Proteomic Profile of Flaxseed (Linum usitatissimum L.) Products as Influenced by Protein Concentration Method and Cultivar

The research is focused on the quantitative evaluation of the flaxseed (Linum usitatissimum L.) proteome at the level of seed cake (SC), fine flour-sieved a fraction below 250 µm (FF)-and protein concentrate (PC). The evaluation was performed on three oilseed flax cultivars (Agriol, Raciol, and Libra) with different levels of α-linolenic acid content using LC-MS/MS (shotgun proteomics) analysis, which was finalized by database searching using the NCBI protein database for Linum usitatissimum and related species. A total of 2560 protein groups (PGs) were identified, and their relative abundance was calculated. A set of 33 quantitatively most significant PGs was selected for further characterization. The selected PGs were divided into four classes-seed storage proteins (11S globulins and conlinins), oleosins, defense- and stress-related proteins, and other major proteins (mainly including enzymes). Seed storage proteins were found to be the most abundant proteins. Specifically, 11S globulins accounted for 41-44% of SC proteins, 40-46% of FF proteins, and 72-84% of PC proteins, depending on the cultivar. Conlinins (2S albumins) were the most abundant in FF, ranging from 10 to 13% (depending on cultivar). The second most important class from the point of relative abundance was oleosins, which were represented in SC and FF in the range of 2.1-3.8%, but only 0.36-1.20% in PC. Surprisingly, a relatively high abundance of chitinase was found in flax products as a protein related to defence and stress reactions.

Control of sweet potato whitefly (Bemisia tabaci) using entomopathogenic fungi under optimal and suboptimal relative humidity conditions

BACKGROUND

Sweet potato whitefly (Bemisia tabaci) is one of the most destructive pests to an extensive range of crops and vegetables. Pesticide-dependent management programs have led to severe health problems, including pesticide poisoning and cancer in human beings, as well as pesticide resistance in insect pests. Entomopathogenic fungi (EPF) are considered safe and highly effective against many pests. Therefore, identifying the pathogenicity and virulence of EPFs against Bemisia tabaci is a valuable addition to the management of their infestations. In this study, we investigated the efficacy of conidia suspensions of Aschersonia aleyrodis, Isaria fumosorosea, Beauveria bassiana, and Akanthomyces muscarius (= Lecanicillium muscarium) against nymphal stages of Bemisia tabaci in cucumber seedlings under both optimal and suboptimal conditions.

RESULTS

All of the EPFs demonstrated significant ovicidal effects, with the highest cumulative mortalities observed in Aschersonia aleyrodis (96.46%) and I. fumosorosea-treated (94.60%) seedlings against host eggs and crawlers. Similarly, in the L4-instars experiment, Aschersonia aleyrodis and I. fumosorosea were the most efficient, resulting in cumulative mortalities of 94.82% and 94.75%, respectively. However, Bemisia tabaci cumulative mortalities on seedlings treated with Akanthomyces muscarius (78.36%) and Beauveria bassiana (85.90%) were also significantly different from untreated seedlings (7.10%). Under suboptimal relative humidity (RH) conditions (≤ 45% RH), Aschersonia aleyrodis exhibited greater tolerance to harsh conditions, causing a significantly higher infection rate in L1-L2 nymphs (~92%) compared to the approximately 32% infected young nymphs observed in I. fumosorosea-treated seedlings.

CONCLUSION

All the selected EPF were more effective against the young nymphal instars. Our results also highlight the efficacy of Aschersonia aleyrodis under suboptimal conditions. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Silica Nanoparticles from Coir Pith Synthesized by Acidic Sol-Gel Method Improve Germination Economics

Lignin is a natural biopolymer. A vibrant and rapid process in the synthesis of silica nanoparticles by consuming the lignin as a soft template was carefully studied. The extracted biopolymer from coir pith was employed as capping and stabilizing agents to fabricate the silica nanoparticles (_nSi). The synthesized silica nanoparticles (_nSi) were characterized by ultraviolet–visible (UV–Vis) spectrophotometry, X-ray diffraction analysis (XRD), Scanning Electron Microscope (SEM), Energy-Dispersive X-ray Analysis (EDAX), Dynamic Light Scattering (DLS) and Fourier-Transform Infrared Spectroscopy (FTIR). All the results obtained jointly and independently verified the formation of silica nanoparticles. In addition, EDAX analysis confirmed the high purity of the _nSi composed only of Si and O, with no other impurities. XRD spectroscopy showed the characteristic diffraction peaks for _nSi and confirmed the formation of an amorphous nature. The average size of _nSi obtained is 18 nm. The surface charge and stability of _nSi were analyzed by using the dynamic light scattering (DLS) and thus revealed that the _nSi samples have a negative charge (−20.3 mV). In addition, the seed germination and the shoot and root formation on Vigna unguiculata were investigated by using the _nSi. The results revealed that the application of _nSi enhanced the germination in V. unguiculata. However, further research studies must be performed in order to determine the toxic effect of biogenic _nSi before mass production and use of agricultural applications.

