Boris Hrasovec | University of Zagreb, Forestry Faculty (original) (raw)

Papers by Boris Hrasovec

Sumarski List, Oct 31, 2010

SAŽETAK: U radu se prvi puta opisuje prisutnost karantenskog štetnika pitomog kestena, kestenove ... more SAŽETAK: U radu se prvi puta opisuje prisutnost karantenskog štetnika pitomog kestena, kestenove ose šiškarice (Dryocosmus kuriphilus) u Hrvatskoj. Šiške smanjuju fotosintetsku površinu, zaustavljaju rast izbojaka i smanjuju urod pitomog kestena. Porijeklom je iz Kine, a u Europi je prvi puta zabilježen 2002. godine u Italiji. Domaćini su vrste iz roda Castanea. U radu je opisana biologija ovog štetnika, simptomi napada, načini širenja, štetnost i mjere zaštite. Navedeni su točni lokaliteti i datumi prvog nalaza ovog štetnika u Hrvatskoj, na temelju čega je napravljena karta rasprostranjenosti u 2010. godini. Kestenova osa šiškarica može se smatrati novom, invazivnom vrstom štetnika u Hrvatskoj i sljedećih godina se može očekivati njezino širenje u svim kestenovim sastojinama.

Radovi, Sep 24, 2006

Zbog u~estalih problema s potkornjacima posljednjih godina u Hrvatskoj, postavlja se pitanje njih... more Zbog u~estalih problema s potkornjacima posljednjih godina u Hrvatskoj, postavlja se pitanje njihovog u~inkovitog suzbijanja. U koncept integrirane za-{tite {uma sve vi{e se nastoji uvesti ekolo{ki prihvatljive metode za{tite, kakve su primjerice feromonske klopke. U obavljenom istra`ivanju feromonski pripravak Curviwit ® , deklariran kao feromon jelovog krivouzubog potkornjaka Pityokteines curvidens, testiran je u kombinaciji s klopkama Theysohn ® i IPM ® . Cilj ovog rada bio je dobiti spoznaje o mogu}nostima primjene feromonske klopke za ulov jelovih potkornjaka. Rezultati ulova u klopkama ukazuju kako let proljetne generacije P. curvidens ovisi o kretanju srednje dnevne temperature koja mora posti}i 10°C. Rojenje po~inje po~etkom travnja, a glavni let i najve}i ulov u klopkama dostignu se krajem travnja i po~etkom svibnja. Nakon najve}ih ulova kukaca sljedi nagli pad, a ulovi nakon tog vrlo su niski i nakon ljetne zamjene feromona. Broj ulovljenih mu`jaka u klopkama u po~etku rojenja vi{estruko je ve}i od enki, ali se pri najve}im ulovima izjedna~ava na 1:1.

Agronomski Glasnik, 2005

Poznavanje vrsta drve a i njihove osjetljivosti na pojedine bolesti i štetnike, u specifi nim eko... more Poznavanje vrsta drve a i njihove osjetljivosti na pojedine bolesti i štetnike, u specifi nim ekološkim uvjetima, od izuzetne je važnosti za njihov odabir u krajobraznoj arhitekturi. Istraživanjima tijekom zadnjih godina u Hrvatskoj zapaženi su zna ajni problemi sa zdravstvenim stanjem drve a u šumskim ekosustavima, uzrokovani poznatim i do sada manje poznatim uzrocima. U urbanim sredinama utvr ene su sli ne i još naglašenije promjene na nekim vrstama drve a. Ona su podvrgnuta razli itim štetnim abiotskim imbenicima (suša, visoke temperature, zra ni polutanti, prekomjerne depozicije razli itih kemijskih elemenata u tlu, i dr.) te isto tako i biotskim imbenicima, od štetna utjecaja ovjeka do razli itih uzro nika bolesti (fitopatogene gljive, parazitske cvjetnice, i dr.) i štenih životinjskih vrsta (kukci, grinje, i dr.).

