Insect pests in the forests of Bulgaria and their economic importance

Based on the forest-pathological inventories for the last 30 years, the economic importance of the insect pests in the Bulgarian forests and its dynamics for the periods 1990–2002 and 2003–2018 were determined. Insect pest attacks have declined sharply in the last sixteen years- in coniferous forests they have decreased three times and in deciduous ones - almost six times. Generally, the health status of the forests, with regard to pest status, after 2003 is improving, and this is more clearly expressed in the deciduous forests. As a result of this development, the pest control measures areas gradually shifted from deciduous to coniferous forests. Since 2003, deterioration in the health status of ageing coniferous plantations has been identified, however, with the attacks of two major groups of pests escalating- pine sawflies and bark beetles.

The influence of stand and habitat characteristics on the occurrence of pine sawflies Diprion pini L. and Gilpinia virens (Klug) (Hymenoptera, Diprionidae) in selected areas of northern Poland

Pine sawflies (Hymenoptera: Diprionidae) belong to the most common pests of Scots pine Pinus sylvestris L. in the area of the Regional Directorates of State Forests in Toruń and Gdańsk. The two most destructive species, Diprion pini L. in the area of Puszcza Bydgoska and Gilpinia virens (Klug) in Bory Tucholskie, were investigated in this study. Our main aim was to characterise the two species in the Bydgoszcz Forest District in RDSF in Toruń and Kaliska in RDSF in Gdańsk, respectively, based on data gathered during outbreaks between 1991 and 2011. For this purpose, a geometric database was created, containing information about the year of outbreak, number of larvae observed after tree felling as well as selected stand and site features including stand age and species composition, stocking index, canopy closure, site index, humidity and fertility. By analysing the occurrence of both species in relation to stand and site features, we were able to determine their environmental requirements, which are quite different from one another. D. pini preferred older stands, with a stocking index between 0.8–0.9, growing on fresh and dry coniferous sites, while species composition (share of pine), canopy closure or site index did not have any influence on its abundance. G. virens preferred middle-aged pure pine stands, with relatively open canopies, on fresh coniferous sites and poorer soils. The stocking index did not affect its occurrence.

CONTRIBUTION OF UFA SCIENTISTS TO THE CHEMISTRY OF OPTICALLY ACTIVE SEX PHEROMONE OF PINE SAWFLIES

Pine sawflies of the genera Neodiprion, Diprion and Gilpinia (Diprionidae) are malignant and economically important pests of coniferous trees. The most effective and environmentally safe method of controlling and regulating the number of pine sawflies is the use in traps of synthetically obtained sex feromone, identified for its different species as acetates and propionates of 3,7-dimethyl-2-pentadecan-2-ol (diprionol) in the form of various stereoisomeric forms due to the presence of three asymmetric carbon atoms. At the same time, it was noted that the 2S configuration of the optical centre of the erythro-isomerium is crucial for the stereochemistry of the sex pheromone of pine sawflies. The article presents the results of research of the laboratory of insect bioregulators of the Ufa Institute of chemistry of the UFIC RAS in the field of synthesis of optically active pine Sawfly pheromone, its stereoisomers and analogues based on (S)-(+)-dihydromircene and (-)-mentolactone obtained from available natural monoterpenes – (+)-α-pinene and l-menthol, respectively.

Diprion pini L. (Hymenoptera, Symphyta, Diprionidae) population dynamics in the Low Dnieper region

Pine sawflies (Hymenoptera, Symphyta, Diprionidae) are the most spread foliage browsing insects of pine forests in Europe, especially monovoltinous European pine sawfly Neodiprion sertifer (Geoffroy, 1785) and common pine sawfly Diprion pini (Linnaeus, 1758), which develops in one or two generations per year depending on weather. The outbreaks of both pine sawflies are the most frequent and intensive in the Steppe zone of Ukraine, especially in the Low Dnieper region, where pine forest (Pinus sylvestris Linnaeus and Pinus pallasiana D. Don) was planted on moving sands in the sixties of the 20th century. This research is aimed at the evaluation of the parameters for D. pini outbreak dynamics in the Low Dnieper region. Outbreak severity, specific foci area and mean score of stand threat by D. pini were evaluated from the regional statistical reports. In the regional scale for 1979–2017, notable outbreaks of D. pini were registered in 1982, 1993, 2002, 2006 and 2017. An interval between maximums was from 4 to 11 years, in average 9 years. The growth of foci area in 1979–1998 as compared to 1999–2017 as well as correlation between pine stand area and annual area of this pest’s foci in different forests was not statistically significant. Graphical analysis of dynamics of D. pini focal area for 2010–2017 was done based on individual threat levels. Our study confirms the fact of three outbreaks for this period in three forest and hunting enterprises (FHE), two outbreaks in one FHE and one outbreak in one FHE. An interval between the outbreaks makes three or six years. The causes of such shortening of interval are discussed.

Key Plant, Key Pests: Pine Species (Pinus sp.)

This series of Key Plant, Key Pests publications are designed for Florida gardeners, horticulturalists and landscape professionals to help identify common pests associated with common Florida flora. This publication, the seventh in the Key Plant, Key Pests series, helps identify the most common pests found on Pinus sp. This publication provides information and general management recommendations for borers, pine sawflies, pine bark beetles, pine tip moths, fusarium rust, pine chlorosis, and pitch canker.

GIS-based prediction of the foliage browsing insects' outbreaks in the pine stands of the SE "Kreminske FHE"

To improve the detection and prevention of foliage browsing insects' outbreaks it is very important to reveal the forest plots, which are the most favorable for these pests. The aim of this research was to predict using GIS technologies the spatial dynamics of foliage browsing insects' outbreaks in the pine stands of the State Enterprise "Kreminske FHE" (Luhansk region). Forest inventory databases of Production Association "Ukrderzhlisproekt" were analyzed for the SE "Kreminske FHE" as of 2001 and 2011. Rating of forest plots preferences for common pine sawfly (Diprion pini L.) and European pine sawfly (Neodiprion sertifer Geoffr.) considered the type of forest site conditions, age of stand, density of stocking, and the part of pine in the stand composition. If forest plot bordered with clear-cut, then 1 point was added to the general score of the threat. It was shown, that the area with high threat of European pine sawfly and common pine sawfly outbreaks for 2001–2011 increased in the forest fund of the SE "Kreminske FHE" by 702.8 and 2004.2 hectares respectively. The part of foci area made up 27.5 and 32 % from forest fund area, 42.5 % and 49.5 % from pine stands area for European pine sawfly and common pine sawfly respectively. The areas of pine sawflies foci increased mainly in result of decrease the stocking density of pine stands and increase the number of plots which border with clear-cuts. The survey for pine sawflies is recommended to carry out first of all in the plots with high threat of foci appearance.