Spatial genetic structure in populations of the green oak leaf roller, Tortrix viridana L. (Lepidoptera, Tortricidae)

The green oak leaf roller (Tortrix viridana L.) is a major pest on oaks. The green oak leaf roller is one reason within a disease complex for the oak decline, and it leads to defoliation of oaks in spring. In Germany, Quercus robur L. is mainly affected. The partitioning of genetic variation within and among populations of forest pests is linked to their capacities for migration. And the capacity for migration is the basis for dispersal of the pest species to different host trees and host populations and, therefore, for further outbreak events. Thus, the within population spatial genetic structure (SGS) of T. viridana was investigated based on nuclear (AFLP) markers to analyse the dispersal capacity of this insect pest species at a very small spatial scale. A total of 401 individuals of the green oak leaf roller from four stands in North Rhine-Westphalia (Western Germany) were examined. In three of four populations, the AFLP markers revealed clearly SGS up to 40 m, which can be explained by the mating behaviour within this species.     

Multiple invasions of Bemisia argentifolii into Australia and its current genetic connectivity across space

Detecting the number of invasions is crucial to understanding the process of invasion and perhaps the success of some invasive pest species. Detecting multiple invasions can be difficult using partial mitochondrial COI, however, due to lack of variation. To examine the post-invasion history of Bemisia argentifolii (also called B. tabaci Middle East-Asia Minor 1 and B biotype) in Australia and test for the presence of spatial genetic structure, we developed microsatellite loci based on the whole-genome sequence of B. argentifolii. We investigated gene flow among populations of B. argentifolii collected between 1995 and 2018, covering the time since the first detection in Australia (1994). Structure plots and PCAs of the microsatellite data revealed three clusters in 1995–1996, indicating multiple introductions. Since then, B. argentifolii has become a widespread single genetic population across the continent, with no geographic genetic structure in recent samples. The haplotype network generated from mitochondrial COI shows that Australian B. argentifolii mostly has the same haplotype as the invasive populations established elsewhere around the world. Analysis of the more recent samples showed that gene flow was high across regions, indicating movement of B. argentifolii across Australia is currently extensive. Undesirable traits and pathogens not already present in Australia, including insecticide resistance and plant viruses, could arrive with any new introductions of B. argentifolii and are likely to spread rapidly and be difficult to contain. This highlights the importance of biosecurity and continued quarantine measures to prevent new incursions, even when a species has already established.

     

Combining banker plants to achieve long-term pest control in multi-pest and multi-natural enemy cropping systems

Banker plants increase biological pest control by supporting populations of non-pest arthropod species, used as alternative hosts or prey by natural enemies. Due to the specificity of trophic interactions, banker plants may not efficiently promote natural enemies with different ecologies. Yet in most cropping systems, different pest species are present together and require different biocontrol agents to efficiently control them. In the present study, we tested the combined use of two banker plants and their associated prey/host to enhance populations of the specialist parasitoid Encarsia formosa targeting the main tomato pest Bemisia tabaci, and a polyphagous ladybird Propylea japonica targeting the secondary pest Myzus persicae in tomato crops. In a laboratory and a greenhouse experiment, we measured the abundances of these four species using the Ricinus communis—Trialeurodes ricini banker plant system alone, in combination with the Glycines max—Megoura japonica system, or in absence of banker plants. We found that the first banker plant system enhanced populations of E. formosa, resulting in increased suppression of B. tabaci populations and the suppression of their outbreak in both our laboratory and greenhouse experiment. Conversely, abundances of P. japonica were not affected by this first system, but were significantly increased when the second was present. This resulted in increased control of M. persicae populations and the suppression of their early and late outbreaks. Our study demonstrates the potential for combined banker plants to provide long-term, sustainable control of multiple pests by their target natural enemies in complex agroecosystems.

     

First record of the invasive pest <Emphasis Type="Italic">Drosophila suzukii</Emphasis> in Ukraine indicates multiple sources of invasion

Drosophila suzukii, commonly known as the spotted-wing Drosophila, is an invasive polyphagous fruit pest, which has emerged as a global threat to agriculture in the Americas and in Europe. Due to the rapid spread, great economic losses and its pest behavior, D. suzukii represents a powerful model for invasion biology and pest management studies. However, its current European distribution, invasion routes and levels of genetic diversity in populations of D. suzukii are poorly understood. We present the first report of D. suzukii from Ukraine, with the invasion likely occurring close to 2014. The pattern of genetic variation at cytochrome oxidase I among D. suzukii populations from Europe, USA and Asia reveals comparatively high genetic diversity in the Ukrainian population of this pest species, suggesting a complex invasion scenario from multiple sources. Further monitoring patterns of genetic variation across space and time, to better understand the invasion routes of this invasive insect pest, will be an essential part for developing successful pest management strategies.     