Croatian Journal of Forest Engineering, Apr 8, 2011

Istra`ivanjem mjesta i na~ina prezimljavanja smrekova pisara do{lo se do novih spoznaja zna~ajnih... more Istra`ivanjem mjesta i na~ina prezimljavanja smrekova pisara do{lo se do novih spoznaja zna~ajnih za {umarsku operativu u dijelu postupaka i zahvata usmjerenih na sanaciju`ari-{ta i redukcije njegovih populacija u napadnutim smrekovim sastojinama. Na dvjema pokusnim plohama koje su postavljene u prolje}e 2008. godine na sjevernom Velebitu, metodom je eklektora utvr|eno da dio imaga smrekova pisara, osim kore napadnutih dube}ih smreka, za prezimljavanje se koristi i {umskom steljom. Udio zimuju}e populacije imaga u stelji na objema lokacijama istra`ivanja zna~ajan je i iznosi do 40 % u [tirova~i (1080 m n.v.) i do 50 % u blizini Zavi`ana (1404 m n.v.). Istra`ivanjem su tako|er utvr|ena i neka fenolo{ka obilje`ja populacija potkornjaka u vr{noj zoni Velebita i u [tirova~i, poput duljega trajanja prvoga proljetnoga rojenja u [tirova~i (~etiri tjedna) u odnosu na Zavi`an (dva tjedna), te vremenskoga pomaka od dva tjedna u po~etku i vrhunjenju rojenja izme|u tih dviju lokacija istra`ivanja. Poredbenom ra{~lambom izlazaka i aktivacije imaga potkornjaka na postavljenim eklektorima i ulovima obli`njih feromonskih klopki utvr|eno je da se prvi ulovi u feromonskim klopkama pojavljuju tri tjedna nakon {to su zabilje`eni izlasci iz kore dube}ih smreka i {umske stelje. Takav je odmak uo~en u [tirova~i, dok je u vr{noj zoni Zavi`ana iznosio oko dva tjedna. Rezultati provedenih biolo{kih i fenolo{kih istra`ivanja omogu}uju racionalniji pristup u sanaciji`ari{ta napada smrekova pisara maksimiziranjem napora u razdoblju prije po~etka jeseni, u vrijeme dok se jo{ nije rasula populacija potkornjaka na dio koji ostaje pod smrekovom korom i dio koji se zavla~i u~etinjak. U situacijama kada to nije provedivo, mo`e se o~ekivati povoljniji u~inak ranih proljetnih mjera sanacije na terenima ni`ih nadmorskih visina gdje je manji udio populacije imaga potkornjaka koji se za prezimljavanje koriste {umskom steljom. Klju~ne rije~i: Ips typographus, prezimljavanje, proljetna generacija, suzbijanje Croat. j. for. eng. 32(2011)1 211 Znanstveni rad -Research article 212 Croat. j. for. eng. 32(2011)1 B. Hra{ovec i dr. Prezimljavanje smrekova pisara (Ips typographus) u smrekovim {umama sjevernoga Velebita (211-222) 214 Croat. j. for. eng. 32(2011)1 B. Hra{ovec i dr. Prezimljavanje smrekova pisara (Ips typographus) u smrekovim {umama sjevernoga Velebita (211-222) Croat. j. for. eng. 32(2011)1 216 Croat. j. for. eng. 32(2011)1 B. Hra{ovec i dr. Prezimljavanje smrekova pisara (Ips typographus) u smrekovim {umama sjevernoga Velebita (211-222) Croat. j. for. eng. 32(2011)1 B. Hra{ovec i dr. Prezimljavanje smrekova pisara (Ips typographus) u smrekovim {umama sjevernoga Velebita (211-222)

During field evaluations of pheromone blends used for monitoring Tomicus piniperda beetles, many ... more During field evaluations of pheromone blends used for monitoring Tomicus piniperda beetles, many non-target beetles were captured and identified. Five pheromone blends, plus commercially available TOMODOR were used in two different traps: the IPM Tech Intercept PTBB and the THEYSOHN intercept barrier trap. In addition to Tomicus bark beetles we trapped 3,469 other Coleoptera in three of the 10 replications that represented 53 species distributed among 27 families. Most numerous were representatives of Staphyllinidae, Elateridae, Cleridae and Rhizophagidae. Temporal distribution of the most important predatory species as well as their responsiveness to pheromone blends is presented. The results are discussed in terms of interspecies chemical communication and few practical aspects relevant for the potential use in Tomicus monitoring or suppression activities.

