Katarina Kos

On the Identity of Cereal Aphid Parasitoid Wasps Aphidius uzbekistanicus, Aphidius rhopalosiphi, and Aphidius avenaphis (Hymenoptera: Braconidae: Aphidiinae) by Examination of COI Mitochondrial Gene, Geometric Morphometrics, and Morphology

ABSTRACT In this study, the relationships among and the taxonomic status of three closely related parasitic wasps that are widely used as biological control agents of cereal aphids, Aphidius uzbekistanicus Luzhetzki, Aphidius rhopalosiphi De Stefani Perez, and Aphidius avenaphis (Fitch), were examined. Genetic divergence at an average of 6% was recorded between A. uzbekistanicus and A. rhopalosiphi by using the mitochondrial (mt) gene cytochrome oxidase I (COI) barcoding region. Identical mtCOI gene sequences were observed in A. uzbekistanicus specimens that originated from Eurasia and in the North American species A. avenaphis. The haplotype fluctuation in A. rhopalosiphi specimens that originated from the west Palaearctic was an average of 1.5% (maximum, 2.4%). In contrast, specimens of A. uzbekistanicus from central and western parts of Eurasia were largely homogenous, with only a single mutation recorded in a specimen from eastern Europe (Serbia). The morphological and genetic diversity found in A. rhopalosiphi may suggest the existence of cryptic species, especially for lineages that have a large degree of mtCOI diversity and sympatric occurrence. The geometric morphometric analysis of stigma shape presented in this study demonstrated that members of A. uzbekistanicus have a shorter forewing r vein and a more elongated stigma, relative to those of A. avenaphis. Our research validates the use of stigma shape and flagellomere 1 color for morphological discrimination between wasp species.

Sensitivity of the entomopathogenic fungus Beauveria bassiana (Bals.-Criv.) Vuill. to selected herbicides

BACKGROUND The in vitro effect of six commonly used herbicides viz., amidosulfuron, dicamba, metribuzin, pyridate, S-metolachlor and tembotrione on mycelial growth of entomopathogenic fungus Beauveriabassiana (ATCC 74040) was investigated. Mycelial growthrates at 15 and 25°C were evaluated on PDA plates containing 100, 75, 50, 25, 12.5, 6.25 and 0% of the recommended application rate of each selected herbicide. The tested herbicides were classified in 4 scoring categories based on reduction of mycelial growth in toxicity tests. RESULTS All six herbicides had a fungistatic effect of varying intensities, dependent on their rate in medium, on B. bassiana. The present study showed that B. bassiana is sensitive to all tested herbicides, particularly at recommended as well as lower field rates. Metribuzin, S-metolachlor and tembotrione had a strong fungistatic effect on mycelial growth even at rates 25 and 12.5%.Pyridate was slightly harmful, depending on the rate and temperature. Dicamba and amidosulfuron had slight effect on mycelial growth. Sporulation and conidial germination of B. bassiana were significantly inhibited by all tested herbicides. Amidosulfuron and dicamba, both at 100% rate, had the lowest inhibitory effect on sporulation, i.e. 24% and 44%, respectively. Other herbicides in test showed much higher inhibitory effect on sporulation (69-95%). With exception of dicamba with 33% of conidial germination inhibition all other herbicides in test inhibited conidial germination for 70-100%. At 200% dosage, inhibition rates even increased. CONCLUSION Of all tested herbicides, amidosulfuron and dicamba showed the least adverse effects and are therefore probably compatible with B. bassiana in the field.

Success of classical biocontrol agent Torymus sinensis within its expanding range in Europe

Torymus sinensis Kamijo (Hymenoptera, Torymidae), a classical biocontrol agent of chestnut gall wasp Dryocosmus kuriphilus (Hymenoptera, Cynipidae), was released in Croatia, Slovenia and Hungary in 2015. Following the introduction, the research of parasitism rates and population genetic indices on 40 different sites was performed to monitor and evaluate the success of establishment. The observed parasitism rates were unexpectedly high and negatively correlated with the distance from westernmost locality, while population genetic indices showed that populations of T. sinensis did not suffer from bottleneck‐induced founder effect phenomenon. Moreover, lack of genetic differentiation demonstrates that all populations share similar genetic structure, which could be shaped only by high levels of gene flow. We conclude that T. sinensis established viable and genetically diverse populations and successfully spread naturally from Italy across Slovenia to Croatia and Hungary.

