus, Crypturgus pusillus and Pityogenes chalcographus in 2021. The most abundant species was I. amitinus with 75.2%, followed by P. chalcographus (21.9%) and C. pusillus (2.9%)

A checklist and areography of longhorn beetles (Coleoptera: Cerambycidae) in Rila Mountain

The complex of longhorn beetles in Rila Mt. in Bulgaria was studied by literature data and original biological materials. As a result, 126 taxa from six subfamilies were established, as follows: Prioninae (four taxa), Lepturinae (43 taxa), Necydalinae (two taxa), Spondylidinae (seven taxa), Cerambycinae (31 taxa) and Lamiinae (39 taxa).In this study, two new records for Rila Mt. (Stenurella nigra nigra and Xylosteus spinolae) and new localities or additional information for 24 cerambycid taxa were reported. The longhorn beetles belong to 18 zoogeographical categories and seven complexes. The European complex occupies a dominant position (37.3%), followed by the Palaearctic (23.8%), Eurosiberian (13.5%), Mediterranean (11.1%), European-Iranoturanian (7.1%), Balkan endemic (4.0%) and Holarctic (3.2%) complexes

First penetration of pine processionary moth (Thaumetopoea pityocampa) in North Bulgaria

The pine processionary moth (Thaumetopoea pityocampa) was reported for the first time in North Bul-garia in 2022. Winter nests of the pest were observed in a number of pine plantations in more than 10 sites of four Forest State Enterprises (Troyan, Sevlievo, Gabrovo, Plachkovtsi). The penetration of the pest into the new localities is due to a long-distance dispersion by vehicles. In January 2023, the nests in new localities contained fifth-instar larvae of T. pityocampa. Only about 3% of them were empty as larvae had descended in the soil for pupation. Based on the high population density and presence of old nests in some localities, it was assumed that the pest penetrated into Northern Bulgaria most likely 3-4 years ago.