The larvae of Tomostethus nigritus F. (Hym.: Tenthredinidae) began causing severe defoliation on ... more The larvae of Tomostethus nigritus F. (Hym.: Tenthredinidae) began causing severe defoliation on ash along avenues and tree lines in Zagreb, Croatia since 1997. The phenomenon of population outbreaks in periurban and urban environments is known but poorly documented in the literature; the fact that it has not yet been recorded in Croatian forests has spurred authors to investigate further into this natural event. Populations achieved outbreak levels in the second year after defoliation was first recorded. Although only Fraxinus excelsior L. was attacked; palatability tests indicate that larvae show no preference among several ash species, larval development in situ and their dispersion in the field suggest that phenology of the host tree was the dominant factor in host selection. Based on foliage availability, F. excelsior proved to be the most suitable species for females during their oviposition period. Detailed study of all developmental stages, especially the late larval and prepupal stages, confirmed earlier published knowledge on this sawfly but provided also some new facts and practical solutions that can be utilized for monitoring and managing this species. Parasitoid fauna have also been studied and, despite the relatively small impact that was recorded from laboratory rearings, it is assumed that parasitoids and floods are the most important natural controlling factors affecting this species in forests. Based on the spread and intensity of the recent outbreak and its similarity to European outbreaks, we presume that environmental factors, mainly the impact of late fall and early spring floods, are the most important trigger mechanism involved in this phenomenon.

The Huchen or Danube Salmon is one of the most enigmatic species of Europe's freshwater fauna... more The Huchen or Danube Salmon is one of the most enigmatic species of Europe's freshwater fauna. It is a sensitive indicator species for some of the most ecologically valuable rivers in the Danube drainage. Historically, the species was wide-spread across the entire Danube basin. Since the late 19th century, however, Huchen populations declined by two thirds and the remaining populations are now highly endangered by hydropower development. But knowledge on the distribution of the Huchen on the Balkan Peninsula has been incomplete. In this study, we review the actual occurrence of Huchen in the Balkan region. A total of 1842 river km supporting self-sustaining populations of Huchen in the Balkan region have been identified, making the region the global hot spot for the species. These populations are found in 43 rivers or distinct river reaches in Slovenia, Croatia, Bosnia-Herzegovina, Serbia and Montenegro. About 65% of all Huchen rivers globally are located in these countries, hig...

The knowledge of tree species, its biological features and susceptibility to pests and diseases p... more The knowledge of tree species, its biological features and susceptibility to pests and diseases plays an important role in the process of tree species selection in landscape arhitecture. The research in this field in Croatia in the last decade revealed some cases of severe pest and disease related problems in some tree species, both in urban forests and in parks and tree lanes. Some of these are well known from the past but several are quite new and poorly known. These problems are even more accentuated in harsh urban environment. Aside from negative abiotic impacts (drought, high temperatures, air pollution, soil pollution, and other), biotic agents appear to be at least equally important and sometimes even detrimental to tree's health (parasitic fungi, parasitic weeds, insects, mites, etc.). Simultaneous action of several detrimental factors may add significantly to trees health status. One of the dominant in the past few years, drought, acted as a predisposing factor enabling...

Sumarski List

European Journal of Entomology, 2014

ABSTRACT Boundaries between habitats are usually accompanied by transitions in the diversity and ... more ABSTRACT Boundaries between habitats are usually accompanied by transitions in the diversity and structural complexity of insect assemblages. Edge effects on carabid beetle assemblages across forest-meadow ecotones in Dinaric beech-fir forests were determined in the Gorski Kotar region of western Croatia. Carabid beetles were sampled using pitfall traps set along gradients extending 60 m from the forest edge into its interior and 60 m into the meadow. Embedded forest edges were greater than 100 years old and had a similar composition and structure of vegetation to that in the adjacent forest. A total of 20,526 individuals belonging to 66 carabid beetle species were recorded. Carabid assemblages in the ecotones were more similar to those in the forest interiors than those in the meadows. The classical edge effect hypothesis was not supported, since the ecotones were less diverse than the meadows, while the carabid assemblages of the forest interiors were the least diverse. Soil temperature, soil humidity and light intensity did not differ significantly between the ecotones and the forest interior. Therefore, embedded forest edges reduced the microclimate edge effect by providing stable microclimatic conditions for carabid assemblages similar to those in the forest interior. In addition, this enabled forest specialists and generalists to occur right up to the forest edge and maintain stable populations in the ecotone. On the other hand, ecotones acted as filters for certain forest generalist species and true barriers for most open-habitat species. This study confirmed that the structure and ages of the vegetation at edges may play a key role in determining the spatial pattern of carabid beetles across forest-meadow ecotones.

Background and Purpose: The three palearctic species Pityokteines spinidens, P. curvidens and P. ... more Background and Purpose: The three palearctic species Pityokteines spinidens, P. curvidens and P. vorontzowi are main pests on Abies species and their impact on Abies stands is increasing. As the three scolytid species, particularly females, are difficult to distinguish, this study aimed to find additional morphological characters for identification. Further, part of the mitochondrial COI gene was sequenced to develop a significant barcode marker for future use. Material and Methods: All three bark beetle species were collected from logs in Croatia (Litori} and Trako{}an), in order to quantify the number of strial and interstrial punctures. Insect DNA was extracted and PCR products were purified, directly sequenced, aligned and analyzed by MP analysis and Bayesian analysis. Results and Conclusion: The number of punctures in the first and second interstriae between the elytral base and the sutural tubercle proved to be a valuable tool for the differentiation of P. spinidens from P. cu...

