Využitie repelentov na ochranu proti kukuričiarovi koreňovému (Diabrotica virgifera virgifera LeConte, 1868)

The aim of the study was to find the level of repellent effect of two chemical substances (DEET and 2-Undecanone) and two essential oils (from Allium sativum and Eucalyptus oil) on the Western corn rootworm (WCR), Diabrotica virgifera virgifera LeConte, 1868 in field conditions. Repellents were used in the area of 5 x 4 meters with four replications. They were applied as a solution of 700 μl chemical/essential oil in one litter of water. TWEEN 80 was used as a surfactant. After 24 and 48 hours, the repellent effect was checked by visual observation. After 24 hours, yellow sticky traps were installed in each plot and checked after the next 24 hours for the detection of the WCR adult beetles. The experiment was carried out during two years (2019 and 2020) in a maize field in Mojmírovce (48.199284°N, 18.038637°E), Slovakia. The results showed significant repellent effect of chemicals DEET and 2-Undecanone on WCR adults. After 48 hours the number of beetles per plant was significantly higher compared to the control for both DEET and 2-Undecamone. This was confirmed by yellow sticky traps in 2020, but not in 2019, probably due to the lower catching of WCR adults. The results indicate that repellent substances can influence the number of the WCR adults in maize fields.Cieľom práce bolo zistiť hladinu repelentného účinku dvoch chemických látok DEET, 2-Undecanone a esenciálnych olejov z Allium sativum a eukalyptového oleja na kukurici siatej proti kukuričiarovi koreňovému (WCR), Diabrotica virgiera virgifera LeConte, 1868 v poľných podmienkach. Repelenty boli použité na ploche 5 x 4 metre so štyrmi opakovaniami. Aplikovali sa ako roztok 700 μl chemického/esenciálneho oleja v jednom diely vody. Ako rozpúšťadlo sa použil TWEEN 80. Po 24 a 48 hodinách sa repelentný účinok skontroloval vizuálnym pozorovaním. Po 48 hodinách sa na detekciu výskytu dospelých chrobákov použili žlté lapače. Pokus sa uskutočnil v dvoch termínoch na kukuričnom poli v Mojmírovciach (48.199284°N, 18.038637°E) na Slovensku. Naše výsledky ukázali, že preukazný účinok chemikálií DEET a 2-Undekanone na imága kukuričiara koreňového. Po 48 hodinách bol počet imág v obidvoch prípadoch preukazne nižší ako v kontrolnom variante. Toto sa potvrdilo pri použití žltých lepových lapačov v roku 2020, ale nie v roku 2019 pravdepodobne z dôvodu nižšieho počtu nachytaných imág. Výsledky naznačujú, že repelentné látky môžu ovplyvniť početnosť imág kukuričiara koreňového na kukuričnom poli

BIOLOGICKÉ VLASTNOSTI SLOVENSKÝCH IZOLÁTOV ENTOMOPATOGÉNNEJ HUBY PANDORA NEOAPHIDIS (REMAUDIÈRE ET HENNEBERT) HUMBER (ZYGOMYCETES, ENTOMOPHTHORALES)

