On the influence of different host plants and of insecticide treatments on the population development of the western corn rootworm Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae)

D. virgifera virgifera is classified as a quarantine pest in Germany, therefore the trials, presented in this paper, were performed in the western part of Romania, where the pest is well established since more than ten years. The field tests were carried out in close collaboration with Banat’s University of Agricultural Sciences and Veterinary Medicine, Timişoara.On sites highly infested by D. virgifera virgifera, 1 m² plots in four replications per variable were planted with maize for the chemical treatments and alternative crops (cereals and weeds). Gauze covered hatch cages were used for weekly counts of the emerged adult Diabrotica during the hatch period from mid of June to mid of August.It could be asserted that matured cereals are no host-plants for the western corn rootworm. In four years of trials not even one adult beetle hatched in the related cages.Setaria viridis and Digitaria sanguinalis reduced the number of hatched imagines significantly, nevertheless some individuals survived. Therefore an effective herbicide management against grass weeds in maize is recommended to limit the chance of survival of the pest.Clothianidin and Tefluthrin are effective against D. virgifera virgifera. 20% to 100% efficiency was assessed in the trials, strongly depending on precipitation and soil moisture in time of application. The insecticides decreased the maize root injury caused by larvae of the western corn rootworm significantly.Keywords: Insecticides, crop rotation, host-plants, hatch cagesZum Einfluss verschiedener Wirtspflanzen und Insektizid Behandlungen auf die Populationsentwicklung des Westlichen Maiswurzelbohrers Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae)ZusammenfassungDa der Westliche Maiswurzelbohrer in Deutschland noch als Quarantäneschädling eingestuft wird, wurden die Untersuchungen in Westrumänien durchgeführt, wo der Schädling bereits seit mehr als 10 Jahren etabliert ist. In Zusammenarbeit mit Banat’s University of Agricultural Sciences and Veterinary Medicine, Timisoara, erfolgte die Anlage und Auswertung der Feldversuche.Auf Versuchsflächen mit hohem Diabrotica Besatz wurden 1 m² große Parzellen (in vierfacher Wiederholung) mit Mais, für die Durchführung der Insektizidanwendungen, sowie mit alternativen Kulturen (Getreide und Ungräser) bestellt. Schlupfkäfige, die über die Parzellen gestellt wurden, dienten der wöchentlichen Zählung der aus dem Boden schlüpfenden Käfer während der Schlupfperiode, von Mitte Juni bis Mitte August.Es konnte festgestellt werden, dass die weit entwickelten Getreidearten keine Wirtpflanze für den Westlichen Maiswurzelbohrer darstellten. In den vierjährigen Versuchen konnte kein Käfer in den entsprechenden Käfigen gefunden werden.Setaria viridis and Digitaria sanguinalis reduzierten die Anzahl der gefangenen adulten D. virgifera virgifera signifikant, einige Exemplare überlebten jedoch auch. Eine wirksame Ungras Bekämpfung im Mais und den nachfolgenden Kulturen wird deshalb empfohlen um die Überlebensmöglichkeiten für D. virgifera virgifera zu begrenzen.Clothianidin und Tefluthrin reduzierten die Anzahl der schlüpfenden Imagines. Wirkungsgrade von 20% bis 100% konnten ermittelt werden, weitgehend unabhängig von der Formulierung. Dabei war die Wirksamkeit der Insektizide sehr stark abhängig von der Bodenfeuchte bei und kurz nach der Anwendung. Die eingesetzten Präparate verminderten die Schäden an den Maiswurzeln signifikant.Stichwörter: Insektizide, Fruchtfolge, Wirtspflanzen, Schlupfkäfig

TYPES OF ECOSYSTEMS STARTING FROM PHYSICOCHEMICAL PROPERTIES OF HAPLIC LUVISOILS FROM THE FOREST PLAIN OF TIMIŞ FOREST DIRECTORATE

