THE IMPORTANCE OF SOIL IN THE SPREAD OF THE PINE PROCESSIONARY MOTH IN CENTRAL BULGARIA

Available geo-referenced data about the pine processionary moth (PPM) attacks in Stara Zagora province in Central Bulgaria were used to study the relationships between the frequency of attacks and soil conditions. It was established that the PPM prefers fresh, deep and fertile soils

Egg parasitoids of Thaumetopoea pityocampa in the region of Gyumyurdzhinski Snezhnik in Eastern Rhodopes, Bulgaria

The region of Gyumyurdzhinski Snezhnik in the Eastern Rhodopes is the closest in Bulgaria to the Aegean Sea. However, the climate is characterized by specific parameters that are determined by its relief. It is poorly protected from the invasion of cold air masses from the north. From the south, the Gyumyurdzhinski Snezhnik hill restrains the Mediterranean influence. The orography of the area favors the retention of cold air masses and a further drop in temperatures. The experimental material for the study includes 5 generations of Thaumetopoea pityocampa (2016, 2017, 2018, 2019, and 2022), collected in 31 locations of four State Forestry Enterprises: Kirkovo, Ardino, Momchilgrad, and Zlatograd. The sample for analysis included 693 egg batches with 148420 eggs in them. Seven primary egg parasitoids were established in this region: Ooencyrtus pityocampae, Baryscapus servadeii, Pediobius bruchicida, Anastatus bifasciatus, Eupelmus vesicularis, E. vladimiri, Trichogramma sp. and one hyperparasitoid (B. transversalis). Dominant parasitoids were B. servadeii and O. pityocampae, and E. vladimiri and P. bruchicida – occasional parasitoids. The hyperparasitoid B. transversalis participated in the complex with a relatively low share. The survival of the egg parasitoids in the laboratory conditions, in which the samples were kept, was low. The total mortality of the parasitoids in larval and adult stages was 47.8%. After collecting the samples, in laboratory conditions, a total of 442 individuals of the hyperparasitoid B. transversalis emerged, of which 56.3% were females and 43.7% were males. The average number of pine processionary moth eggs in a batch was 214.2. 70.8% of all the eggs in the samples hatched successfully. The egg parasitoids are a very serious natural factor, regulating the density of the pine processionary moth, but their impact varied from 2.1% to 30.3%. The natural characteristics of the area, the air temperature during the stages of eggs and young larvae, are favorable for the development of the pine processionary moth. Unhatched larvae without the influence of entomophages were 7.2%

Factors affecting Thaumetopoea pityocampa emergence in laboratory conditions

To investigate the factors affecting the emergence of the pine processionary moth (Thaumetopoea pityocampa) in laboratory conditions, a number of 1487 larvae, prepupae and pupae were collected in the period February-May 2019 from five pest habitats: Fotinovo and Kandilka villages (inhabited by a summer phenological form), Sandanski and Klisura towns (winter phonological form occurs) and Sarnak village (both forms occur). At the date of collection, the rate of parasitism was very low (0-0.1%). Throughout the study, significant differences in the characteristics of pupal stage and mortality between both phenological forms were established. The rate of emerged adults varied from 21.4% to 77.6% in the observed habitats. The sex ratio between female and male specimens was almost equal. Only 0.6% of samples emerged in the second year, after diapause. In four localities (Fotinovo, Kandilka, Sandanski and Sarnak), the rate of infection by entomopathogens was between 6.0% and 20.8%, and the parasitism caused by tachinids – between 0.9% and 3.4%. The flight period of the summer and winter phenological forms of T. pityocampa were clearly differentiated with about a month. In summer form, the flight began in late May and ended in the last decade of June, and in winter form – from early July to the end of August. The duration of the flight period in both forms lasted 30 to 50 days with an equal number of emerged male and female specimens

Egg parasitoid complex of the pine processionary moth (Thaumetopoea pityocampa) on the Thasos Island, Greece