Effects of selected herbicides and fungicides on growth, sporulation and conidial germination of entomopathogenic fungus Beauveria bassiana

BACKGROUND The in vitro fungicidal effects of six commonly used fungicides, namely fluazinam, propineb, copper(II) hydroxide, metiram, chlorothalonil and mancozeb, and herbicides, namely isoxaflutole, fluazifop-P-butyl, flurochloridone, foramsulfuron, pendimethalin and prosulfocarb, on mycelial growth, sporulation and conidial germination of entomopathogenic fungus Beauveria bassiana (ATCC 74040) were investigated. Mycelial growth rates and sporulation at 15 and 25 °C were evaluated on PDA plates containing 100, 75, 50, 25, 12.5, 6.25 and 0% of the recommended application rate of each pesticide. The tested pesticides were classified in four scoring categories based on reduction in mycelial growth and sporulation. RESULTS All pesticides, herbicides and fungicides tested had fungistatic effects of varying intensity, depending on their rate in the medium, on B. bassiana. The most inhibitory herbicides were flurochloridone and prosulfocarb, and fluazinam and copper(II) hydroxide were most inhibitory among the fungicides, while the least inhibitory were isoxaflutole and chlorothalonil. Sporulation and conidial germination of B. bassiana were significantly inhibited by all tested pesticides compared with the control treatment. Flurochloridone, foramsulfuron, prosulfocarb and copper(II) hydroxide inhibited sporulation entirely at 100% rate (99-100% inhibition), and the lowest inhibition was shown by fluazifop-P-butyl (22%) and metiram (33%). At 100% dosage, all herbicides in the test showed a high inhibitory effect on conidial germination. Conidial germination inhibition ranged from 82% with isoxaflutole to 100% with fluorochloridone, pendimethalin and prosulfocarb. At 200% dosage, inhibition rates even increased (96-100%). CONCLUSIONS All 12 pesticides tested had a fungistatic effect on B. bassiana of varying intensity, depending on the pesticide and its concentration. B. bassiana is highly affected by some herbicides and fungicides even at very low rates. Flurochloridone, foramsulfuron, prosulfocarb and copper(II) hydroxide stopped sporulation. Of all tested pesticides, isoxaflutole, fluazifop-P-butyl and chlorothalonil showed the least adverse effects and therefore probably could be compatible with B. bassiana in the field.

Qualitative Analysis of Aphid and Primary Parasitoid Trophic Relations of Genus Alloxysta (Hymenoptera: Cynipoidea: Figitidae: Charipinae)

ABSTRACT Charipinae hyperparasitoids affect effectiveness of the primary parasitoids of aphids by decreasing their abundance and modifying their behavior. As a result, increase of aphid populations can cause severe yield losses in some crops. Therefore, ecological studies on the subfamily Charipinae have a great economical and biological importance. Host specificity of these hyperparasitoids is still under debate and for many Charipinae species very little is known about their trophic relations. Here, we give a comprehensive overview of the trophic relationships between the Charipinae species of the genus Alloxysta Förster and their aphid and primary parasitoids hosts, worldwide. Within this subfamily, Alloxysta arcuata (Kieffer), Alloxysta brevis (Thomson), Alloxysta fuscicornis (Hartig), and Alloxysta victrix (Westwood) are the most generalist species sharing many aphid hosts, while for primary parasitoid hosts these are A. arcuata, A. brevis, Alloxysta pleuralis (Cameron), and A. victrix. Alloxysta citripes (Thomson), Alloxysta halterata (Thomson), Alloxysta leunisii (Hartig), and Alloxysta ramulifera (Thomson) appear, up to now, as the most specialized in relation to the primary parasitoid hosts. Primary parasitoids of the genera Aphidius Nees, Lysiphlebus Förster, Praon Haliday, and Trioxys Haliday are the most common hosts for Alloxysta species, and the common host aphid species belong to the genera Aphis L., Uroleucon Mordvilko, Myzus Passerini, and Sitobion Mordvilko. Host range is analyzed for each Alloxysta species, as well as the extent of overlap between them. We used Jaccards distance and a hierarchical cluster analysis to determine the host range dissimilarity. A permutation test has been applied to analyze if the host range dissimilarity is significantly different from what is expected by chance. We have calculated additional qualitative measures that complement well the Alloxysta niche overlap analysis and evaluated their host specificity using different indices and bipartite networks.