Timiş County, a typical plain county, covered by 11% forest stands, has a highly fragmented territory. The studied area is enclosed as altitude in O1 subregion Timiş Plain, meadow and ground depressions oak stands. The investigations were focused on a surface of 7158,9 ha, 5491,3 ha in Lunca Timişului Forest District and 1667,6 ha in  Timişoara Forest District. They were subjected to analysis of their physicochemical characteristics of Haplic Luvisoils, based on the analyses from management plan for forest plains, in productive correlation of forest species in compartments with soil profiles. In order to analyze the synergistic effect of soil physicochemical characteristics on productivity, three soil classes were formed: A) Luvic Phaeozems (Ao-Bt-C), Luvic Phaeozems (Am-Bt-C) and Luvic Phaeozems (Am-BtGo-C); B) Stagnic Luvisoils (Aow-Btw-C) and  C) Stagnic Luvisoils (Aow-El-Bt-C), on soils of Class A, a higher productivity of the stands is achieved, and on the soils of the other two classes by middle or inferior productivity Attempts were made to identify the main less favorable features of soil classes B and C (unbalanced water and air regimes, lower humus content, soil reaction, etc.) which has led to decline of forest stands productivity. Starting from the data obtained from analysis, the studied areas were establish as forest site types, forests types, passing to their ecosystem types

Agriculture in responsibility for our common world

The vocational training course program Agriculture in Responsibility for our common World organised within the frame of the Banat Green Deal Project GreenERDE (Education and Research in the context of the digital and ecological transformation of agriculture in the Banat Region and Baden-Württemberg - towards resource efficiency and resilience) and delivered between June 2021 and May 2022 targets the knowledge and experience transfer to the farmer community in the Banat Region, Romania and other parts of the world. Current and future challenges, such as the ecological conversion and digital transformation of agricultural production, but also social, economic and cultural aspects haven been addressed transcending prevailing patterns. The innovative and relevant knowledge originating from practice, experiments, research or development projects throughout Europe and other continents is presented in a training format for interested participants.Das im Rahmen des Banat Green Deal Projekts GreenERDE (Bildung und Forschung im Kontext der digitalen und ökologischen Transformation des Agrarbereichs im Banat und Baden-Württemberg - auf dem Weg zu Ressourceneffizienz und Resilienz) von Juni 2021 bis Mai 2022 durchgeführte Fortbildungsprogramm Landwirtschaft in Verantwortung für unsere gemeinsame Welt), zielt auf den Wissens- und Erfahrungstransfer unter Landwirten und anderen interessirten Personen in der Banat-Region, Rumänien und anderen Teilen der Welt ab. Aktuelle und zukünftige Herausforderungen, wie die ökologische Umstellung und die digitale Transformation der landwirtschaftlichen Produktion, aber auch soziale, wirtschaftliche und kulturelle Aspekte wurden jenseits vorherrschender Muster adressiert. Das innovative und relevante Wissen aus Praxis, Forschungs- oder Entwicklungsprojekten in ganz Europa und anderen Kontinenten wird in einem Trainingsformat für interessierte Teilnehmer präsentiert

Associational susceptibility of crop plants caused by the invasive weed Canadian goldenrod, Solidago canadensis, via local aphid species