An optimized, patented lure for the larger pine shoot beetle, Tomicus piniperda has been develope... more An optimized, patented lure for the larger pine shoot beetle, Tomicus piniperda has been developed and tested in the United States, Poland, and Croatia. Seven different beetle attractants were tested: αpinene, α-pinene oxide, ethanol, nonanal, myrtenal, myrtenol, and trans-verbenol. α-pinene was tested alone or in combination with two or more of the remaining compounds. Attraction of all candidate lures was compared to attraction of Tomodor, a Polish commercial lure for T. piniperda, using the Intercept™ Panel Trap (PT). A lure containing α-pinene, α-pinene oxide, nonanal, myrtenal, myrtenol, and trans-verbenol was used to compare trap captures in Intercept PT with 12unit multi-funnel traps in USA, Theyson trap in Croatia, and IBL-3 trap in Poland. This study demonstrated that at least a quaternary semiochemical combination, including α-pinene, nonanal, trans-verbenol, and myrtenol is required to assure maximum trap captures. The best IPM Tech lure was significantly more attractive than Tomodor when tested in Poland and Croatia. Catches of T. piniperda in the Intercept PT were significantly higher than in the IBL-3 trap or Theyson trap.

3rd Slovenian Symposium on Plant …, 2002

Pityokteines spinidens commonly occurs in Europe where it infests Silver fir and occasionally oth... more Pityokteines spinidens commonly occurs in Europe where it infests Silver fir and occasionally other conifers. Together with the two additional Pityokteines species (P. curvidens and P. vorontzowi) it has been reported as an important factor in Silver fir decline in some parts of Europe. Bark beetles are known to be associated with diverse guilds of arthropods and microorganisms of which phoretic mites and ophiostomatoid fungi are among the best-known associates. Some ophiostomatoid fungi associated with bark beetles display high levels of virulence to their host trees and they are thus suspected to aid their bark beetle vectors in overcoming the defense mechanisms of living hosts. Increased local populations of P. curvidens, P. spinidens and P. vorontzowi have been recently noted in conifer forests in various parts of Croatia, resulting in high damage levels on Silver fir. This increase in the importance of Pityokteines species as forest pests of Silver fir in Croatia, prompted rese...

Journal of Animal Ecology, 2013

1. We show that the population ecology of the 9-to 10-year cyclic, broadleaf-defoliating winter m... more 1. We show that the population ecology of the 9-to 10-year cyclic, broadleaf-defoliating winter moth (Operophtera brumata) and other early-season geometrids cannot be fully understood on a local scale unless population behaviour is known on a European scale. 2. Qualitative and quantitative data on O. brumata outbreaks were obtained from published sources and previously unpublished material provided by authors of this article. Data cover six decades from the 1950s to the first decade of twenty-first century and most European countries, giving new information fundamental for the understanding of the population ecology of O. brumata. 3. Analyses on epicentral, regional and continental scales show that in each decade, a wave of O. brumata outbreaks travelled across Europe. 4. On average, the waves moved unidirectionally ESE-WNW, that is, toward the Scandes and the Atlantic. When one wave reached the Atlantic coast after 9-10 years, the next one started in East Europe to travel the same c. 3000 km distance. 5. The average wave speed and wavelength was 330 km year À1 and 3135 km, respectively, the high speed being incongruous with sedentary geometrid populations. 6. A mapping of the wave of the 1990s revealed that this wave travelled in a straight E-W direction. It therefore passed the Scandes diagonally first in the north on its way westward. Within the frame of the Scandes, this caused the illusion that the wave moved N-S. In analogy, outbreaks described previously as moving S-N or occurring contemporaneously along the Scandes were probably the result of continental-scale waves meeting the Scandes obliquely from the south or in parallel. 7. In the steppe zone of eastern-most and south-east Europe, outbreaks of the winter moth did not participate in the waves. Here, broadleaved stands are small and widely separated. This makes the zone hostile to short-distance dispersal between O. brumata subpopulations and prevents synchronization within meta-populations.

