Robert Rossa

Citizen monitoring of invasive species: wing morphometry as a tool for detection of alien Tetropium species

The increasing threat of alien wood‐boring insect has resulted in the initiation of large‐scale monitoring programmes. These programmes are most often based on pheromone‐bailed traps, which allow the early detection and monitoring of invasive species. This approach is expensive because it entails the processing and accurate identification of large numbers of specimens. One of the most often suggested solutions to this problem is citizen participation in the monitoring of invasive species. Such an approach has the potential for reducing costs as well as providing data from a larger number of sites. However, citizens vary in taxonomic expertise and experience which can result in identification errors. This may be particularly important in the case of wood borers which include many morphologically similar species. In this study, we develop and discuss a semi‐automated method of identifying four morphologically similar and invasive Tetropium spp. wood borers as a potential tool for citizen‐based monitoring programmes. Identification is based on wing measurements and requires neither specialist knowledge nor expensive equipment. The method correctly identified the species of Tetropium with an error ranging from 1.3% for T. fuscum to 7.5% for T. cinnamopterum. We found that experience level of the individual user was not essential for correct identification; on average, inexperienced volunteers correctly identified the Tetropium species in 93% of cases. Further development of this method may be a significant step to overcoming the taxonomical impediment to citizen monitoring of taxonomically challenging groups of insects.

Within- and Between-Species Variation of Wing Venation in Genus Monochamus (Coleoptera: Cerambycidae)

We have described the morphological variation of five Western Palaearctic species of Monochamus Dejean, 1821. The variation was assessed using wing measurements. Special emphasis was placed on the differences between Monochamus sartor (F., 1787) and Monochamus urussovii (Fischer-Waldheim, 1805). There was an interesting pattern of variation between the two species. Individuals of M. sartor from the Carpathians differed markedly from individuals of M. urussovii from Siberia, but individuals from north-eastern Poland were intermediate between those two populations. The intermediate individuals were more similar to the Siberian M. urussovii than to the Carpathian M. sartor despite the relatively large geographic distance between north-eastern Poland and Siberia. The occurrence of the intermediate individuals in north-eastern Poland may be the effect of hybridization between M. urussovii and M. sartor, which might have occurred after secondary contact between the two species in the Holocene.

Elytra reduction may affect the evolution of beetle hind wings

Beetles are one of the largest and most diverse groups of animals in the world. Conversion of forewings into hardened shields is perceived as a key adaptation that has greatly supported the evolutionary success of this taxa. Beetle elytra play an essential role: they minimize the influence of unfavorable external factors and protect insects against predators. Therefore, it is particularly interesting why some beetles have reduced their shields. This rare phenomenon is called brachelytry and its evolution and implications remain largely unexplored. In this paper, we focused on rare group of brachelytrous beetles with exposed hind wings. We have investigated whether the elytra loss in different beetle taxa is accompanied with the hind wing shape modification, and whether these changes are similar among unrelated beetle taxa. We found that hind wings shape differ markedly between related brachelytrous and macroelytrous beetles. Moreover, we revealed that modifications of hind wings have followed similar patterns and resulted in homoplasy in this trait among some unrelated groups of wing-exposed brachelytrous beetles. Our results suggest that elytra reduction may affect the evolution of beetle hind wings.

Hind wing variation in Leptura annularis complex among European and Asiatic populations (Coleoptera, Cerambycidae)

Abstract The ability to quantify morphological variation is essential for understanding the processes of species diversification. The geometric morphometrics approach allows reliable description of variation in animals, including insects. Here, this method was used to quantify the morphological variation among European and Asiatic populations of Leptura annularis Fabricius, 1801 and its closely related species L. mimica Bates, 1884, endemic for Japan and Sakhalin islands. Since the taxonomic status of these two taxa is differently interpreted by taxonomists, they are collectively called “Leptura annularis complex” in this paper. The analysis was based on the measurements of hind wings of 269 specimens from six populations from Europe and Asia. The level of morphological divergence between most of continental European and Asiatic populations was relatively small and proportional to the geographic distance between them. However, distinct morphotype was detected in Sakhalin Is. and Japan. These data confirm the morphological divergence of the endemic L. mimica species. Obtained results highlight the potential of the geometric morphometric method in studying morphological variation in beetles.

Dead Wood Complexity Shapes the Pattern of the Occurrence of Threatened Saproxylic Beetle Cucujus cinnaberinus

ABSTRACT Saproxylic beetles are essential for the proper functioning of forest ecosystems. However, intensive forest management has led to the disappearance of suitable microhabitats of many species associated with dead wood. Cucujus cinnaberinus is an endangered saproxylic beetle which develops under the bark of dead wood. The species usually occurs in protected areas, however, some populations inhabit long-term managed forests in Central Europe. In this study, we analyzed the effect of nine silviculture-related and decay-related factors on the C. cinnaberinus microhabitat selection in managed forests. We found that potential sun exposure, bark thickness, dead wood moisture and the hardness of dead wood have a significant effect on the C. cinnaberinus microhabitat selection. The species prefers sun-exposed dead wood with thicker bark at an intermediate stage of decay with undecomposed xylem, but avoids completely dry pieces. Furthermore, we found no confirmation of a direct connection between dead wood diameter and the occurrence of C. cinnaberinus. We stressed that logging residues or stumps are mostly unsuitable for C. cinnaberinus development.