Parasitoids of European species of the genus Yponomeuta Latreille 1796 (Lepidoptera: Yponomeutidae): new findings with an updated checklist

The species of the genus Yponomeuta Latreille (Lepidoptera: Yponomeutidae) are known as ermine moths and can be found on various host plant species, sometimes appearing as pests. They are attacked by a wide range of parasitoids. We studied parasitoid complexes of several communities in Austria, Poland, Serbia, Slovenia and Sweden during 2014–2018. From four species, Yponomeuta cagnagella (Hübner), Yponomeuta evonymella (Linnaeus), Yponomeuta malinellus Zeller and Yponomeuta padella (Linnaeus), we reared 15 parasitoid species of seven hymenopteran and one dipteran family. In this study, the family Ichneumonidae is the most numerous, while Ageniaspis fuscicollis (Dalman) (Hymenoptera: Encyrtidae) was found in all four Yponomeuta species. Within reared parasitoids, A. fuscicollis is new record for Slovenia and Austria, Baryscapus evonymellae (Bouché) (Hymenoptera: Eulophidae) and Diadegma armillatum (Gravenhorst) (Hymenoptera: Ichneumonidae) are new records for Slovenia and Agrypon canaliculatum (Ratzeburg) (Hymenoptera: Ichneumonidae), Dolichogenidea dilecta (Haliday) (Hymenoptera: Braconidae), Elasmus steffani Viggiani (Hymenoptera: Eulophidae), Herpestomus brunnicornis (Gravenhorst) (Hymenoptera: Ichneumonidae), Trieces tricarinatus (Holmgren) (Hymenoptera: Ichneumonidae) and Mesochorus nuncupator (Panzer) (Hymenoptera: Ichneumonidae) are new records for Serbia. Also, Yponomeuta cagnagella is a new host record for Pteromalus semotus (Walker) (Hymenoptera: Pteromalidae) and Y. padella for E. steffani. Finally, we reviewed parasitoids of European Yponomeuta species and their associated host plants. In total 154 species are recorded from nine hymenopteran and one dipteran family.

Fusarium spp. incidence and DON Contamination in different wheat varieties correlated with the environmental factors

The genus Fusarium consists of multiple diverse species, which, as a result of their frequency in nature and pathogenicity, are significant in agriculture, as well as in human and veterinary medicine. In the course of field trials, by using standard phytopathological methods, and performing analyses of 19 different varieties of wheat and a portion of infected grains gathered from two distinct locations in Slovenia, we have determined the presence of various phytopathogenic species of the genus Fusarium. Because of the reliability, the experiment was performed in two consecutive years, 2012 and 2013. A laboratory analysis was conducted with an ELISA test on all grain samples for the determination of deoxynivalenol (DON) concentration. The results show that the main differences in the infection levels (F. culmorum + F. graminearum; FC + FG) of wheat samples were found in Jable (humid area), at the same time showing higher levels of DON content than Rakican (dry area). Such a statement is supported by correlation test, where correlation is evident between FC + FG and DON in every variation. The data for both wheat types (awned and awnless) together showed that the grain in Jable is statistically significant more infected by FC + FG when compared to that in Rakican. Moreover, our descriptive analysis confirms that the infection rate of grain with FC and FG shows a strong correlation with the emergence of DON.

High genetic diversity and a new cryptic species within the Ephedrus persicae species group (Hymenoptera: Braconidae: Aphidiinae)

Abstract In this study we used molecular markers to characterize various populations of the Ephedrus persicae species group originating from different aphid hosts and different habitat types. Twelve different haplotypes were identified in 15 E. persicae specimens, and thus there were no shared haplotypes between specimens from different aphid hosts. All haplotypes were clustered in two distinct phylogenetic clades (“persicae 1” and “persicae 2”), the average genetic distance between these two clades being 3.1%. Ephedrus persicae specimens from the “persicae 1” clade parasitize leaf-curling aphids from Prunus and Malus orchards. Furthermore, there was significant differentiation of the “persicae 2” clade into two distinct evolutionary groups, with a genetic distance of 2.5% between them. On the basis of the genetically isolated position of Ephedrus specimens associated with Brachyunguis tamaricis on Tamarix gallica (more than 5.7% genetic distance), we describe Ephedrus tamaricis sp. n. as an additional member of the E. percicae species group. Key for identification of parasitoids belonging to the E. persicae species group is provided.