Plant Protection News (Vestnik Zashchity Rasteniy)

Features of the relationship between the parasite and the host in the pathosystem “Triticum aestivum – Pyrenophora tritici-repentis”

N. V. Mironenko — 2025-11-19

Tan spot is a widespread disease of wheat, belongs to the group of dangerous, causes yield losses and worsens grain quality. The causative agent of the disease is the ascomycete fungus Pyrenophora tritici-repentis. In the last three decades, genetic mechanisms of relationships in the pathosystem “Triticum aestivum – Pyrenophora tritici-repentis” have been actively studied. The interaction of the parasite and host plant genes occurs according to the inverse type, in contrast to the classical concept, proposed by Flor. The known data on the genetics of soft wheat resistance to the causative agent of tan spot and examples of interactions of wheat susceptibility genes with the main pathogenicity factors of P. tritici-repentis are presented. The complexity of the pathosystem “Triticum aestivum – Pyrenophora tritici-repentis” is noted, which includes not only race-specific interactions determined by fungal NEs and host susceptibility genes, but also many QTLs associated with resistance to several races.

Exometabolites of basidiomycetes as a means to increase wheat resistance to toxic action of aluminum

D. V. Popyvanov — 2025-11-19

The effect of exometabolites of basidial fungi on the morphometric parameters of soft wheat seedlings (Triticum aestivum) of the Premium variety under aluminum stress was studied. Extracellular metabolites were evaluated, obtained by deep cultivation on beer wort medium of six species of xylotrophic fungi: Trametes pubescens, Fomes fomentarius, Fomitopsis betulina, Plicaturopsis crispa, Schizophyllum commune, and Hypsizygus marmoreus. The filtrate of cultural fluids (CF) in dilutions of 1:10 and 1:100 was used in the work. The most pronounced positive effect on the growth parameters of T. pubescens filtrate was found at a dilution of 1:100. A partial increase in root length and shoot height was observed compared to the positive control with aluminum. Other exometabolites didn’t show a noticeable protective effect, and in some cases (F. fomentarius), wheat growth inhibition was increased. The effect of exometabolites strongly depended on the fungal species and concentration of the filtrate. The data obtained indicate the toxicity of some exometabolites of basidiomycetes to plants.

A novel approach of using Cryptolaemus montrouzieri (Coleoptera: Coccinellidae) in greenhouses of botanical gardens

Yu. B. Polikarpova — 2025-11-19

Mealybug infestations remain a significant challenge in botanical garden greenhouses. Conventional summer deployment of the mealybug-feeding Cryptolaemus montrouzieri (Coleoptera: Coccinellidae) often proves ineffective. This study aimed to evaluate the feasibility of using adult, cold-resistant Cryptolaemus cultures during winter and spring to suppress early mealybug outbreaks. Laboratory cultures were established from wild specimens collected along the Black Sea coast of the Caucasus. The field experiments were conducted in two tropical greenhouses at the Peter the Great Botanical Garden (St. Petersburg, Russia). Populations of mealybug Planococcus ficus (Hemiptera: Pseudococcidae) and the predator’s larvae were monitored on seven model plant species. In the “Tropical Fruit Plants” greenhouse, experiments were conducted on Coffea arabica, Mangifera indica, Tectona grandis, and Theobroma cacao. In the “Large Palm Greenhouse,” the trials involved Combretum fruticosum, Ptychosperma elegans, and Cedrela glaziovii. Results demonstrated that cold-tolerant Cryptolaemus individuals could reproduce at 17–18 °C. Predator’s larvae, observed from January to March, effectively suppressed mealybug population growth during spring. This suppression created favorable conditions for pest management in the subsequent summer. A long-term program utilizing cold-resistant Cryptolaemus cultivars allowed maintaining the mealybug populations at levels not causing significant damage to the plants, indicating a sustainable and effective biological control strategy for greenhouse environment.

Salivary gland alpha-amylases retain activity in wheat grains damaged by Eurygaster (Heteroptera: Scutelleridae) Sunn bugs

A. V. Konarev — 2025-11-19

The Sunn pest Eurygaster integriceps and related wheat bugs (Sunn bugs) cause great damage to the wheat crop by injecting hydrolytic enzymes into the grain that liquefy the endosperm during extraintestinal digestion. The main harmful factor of bugs is considered to be their proteases, which are retained in the endosperm of damaged grain and flour and hydrolyze gluten proteins during dough kneading. Thus, the quality of bread deteriorates sharply. Salivary gland proteases provide protein nutrition for the wheat bugs. However, the main source of energy that allows them to accumulate fat necessary for wintering is the endosperm starch, hydrolyzed by alpha-amylases. Alpha-amylases of wheat bug salivary glands have not been sufficiently studied. There is still no consensus on the role of these enzymes in the nutrition of bugs, on their presence in damaged mature grain, and on their influence on the technological qualities of flour, which may be partly due to the lack of methods for detecting the actual bug alpha-amylases in grain. Using a new simple method, including inactivation of plant beta-amylases interfering with the analysis by sodium p-chloromercuribenzoate, we obtained alpha-amylase banding patterns similar to the patterns of wheat bug salivary gland alpha-amylases as a result of protein isoelectric focusing of some samples of damaged grain. The developed approach can be recommended for use in the technological assessment of damaged grain, in studying the mechanisms of plant immunity to pests as well as for diagnostics of grain damage by insects.