Blue Heart of Europe

The Huchen or Danube Salmon is one of the most enigmatic species of Europe's freshwater fauna. It... more The Huchen or Danube Salmon is one of the most enigmatic species of Europe's freshwater fauna. It is a sensitive indicator species for some of the most ecologically valuable rivers in the Danube drainage. Historically, the species was wide-spread across the entire Danube basin. Since the late 19th century, however, Huchen populations declined by two thirds and the remaining populations are now highly endangered by hydropower development. But knowledge on the distribution of the Huchen on the Balkan Peninsula has been incomplete. In this study, we review the actual occurrence of Huchen in the Balkan region. A total of 1842 river km supporting self-sustaining populations of Huchen in the Balkan region have been identified, making the region the global hot spot for the species. These populations are found in 43 rivers or distinct river reaches in Slovenia, Croatia, Bosnia-Herzegovina, Serbia and Montenegro. About 65% of all Huchen rivers globally are located in these countries, highlighting the importance of Balkan Rivers for the survival of the species. Core areas, representing the largest and healthiest Huchen populations have been identified for each country and include the Sava River and its tributaries in Slovenia, the Kolpa / Kupa River along the Slovenian-Croatian border, the Una River along the Croatian-Bosnian-Herzegovinian border, the upper Drina River and its tributaries in Bosnia-Herzegovina and Serbia, and the Lim River in Montenegro. The Balkans harbour nearly all major habitats for Huchen in terms of size. In this region we find six of the seven > 100 km long river reaches representing Huchen habitat globally (Sava, Kolpa/Kupa, Una, Sana, Drina & Lim rivers). The major threat to these populations is a massive hydropower development plan. Practically all Huchen Rivers are targets of substantial hydropower exploitation. A total of 93 dam projects were identified directly in river reaches supporting Huchen and a large number of additional projects are located in tributaries or headwater reaches upstream of Huchen habitat that will invariably degrade environmental conditions downstream. If these dams would be constructed, at least 1.000 km of Huchen habitat would be drowned by reservoirs or severely degraded by hydropeaking below the dams. If these plans are carried out, we predict that at least 60-70% of the Balkan population and about 35-40% of the global population of Huchen would be lost with the remaining populations being small and severely fragmented and eventually no longer able to survive in the long term. We urge that the remaining free-flowing Balkan rivers holding self-sustaining populations of Huchen be left undammed, and efforts be made to restore former rivers reaches where Huchen once occurred but are now absent. We emphasize that Huchen, as an apex predator, is an indicator of relatively healthy riverine ecosystems. These systems provide a number of ecosystem services and are home to a large number of species, including at least 16 fish (such as the sculpin, zingel and streber) that at are themselves legislatively protected. The existence of Huchen and these species with such hydropower development is incompatible. For governments, this data is paramount to fulfilling their conservation commitments, as the Huchen is protected by the EU Natura Habitats Directive and the Bern Convention and is a key species for achieving the goals of the EU Water Framework Directive.

Ecological Modelling, 2006

27 a b s t r a c t In this paper, we analyze the phenology of spruce bark beetles (Ips typographu... more 27 a b s t r a c t In this paper, we analyze the phenology of spruce bark beetles (Ips typographus and Pityogenes chalcographus) in the Dinaric mountain forests of southwestern Slovenia. The study of I. typographus took place from 1986 to 2000, while that of P. chalcographus took place from 1993 to 2000 in an area characterized as a Dinaric Fir-Beech forest community (Abieti-Fagetum dinaricum) on the Karst plateau (447-751 m above sea level). On the studied area Norway spruce (Picea abies) has been planted between 60 and 90 years ago on approximately 1000 ha. Frequent catastrophic weather conditions are characteristic for this area, followed by an increased trophic capacity of the forest for the various bark beetle species. The population density of spruce bark beetles was monitored at five locations at varying exposures using commercial pheromones (Pheroprax ® and Chalcoprax ® ) in traps under the trade name Theyson. Both species studied (I. typographus and P. chalcographus) have a relatively high abundance and have two main generations per year; both species may also produce two sister generations. Data on some environmental factors as well as data on bark beetle catches have been collected and then analyzed to model the dependence of spruce bark beetle catches on the environmental factors. The machine learning methodology of liner regression as well as model tree induction was used for this purpose. The following attributes were used to analyze the occurrence of both species of bark beetle: position (NW, NE, W, E, N and S), age of pheromone, number of days since last monitoring, average monthly temperature, monthly precipitation, month and previous number of bark beetles. There was a strong correlation between a high population density of I. typograpus and north (N) and west (W) positions, and a high density of populations of P. chalcographus and north (N) and east (E) positions.