Deleterious effect of LiCl on honeybee (Aphis mellifera) grubs and no effect on Varroa mites (Varroa destructor) under normal beekeeping management

A 2-year field experiment was performed to test lithium chloride, LiCl, application in a normal beekeeping management system. The effect of LiCl on bee larval mortality, beehive weight (honey production) and Varroa mite mortality were tested. Spectrometric quantification of Li on honey and the larval body were made to test the effectiveness of the presence of LiCl. Li was detected in bee larval bodies and in honey over 2 years, from 2018 to 2019. According to the results, no effect of LiCl on mite mortality or bee larval mortality was detected in the first year of application. By assessing the weight variation of beehives, only one LiCl-treated hive showed a significantly higher weight, whereas no other differences were detected between treatments and control. The same trend seen in 2018 was repeated in 2019, while a total bee larval mortality was observed after the first LiCl application, and still no differences in Varroa mite mortality were observed. According to these results, it was concluded that LiCl has no effect on Varroa mite mortality during normal beekeeping practice; furthermore, the recommended amount of treatment (25 mM) had a lethal effect (i.e., total mortality) on larvae following repeated applications.

Evaluation of two artificial defoliation methods to simulate damage by the cereal leaf beetle (Oulema melanopus) larvae in winter wheat

Defoliation reduces photosynthetic area, negatively effecting overall plant vitality, which at the end, severely impacts seed quality and production. The economic importance of the loss in winter wheat (Triticum aestivum L.) due to larvae of the cereal leaf beetle (Oulema melanopus, CLB) generated studies investigating the significance of the flag leaf. Simultaneously, the role of other leaves remains rather undiscovered. We simulated herbivory caused by CLB larvae in a two-year study between 2017 and 2018. We removed different amounts of leaf material from two winter wheat cultivars, either from the flag leaves only, or from all leaves. The impact of artificial defoliation was measured in grain production per ear, and related to natural CLB larval herbivory. Removing all leaves simulated CLB larval herbivory more closely than the artificial defoliation of flag leaves only. Our results suggest that the relative importance of flag leaves in seed production may be lower than previously assumed. Further studies involving various cultivars are invited to enhance the knowledge on the significance of the damage done by CLB larvae.

Composted Municipal Green Waste Infused with Biocontrol Agents to Control Plant Parasitic Nematodes-A Review

The last few years have witnessed the emergence of alternative measures to control plant parasitic nematodes (PPNs). We briefly reviewed the potential of compost and the direct or indirect roles of soil-dwelling organisms against PPNs. We compiled and assessed the most intensively researched factors of suppressivity. Municipal green waste (MGW) was identified and profiled. We found that compost, with or without beneficial microorganisms as biocontrol agents (BCAs) against PPNs, were shown to have mechanisms for the control of plant parasitic nematodes. Compost supports a diverse microbiome, introduces and enhances populations of antagonistic microorganisms, releases nematicidal compounds, increases the tolerance and resistance of plants, and encourages the establishment of a "soil environment" that is unsuitable for PPNs. Our compilation of recent papers reveals that while the scope of research on compost and BCAs is extensive, the role of MGW-based compost (MGWC) in the control of PPNs has been given less attention. We conclude that the most environmentally friendly and long-term, sustainable form of PPN control is to encourage and enhance the soil microbiome. MGW is a valuable resource material produced in significant amounts worldwide. More studies are suggested on the use of MGWC, because it has a considerable potential to create and maintain soil suppressivity against PPNs. To expand knowledge, future research directions shall include trials investigating MGWC, inoculated with BCAs.

Preliminary assessment of cavity-nesting Hymenopterans in a low-intensity agricultural landscape in Transylvania

