Testiranje biološke učinkovitosti feromona i klopki za ulov mediteranskog potkornjaka Orthotomicus erosus (Coleoptera, Curculionidae)

In the Aleppo pine forests at the Croatian Mediterranean in 2017, a Mediterranean bark beetle (Orthotomicus erosus) appeared in population densities that had not been recorded before and until then was not considered a significant pest in that area. Natural enemies are not able to follow a sudden increase of the bark beetle population, which results in rapid increase of drying trees. As a part of the suppression of the Mediterranean bark beetle in 2018, pheromone traps have been installed in Croatia for monitoring purposes. Although there are multiple options for applying different types of traps and pheromone preparations for the Mediterranean bark beetle, so far the differences in catches of different types of traps and their selectivity have not been investigated. In 2019, 40 pheromone traps were placed in the Forest Park ​​Marjan (Split) on 196 ha of forest area. A pairs of pheromone preparations Pheroprax and Erosowit were compared, a system of three traps (Triplet) with a single flight barrier trap as well as the modified wet flight barrier trap with a regular flight barrier trap. In addition to the average number of catches in pheromone traps, particular attention was given to selectivity. Two predator species Tanasimus formicarius and Temnochila caerulea were found in traps, with T. formicarius in insignificant quantities relative to T. caerulea. The results indicate that Erosowit exhibits significantly higher catches compared to Pheroprax and is significantly more selective. Pheroprax has a very high catches of T. caerulea predators and is not recommended for practical use. The Triplet had only slightly better catches compared to the single flight barrier trap, but also showed slightly better selectivity. The Triplet did not show the expected effect due to the amount of the catch, which was slightly higher than in the single trap, but not significantly in order to recommend their use. The wet flight barrier trap turned out not to be satisfactory as it does not produce significantly higher catches than a regular flight barrier trap, and is twice less selective. Given the additional costs (trap adaptation, fluid that needs to be changed, slower collection), this trap type is not recommended for use. Comparing the results of the catch in 2019, the number of bark beetles was found to be almost 5 times lower than in 2018.

Presence of birch bark beetle (Scolytus ratzeburgi) in Croatia

Potkornjaci su jedna od najvažnijih skupina šumskih štetnika, a u posljednjih nekoliko godina zabilježene su štete od istih u dvije biogeografske regije Hrvatske. Smrekov pisar (Ips typographus) na području alpinske i mediteranski potkornjak (Orthotomicus erosus) na području mediteranske regije ukazali su na njihovu važnost. Brezov potkornjak bjelikar (Scolytus ratzeburgi) je jedina vrsta iz roda Scolytus kojoj su domaćini vrste iz roda Betula spp. te kao takva može predstavljati potencijalnu opasnost u Hrvatskoj. Prisutnost ove vrste je vidljiva po rupicama na kori, ispod kojih se nalazi materinski hodnik (Slika 2), a mužjak i ženka se razlikuju po količini dlaka na prednjem dijelu glave te po izbočini na zadku (Slika 1). Kako bi utvrdili prisutnost brezovog potkornjaka bjelikara na području Hrvatske, u ovom radu je napravljen pregled povijesnih zapisa (entomološke zbirke i literatura) i sastojina obične breze (B. pendula). Na terenu su sakupljeni uzorci (trupčići) na kojima je uočena prisutnost brezovog potkornjaka bjelikara te je napravljena laboratorijska analiza. Pregledom literature utvrđen je posljednji zabilježeni pronalazak brezovog potkornjaka bjelikara od prije više od 100 godina (1913. godina), a primjerci u entomološkim zbirkama potječu iz susjednih zemalja. Terenski pregled sastojina obične breze utvrdio je pet novih lokacija na kojima je vidljiva prisutnost brezovog potkornjaka bjelikara (Slika 3; Tablica 1). Gustoća populacije ove vrste u šumskim i urbanim područjima Hrvatske je niska, ali bez obzira na tu činjenicu brezov potkornjak bjelikar predstavlja važan dio entomofaune Hrvatske. Nastavak istraživanja trebao bi razjasniti povezanost brezovog potkornjaka bjelikara s patogenim gljivičnim bolestima i foretičkim grinjama s obzirom na moguće promjene na južnom rubu područja rasprostranjenja obične breze.

Outbreak of Orthotomicus erosus (Coleoptera, Curculionidae) on Aleppo Pine in the Mediterranean Region in Croatia