Diversity of Ophiostomatales species associated with conifer-infesting beetles in the Western Carpathians

Bark beetles (Coleoptera: Curculionidae, Scolytinae) are commonly recognised as important agents of tree mortality in coniferous forests of the Western Carpathians. They, together with weevils, are consistently associated with ophiostomatoid fungi. Information regarding conifer beetle-associated fungi in the Western Carpathians remains incomplete and unreliable, particularly with respect to fir-infesting bark beetles. This study aims to clarify associations between fungi in the genera Graphilbum, Leptographium, Ophiostoma and Sporothrix (Ophiostomatales) and their beetle vectors in Norway spruce (Picea abies), European larch (Larix decidua) and silver fir (Abies alba). Samples associated with 20 bark beetle species and weevils were collected from nine stands in Poland and the Czech Republic. Fungi were isolated from adult beetles and galleries. Isolates were identified based on morphology, DNA sequence comparisons for four gene regions (ITS, LSU, ß-tubulin, TEF 1-α) and phylogenetic analyses. In total, 46 distinct taxa were identified, including 25 known and 21 currently unknown species. Several associations between fungi and subcortical insects were recorded for the first time. In addition, O. borealis and O. quercus were detected from A. alba for the first time. The composition of the fungal communities varied among the studied tree species and to a lesser degree among the beetle species. The spruce-infesting bark beetles were commonly associated with species of Leptographium s. l. and Ophiostoma s. str.; the larch-infesting bark beetles were often associated with Ophiostoma s. str. and Sporothrix, while the fir-infesting bark beetles were commonly associated with Ophiostoma s. str. and Graphilbum. The most commonly encountered fungal associates of the examined insects were (a) Grosmannia cucullata, G. piceiperda, Grosmannia sp. 1, Ophiostoma macroclavatum and O. piceae with the spruce-infesting bark beetles; (b) O. pseudocatenulatum and Sporothrix sp. 1 with the larch-infesting bark beetles; and (c) O. piceae, Ophiostoma sp. 2 and Graphilbum sp. 2 with the fir-infesting bark beetles. The differences in fungal associates among the bark beetle species occurring on P. abies, L. decidua and A. alba could be linked to the different habitats that these beetles occupy.

A preliminary study on the pathogenicity of three blue-stain fungi associated with Tetropium spp. to Norway spruce in Poland

Wstępne badania nad patogenicznością trzech grzybów siniznowych związanych z Tetropium spp. na świerku pospolitym w Polsce A preliminary study on the pathogenicity of three blue-stain fungi associated with Tetropium spp. to Norway spruce in Poland To evaluate pathogenicity of some fungi associated with Tetropium spp. (Coleoptera: Cerambycidae): Grosmannia piceiperda, Grosmannia penicillata and Ophiostoma tetropii the inoculation of Norway spruce (Picea abies) trees experiment was performed. The inoculation densities were 400 and 800 points/m2 in a 60 cm wide band at breast height. The effects of inoculation were examined 23 weeks after treatment. Two trees inoculated with G. piceiperda were dying at harvest. Inoculation with G. piceiperda produced significantly greater phloem and sapwood lesions in comparison with other fungi and control. Moreover, the percentage of occluded sapwood was also highest following G. piceiperda inoculations at 800 points/m2. Ophiostoma tetropii, however, produced more occlusions than G. piceiperda at 400 points/m2. These preliminary results suggest that G. piceiperda is pathogenic and may contribute to the mortality of spruces infested by Tetropium beetles.

Developmental Costs of Biological Invasion: The Exotic Wood Borer Tetropium fuscum (Coleoptera: Cerambycidae) is More Asymmetric and Smaller in Invaded Area

Abstract Biological invasions provide a unique opportunity to gain insight into basic biological processes occurring under new circumstances. During the process of establishment, exotic species are exposed to various stressors which may affect their development. Presence of the stressors is often detected by measurements of left–right body asymmetry, which consists of two main components: fluctuating asymmetry and directional asymmetry. Fluctuating asymmetry constitutes random differences between the two body sides, whereas directional asymmetry occurs when a particular trait is bigger on one of the sides. The relation between these two asymmetry components is still not fully understood. Our goal was to investigate the potential differences in asymmetry patterns between native and invasive populations of Tetropium fuscum (Fabr. 1787) (Coleoptera: Cerambycidae), a harmful forest pest native to Europe and introduced to North America. Wing asymmetry assessment was based on the geometric morphometrics of hind wings. We found that specimens from invaded area were markedly smaller and have more asymmetric wings than individuals from native population, suggesting some unfavorable conditions in the invaded area. Moreover, we found significant directional asymmetry in the native but not in the invasive population. On the other hand, differences between left and right hind wings were similar in the native and invasive populations, in terms of direction. This suggests that a high level of fluctuating asymmetry in the invasive population may blur the intrinsic directional asymmetry and hinder its detection. Our data show that fluctuating asymmetry has a potential as an indicator of developmental stress in invasive species.