Endophytic fungus Beauveria bassiana induces antioxidant enzyme activities and enhances the growth of Rhizoctonia solani-infected potato plants

O. G. Tomilova — 2025-11-19

The physiological and biochemical changes in potato plants colonized by the endophytic form of the entomophatogenic fungus Beauveria bassiana (Ascomycota: Hypocreales) were analyzed under biotic stress caused by infection with the phytopathogen Rhizoctonia solani (Basidiomycetes: Ceratobasidiales). A high level of plant colonization by entomopathogenic endophyte was observed, and infection with R. solani did not have a significant effect on the degree of plant colonization. The colonization of potatoes by B. bassiana compensated for the growth retardation of Rhizoctonia-infected plants, especially the roots, and significantly reduced Rhizoctonia damage to stems and developing stolons. Inoculation of plants with both fungi resulted in an increase in antioxidant activity, with B. bassiana contributing to this effect. There were significant increases in the activity of the following antioxidant enzymes: peroxidases, superoxide dismutases, polyphenol oxidases and phenylalanine-ammonia-lyase. B. bassiana triggered the host plant’s defense system, namely a complex of antioxidant enzymes, to overcome biotic stress caused by R. solani. Therefore, B. bassiana is a promising modulator of plant defense metabolism against phytopathogens.

The use of integrated methods for controlling the tobacco thrips Thrips tabaci on eggplant under greenhouse conditions

D. Undarmaa — 2025-11-19

The tobacco thrips Thrips tabaci is a prevalent insect-pest found worldwide, extensively distributed in greenhouses of Mongolia. This study aimed to evaluate the effectiveness of predatory mites and botanical pesticides in controlling tobacco thrips populations in eggplant crops. An experiment was conducted in a 120 m² greenhouse at the “Agropark” Experimental Research Center of the Mongolian University of Life Sciences. Four treatments were applied to infested eggplant plots: a) the predatory mite Amblyseius swirskii, b) A. swirskii combined with Neem oil; c) Neem oil alone; and d) Neem oil combined with bio-stimulant BEB containing extract of the fungus Ganoderma lucidum. The average mortality rates of tobacco thrips across three years ranged from 45 % to 93 % due to A. swirski, 77 % to 97 % due to A. swirskii plus Neem oil, 75 % to 96 % due to Neem oil; and 77 % to 96 % due to Neem oil plus BEB. All treatments demonstrated promising results in significantly reducing thrips populations under greenhouse conditions. However, to ensure the effectiveness of biological control, it is important to release predatory mites at least five days after the application of botanical insecticides, such as Neem oil. Based on the findings, we recommend the use of Amblyseius swirskii, either alone or in combination with botanical products, as a safe and effective plant protection measure for controlling tobacco thrips in greenhouse-grown eggplants.

Monitoring of Okra Yellow Vein Mosaic Virus in the Sargodha Division, Pakistan

M. A. Shabbir — 2025-11-19

Okra Yellow Vein Mosaic Virus (OYVMV) is an important and significant threat to okra production, causing great yield losses in tropical and subtropical regions. The distribution and prevalence of OYVMV infection were estimated in the okra fields of Punjab, Pakistan, during 2020 and 2021. Surveys were conducted across Sargodha division (Sardogha, Khushab, Mianwali, and Bhakkar districts) to collect symptomatic and asymptomatic leaf samples. The presence of OYVMV was confirmed through PCR using specific primers. Disease incidence and severity were calculated using established formulas and rating scales. Significant differences were found in the incidence and severity of OYVMV infection among the districts and crop varieties. In 2020, Sargodha had the highest incidence and severity (80 % and 52 %), followed by Mianwali and Khushab, while in Bhakkar, the lowest incidence and severity were recorded (70 % and 47 %). In 2021, Mianwali showed the highest incidence and severity (73 % and 47 %), followed by Bhakkar and Khushab with Sargodha showing the least values for both parameters (69 % and 44 %). Among the varieties, Sultan-121 displayed the highest incidence and severity of the disease, while Sabz Pari had the lowest indices. Heat maps were utilized to visualize spatial variations in the incidence and severity of the virus infection. These findings highlight the widespread presence of OYVMV in Sargodha division and determine a baseline for future control and management strategies intended to mitigate the OYVMV-incurred losses in okra production.

Damage to winter triticale grain by herbivorous bugs in the Leningrad region

A. M. Shpanev — 2025-11-19

Damage to grains by some species of herbivorous bugs can lead to a significant decrease in the quantitative and qualitative parameters of the formed crop. Given the species composition and abundance of bugs in the North-West region, such a problem does not exist, at the same time, there are no actual data on the damage to grains of cultivated grain crops. Based on the results of the analysis of samples performed using infrared microscopy, low damage to winter triticale grain by herbivorous bugs was determined in 2022-2024 in the fields of the Menkovsky branch of the Agrophysical Research Institute in the Leningrad Region. The share of damaged grains in the total mass of the harvested crop varied from 1.2 to 4 % over the years. In the vast majority of cases, the grains had a slight degree of damage. The damage caused by the species Aelia acuminata, Carpocoris purpureipennis and Dolycoris baccarum was predominant. Spring fertilization with nitrogen fertilizers led to an extension of the ripening period of winter triticale and an increase in grain damage by herbivorous bugs. The highest proportion of damaged grains corresponded to the experimental variants with high doses of nitrogen fertilizers and amounted to 1.3 to 5 % in different years.