Genetic analysis and conservation of endangered medicinal tree species <Emphasis Type="Italic">Taxus wallichiana</Emphasis> in the Himalayan region

Taxus wallichiana is one of the most important medicinal tree species of the Himalayan region. Leaf and bark of the species yield an important drug called taxol, which is used for treatment of many types of cancer. There is a serious threat to the existence of the species due to over exploitation in its native habitat. Adequate information on the nature and the extent of genetic diversity in this important species is required for developing suitable strategy for its conservation. Random amplified polymorphic DNA (RAPD) and amplified fragment length polymorphism (AFLP) were used to assess genetic variation in nine natural populations of T. wallichiana from western part of the Himalayan ranges. Both the markers revealed low genetic diversity in these populations. Average heterozygosity for AFLP and RAPD were 0.3715 and 0.3072, respectively. Φ_ST values derived from molecular variance were 0.0855 and 0.1005 for AFLP and RAPD, respectively, whereas the corresponding G_ST values were 0.1796 and 0.2140. Most part of the genetic variation was present within the populations. However, between population variation was low but statistically significant, which suggested that the sampled populations might not constitute a single panmictic population. Cluster analysis and Mantel’s correlation revealed that genetic differentiation broadly followed geographic distribution of the populations. T. wallichiana thus urgently needs to be conserved using both in situ and ex situ conservation approaches.     

A molecular toolkit for population genetic investigations of the ash dieback pathogen Hymenoscyphus pseudoalbidus

The recently described ascomycete fungus Hymenoscyphus pseudoalbidus (anamorph: Chalara fraxinea) causes the current dieback of ash (Fraxinus excelsior) in large parts of Europe. The origin of this species and its relation to the native cryptic species Hymenoscyphus albidus are still enigmatic. The spatiotemporal pattern of the epidemic is typical for an introduced invasive species. However, the presence of two cryptic species indicates that hybridization or mutation might have been involved in driving speciation in this case. In this study, we present a set of 18 polymorphic microsatellite markers to study these processes in more detail on a population genetic level. Markers were designed such that they can be amplified in three individual multiplex PCRs and analysed in two fragment analysis runs. We thoroughly tested the marker set for pairwise linkage among loci, selective neutrality and Mendelian inheritance. Additionally, the markers were applied on two large collections of isolates derived from study sites in Germany. Population genetic calculations suggested a low yet significant level of differentiation, a large genotypic diversity and a limited genetic diversity within populations. Furthermore, we present additional data concerning the phylogenetic relation between H. albidus and H. pseudoalbidus, which seems to be more distantly related to each other than expected previously.     

Patterns of genetic diversity that result from bottlenecks in Scots Pine and the implications for local genetic conservation and management practices in Bulgaria

As one of the principal coniferous species of commercial importance in Bulgaria, Scots Pine has been subjected to strict management, which has posed a challenge for the conservation and management of its gene pool. In this study, we measured genetic diversity and population structure using 6 microsatellite loci in 12 populations from Bulgarian mountain ranges. Our analysis showed good intrapopulation divergence (18.22%; AMOVA) and genetic evidence of bottlenecks. “NJ-IAM” and “non-admixing” clusters divided the populations into 3 large groups. Our microsatellite analysis was consistent with the documented “mountain effect” influence on genetic diversity. Two methods—the Coalescent Bayesian model and M-stat analysis—implicated recent bottlenecks for all populations, suggesting that the genetic structure of Bulgarian Scots Pine was shaped over a long period (one thousand generations; i.e. 20,000 years) by the interaction of genetic and autoecological processes. Our results suggest that conservation and management practices should strive to maintain this genetic differentiation, specifically by emphasizing reforestation efforts with stocks from local provenances to avoid nonlocal introductions.     

Assessment of morphological and genetic diversity in <Emphasis Type="Italic">Gmelina arborea</Emphasis> Roxb.