In the present study, field surveys were conducted to detect potential associational susceptibility of crop plants (potato, alfalfa and maize) caused by Canadian goldenrod, Solidago canadensis (L.), one of the most common invasive weeds in Central and Eastern Europe, via plant associated virus vectoring aphids. Assessments were made in two major agricultural land types: crops grown under high input vs. low-input (LIF) conditions, with and without fertilizers and pesticides. The two most frequent aphid species, found both on Canadian goldenrod and crop plants, were the leaf-curling plum aphid, Brachycaudus helichrysi Kaltenbach and the glasshouse-potato aphid, Aulacorthum solani (Kaltenbach). Plant viruses in both weed and crop plants were identified using high-throughput sequencing of small RNAs. Peroxidase (POD) enzyme activity was tested in weed and crop plants to connect aphids feeding processes in weeds and crops. In addition, conceptual modeling was used to detect direct relationships between viruses and other crops. The Canadian goldenrod density was only relevant in the LIF regime. Furthermore, its association with B. helichrysi and associational susceptibility was detected only in LIF. In total, 18 viruses comprising 17 plant and one insect virus were detected in Canadian goldenrod, of which 11 were also detected in potato and alfalfa crops. POD activity was high and correlated with high aphid density in both weed and crop plants, suggesting a direct associational susceptibility between these plants through aphid infestation and viral transmission

Endosymbiotic bacterial diversity of corn leaf aphid, Rhopalosiphum maidis Fitch (Hemiptera: Aphididae) associated with maize management systems

In this study, different maize fields cultivated under different management systems were sampled to test corn leaf aphid, Rhopalosiphum maidis, populations in terms of total and endosymbiotic bacterial diversity. Corn leaf aphid natural populations were collected from traditionally managed maize fields grown under high agricultural and natural landscape diversity as well as conventionally treated high-input agricultural fields grown in monoculture and with fertilizers use, hence with low natural landscape diversity. Total bacterial community assessment by DNA sequencing was performed using the Illumina MiSeq platform. In total, 365 bacterial genera were identified and 6 endosymbiont taxa. A high abundance of the primary endosymbiont Buchnera and secondary symbionts Serratia and Wolbachia were detected in all maize crops. Their frequency was found to be correlated with the maize management system used, probably with fertilizer input. Three other facultative endosymbionts (“Candidatus Hamiltonella”, an uncultured Rickettsiales genus, and Spiroplasma) were also recorded at different frequencies under the two management regimes. Principal components analyses revealed that the relative contribution of the obligate and dominant symbiont Buchnera to the aphid endosymbiotic bacterial community was 72%, whereas for the managed system this was only 16.3%. When facultative symbionts alone were considered, the effect of management system revealed a DNA diversity of 23.3%

On the influence of different soil cultivation practices in autumn and spring on the population development of the western corn rootworm Diabrotica virgifera virgifera LeConte (Col.: Chrysomelidae)

It can be expected that intensity and depth of soil cultivation have an impact on the eggs of Diabrotica virgifera virgifera, which are predominantly positioned 10 to 15 cm below soil surface. Main aim of this study was to investigate the relationship between different cultivation measures in autumn and spring and the hatching of adult D. virgifera virgifera as well as the maize root damage, caused by larvae. Gauze covered hatch-cages (2 per plot) were used to count the emerged imagines. Variants: Plough and grub, both 25 cm working depth, in autumn and superficial tillage with disc-harrow in spring. The trials were performed on fields with a significant natural D. virgifera virgifera infestation, in West Romania. The number of hatched adult D. virgifera virgifera was unsteady in the different years and did not correlate with soil-cultivation practices. This finding can be explained with the different climatic conditions in the single years. The maize-root damage under the hatch-cages was not significantly different between variants. This may on the one hand result from the limited number of samples (2 cages per plot) on the other hand also from the artificial growth circumstances for the maize under the small cages. The maize-root damage assessed in the surrounding plots was significantly lower in the plough-variant compared to those in the grubber- and disc-harrow-plots, in two of three years. A summary of all data achieved in three years, showed a significant correlation between the number of adult D. virgifera virgifera and the maize-root damages in the field (p=0.0001, r=0.605)

Effect of Entomopathogenic Fungi, Beauveria bassiana (Cordycipitaceae), on the Bark Beetle, Ips typographus (L.), under Field Conditions

