Effectiveness of biological protection of cabbage against pests in the conditions of the Primorsky Territory

The results of the use of entomophages and biological products to regulate the number of cabbage pests (cabbage moth Mamestra brassicae L., cabbage butterfly Pieris brassicae L., turnip butterfly Pieris rapae L., diamondback moth Plutella xylostella L.) are presented. The study was carried out in the Primorsky Territory in 2018-2020. The efficiency of Trichogramma ussuricum Sorokina applications was assessed on cabbage varieties. The effectiveness of the entomophage against the cabbage moth varied from 33.3 to 66.6%, against the turnip butterfly - from 32.6 to 70.2%. In field experiments the effectiveness of biological products Fitoverm EC (0.09 l/ha), Akarin EC (1.6 l/ha), Proclaim WG (0.3 kg/ha), Bitoxibacillin (10 l/ha), Bitoxibacillin P (2 kg/ha), Lepidocid SC (2 l/ha), Lepidocid P (2 kg/ha) against diamondback moth are studied. Cabbage plants were sprayed with the preparations once. Pest counts were carried out before treatment and after treatment on the 5th, 10th and 15th day in accordance with the approved methods. Bioinsecticide Proclaim showed a high efficiency of 93.0-100% on the 5-10th day. The effectiveness of preparations based on aversectin C and avertin N was 65.0-88.6%. Using the biological product Bitoxibacillin and Lepidocid a decrease the number of diamondback moth relative to the control by 61.2-97.5 и 65.0-78.0% was registered.

Glucosinolate Induction and Resistance to the Cabbage Moth, Mamestra brassicae, Differs among Kale Genotypes with High and Low Content of Sinigrin and Glucobrassicin

The cabbage moth, Mamestra brassicae L. (Lepidoptera: Noctuidae), is a generalist insect pest of cruciferous crops. We tested glucosinolate induction by jasmonic acid (JA) and salicylic acid (SA), and by these phytohormones combined with feeding by M. brassicae larvae in four genotypes of kale, Brassica oleracea L. var. acephala (Brassicaceae). The genotypes tested had high glucobrassicin (genotype HGBS), low glucobrassicin (genotype LGBS), high sinigrin (genotype HSIN), and low sinigrin content (genotype LSIN). Application of JA increased indolic and total glucosinolate content in all kale genotypes 1, 3, and 9 days after treatment. For SA-treated plants, glucosinolate induction varied depending on the number of days after treatment and the genotype. Overall, herbivory by M. brassicae accentuated and attenuated the effects of JA and SA, respectively, on plant glucosinolate content. Larvae of M. brassicae gained less weight on leaves from plants treated with JA compared to leaves from control plants and plants treated with SA. In bioassays with leaf discs, a significant reduction of defoliation only occurred in JA-treated plants of the HSIN genotype. This research shows that previous herbivory alters the susceptibility of kale to M. brassicae and that induction of glucosinolates varies among kale genotypes differing in their glucosinolate content.

Insilico Molecular Docking Studies of Volatile Compounds Identified by GC-MS from Tagetes Species Against Mamestra brassicae (Linnaeus, 1758)

Plants evolved to be a potential source of pharmacologically active compounds that are being widely accepted as insect repellent compounds for generations. Products of natural origin are mostly preferred over synthetic compounds because of fewer side effects on human health and the environment, have the potential to be produced locally, cost-effective, and are proved to be more efficient. They are best suited in organic food production and can play a much greater role in developing countries as a new class of eco-friendly products for controlling pests. In turn, the development of repellents is desirable alternatives to synthetic chemical insecticides for controlling pests. In the process of continual search for insect-based repellents of natural origin, a wide number of Tagetes species have been archived and all parts of this plant from root to seed possess a range of phytochemicals that are responsible for the repellent activity. The present study concentrates on the identification of active volatile compounds from Tageteserecta leaves by Gas chromatography-mass spectrometry (GC-MS) analysis and further evaluation through molecular docking studies of identified compounds against Mamestra brassicae.

Host-virus and virus-virus interactions in broad host range alphabaculoviruses: implications for the development of virus-based insecticides

This thesis examined the insecticidal potential of the broad host range baculovirus Mamestra brassicae multiple nucleopolyhedrovirus (MbMNPV), and this interaction with Helicoverpa armigera multiple nucleopolyhedrovirus (HaMNPV) during the coinfection of a shared host. The results provide greater understanding of host-virus and virus-virus interactions in broad host range alphabaculoviruses that should help define effective strategies for pest control in field and greenhouse crops. First, the insecticidal activity and stability of the two closely related alphabaculovirus isolates, HearMNPV and MbMNPV derived from the commercial bioinsecticide Mamestrin®, were evaluated in a permissive (Spodoptera exigua) and a semi-permissive host (Spodoptera littoralis). The genetic structure of MbMNPV derived from the biological insecticideMamestrin® was then studied with the aim of assessing the insecticide properties of the genotypic variants comprised this wild-type isolate. Finally, interactions between two phylogenetically closely related viruses during coinfection of a shared host were analysed. In conclusion, the results obtained in this thesis contribute to a better understanding of the interactions between viruses and their hosts, which can contribute to the development of baculovirus-based insecticides and to design of effective strategies for the control of lepidopteran pest complexes.