In this study, our aim was to assess several traits of cavity-nesting Hymenopteran taxa in a low-intensity agricultural landscape in Transylvania. The study took place between May and August 2018 at eight study sites in the hilly mountainous central part of Romania, where the majority of the landscape is used for extensive farming or forestry. During the processing of the trap nest material, we recorded several traits regarding the nests of different cavity-nesting Hymenopteran taxa and the spider prey found inside the nests of the spider-hunting representatives of these taxa. We also evaluated the relationship between the edge density and proportion of low-intensity agricultural areas surrounding the study sites and some of these traits. The majority of nests were built by the solitary wasp genus Trypoxylon, followed by the solitary wasp taxa Dipogon and Eumeninae. Solitary bees were much less common, with Hylaeus being the most abundant genus. In the nests of Trypoxylon, we mostly found spider prey from the family of Araneidae, followed by specimens from the families of Linyphiidae and Theridiidae. In the nests of Dipogon, we predominantly encountered spider prey from the family of Thomisidae. We found significant effects of low-intensity agricultural areas for the genera of Auplopus, Megachile, Osmia, and the Thomisid prey of Dipogon. We also found that the spider prey of Trypoxylon was significantly more diverse at study sites with higher proportions of low-intensity agricultural areas. Our results indicate that solitary bees seem to be more abundant in areas, where the influence of human activities is stronger, while solitary wasps seem to rather avoid these areas. Therefore, we suggest that future studies not only should put more effort into sampling in low-intensity agricultural landscapes but also focus more on solitary wasp taxa, when sampling such an area.

Landscape structure affects the sunflower visiting frequency of insect pollinators

Mass-flowering crop monocultures, like sunflower, cannot harbour a permanent pollinator community. Their pollination is best secured if both managed honey bees and wild pollinators are present in the agricultural landscape. Semi-natural habitats are known to be the main foraging and nesting areas of wild pollinators, thus benefiting their populations, whereas crops flowering simultaneously may competitively dilute pollinator densities. In our study we asked how landscape structure affects major pollinator groups’ visiting frequency on 36 focal sunflower fields, hypothesising that herbaceous semi-natural (hSNH) and sunflower patches in the landscape neighbourhood will have a scale-dependent effect. We found that an increasing area and/or dispersion of hSNH areas enhanced the visitation of all pollinator groups. These positive effects were scale-dependent and corresponded well with the foraging ranges of the observed bee pollinators. In contrast, an increasing edge density of neighbouring sunflower fields resulted in considerably lower visiting frequencies of wild bees. Our results clearly indicate that the pollination of sunflower is dependent on the composition and configuration of the agricultural landscape. We conclude that an optimization of the pollination can be achieved if sufficient amount of hSNH areas with good dispersion are provided and mass flowering crops do not over-dominate the agricultural landscape.

A new microscopic method to analyse desiccation-induced volume changes in aeroterrestrial green algae

Aeroterrestrial green algae are exposed to desiccation in their natural habitat, but their actual volume changes have not been investigated. Here, we measure the relative volume reduction (RVRED ) in Klebsormidium crenulatum and Zygnema sp. under different preset relative air humidities (RH). A new chamber allows monitoring RH during light microscopic observation of the desiccation process. The RHs were set in the range of ∼4 % to ∼95% in 10 steps. RVRED caused by the desiccation process was determined after full acclimation to the respective RHs. In K. crenulatum, RVRED (mean ± SE) was 46.4 ± 1.9%, in Zygnema sp. RVRED was only 34.3 ± 2.4% at the highest RH (∼95%) tested. This indicates a more pronounced water loss at higher RHs in K. crenulatum versus Zygnema sp. By contrast, at the lowest RH (∼4%) tested, RVRED ranged from 75.9 ± 2.7% in K. crenulatum to 83.9 ± 2.2% in Zygnema sp. The final volume reduction is therefore more drastic in Zygnema sp. These data contribute to our understanding of the desiccation process in streptophytic green algae, which are considered the closest ancestors of land plants.

[Basic proteins in the granules of mast cells. Demonstration of masked proteins, acidophilic staining of the granules]

Basic proteins of the granules of mast cells in nativ, formalin-, alcohol- and aceton fixed preparations without any preliminary treatment, when stained with acidic dye at the pH 9 cytochemically seem to be masked. After various preliminary treatment (treatment with acid, with cetylpiridinumchlorid, CPC) mast-cell granula stained with acidic-dye at pH 9 appear intensively acidophile. This phenomenon can be explained by the presence of basic proteins in the mast cell granula. Preliminary treatment with CPC inhibits acid radicals of the heparin. This may lead to the disintegration of the linkage between proteins of the heparin, thus amino-group of the basic proteins become reactivated and can be identified by acidic dyes. It can not be excluded as well, that CPC linked to the heparin with free positive radicals reveals acidic-dye-binding capacity. In cases of preliminary treatment with various acids this mechanism does not seem possible to lay on the base of changing of the dye binding capacity.