Background and Purpose: Orthotomicus erosus, Mediterranean pine engraver, is widely distributed across the Mediterranean and southern Europe, Asia and North Africa. It is considered as secondary pest found on recently dead or felled trees, but can also attack weakened living trees. In high population levels this species can attack healthy trees and cause their dieback. Severe outbreaks occur after dry periods, or after fire in adjoining stands in warmer parts of the Mediterranean region, while this scenario has never happened in Croatia up to now. Bark beetles are important forest pests which have already been researched and discussed in relation to climate change, indicating that the predicted increase in temperature would lead to higher survival rates and faster development, thus directly influencing their population dynamics. Increase in temperature may stimulate changes in insects’ rate of development, voltinism, population density, size, genetic composition, extent of host plant exploitation, longitudinal and latitudinal distribution. Since climate conditions might have changed in the last few years as predicted in the Mediterranean region, the aim of our research is to document the first outbreak with high population levels of O. erosus in Croatia. Materials and Methods: The extent of dieback was evaluated by counting trees with dieback symptoms on diagonal transects plotted through each of 33 forest management sections of Marjan Forest Park (Split). Trunk sections from several trees with early stage symptoms were collected for further laboratory analysis, which consisted of incubation phase and subsequent morphological identification. During regular yearly surveys in forests of Croatia, the pest was observed on several sites and damages were recorded for both years 2017 and 2018. The records were entered into a map using QGIS version 3.2.1-Bonn. Spatial data was downloaded from DIVA-GIS server. Monitoring efforts were initiated in affected areas where 13 flight barrier pheromone traps (Theyson®) equipped with pheromone lure Erosowit® (Witasek, Austria) were set-up in late March in state-owned and privately owned forests across Dalmatia. Catches in the traps were collected and O. erosus adults were counted on a weekly basis in order to identify the abundance of the pest in monitored sites, as well as to obtain the first information about population dynamics and to assess voltinism. Results: On-site survey and the evaluation of dieback extent included sampling of 5% of all trees in Marjan Forest Park ,and the results showed that 23% of all trees in the forest park were affected by dieback symptoms. Visual examination of trunks, branches and bark showed symptoms of bark beetle infestation, while preliminary on-site examination of the observed adults pointed out to O. erosus. After two weeks in controlled conditions, bark beetle adults started to emerge from trunk sections which were placed in several mesh cages for incubation. Morphological identification by using stereomicroscope and the key for European bark beetles resulted in identification of O. erosus species. Over the course of the year 2017 one more site was reported to be infested with O. erosus, and eight additional sites were reported over the course of year 2018. In total, 446 ha were reported as infested, varying in intensity, in several different management units of state-owned and privately owned forests. The total number of trapped beetles in pheromone traps varied largely among sites. Our data indicate that several generations (at least 5 generations per year) were present in the year 2018. Conclusions: Sudden surge in observed damages, as well as the number of beetles trapped during monitoring, in years 2017 and 2018 throughout Aleppo pine forests in Dalmatia are the first record of O. erosus outbreak in Croatia. O. erosus is native to Croatia and so far it has been considered only as a minor pest whose outbreaks have never been recorded. Drought intensity and frequency and aridification trends in the research area (Dalmatia, Croatia) cause cumulative stress to trees and have increased O. erosus occurrence. O. erosus is expected to exhibit increased voltinism, better overwintering performance and earlier spring flights. Our first results confirm this epidemic stage of O. erosus with high abundances in Dalmatia in 2018 and at least 5 generations per year, which alter the population level of this pest. Finally, with high dispersal abilities of O. erosus through active flight and easy transportation with infested material (logs and branches with bark), O. erosus has the potential to become an important forest pest in Croatia. Thus, extensive studies on its biology, ecology, natural enemies and interaction with ophiostomatoid fungal species are needed in order to predict further spread and suggest viable and effective management measures.

Antifungal actinomycetes associated with the pine bark beetle, Orthotomicus erosus, in South Africa

Actinomycete bacteria are often associated with insects that have a mutualistic association with fungi. These bacteria are believed to be important to this insect–fungus association as they produce antibiotics that exclude other saprophytic fungi from the immediate environment. The aim of this study was to investigate the presence of potentially protective actinomycetes associated with Orthotomicus erosus, an alien invasive pine bark beetle, in South Africa. This bark beetle and its relatives have an association with Ophiostomatales species which are often the only fungi found in the bark beetle galleries. We hypothesised that antibiotic-producing actinomycetes could be responsible for the paucity of other fungi in the galleries by producing compounds to which the Ophiostoma spp. are tolerant. Several actinomycetes in the genus Streptomyces and one Gordonia sp. were isolated from the beetle. Interestingly, most isolates were from the same species as actinomycetes associated with other pine-infesting insects from other parts of the world, including bark beetles and the woodwasp Sirex noctilio. Most actinomycetes isolated had strong antifungal properties against the selected test fungi, including Ophiostoma ips, which is the most common fungal symbiont of Orthotomicus erosus. Although the actinomycetes did not benefit Ophiostoma ips and the hypothesis was not supported, their sporadic association with Orthotomicus erosus suggests that they could have some impact on the composition of the fungal communities present in the bark beetle galleries, which is at present poorly understood.

Faunistic review of Polish Platypodinae and Scolytinae (Coleoptera: Curculionidae)

Faunistic review of Polish Platypodinae and Scolytinae (Coleoptera: Curculionidae)Based on a survey of the literature and collections, the distributions of the Platypodinae and Scolytinae (Curculionidae) within the present-day borders of Poland are summarized. An updated and annotated checklist is given of Polish pinhole borers (1 genus, 1 species) and bark beetles (35 genera, 110 species).Carphoborus cholodkovskyiSpessivtsev has been removed from the list; the presence ofHylastinus obscurus(Marsham),Pteleobius kraatzii(Eichhoff),Pityophthorus exsculptus(Ratzeburg),Cryphalus saltuariusWeise,Thamnurgus kaltenbachii(Bach),T. varipesEichhoff,Pityogenes irkutensis monacensisFuchs,P. saalasiEggers,Xyleborus eurygraphus(Ratzeburg) andX. pfeilii(Ratzeburg), reported by previous authors, needs to be confirmed by new findings.Pitophthorus carniolicusWichmann,Xylosandrus germanus(Blandford) andCrypturgus subcribrosusEggers were recorded generally from Poland.Hylastes plumbeusBlandford,Phloeosinus aubei(Perris),Gnathotrichus materiarius(Fitch),Orthotomicus erosus(Wollaston),Scolytus sulcifronsRey andTrypodendron laeveEggers (Knížek 2011) were erroneously recorded from Poland.