Ljubljana, Slovenia
Ljubljana, Slovenia

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Laboratory experiments were carried out to evaluate the impact of diatomaceous earth (DE) samples of different origin with their insecticidal properties to control one of the most important primary pest in stored grain. We tested the efficacy of three local DE, from Serbia, Greece and Slovenia, and commercial formulation SilicoSec against the rice weevil, Sitophilus oryzae, adults in stored wheat. The experiments were carried out at three temperatures (20, 25 and 30 °C) and two relative humidity (RH) levels (55 and 75%). Mortality of pest was counted 7, 14 and 21 days after exposure (DAT) at the following DE dose rates: 100, 300, 500 and 900 ppm. The mortality of adults normally increased with increasing dose rates and DAT. In all samples the mortality of rice weevil adults (dose rate 900 ppm, 21 DAT) was above 90%, except at Slovenian DE (at 20 °C and 55% RH) and Greek DE (at 25 °C and 75% RH), when the mortality was 85.3 and 67.6%, respectively. With 100% mortality (14 DAT and at 900 ppm) the most effective was SilicoSec. Slovenian DE was more effective at 55% RH than at 75% RH (7 DAT at all temperatures).

The efficacy of three strains (B30, B49 in 3162) of Steinernema feltiae to control adults of rice weevil (Sitophilus oryzae) was tested in a laboratory experiment in 2009. The activity of entomopathogenic nematodes was assessed at five different concentrations (125, 250, 500, 1000 and 2000 infective juveniles/individual) and four different temperatures (15, 20, 25 and 30 °C). Results demonstrated that all strains acted most effective at 25 °C and at highest concentration of nematode suspension, meanwhile the lowest mortality of rice weevil adults was attained at 30 °C. The results of our research showed that at high concentrations entomopathogenic nematodes are an effective biological agent for controling the studied primary stored products pest.

The chestnut gall wasp, Dryocosmus kuriphilus (Hymenoptera: Cynipidae), is considered to be one of the most important pest of chestnut (Castanea sp. and Castanopsis sp.) worldwide. The larvae of chestnut gall wasp feed on plant tissue, causing formation of galls on the shoots and leaf veins, resulting in severe reduction of fruit yield and vitality of plant. The wasp is of Chinese origin and it invaded Europe and the rest of the world with infected plant material. In Slovenia, chestnut gall wasp appears in Goriška region in 2004 for the first time, but in Italy it appeared three years earlier and is yet widespread in chestnut orchards and forests causing great damage. Introducing parasitoid wasps of chestnut gall wasp seems to be the most promising biological control method to reduce this pest and its damage. The most effective parasitoid species is Torymus sinensis (Hymenoptera: Torymidae), which originate from China and it has been yet successfully introduced and widespread in Japan. The chestnut gall wasp has many parasitoids, but they are not that effective in reducing the population of the pest. 15 species of chestnut gall wasp are presented in Italy. In Slovenia, we have not found any native chestnut gall wasp parasitoids yet, but the research is in process, because of the danger of spreading this important pest throughout Slovenia chestnut orchards and forests.

Kocjan Acko D.,Jamnikarjeva 101
Acta Agriculturae Slovenica | Year: 2010

A number of factors influenced the increased number of crops on Slovenian farms legal limitation of maize production to two years on the same field, introduction of integrated crop production and certain measures of the Slovene Agri-Environmental Programme. Crop rotation on hop fields that has already been analyzed on 22 hop growing and livestock farms in Spodnja Savinjska dolina in 2008 show that the maize monoculture has been supplemented by some other crops like wheat, barley, lucerne, clover-grass mixtures and high beans; compared to the conventional production in the past, the crop rotation is now longer. Phytosanitary adequacy of two- and three-year rotation could be improved with supplementary crops, that is with fodder crucifers (fodder rapeseed and rape, forage kale), green manure (white mustard, oil radish), legume crops (soya, peas, vetch, field bean, white lupin, crimson clover, Persian clover, Egyptian clover) and compound fodders like Landsberger mixture and mixtures of vetch with oat or barley. Prohibition to sow broad-leafed plants in the quarantine rotation due to hop wilting limits the selection of crops to grasses (Italian rye-grass) and fodder grains (maize, barley), but the farmers could increase the selection of grains with oats, rye, triticale, mixture of wheat and rye, millet, sorghum and Sudan grass. With the use of recommended crop rotations in two-, three- and four-year rotation, we can expect the increased influence of crop rotation on improved health condition of the new hop plantations in the future with simultaneous reduction of the use of pesticides as well.

