The Ecological Significance of Aphid Cornicles and Their Secretions

Aphid cornicles are abdominal appendages that secrete an array of volatile and nonvolatile compounds with diverse ecological functions. The emission of alarm pheromones yields altruistic benefits for clone-mates in the aphid colony, which is essentially a superorganism with a collective fate. Secreted droplets also contain unsaturated triglycerides, fast-drying adhesives that can be lethal when smeared on natural enemies but more often impede their foraging efficiency. The longest cornicles have evolved in aphids that feed in exposed locations and are likely used to scent-mark colony intruders. Reduced cornicles are associated with reliance on alternative defenses, such as the secretion of protective waxes or myrmecophily. Root-feeding and gall-forming lifestyles provide protected feeding sites and are associated with an absence of cornicles. In some eusocial gall-formers, soldier morphs become repositories of cornicle secretion used to defend the gall, either as menopausal apterae that defend dispersing alatae or as sterile first instars that dispatch predators with their stylets and use cornicle secretions as a construction material for gall repair. Collectively, the evidence is consistent with an adaptive radiation of derived cornicle functions molded by the ecological lifestyle of the aphid lineage.

Yield and quality of bell pepper with integrated application of fertilizers and irrigation on ordinary chernozem

Для обеспечения населения РФ качественной, полезной и экологически безопасной овощной продукцией в требуемом количестве необходимо изучение потенциальной продуктивности новых сортов и гибридов овощных культур, применение современных элементов технологии и продуктов в области агротехнологий выращивания. Хороший вкус, высокое содержание ценных для человека витаминов, микроэлементов и органических кислот вывело сладкий перец в ранг наиболее популярных овощных культур. В мире выведено и культивируется огромное количество сортов сладкого перца. В нашей стране наиболее распространенным сортотипом является перец сладкий (Capsicum annuum), или болгарский. На обыкновенных черноземах Бирючекутской селекционной опытной станции (Новочеркасский район Ростовской области), имеющих слабощелочную реакцию среды, мощный гумусовый горизонт, среднюю обеспеченность подвижным фосфором и высокую обменным калием, в 2017–2018 годах была исследована потенциальная продуктивность перца сладкого гибрида Темп при высоком уровне обеспеченности растений влагой и питательными элементами. Оценено комплексное действие основного внесения расчетных доз минеральных удобрений, капельного орошения, трехкратной подкормки водорастворимыми удобрениями «Мастер» и органоминеральным наноудобрением «Арксойл» на урожайность и качество перца сладкого. Выяснено, что основное удобрение и подкормки влияют, в первую очередь, на число плодов на одном растении, увеличивая их в 2–3,3 раза при незначительном повышении массы плода. Установлено, что без применения минеральных удобрений при капельном поливе было получено 25–27 т/га плодов. Использование рекомендованной дозы удобрений N120P120K120 увеличило урожайность перца до 50,5 т/га, а комплексное применение основного удобрения с 3-кратной корневой подкормкой водорастворимым удобрением «Мастер» позволило получить урожайность перца до 64,8 т/га. Наиболее высокая продуктивность растений была получена при комплексном использовании расчетной дозы на урожайность 90 т/га в сочетании с корневой подкормкой – 86,8 т/га при хорошем качестве плодов перца. To provide the population of the Russian Federation with high-quality, healthy and environmentally friendly vegetable products in the required amount, it is necessary to study the potential productivity of new varieties and hybrids of vegetable crops, use modern elements of technology and products in the field of agricultural technologies. Good taste, high content of vitamins, microelements and organic acids valuable for humans have made sweet peppers one of the most popular vegetable crops. A huge number of varieties of sweet peppers have been bred and cultivated in the world. In our country, the most common cultivar type is bell pepper (Capsicum annuum) or Bulgarian. On ordinary chernozems of the Biryuchekutskaya selection experimental station (Novocherkassk district of the Rostov region), which have a weakly alkaline reaction of the environment, a powerful humus horizon, an average supply of mobile phosphorus and high exchangeable potassium, in 2017-2018, the potential productivity of sweet pepper the level of supply of plants with moisture and nutrients. The complex effect of the main application of the calculated doses of mineral fertilizers, drip irrigation, 3-fold top dressing with water-soluble fertilizers Master and organomineral nanofertilizers Arxoil on the yield and quality of bell peppers was evaluated. It was found that the main fertilization and feeding affect, first of all, the number of fruits per 1 plant, increasing them by 2-3.3 times with a slight increase in the weight of the fruit. It was found that without the use of mineral fertilizers with drip irrigation, 25-27 t/ha of fruits were obtained. The use of the recommended dose of fertilizers N120P120K120increased the yield of pepper to 50.5 t/ha, and the complex application of the main fertilizer with 3-fold root feeding with the water-soluble fertilizer Master allowed to obtain the yield of pepper up to 64.8 t/ha. The highest plant productivity was obtained with the integrated use of a calculated dose for a yield of 90 t / ha in combination with root feeding - 86.8 t/ha with good quality pepper fruits.