Gmelina arborea is an important timber-yielding tree that grows naturally in the tropical and subtropical regions of Southeast Asia and has also been introduced as a plantation species outside these regions. Genetic diversity in this tree species was observed in stone/seed-related traits and in vitro responses of cultured nodal segments from plants of eight different populations representing natural forests, fragmented forests and plantations. Variance analysis showed significant differences between populations for these traits. However, it was not possible to separate the different populations using these traits by multivariate analysis, even after environmental variation was reduced over six subcultures. Genetic diversity was therefore analysed using molecular markers. Inter-simple sequence repeat (ISSR) primers yielded 95% polymorphic loci among the eight populations and UPGMA analysis enabled separation of these populations on the basis of their genetic distances. Diversity was also analyzed using population genetics parameters like Nei’s genetic diversity and gene differentiation. Nei’s genetic diversity was 0.29 between populations and 0.11 within populations. AMOVA analysis indicated 41 and 59% within- and between-population genetic diversity, respectively. Mantel test suggested that genetic differentiation between six Indian populations was positively correlated to geographic distance (r = 0.626, P = 0.029). Assessment of the genetic variation in G. arborea populations is an important step in selection of conservation strategies for this species since diversity forms the basis for species adaptation.     

Timing and order of different insecticide classes drive control of Drosophila suzukii; a modeling approach

The spotted-wing drosophila, Drosophila suzukii Matsumura, is an invasive pest causing significant damage to soft skinned fruits. Control of D. suzukii is critical since there is no tolerance for infested fruit in the market. While most insecticides control one or more D. suzukii life-stages (e.g., egg, larvae, and adult), the impact of insecticides that are toxic to immature stages  is unclear on the subsequent generation of a field population. Insecticides were applied at field recommended rates on cherries and blueberries in the laboratory to determine immature D. suzukii mortality. Spinetoram, cyantraniliprole, malathion, methomyl, spinosad, and phosmet resulted in relatively high mortality of all immature life stages. Zeta-cypermethrin, cyclaniliprole, and fenpropathrin resulted in lower mortality of egg and all larval instars. Malathion was also applied to lowbush blueberries with different fruit sizes (small, medium, and large) in the laboratory and there was no statistical difference in mortality rates depending on fruit sizes. Mortality data from the laboratory experiments were used to parameterize a refined D. suzukii population model. The model revealed that the timing and order of different insecticide classes are important to control D. suzukii population. Model runs that included early applications of more effective insecticides resulted in high immature mortality and greater reduction of D. suzukii populations compared to treatments applied later.

     

Pruning methods to restore Castanea sativa stands attacked by Dryocosmus kuriphilus

Dryocosmus kuriphilus Yasumatsu, an invasive gall wasp originating from Asia, is the latest serious pest attacking Castanea sativa Mill. in Europe; the negative effects on fruit and wood production are considerable. The most effective defense strategy is biological control, but parasitoid effectiveness requires at least 6–10 years to reduce damage to acceptable levels. In Italy, prolonged productivity losses could adversely affect human activity in chestnut orchard stands, resulting in negative socio-economic and hydrogeologic consequences. Thus, it is necessary to quickly reduce the impacts of the infestation to avoid degradation of chestnut stands during the time delay required for parasitoid efficiency. We examined green pruning as a means to reduce negative impacts of gall wasps and stimulate healthy shoots in a young chestnut coppice in Central Italy. Two different pruning cuts (Long- and Short-cut) on growing shoots and four timings of application were tested. The development and phytosanitary status of nodes was observed over 2 years on pruned and control sprouts. Pruning was effective in reducing gall wasp damage though responses varied among pruning techniques and application times. Long-cut pruning made in spring during the full growth phase induced a higher number of new and better-developed shoots. Pruning during the end of the egg-laying period of the gall wasps promoted development of only healthy new shoots. Our results indicate that is possible, by choosing the best combination of time and technique, to identify a pruning method useful to maintain growth and development of C. sativa stands threatened by D. kuriphilus.

     

AFLP analysis of genetic variation of Hyphantria cunea (Drury) populations in Beijing and a nearby site

Hyphantria cunea (Drury) is a severe invasive pest in Beijing. It is important to understand the reason for its successful invasion and outbreak. Accordingly, this study was tailored to assess molecular variation and genetic relationships among three H. cunea populations in Beijing and one population from Sanhe in Hebei Province as control (totally 100 individuals). A silver-labeled amplified fragment length polymorphisms (AFLP) DNA profiling method was used to detect the genetic diversity and relationship among the populations. Five EcoRI and MseI primer combinations produced a total of 171 (91.2% polymorphic) informative fragments. The average Nei’s genetic diversity in four H. cunea populations analyzed by Popgene3.2 software was 0.2287, and the level of genetic diversity ranked in the order BDR (reared population in Daxing, Beijing) > BDN (natural population in Daxing, Beijing) > HSN (natural population in Sanhe, Hebei Province) > BFN (natural population in Fengtai, Beijing). The value of genetic differentiation among populations was 0.3321, and the gene flow was 1.0057. The genetic distance between these populations ranged from 0.0735 to 0.3309, 0.0531 on average. The result of UPGMA (unweighed pair group method with arithmetic averages) clustering showed that populations BFN and HSN were closely related, while BFN and BDN had the largest genetic distance. These results indicate that H. cunea populations in Beijing might originate from several areas.     