Intraspecific variability of biological characteristics within entomopathogenic fungus Pandora neoaphidis was evaluated. Fifteen isolates of the fungus were obtained from 5 aphid species in Slovakia. Size of conidia, conidial germination, virulence, radial growth, and biomass production were evaluated. Conidial size varied considerably with exception of isolates originating from the same host population. Conidial germination was observed on all the surfaces tested and it was greatest at saturated humidity. Virulence, daily rate of radial growth and biomass production varied depending on isolates. Isolates obtained from the same host colonies during fungal epizootics shoved also significant differences in the characteristics, what may suggest that epizootics in aphid populations are caused by associations of strains and not by prevalence of a single virulent strain.V práci sa hodnotila vnútrodruhová variabilita biologických vlastností entomopatogénnej huby Pandora neoaphidis. Hodnotilo sa 15 izolátov získaných z 5 druhov vošiek. Posudzovali sa nasledovné vlastnosti: veľkosť a klíčivosť konídií, virulencia, radiálny rast a produkcia biomasy izolátov. Zistili sa preukazné rozdiely vo veľkosti konídií, s výnimkou izolátov získaných z vošiek pochádzajúcich z rovnakých populácií. Konídie klíčili na všetkých hodnotených povrchoch, najvyššia klíčivosť bola pri 100% relatívnej vlhkosti. Virulencia izolátov, denná rýchlosť rastu a produkcia biomasy varírovala v závislosti od izolátu. Izoláty, ktoré boli získané z rovnakých kolónií vošiek počas epizoócií patogéna preukázali tiež významné rozdiely v hodnotených vlastnostiach. Toto poukazuje na skutočnosť, že epizoócie v populáciách vošiek sú vyvolávané asociáciou viacerých a nie prevalenciou jedného virulentného kmeňa patogéna

BIOLOGICAL CHARACTERISTICS OF SLOVAK ISOLATES OF ENTOMOPATHOGENIC FUNGUS PANDORA NEOAPHIDIS (REMAUDIÈRE ET HENNEBERT) HUMBER (ZYGOMYCETES, ENTOMOPHTHORALES)

Intraspecific variability of biological characteristics within entomopathogenic fungus Pandora neoaphidis was evaluated. Fifteen isolates of the fungus were obtained from 5 aphid species in Slovakia. Size of conidia, conidial germination, virulence, radial growth, and biomass production were evaluated. Conidial size varied considerably with exception of isolates originating from the same host population. Conidial germination was observed on all the surfaces tested and it was greatest at saturated humidity. Virulence, daily rate of radial growth and biomass production varied depending on isolates. Isolates obtained from the same host colonies during fungal epizootics shoved also significant differences in the characteristics, what may suggest that epizootics in aphid populations are caused by associations of strains and not by prevalence of a single virulent strain

Vývin kukuričiara koreňového Diabrotica virgifera virgifera v pôde

Monitoring of developmental stages of the Western corn rootworm (WCR) (Diabrotica virgifera virgifera) is an important aspect of its control. In the experiment there were analysed randomly selected plants of maize on six localities in western Slovakia, in the years 2008-2010 a 2014-2015. The aim of the study was to identify exact time of the emergence of the WCR adults in the consequence of different years and different localities and to find the best date for their eradication. The most of the WCR individuals at the northern locality were observed on 29 June and the first adults were found on 07 June, during colder year 2006. The development started about nine days earlier in the next year in southern Slovakia, because of extremely hot weather. The population of pest increased slower in 2008 than in previous years, and the highest appearance was monitored up-to 02 July. The first adults were monitored on 27 June in the years 2009-2010 as well as 2014-2015. Generally, the highest numbers of the first instar larvae were observed on 22 June at the locality Čiližská Radvaň. The second instar larvae and the most of adults was found on 20 June in Sokolce. On 29 June it was monitored the largest amount of the third instar larvae at the locality Čiližská Radvaň. The differences in the time of the emergence of adults depended on the year. Based on the monitoring in Slovakia, it can be expected the third instar larvae from second decade of June and the first adults in the last decade of June and in the first decade of July.Monitorovanie vývinových štádií kukuričiara koreňového je dôležitým aspektom jeho regulácie. V experimente boli analyzované náhodne vybrané rastliny kukurice na šiestich vybraných lokalitách Západného Slovenska, v rokoch 2008-2010 a 2014-2015. Cieľom tejto štúdie bolo určiť presný čas výskytu dospelých jedincov kukuričiara koreňového (Diabrotica virgifera virgifera) v dôsledku vplyvu ročníka a rôznych lokalít a nájsť najlepší dátum pre ich reguláciu. Počas chladnejšieho roku 2006 bolo v severnejšej lokalite najviac jedincov detekovaných 29. júna, a prvé imágo bolo pozorované 7. júla. O rok neskôr sa vývin na juhu Západného Slovenska vplyvom extrémne teplého počasia uskutočnil o 9 dní skôr. Nárast populácie škodcu bol v roku 2008 menší ako v predchádzajúcich rokoch, a maximálny počet imág bol zaznamenaný až 2. júla. Prvé imága v rokoch 2009-2010 a taktiež 2014-2015 boli pozorované 27. júna. Všeobecne, najvyšší počet lariev prvého instaru bol pozorovaný 22. júna v Čiližskej Radvani. Druhý instar lariev a najviac imág bolo sledovaných 20. júna v Sokolciach. Dňa 29. júna bolo monitorované najväčšie množstvo lariev tretieho instaru na lokalite Čiližská Radvaň. Rozdielnosť v čase výskytu imág ovplyvňoval ročník. Na základe monitoringu môžeme na Slovensku očakávať larvy tretieho instaru od druhej dekády júna, a prvé imága v poslednej dekáde júna a v prvej dekáde júla