Grape Phylloxera Genetic Structure Reveals Root–Leaf Migration within Commercial Vineyards

Depending on their life cycle, grape phylloxera (Daktulosphaira vitifoliae Fitch) leaf-feeding populations are initiated through asexually produced offspring or sexual recombination. The vine’s initial foliar larvae may originate from root-feeding phylloxera or wind-drifted foliar larvae from other habitats. Though some studies have reported phylloxera leaf-feeding in commercial vineyards, it is still unclear if they are genetically distinct from the population structure of these two sources. Using seven SSR-markers, this study analyzed the genetic structure of phylloxera populations in commercial vineyards with different natural infestation scenarios and that of single-plant insect systems that exclude infestation by wind-drifted larvae. We saw that during the vegetation period, phylloxera populations predominately go through their asexual life cycle to migrate from roots to leaves. We provided evidence that such migrations do not exclusively occur through wind-drifted foliar populations from rootstock vines in abandoned thickets, but that root populations within commercial vineyards also migrate to establish V. vinifera leaf populations. Whereas the former scenario generates foliar populations with high genotypic diversity, the latter produces population bottlenecks through founder effects or phylloxera biotype selection pressure. We finally compared these population structures with those of populations in their native habitat in North America, using four microsatellite markers.

Grain quality of spring barley depending on the fertilization of plants with mineral nitrogen

The influence of root feeding on the quality indicators of spring barley grain on podzolized chernozem of the Right-Bank Forest-Steppe of Ukraine has been investigated. It has been established that the use of root feeding of spring barley plants with mineral nitrogen simultaneously with an increase in grain yield also contributes to an increase in the quality of feed. At the same time, the crude protein and the amount of sugars increase, and the amount of fiber in the grain decreases. The amount of crude protein in spring barley grain on average for 2018–2020 varied depending on the dose of nitrogen when carrying out root fertilization with nitrogen. In the control without fertilizers, it was 12.9 %, when root feeding of plants with nitrogen at a dose of 20 kg/ha – 13.2 %; 30 kg/ha – 14.5 %; 60 kg/ha – 15.8 %; 90 kg/ha – 15.9 %. At the same time, it is observed that the crude protein in barley grain increases with an increase in the nitrogen dose to 60 kg/ha, and a further increase in the nitrogen dose is not accompanied by an increase in crude protein in barley grain. Simultaneously with an increase in the content of crude protein in the grain of barley, the percentage of fiber in the grain decreases during the root feeding of plants with mineral nitrogen. The percentage of mineral salts in barley grain during root feeding with nitrogen remained at the control level. The amount of sugars increases when using root feeding of spring barley plants with mineral nitrogen. If in the control the sum of sugars was at the level of 5.20 % for the air dry matter of barley grain, then in the variants of root feeding with nitrogen it reached the level of 5.31 ... 5.56 percent. Consequently, an increase in the level of crude protein in barley grain during root feeding with nitrogen was not accompanied by a deterioration in the sugar-protein ratio in feed. This is very important for increasing livestock productivity. The studied method of root feeding of barley plants with mineral nitrogen promoted an increase in protein in barley grain. On the control, 358.9 kg of protein was obtained from 1 hectare of spring barley crops, 533.2 kg of protein per 1 hectare was collected on the root application with nitrogen 60 kg/ha, and 568.5 kg of protein was collected on the version of root feeding with nitrogen 90 kg/ha. per hectare.

Calcium-alginate beads as a formulation for the application of entomopathogenic nematodes to control rootworms

Entomopathogenic nematodes (EPN) have great potential as biological control agents against root-feeding insects. They have a rapid and long-lasting mode of action, minimal adverse effects on the environment and can be readily mass-produced. However, they have a relatively short shelf-life and are susceptible to desiccation and UV light. These shortcomings may be overcome by encapsulating EPN in Ca2+-alginate hydrogels, which have been shown to provide a humid and UV protective shelter. Yet, current Ca2+-alginate formulations do not keep EPN vigorous and infectious for a prolonged period of time and do not allow for their controlled release upon application. Here, we introduce solid Ca2+-alginate beads which we supplemented with glycerol to better retain the EPN during storage and to ensure a steady release when applied in soil. Glycerol-induced metabolic arrest in EPN (Heterorhabditis bacteriophora) resulting in quiescence and total retainment of EPN when added to beads made with 0.5% sodium alginate and 2% CaCl2·2H2O solutions. More than 4,000 EPN could be embedded in a single 4–5-mm diameter bead, and quiescence could be broken by adding water, after which the EPN readily emerged from the beads. In a field trial, the EPN beads were as effective in reducing root damage by the western corn rootworm (WCR, Diabrotica virgifera virgifera) as EPN that were applied in water. Although further improvements are desirable, we conclude that Ca2+-alginate beads can provide an effective and practical way to apply EPN for the control of WCR larvae.