云杉属树种谱系地理学研究

云杉属谱系地理学主要是研究云杉属种群遗传结构的历史动态规律，以及气候振荡和地质变迁对种群分布范围、种群间基因渐渗及遗传分化的影响。文中综述了国内外云杉属谱系地理学的研究进展，结论如下:我国西南山区和青藏高原（QTP）地区云杉属树种谱系地理学研究，验证了上新世QTP上升和第四纪冰期气候振荡对该物种进化起到推动作用，该物种在这2个时期快速分化；在云杉属争议种的研究中，通过对云杉属复合种群的群体结构展开研究，揭示了种群间的基因渐渗常存在于有较低基因流的基因组，方向通常是由本土树种向入侵树种渗透；某些种群之间的基因渐渗可有助于在一些基因位点上增加这些种群和其他种群之间的分化，导致生殖隔离的产生；云杉属天然杂种多被发现在种群的对称分布区边缘、或者其重叠分布区，杂种经过异地扩张又形成了新种，验证了云杉属网状进化的历史，并证明了生境特征决定杂交优势种的分布边界。     

Whitefly endosymbionts: IPM opportunity or tilting at windmills?

Whiteflies are sap-sucking insects responsible for high economic losses. They colonize hundreds of plant species and cause direct feeding damage and indirect damage through transmission of devastating viruses. Modern agriculture has seen a history of invasive whitefly species and populations that expand to novel regions, bringing along fierce viruses. Control efforts are hindered by fast virus transmission, insecticide-resistant populations, and a wide host range which permits large natural reservoirs for whiteflies. Augmentative biocontrol by parasitoids while effective in suppressing high population densities in greenhouses falls short when it comes to preventing virus transmission and is ineffective in the open field. A potential source of much needed novel control strategies lays within a diverse community of whitefly endosymbionts. The idea to exploit endosymbionts for whitefly control is as old as identification of these bacteria, yet it still has not come to fruition. We review where our knowledge stands on the aspects of whitefly endosymbiont evolution, biology, metabolism, multitrophic interactions, and population dynamics. We show how these insights are bringing us closer to the goal of better integrated pest management strategies. Combining most up to date understanding of whitefly–endosymbiont interactions and recent technological advances, we discuss possibilities of disrupting and manipulating whitefly endosymbionts, as well as using them for pest control.

     

Attract,reward and disrupt: responses of pests and natural enemies to combinations of habitat manipulation and semiochemicals in organic apple

The widespread use of pesticides along with the simplification of the landscape has had undesirable effects on agroecosystems, such as the loss of biodiversity and the associated ecosystem service biological control. How current production systems can be remodelled to allow for a re-establishment of biological pest control, while preserving productivity, is a major challenge. Here, we tested whether a combination of tools could augment or synergize biological control of insect pests in apple (Malus domestica), comprised of a tortricid pest complex, a geometrid pest complex and the rosy apple aphid. The tools aimed at disrupting mating behaviour of multiple pest species (multispecies mating disruption, “Disrupt”, MMD), attracting natural enemies (a blend of herbivory-induced volatiles, “Attract”, A), or providing refuge and rewards for a diverse insect community (perennial flower strip, “Reward”, R) over a 3-year period. Suction samples were consistently richer in generalist predators but not in parasitoids when multiple tools including MMD?+?A?+?R or MMD?+?A were employed. In addition, lepidopteran pest levels were significantly lower in these plots than in MMD or MMD?+?R at the end of the 3-year experiment. This was, however, not reflected in survival of artificially established aphid colonies. Our data indicates that multiple, complementary tools can greatly enhance natural enemy level, but also that long-term implementation is needed to fully realize the augmentatory or synergistic potential of complementary components and restore biological control as an ecosystem service of practical relevance.