The Effects of Nosema pyrausta Infection on European Corn Borer Populations from Five European Countries

Ostrinia nubilalis populations from Slovakia, Romania, Austria, Serbia and Germany were collected in the autumn when the insects were in the larval stage. These insects were then established as laboratory populations. The number of pupae and adults that developed was always higher in the Nosema pyrausta non-inoculated (uninfected) populations than in the populations treated by the pathogen N. pyrausta (infected). Significant differences were also found among the populations from different countries. Infected females laid significantly fewer eggs compared to uninfected females. The average time for pupal eclosion or adult emergence was not signifi cantly different between the uninfected and infected populations of O. nubilalis. However, it was found that the infected females laid their eggs significantly sooner as compared to the uninfected females (37.383 days compared to 40.089 days). Under the same conditions, populations from colder regions developed faster than those from warmer regions. The place of origin of the population did not significantly influence larval weight, larval length or pupal weight. However, larvae infected with N. pyrausta spores had signifi cantly lower weight (average 0.0797 g) than uninfected larvae (0.0901 g). With regard to pupal weight, the difference between the infected and uninfected individuals was not signifi cant. It was confi rmed that N. pyrausta from one European country can infect and infl uence host larvae originating in other countries. Although there have been several statistically significant interactions with regard to the country of origin and N. pyrausta infection, it was not believed that N. pyrausta from one country would have specific effects on the mortality, developmental rate and larval or pupal weight of O. nubilalis populations from different countries

Seasonal effects on the population dynamics of soil nematodes in a maize field

A study on the seasonal changes of nematode population was conducted during period of May to September, 2011 in maize field Komoca in Slovak Republic. A total of 37 nematode species from 32 genera were found. The identified nematode species belonged mainly to the orders Dorylaimida Pearse, 1942, Tylenchida Thorne, 1949 and Rhabditida Chitwood, 1933. Dominant species were Acrobeloides nanus (de Man, 1880), Cephalobus persegnis Bastian, 1865 and Eucephalobus striatus (Bastian, 1865). Dominance of many species changed during the season. In May it was found dominance of Rhabditis spp. (almost 80 % of total nematodofauna) but this dominance dropped during the season. On the other hand, dominance of C. persegnis, Aphelenchoides minimus, Bitylenchus dubius increased during the season. Nematode species C. persegnis, E. striatus, Filenchus vulgaris and Mylonchulus brachyuris had a frequency of occurrence over 90%. The highest abundance of nematodes was found in May and the lowest abundance was found in September