Interactive Effects of Mycorrhizae, Soil Phosphorus, and Light on Growth and Induction and Priming of Defense in Plantago lanceolata

Increasing demands to reduce fertilizer and pesticide input in agriculture has triggered interest in arbuscular mycorrhizal fungi (AMF) that can enhance plant growth and confer mycorrhiza-induced resistance (MIR). MIR can be based on a variety of mechanisms, including induction of defense compounds, and sensitization of the plant’s immune system (priming) for enhanced defense against later arriving pests or pathogens signaled through jasmonic acid (JA). However, growth and resistance benefits of AMF highly depend on environmental conditions. Low soil P and non-limiting light conditions are expected to enhance MIR, as these conditions favor AMF colonization and because of observed positive cross-talk between the plant’s phosphate starvation response (PSR) and JA-dependent immunity. We therefore tested growth and resistance benefits of the AMF Funneliformis mosseae in Plantago lanceolata plants grown under different levels of soil P and light intensity. Resistance benefits were assessed in bioassays with the leaf chewing herbivore Mamestra brassicae. Half of the plants were induced by jasmonic acid prior to the bioassays to specifically test whether AMF primed plants for JA-signaled defense under different abiotic conditions. AMF reduced biomass production but contrary to prediction, this reduction was not strongest under conditions considered least optimal for carbon-for-nutrient trade (low light, high soil P). JA application induced resistance to M. brassicae, but its extent was independent of soil P and light conditions. Strikingly, in younger plants, JA-induced resistance was annulled by AMF under high resource conditions (high soil P, ample light), indicating that AMF did not prime but repressed JA-induced defense responses. In older plants, low soil P and light enhanced susceptibility to M. brassicae due to enhanced leaf nitrogen levels and reduced leaf levels of the defense metabolite catalpol. By contrast, in younger plants, low soil P enhanced resistance. Our results highlight that defense priming by AMF is not ubiquitous and calls for studies revealing the causes of the increasingly observed repression of JA-mediated defense by AMF. Our study further shows that in our system abiotic factors are significant modulators of defense responses, but more strongly so by directly modulating leaf quality than by modulating the effects of beneficial microbes on resistance.

Brassica oleracea var. acephala (kale) improvement by biological activity of root endophytic fungi

Brassica oleracea var. acephala (kale) is a cruciferous vegetable widely cultivated for its leaves and flower buds in Atlantic Europe and the Mediterranean area, being a food of great interest as a "superfood" today. Little has been studied about the diversity of endophytic fungi in the Brassica genus, and there are no studies regarding kale. In this study, we made a survey of the diversity of endophytic fungi present in the roots of six different Galician kale local populations. In addition, we investigated whether the presence of endophytes in the roots was beneficial to the plants in terms of growth, cold tolerance, or resistance to bacteria and insects. The fungal isolates obtained belonged to 33 different taxa. Among those, a Fusarium sp. and Pleosporales sp. A between Setophoma and Edenia (called as Setophoma/Edenia) were present in many plants of all five local populations, being possible components of a core kale microbiome. For the first time, several interactions between endophytic fungus and Brassica plants are described and is proved how different interactions are beneficial for the plant. Fusarium sp. and Pleosporales sp. B close to Pyrenophora (called as Pyrenophora) promoted plant growth and increased cold tolerance. On the other hand, isolates of Trichoderma sp., Pleosporales sp. C close to Phialocephala (called as Phialocephala), Fusarium sp., Curvularia sp., Setophoma/Edenia and Acrocalymma sp. were able to activate plant systemic resistance against the bacterial pathogen Xanthomonas campestris. We also observed that Fusarium sp., Curvularia sp. and Setophoma/Edenia confered resistance against Mamestra brassicae larvae.