     

Changing patterns in insect pests on trees in The Netherlands since 1946 in relation to human induced habitat changes and climate factors—An analysis of historical data

In The Netherlands, insect pests on trees and shrubs are being monitored continuously since 1946. During these years, almost all insect pest populations showed marked changes, which may be the result of changes in forest management, shifts in forest composition, climate change and the arrival of new pests from the Mediterranean region or from other continents. In order to generate hypothesis about possible relationships between species ecology and environmental factors, we have analyzed 61 years of population development of the 98 most abundant species in the database while paying attention to life history traits and preferred host plants. The 22 species with infestations lasting a few years only were excluded from the analysis. Of the remaining 76 species, 18 were present over the entire observation period of 61 years. Of the other species, 27 showed a decline and 31 showed an increase. On coniferous trees most species showed decreasing populations. Increasing populations were found most on deciduous trees. Not directly climate-related factors such as changes in forest age, tree composition and forest management were identified as the most important causes for the fluctuations in pest insect populations. Climate change is a possible driver of the population increase in Thaumetopoea processionea, Haematoloma dorsatum and of the population decrease in Euproctis chrysorrhoea. The recently increasing exotic species Eupulvinaria hydrangeae and Pulvinaria regalis were exclusively found on trees in cities, presumably in relation to the higher temperatures of the urban habitat.     

Effects of neonicitinoid seed treatments on soybean aphid and its natural enemies

Insecticidal seed treatments are increasingly being applied to soybeans in North America, and several recent studies question what they add to current pest management. Here, we examine the effects of two neonicotinoid insecticidal seed treatments on insect populations (pest and natural enemies) in SD soybeans over 2 years. Moreover, we conducted laboratory experiments to determine the duration that seed treatments remained effective against the soybean aphid (Aphis glycines, Hemiptera: Aphididae) and how thiamethoxam affected survival of one of the aphid’s predators, Orius insidiosus (Hemiptera: Anthocoridae) on soybean. Soybean aphids, thrips, and grasshopper populations were unaffected by the insecticidal seed treatments in the field. The laboratory trial revealed that all bioactivity of the seed treatments against soybean aphids was gone within 46 days after planting, prior to aphid populations damaging the crop. Bean leaf beetles, a sporadic pest in our area, were reduced by the seed treatments. But, there were no yield benefits of insecticidal seed treatments over the 2 years of the study at this location. Natural enemy communities were significantly reduced by thiamethoxam seed treatments relative to the untreated control, particularly populations of Nabis americoferus (Hemiptera: Nabidae). Chrysoperla (Neuroptera: Chrysopidae) adults were reduced in the imidacloprid-treated plots. In the laboratory, rearing O. insidiosus on soybean plants treated with thiamethoxam resulted in higher mortality for both the nymphs and the adult stage. Offering the predator insect prey on the thiamethoxam-treated plants improved survival of the adult stage, but not the nymphal stage. This work confirms that insecticidal seed treatments offer little benefit to soybean producers of the Northern Great Plains and adds to the discussion by suggesting that generalist predators are adversely affected by the insecticides.     

Gene flow pattern and mating system in a small population of Quercus semiserrata Roxb. (Fagaceae)

Pollen flow from external sources is important for the conservation of tree species in fragmented forests or small populations, because it can be sufficient to prevent differentiation among them, and appears to be able to prevent the loss of their genetic diversity through genetic drift. In this study, we examined the genetic heterogeneity of pollen pools accepted by each Quercus semiserrata seed parent at the Khun Wang Royal Agriculture Research Center, Thailand, both within and among two mast fruiting years (2005 and 2007), using paternity analysis and analysis of molecular variance (AMOVA). The mating systems of the trees were also examined using the multilocus mating system model (MLTR), after determining the genotypes at eight microsatellite loci of 26 seed-trees and 435 seeds from 8 seed-trees in the 2 mast fruiting years. The average distance of effective pollen flow within the plot was estimated to be 52.4 m, and 95% of effective pollen was dispersed within 200 m, indicating that effective pollen flow is highly localized and that most effective pollen is contributed by near-neighbor trees. The proportion of effective pollen that immigrated from external sources was estimated to be 26.2%. The AMOVA analysis based on the pollen haplotypes showed that the pollen pools, both total and for each reproductive year, significantly genetically differed among the seed parents. Using a mixed mating model, the estimate of biparental inbreeding for the total population (t_m − t_s) was 0.013, indicating that a low proportion of mating occurred among close relatives. The effective number of pollen donors (N_ep) was estimated to be 9.987 using the TwoGener model, or 10.989 using the mixed mating model. The effective number of pollen donors of seeds was higher in the mast fruiting year 2005 than in the other examined year, 2007. Consequently the allelic richness and genetic diversity of seeds produced in 2005 were higher than those produced in 2007. Overall, the results show that high outcrossing rates, high levels of gene flow from other populations and heterogeneity in the pollen received by an individual may enhance the ability of populations to maintain effective population sizes. Therefore, these processes may be sufficient to prevent loss of genetic diversity through genetic drift of Q. semiserrata at this study site.     