The egg parasitoid complex of the pine processionary moth (Thaumetopoea pityocampa) was surveyed for the first time on the Thasos Island, Greece. A total of 96 egg batches containing 20391 eggs were collected between 06 and 10 of September, 2017 from Aleppo pines (Pinus halepensis) at four sites (Skidia, Thimonia, Alyki and Panagia). Four primary parasitoids were identified (Ooencyrtus pityocampae, Baryscapus servadeii, Anastatus bifasciatus and Trichogramma sp.), as well as the hyperparasitoid B. transversalis. Among the parasitoids groups, O. pityocampae was the most common, followed by B. servadeii, whilst the number of other species was low. The highest survival rate was reported for three species: O. pityocampae, B. servadeii and A. bifasciatus, while the highest was the mortality in Trichogramma sp. All emerged adults of O. pityocampae and B. servadeii were female specimens and in A. bifasciatus – males. The number of females of B. transversalis was three times higher than the one of males. Ooencyrtus pityocampae and B. servadeii were the most important parasitoids of T. pityocampa, destroying respectively 27.1% and 9.9% of the host eggs

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.

A review of Trichogramma Westwood parasitoids on eggs of Thaumetopoea pityocampa (Denis & Schiffermüller) in habitats of the Balkan Peninsula and Asia Minor

Studies on egg parasitoids of the pine processionary moth (Thaumetopoea pityocampa) were conducted during the period 1991-2018 in native localities of the pest on the Balkan Peninsula and in Asia Minor. In Bulgaria the biological material (2510 egg batches and 579273 eggs) was collected in 48 host localities. A number of 650 egg batches and 135611 eggs were studied from the Balkan countries (North Macedonia, Bosnia and Herzegovina, Albania and Greece), and in the Asian part of Turkey (Asia Minor), the biological material was examined from nine habitats. Eight species of egg parasitoids (Ooencyrtus pityocampae, Baryscapus servadeii, B. transversalis, Pediobius bruchicida, Anastatus bifasciatus, Eupelmus vesicularis, E. vladimiri and Trichogramma sp.) were found. The total regulating effect of egg parasitoids in Bulgaria was on average 17.6%, and in the other Balkan countries – 24.9%. Trichogramma sp. was found in 63.1% of the analysed samples in Bulgaria and in 55.6% from the neighboring countries. The percent of parasitism of T. pityocampa eggs by Trichogramma sp. was low - on average 0.39% for Bulgaria and 0.73% for the other Balkan countries. The relative share of the species in the total percentage of parasitised eggs for Bulgaria and the other countries was 2.2% and 2.9%, respectively.

Biotic factors damaging forest stands in Gornata Koria and Chuprene Reserves in Western Balkan Range, Bulgaria

AbstractAssessment and monitoring of health status in deteriorated forest stands in Gornata Koria and Chuprene Reserves in Western Balkan Range (Bulgaria) were conducted in 2017. An integrated approach (based on remote sensing technologies and terrestrial validation) was applied. A series of subsequent terrain observations were carried out in both protected areas mainly in dead or in poor health status stands. As a result, sixteen insect species were identified in Gornata Koria and nine pests in Chuprene Reserves. The predominant number of pests included bark beetles and weevils (Curculionidae), longhorn beetles (Cerambycidae), etc. Attacks caused by the European bark beetle (Ips typographus) formed the main disturbance in the Norway spruce forests in both reserves. Ten parasitic and ten saprophytic fungi were identified in the stands of the Norway spruce (Picea abies), silver fir (Abies alba) and European beech (Fagus sylvatica). Among the parasitic fungi, six species were identified as destructive (Armillaria sp., Heterobasidion annosum, Fomitopsis pinicola, Fomes fomentarius, Ramaria flava and Pholiota squarrosa)

Phenological changes in the pine processionary moth: possible causes, consequences and up-and-coming monitoring methods

International audienc

Phenological changes in the pine processionary moth: possible causes, consequences and up-and-coming monitoring methods

International audienc

Phenological changes in the pine processionary moth: possible causes, consequences and up-and-coming monitoring methods

International audienc