The Role of MicroRNAs in Genome Response to Plant–Lepidoptera Interaction

RNA interference is a known phenomenon of plant immune responses, involving the regulation of gene expression. The key components triggering the silencing of targeted sequences are double-stranded RNA molecules. The regulation of host–pathogen interactions is controlled by miRNA molecules, which regulate the expression of host resistance genes or the genes of the pathogen. The review focused on basic principles of RNA interference as a gene-silencing-based defense mechanism and the role of miRNA molecules in insect genomes. RNA interference as a tool for plant protection management is discussed. The review summarizes current miRNA-based biotechnology approaches for plant protection management

BIOLOGICKÉ VLASTNOSTI SLOVENSKÝCH IZOLÁTOV ENTOMOPATOGÉNNEJ HUBY PANDORA NEOAPHIDIS (REMAUDIÈRE ET HENNEBERT) HUMBER (ZYGOMYCETES, ENTOMOPHTHORALES)

Intraspecific variability of biological characteristics within entomopathogenic fungus Pandora neoaphidis was evaluated. Fifteen isolates of the fungus were obtained from 5 aphid species in Slovakia. Size of conidia, conidial germination, virulence, radial growth, and biomass production were evaluated. Conidial size varied considerably with exception of isolates originating from the same host population. Conidial germination was observed on all the surfaces tested and it was greatest at saturated humidity. Virulence, daily rate of radial growth and biomass production varied depending on isolates. Isolates obtained from the same host colonies during fungal epizootics shoved also significant differences in the characteristics, what may suggest that epizootics in aphid populations are caused by associations of strains and not by prevalence of a single virulent strain.V práci sa hodnotila vnútrodruhová variabilita biologických vlastností entomopatogénnej huby Pandora neoaphidis. Hodnotilo sa 15 izolátov získaných z 5 druhov vošiek. Posudzovali sa nasledovné vlastnosti: veľkosť a klíčivosť konídií, virulencia, radiálny rast a produkcia biomasy izolátov. Zistili sa preukazné rozdiely vo veľkosti konídií, s výnimkou izolátov získaných z vošiek pochádzajúcich z rovnakých populácií. Konídie klíčili na všetkých hodnotených povrchoch, najvyššia klíčivosť bola pri 100% relatívnej vlhkosti. Virulencia izolátov, denná rýchlosť rastu a produkcia biomasy varírovala v závislosti od izolátu. Izoláty, ktoré boli získané z rovnakých kolónií vošiek počas epizoócií patogéna preukázali tiež významné rozdiely v hodnotených vlastnostiach. Toto poukazuje na skutočnosť, že epizoócie v populáciách vošiek sú vyvolávané asociáciou viacerých a nie prevalenciou jedného virulentného kmeňa patogéna

The Effects of Nosema pyrausta Infection on European Corn Borer Populations from Five European Countries

Ostrinia nubilalis populations from Slovakia, Romania, Austria, Serbia and Germany were collected in the autumn when the insects were in the larval stage. These insects were then established as laboratory populations. The number of pupae and adults that developed was always higher in the Nosema pyrausta non-inoculated (uninfected) populations than in the populations treated by the pathogen N. pyrausta (infected). Significant differences were also found among the populations from different countries. Infected females laid significantly fewer eggs compared to uninfected females. The average time for pupal eclosion or adult emergence was not signifi cantly different between the uninfected and infected populations of O. nubilalis. However, it was found that the infected females laid their eggs significantly sooner as compared to the uninfected females (37.383 days compared to 40.089 days). Under the same conditions, populations from colder regions developed faster than those from warmer regions. The place of origin of the population did not significantly influence larval weight, larval length or pupal weight. However, larvae infected with N. pyrausta spores had signifi cantly lower weight (average 0.0797 g) than uninfected larvae (0.0901 g). With regard to pupal weight, the difference between the infected and uninfected individuals was not signifi cant. It was confi rmed that N. pyrausta from one European country can infect and infl uence host larvae originating in other countries. Although there have been several statistically significant interactions with regard to the country of origin and N. pyrausta infection, it was not believed that N. pyrausta from one country would have specific effects on the mortality, developmental rate and larval or pupal weight of O. nubilalis populations from different countries