Generational growth rate estimates of <Emphasis Type="Italic">Diabrotica virgifera virgifera</Emphasis> populations (Coleoptera: Chrysomelidae)

Modelling population dynamics of the maize pest Diabrotica virgifera virgifera LeConte (western corn rootworm; Coleoptera: Chrysomelidae) requires knowledge on the growth rate (=net reproductive rate) of the species. We investigated the generational (=annual) growth rate of D. v. virgifera in isolated maize fields in southern Hungary and eastern Croatia over several years. The population densities of D. v. virgifera were assessed by absolute counts of emerging adults in 90 gauze cages per study field. Emergence ranged from 1.3 to 30.7 adults per m² in continuous maize field sections, and from 0.3 to 5.1 adults per m² in adjacent first-year maize sections. The annual growth rates of D. v. virgifera ranged from 0.5 to 13, and averaged in close to 4. These experimentally assessed growth rates could complement growth estimates in population dynamic models, particularly those for forecasting the population growth to economic thresholds or for estimating population build-ups after new introductions of this alien species in Europe. As an example, the determined growth rate was used to estimate that the first documented successful introduction of this species into Europe occurred between 1979 and 1984, which is 8–13 years before the detection of this species and its larval damage in maize fields near Belgrade, Serbia, in 1992.     

Genetic variability of Italian southern Scots pine (<Emphasis Type="Italic">Pinus sylvestris</Emphasis> L.) populations: the rear edge of the range

Understanding the genetic structure and diversity of edge populations can shed light on the role of peripheral populations and their relevance for conservation strategies. In this study, three fragmented and isolated Apennine populations of Scots pine (Pinus sylvestris L.) belonging to the rear edge of the species’ distribution were analyzed using both nuclear (nSSR) and chloroplast (cpSSR) microsatellites and were compared with an Alpine population belonging to the species’ main range. Although small population size and considerable isolation have probably reduced the genetic variability of Apennine populations, these fragmented populations maintain a high level of within-population genetic diversity. A significant among-population differentiation was found using both nSSR (F _ST = 0.08) and cpSSR markers (ρ = 0.14). Analysis of molecular variance (AMOVA) on the nSSRs attributed all variabilities to the among Apennine populations component supporting the theoretical predictions regarding fragmentation effects on genetic structure. On the other hand, AMOVA on the cpSSRs attributed all variances to the between-region component and no differentiation was found within region, among the Apennine populations. This result suggests the importance of pollen gene flow in homogenizing populations on this geographical scale. Our results confirm the genetic distinctiveness of Apennine populations and their possible derivation from different glacial refugia than those of the Alps. Considering their peculiarity and the high level of intrapopulation genetic diversity that they still retain, fragmented Apennine populations should be considered of high priority for conservation.     

Genomewide identification and development of microsatellite markers for Marssonina brunnea and their applications in two populations

Marssonina brunnea is an important pathogen that causes Marssonina leaf spot disease of poplar (MLDP) in various poplar species. Resistance breeding is considered as the main method for preventing this disease and requires information on genetic diversity and population structure. However, molecular markers that may be utilized in the identification of this fungus are limited. This study investigated the distribution of microsatellites in the M. brunnea genome. A total of 15,356 microsatellite markers (excluding mononucleotide repeats) were isolated from 50.1 Mb of genomic sequence. Eight M. brunnea isolates were evaluated in terms of 102 loci, followed by the selection of markers that could be utilized in investigating the population structure of 47 M. brunnea isolates from two populations. Twenty‐four polymorphic microsatellite markers were developed for M. brunnea. The number of alleles per locus ranged from two to eight (average: 3.75). The polymorphism information content (PIC) of these loci ranged from 0.0408 to 0.6492. The average Shannon's information index of these loci in the two populations was 0.3819 and 0.5351, respectively. Using these markers, M. brunnea isolates were mainly divided into two distinct clusters based on the relatedness of the sampling sites. These results indicate that the selected markers could be effectively utilized in investigating the population genetic structure of M. brunnea. This is the first report on microsatellite markers in M. brunnea.