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.

Substantiation of the terms of effective use of insecticides in the fight against cabbage moth in spring rape crops

The biology of development of cabbage moth in crops of spring rape in the Volga region is shown. The relationship between the development of the phytophage and the host plant has been studied for a long period. The terms of use of means of protection are substantiated, providing a higher efficiency of insecticides in the fight against caterpillars of P. maculipennis.

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.

Susceptibility of different species of lepidoptera insects to strain Bacillus thuringiensis ssp. aizawai

The results of assessing the effect of Bacillus thuringiensis ssp. aizawai strain on fi ve species of lepidopteran pests (Lepidoptera) belonging to different families are presented. The mortality of larvae infected with B. thuringiensis strain varied signifi cantly depending on the species of insect. In four species: the cabbage white butterfl y (Pieris brassicae L.), the cabbage moth (Mamestra brassicae L.), the greater wax moth (Galleria melonella L.) and the black-veined white (Aporia crataegi L.), death of individuals was noted on the second day of the experiment. However, mortality rate was signifi cantly different between species and increased over time. The diamondback moth (Plutella xylostella L.) was more susceptible to the pathogen. Signifi cant mortality of the larvae of this phytophage was observed already on the fi rst day after infection; while on the second day of the experiment all individuals died. Lethal time LT90 of more resistant species (black-veined white) and more sensitive ones (diamondback moth) differed sevenfold. Semi-lethal concentrations of B. thuringiensis strain for the tested insect species were determined: on the third day of the experiment, lethal concentration LC50 for the cabbage moth larvae, the greater wax moth and blackveined white ranged from 1.7 to 4.5 × 108 spores/ ml. For the cabbage white butterfl y, it was much lower (1.8×107 spores/ml). For diamondback moth caterpillars, LC50 was 4.25×107 spores/ml already one day after infection. It was noted that the specifi city of B. thuringiensis strain is associated with various mechanisms of insect protection from pathogens, and is due to individual characteristics of the species. In particular, the pH of excrement of intact caterpillars of the cabbage white butterfl y, a species sensitive to B. thuringiensis, was 2 times higher than that of caterpillars of the greater wax moth – 8.9 and 4.3, respectively, which is one of the reasons for the susceptibility (or resistance) of the species to bacterial entomopathogen.

White head cabbage protection against cabbage moth in Belarus

Cabbage moth is one of the main white head cabbage pests in Belarus. The evaluation of the existing insecticides assortment has shown that their application at the initial pest number from 0.72 to 4.0 caterpillars per inspected plant has allowed reducing cabbage moth harmfulness and number by 84.0–100.0 % and increasing heads yield up to 35.5 %.