The spruce bark beetle, Ips typographus (L.), attack progression (adult and larval galleries) and parental and offspring mortality rate were assessed in managed forests of the Poiana Ruscă and Bihor Mountains, along with Western Romanian Carpathians using fungal (Beauveria bassiana) treatments. The results show that the effect of B. bassiana on adult (maternal) gallery length was similar to the untreated variant and was less effective than the synthetic insecticide lambda-cyhalothrin applied at a dose of 50 g/L. Additionally, its effect on the mean larval gallery number per maternal gallery was low. B. bassiana did not have a significant influence on the attack progression. Significant correlations between log diameter and I. typographus attack progression were detected; such differences were higher than the effect of any treatment. Altogether, abiotic (low humidity, high temperature) and biotic factors (log diameter) influenced the bark beetles’ attack progression and reduced the entomopathogenic fungal effects. Considering the efficacy of the B. bassiana treatment on logs infested with I. typographus, the results showed that parents and offspring were infected, but even if the fungal treatment was applied in high concentrations, the mortality rate remained relatively low. Further research is necessary to test if different B. bassiana strains and their commercially recommended concentrations might be more effective under dry and warm climate conditions, respectively

Table_1_Associational susceptibility of crop plants caused by the invasive weed Canadian goldenrod, Solidago canadensis, via local aphid species.DOCX

In the present study, field surveys were conducted to detect potential associational susceptibility of crop plants (potato, alfalfa and maize) caused by Canadian goldenrod, Solidago canadensis (L.), one of the most common invasive weeds in Central and Eastern Europe, via plant associated virus vectoring aphids. Assessments were made in two major agricultural land types: crops grown under high input vs. low-input (LIF) conditions, with and without fertilizers and pesticides. The two most frequent aphid species, found both on Canadian goldenrod and crop plants, were the leaf-curling plum aphid, Brachycaudus helichrysi Kaltenbach and the glasshouse-potato aphid, Aulacorthum solani (Kaltenbach). Plant viruses in both weed and crop plants were identified using high-throughput sequencing of small RNAs. Peroxidase (POD) enzyme activity was tested in weed and crop plants to connect aphids feeding processes in weeds and crops. In addition, conceptual modeling was used to detect direct relationships between viruses and other crops. The Canadian goldenrod density was only relevant in the LIF regime. Furthermore, its association with B. helichrysi and associational susceptibility was detected only in LIF. In total, 18 viruses comprising 17 plant and one insect virus were detected in Canadian goldenrod, of which 11 were also detected in potato and alfalfa crops. POD activity was high and correlated with high aphid density in both weed and crop plants, suggesting a direct associational susceptibility between these plants through aphid infestation and viral transmission.</p

Endosymbiotic Bacterial Diversity of Corn Leaf Aphid, Rhopalosiphum maidis Fitch (Hemiptera: Aphididae) Associated with Maize Management Systems

In this study, different maize fields cultivated under different management systems were sampled to test corn leaf aphid, Rhopalosiphum maidis, populations in terms of total and endosymbiotic bacterial diversity. Corn leaf aphid natural populations were collected from traditionally managed maize fields grown under high agricultural and natural landscape diversity as well as conventionally treated high-input agricultural fields grown in monoculture and with fertilizers use, hence with low natural landscape diversity. Total bacterial community assessment by DNA sequencing was performed using the Illumina MiSeq platform. In total, 365 bacterial genera were identified and 6 endosymbiont taxa. A high abundance of the primary endosymbiont Buchnera and secondary symbionts Serratia and Wolbachia were detected in all maize crops. Their frequency was found to be correlated with the maize management system used, probably with fertilizer input. Three other facultative endosymbionts ("Candidatus Hamiltonella", an uncultured Rickettsiales genus, and Spiroplasma) were also recorded at different frequencies under the two management regimes. Principal components analyses revealed that the relative contribution of the obligate and dominant symbiont Buchnera to the aphid endosymbiotic bacterial community was 72%, whereas for the managed system this was only 16.3%. When facultative symbionts alone were considered, the effect of management system revealed a DNA diversity of 23.3%