Screening of Honey Bee Pathogens in the Czech Republic and Their Prevalence in Various Habitats

Western honey bee (Apis mellifera) is one of the most important pollinators in the world. Thus, a recent honey bee health decline and frequent honey bee mass losses have drawn attention and concern. Honey bee fitness is primarily reduced by pathogens, parasites, and viral load, exposure to pesticides and their residues, and inadequate nutrition from both the quality and amount of food resources. This study evaluated the prevalence of the most common honey bee pathogens and viruses in different habitats across the Czech Republic. The agroecosystems, urban ecosystems, and national park were chosen for sampling from 250 colonies in 50 apiaries. Surprisingly, the most prevalent honey bee pathogens belong to the family Trypanosomatidae including Lotmaria passim and Crithidia mellificae. As expected, the most prevalent viruses were DWV, followed by ABPV. Additionally, the occurrence of DWV-B and DWV-C were correlated with honey bee colony mortality. From the habitat point of view, most pathogens occurred in the town habitat, less in the agroecosystem and least in the national park. The opposite trend was observed in the occurrence of viruses. However, the prevalence of viruses was not affected by habitat.

The Effect of Artificial Media and Temperature on the Growth and Development of the Honey Bee Brood Pathogen Ascosphaera apis

Ascosphaera apis is a causative agent of chalkbrood, which is one of the most widespread honey bee diseases. In our experiments, the influence of several artificial media and cultivation under different temperatures was evaluated. Concretely, the radial growth of separated mating types was measured, reproductive structures in a Neubauer hemocytometer chamber were counted simultaneously, and the morphometry of spore cysts and spore balls was assessed. The complex set of experiments determined suitable cultivation conditions. A specific pattern between reproductive structure size and temperature was found. The optimal temperature for both mating types was 30 °C. SDA and YGPSA media are suitable for fast mycelial growth. Moreover, the effect of bee brood on fungus growth and development in vitro was investigated by modification of culture medium. The newly modified medium PDA-BB4 was most effective for the production of the reproductive structures. The result suggests that honey bee brood provides necessary nutrients for proper fungus development during in vitro cultivation. As there is no registered therapeutic agent against chalkbrood in most countries, including the European Union, the assessment of A. apis growth and development in different conditions could help to understand fungus pathogenesis and thus control chalkbrood disease.

Dissemination of Isaria fumosorosea Spores by Steinernema feltiae and Heterorhabditis bacteriophora

Entomopathogenic nematodes and fungi are globally distributed soil organisms that are frequently used as bioagents in biological control and integrated pest management. Many studies have demonstrated that the combination of biocontrol agents can increase their efficacy against target hosts. In our study, we focused on another potential benefit of the synergy of two species of nematodes, Steinernema feltiae and Heterorhabditis bacteriophora, and the fungus Isaria fumosorosea. According to our hypothesis, these nematodes may be able to disseminate this fungus into the environment. To test this hypothesis, we studied fungal dispersal by the nematodes in different arenas, including potato dextrose agar (PDA) plates, sand heaps, sand barriers, and glass tubes filled with soil. The results of our study showed, for the first time, that the spreading of both conidia and blastospores of I. fumosorosea is significantly enhanced by the presence of entomopathogenic nematodes, but the efficacy of dissemination is negatively influenced by the heterogeneity of the testing arena. We also found that H. bacteriophora spread fungi more effectively than S. feltiae. This phenomenon could be explained by the differences in the presence and persistence of second-stage cuticles or by different foraging behavior. Finally, we observed that blastospores are disseminated more effectively than conidia, which might be due to the different adherence of these spores (conidia are hydrophobic, while blastospores are hydrophilic). The obtained results showed that entomopathogenic nematodes (EPNs) can enhance the efficiency of fungal dispersal.

Adipokinetic hormone promotes infection with entomopathogenic fungus Isaria fumosorosea in the cockroach Periplaneta americana

The adipokinetic hormones (AKHs) are known to be involved in insect immunity, thus their role in the cockroach Periplaneta americana infected with the entomopathogenic fungus Isaria fumosorosea was examined in this study. The application of I. fumosorosea resulted in a significant increase in both Akh gene expression and AKH peptide levels. Further, co-application of I. fumosorosea with Peram-CAH-II significantly enhanced cockroach mortality compared with the application of I. fumosorosea alone. The mechanism of AKH action could involve metabolic stimulation, which was indicated by a significant increase in carbon dioxide production; this effect can increase the turnover and thus efficacy of toxins produced by I. fumosorosea in the cockroach's body. I. fumosorosea treatment resulted in a significant decrease in haemolymph nutrients (carbohydrates and lipids), but co-application with Peram-CAH-II restored control level of lipids or even further increased the level of carbohydrates. Such nutritional abundance could enhance the growth and development of I. fumosorosea. Further, both I. fumosorosea and Peram-CAH-II probably affected oxidative stress: I. fumosorosea alone curbed the activity of catalase in the cockroach's gut, but co-application with Peram-CAH-II stimulated it. Interestingly, the hormone alone had no effect on catalase activity. Taken together, the results of the present study demonstrate the interactions between the fungus and AKH activity; understanding this relationship could provide insight into AKH action and may have practical implications for insect pest control in the future.