Biological Control Potential of Native Entomopathogenic Nematodes (Steinernematidae and Heterorhabditidae) against Mamestra brassicae L. (Lepidoptera: Noctuidae)

The largest group of cabbage plant pests are the species in the owlet moth family (Lepidoptera: Noctuidae), the most dangerous species of which is the cabbage moth (Mamestra brassicae L.). In cases of heavy infestation by this insect, the surface of plants may be reduced to 30%, with a main yield loss of 10–15%. The aim of the present study was to assess the susceptibility of M. brassicae larvae to nine native nematode isolates of the species Steinernema feltiae (Filipjev) and Heterorhabditis megidis Poinar, Jackson and Klein under laboratory conditions. The most pathogenic strains were S. feltiae K11, S. feltiae K13, S. feltiae ZAG11, and S. feltiae ZWO21, which resulted in 100% mortality at a temperature of 22 °C and a dosage of 100 infective juveniles (IJs)/larva. The least effective was H. megidis Wispowo, which did not exceed 35% mortality under any experimental condition. For most strains, there were significant differences (p ≤ 0.05) in the mortality for dosages between 25 IJs and 50 IJs, and between 25 IJs and 100 IJs, at a temperature of 22 °C. Statistical analysis of the effect of temperature on mortality showed that only strain H. megidis Wipsowo exhibited significant differences (p ≤ 0.05) when applied at dosages of 50 IJs and 100 IJs.

Results of assessment of white cabbage and napa cabbage for resistance to diamondback moth and cabbage moth

Представлены результаты оценки линейного и гибридного материала капусты белокочанной на устойчивость к капустной моли (Plutella xylostella (L.)) и гибридов капусты пекинской на устойчивость к капустной моли и капустной совке (Mamestra brassicae L.). Цель исследований: выделить устойчивые к листогрызущим фитофагам образцы капусты белокочанной для дальнейшей селекционной работы и гибриды капусты пекинской для выращивания безопасной товарной продукции. Задачи исследований: оценить повреждаемость образцов капусты белокочанной гусеницами капустной моли, оценить повреждаемость гибридов капусты пекинской гусеницами капустной моли и капустной совки. Для оценки показателей состояния природной и лабораторной популяций вредителей использовали популяционные характеристики: численность, плодовитость, продолжительность развития, смертность на разных стадиях развития. При работе с белокочанной и пекинской капустой использовали стандартные методики. Повреждаемость растений капусты белокочанной оценивали визуально в фазе розетки и фазе рыхлого кочана по характерным повреждениям, используя шестибальную шкалу ВИЗР. По результатам оценки капусты белокочанной для дальнейшей селекционной работы отобраны линии без признаков повреждения капустных растений: в группе раннеспелых: Су-200м, 3002 а1, Нозом б, Эксп2, в группе среднепоздних 347 и 52, в группе позднеспелых Су–1г54, 5-41, L 11-13, 613. По результатам оценки повреждаемости образцов капусты белокочанной в 2019 году, на жестком фоне заселения из-за благоприятных для фитофага погодных условий, выявлено два образца (504, 505) сильно повреждаемых капустной молью. Шесть образцов (511, 522, 524, 516, 526, 537) имели балл поврежденности 1 и менее. Комплексная энтомологическая оценка гибридов пекинской капусты различными методиками выявила устойчивый гибрид F1 Гидра, который можно рекомендовать для снижения пестицидной нагрузки на агроценоз и получения экологически безопасной продукции. The results of assessment of linear and hybrid material of white cabbage for resistance to diamondback moth (Plutella xylostella (L.)) and hybrids of napa cabbage for resistance to diamondback moth and cabbage moth (Mamestra brassicaeL.) are presented. The purpose of the research: to select breeding samples of white cabbage resistant to leaf-eating phytophagous insect for further breeding work and hybrids of napa cabbage for safe commercial products growing. Research tasks: to assess the damage rate of cabbage lines and hybrids by diamondback moth caterpillars, to assess the damage rate of napa cabbage hybrids by diamondback moth and cabbage moth caterpillars. To assess indicators of the state of natural and laboratory pest populations, we used population characteristics: number, fecundity, development duration, and mortality at different stages of development. When working with white cabbage and napa cabbage, standard methods were used. Damage to cabbage plants was assessed visually by characteristic damage at the stage of rosette and the stage of loose cabbage head using a six-point VIZR scale. According to the results of the assessment of white cabbage for further breeding work, lines without damage were selected: in the early-maturing group: Su-200m, 3002 a1, Nozom b, Exp2, in the middle-late group 347 and 52, in the late-maturing group Su-1g54, 5-41, L 11-13, 613. According to the results of damage assessment of white cabbage in 2019, against a harsh background of colonization due to favorable weather conditions for diamondback moth, two hybrids (504, 505) were found to be severely damaged by these insect. Six hybrids (511, 522, 524, 516, 526, 537) they had a damage score of 1 or less. A comprehensive entomological assessment of napa cabbage hybrids using various methods has revealed as resistant a F1Hydra hybrid that can be recommended for reducing the pesticide press on agrocenosis and obtaining environmentally safe products.