In the period from June to October 2008 we collected 500 slugs from the genus Arion in the area of Ljubljana and Prekmurje (Slovenia). By means of dissection we determined the presence of parasitic nematodes in slug cadavers. Identification of the nematodes was made by a molecular technique (PCR). In these slugs we did not find the parasitic nematode Phasmarhabditis hermaphrodita, however the presence of Alloionema appendiculatum in larger quantities was confirmed. The most infected was a Spanish slug, Arion lusitanicus. In Petri dishes younger slugs showed a satisfactory mortality rate already on the fourth day after the application of the nematode suspension. Unfortunately, we can not confirm with certainly that the nematode A. appendiculatum undergoes a complete life cycle in A. lusitanicus, which is otherwise typical for Phasmarhabditis hermaphrodita.

Diatomaceous earth is used for many purposes, including as a bioinsecticide for protection of stored crops. This material is produced by milling the sedimentary rock called diatomite. There are many types of diatomaceous earth but only diatomaceous earths with less than 7% of crystalline silica are suitable for pest control. Diatomaceous earth is not toxic to mammals, it provides the protection of food on a long-term against harmful insects, and for its application it is used around the same technology as in the conventional application of insecticides and is easily removed during processing. Among some of the negative characteristics is that reduces bulk density of grain, which is the main criterion of assessing the quality of grain. Diatomaceous earth has a high absorption potential and is bound to insect epicuticular waxes, and act practically on all pests that have cuticula protected by wax.

The American Grapevine Leafhopper (AGL) (Scaphoideus titanus Ball, 1932) is a small insect of the family leafhoppers (Cicadellidae), originally spread across North America. Specie has been introduced to Europe, where is known primarily as a vector of phytoplasma Grapevine flavescence dorée (FD), (Candidatus Phytoplasma vitis), a disease-causing grapevine yellows. AGL was first found in Slovenia in 1983. First occurrence of grapevine yellows was confirmed in Slovenia in 2005. Since no effective biological control agents are known to date, AGL populations are suppressed using insecticides during the host plant's growth period. Some researchers reported that it is in both continents (North America, Europe) abundance of natural enemies of the AGL very small. Researchers reported that some parasitoids (Drynidae: Hymenoptera and Pipunculidae: Diptera) parasitize the AGL, but the percentage of efficiency is very low (from 1.3 to 0.8 %). Among the methods of integrated pest management of AGL methods of mating disruption, thermotherapy, and cover crops are used.

The work includes a comprehensive study of phenolic compounds, their occurrence and identification in the residues after pressing of the oil from camelina seeds of Slovenian origin, i.e. oilcake. In addition, the efficiencies of antioxidant determinations using different methods according to different mechanisms are presented. These data demonstrate that almost all of the phenolic compounds in these seeds remain in the seed oilcake. The following antioxidants were confirmed: sinapine, 4-vinylphenol, 4-vinylguaiacol, 4-vinylsyringol, 4-vinylcatechol, ellagic acid, protocatechuic acid, phydroxybenzoic acid, sinapic acid, salicylic acid, catechin, quercetin and quercetin glucoside. The oilcake has high reducing power and radical scavenging activity. Heat treatment of seeds affects the amount of free, soluble and insoluble bound phenolic compounds as well as antioxidant capacity of individual fractions. Potential applications of camelina oilcake in the food industry are further justified by comparisons with other oilcakes and synthetic antioxidant.

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