Diatomejsko zemljo uporabljajo v številne namene, med drugim tudi kot bioinsekticid za varovanje uskladiščenih pridelkov. Ta zemlja nastane z mletjem sedimentnih kamnin, imenovanih diatomiti. Obstaja ...veliko vrst diatomejske zemlje, a le zemlje z manj kot 7 % kristalnega SiO2 so primerne za zatiranje škodljivcev. Diatomejska zemlja ni toksična za sesalce, dolgotrajno varuje živež pred škodljivimi žuželkami, za njen nanos se uporablja približno enaka tehnologija kot pri klasičnem nanosu insekticidov in se med predelavo zlahka odstrani z živeža. Med nekaj negativnimi lastnostmi gre izpostaviti dejstvo, da zmanjša hektolitrsko maso zrnja (zniža nasipno gostoto zrnja), ki je glavno merilo kakovosti zrnja. Diatomejska zemlja ima velik absorpcijski potencial in se veže na epikutikularne voske žuželk, zato deluje praktično na vse škodljivce, ki imajo kutikulo zaščiteno z voski.
Vsi organizmi v ekosistemu so biokemično povezani. Semiokemikalije v receptorjih dražljajev vzbudijo vedenjske ali fiziološke odzive, kar privede do interakcije med dajalcem in prejemnikom ...dražljajev. Medvrstne semiokemikalije, ki jih imenujemo alelokemikalije, povezujejo organizme z različnih trofičnih nivojev in omogočajo naravnim sovražnikom najti gostitelje ali plen in jih prepoznati kot ustrezne. Tudi gostiteljske rastline v tem sistemu niso nevtralne in tako se lahko rastlinojedi ter njihovi naravni sovražniki odzovejo na njihove dražljaje. Številni parazitoidi se odzivajo na vonj rastlin in lahko ločijo med nepoškodovanimi rastlinami, napadenimi rastlinami in celo poškodovanimi rastlinami, na katerih škodljivec ni več prisoten. V prispevku predstavljamo semiokemikalije, ki so vključene v prehranjevalno verigo parazitoidov listnih uši.
In 2008, a lucerne aphid parasitoid Aphidius ervi Haliday was first recorded in Slovenia. This oligophagous parasitoid is used as biological control agent against bigger aphid species. By sampling ...aphid mummies on different locations in Slovenia in 2008, we found parasitoid Aphidius ervi on nine host plants (corn, pea, alfalfa, red clover, winter wheat, oat, onion, potato and winter barley). Among 1812 primary parasitoids found in Slovenia in 2008, there were 46 individuals of Aphidius ervi; 21 male and 25 female parasitoids. In the present paper description of the species, its geographic distribution and host plant-aphid-parasitoid associations are given.
Paper presents a larval cannibalism of green lacewings (Chrysoperla carnea), which was observed during the laboratory bioassay on non-target effect of entomopathogenic nematodes against green ...lacewings larvae. The most probable reason for larval cannibalism were undersized Petri dishes in which the bioassay was performed. Due to large number of larvae per surface unit, frequent crossing of green lacewings larvae appeared and this consequently lead to cannibalism. In most cases larger, elder larvae consumed smaller, younger larvae. Cannibalism increased with temperature rise and was the most intensive at 25 °C. At this temperature the larval mortality was 22.0 % after two days, while after four days the larval mortality reached 31.0 %.
In a paper the results of insecticidal activity of two known insecticides (deltamethrin and imidacloprid), thujone and essential oil of rosemary against the larvae and adults of sycamore lace bug ...(Corythucha ciliata) are presented. The experiment was conducted in a laboratory, under room conditions. We tested the activity of each product in three different concentrations. The most desirable insecticidal activity had deltamethrin, which caused almost 100 % mortality of both developmental stages of the pest at all three concentrations. Succeeding products were imidacloprid, which caused 89.6 % larval mortality at recommended concentration, and essential oil of rosemary, which caused 81.7 % adult mortality at 1 % concentration. Larvae of sycamore lace bug were significantly more susceptible to tested products than adults. Significantly the lowest mortality was determined one day after treatment (41.7 %), while the highest mortality was stated three days after treatment (71.3 %). For future reduction of the damage caused by the studied pest on plane trees, we recommend the application of thujone and essential oil of rosemary, which appeared to be environmentally more acceptable substances. In our study both agents showed a middle satisfying activity in controlling larvae and adults, but they have also obvious repellent activity, which leads to their better efficacy in the open.
In 2008, massive population of parasitoid Encarsia formosa was found for the first time in the greenhouses on the Laboratory Field of Biotechnical Faculty in Ljubljana (Slovenia). This species is ...known for a long time as effective natural enemy of the greenhouse whitefly, Trialeurodes vaporariorum, and other whiteflies in different parts of the world. 1306 wasps from genus Encarsia were found in nymphs of greenhouse whitefly. The most numerous was E. formosa (934 individuals), following by 367 individuals of E. tricolor, 4 males of E. inaron and a male of E. longicornis. Greenhouse whitefly parasitoid was determined on 14 host plants in the greenhouse and E. tricolor on 11 host plants in the greenhouse and on one host plant in the field. E. inaron and E. longicornis appeared only on one host plant in a greenhouse. For the time being the use of wasp E. formosa is not yet permitted in controlling greenhouse whitefly in Slovenia, but there is possibility to include it in the programs of biological control of pests on ornamentals and vegetable plants in the greenhouses. Consequently, the use of chemical insecticides will be reduced.
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.
The nontarget effect of Steinernema feltiae, Steinernema carpocapsae, Heterorhabditis bacteriophora, and three mixed suspensions of two species of entomopathogenic nematodes on the larvae of the ...twospotted lady beetle, Adalia bipunctata (L.) (Coleoptera: Coccinellidae), and on the larvae of the lacewing Chrysoperla cornea (Stephens) (Neuroptera: Chrysopidae), were studied in a laboratory bioassay. The assay was performed at three temperature (15, 20, and 25°C) and at three different concentrations of the suspension (500, 2,500, and 5,000 infective juveniles IJs/ml). The larvae of A. bipunctata were more susceptible to nematode attack than the larvae of C.. cornea. Four days after treatment, significantly the lowest mortality of A.. bipunctata and C.. cornea larvae was recorded at 15°C, whereas no significant differences were noted between 20 and 25°C. At 500 IJs/ml, the nematodes had significantly the lowest nontarget effect on the larvae of both aphid predators, whereas no significant differences in this regard were established between 2,500 and 5,000 IJs/ml. We conclude that the entomopathogenic nematodes under investigation exhibit a pronounced nontarget effect on the larvae of both predators mentioned.
Ethanol extracts of Rosmarinus officinalis, Lavandula angustifolia and Ruta graveolens were tested against adults of Acanthoscelides obtectus and Leptinotarsa decemlineata. Using a newly developed ...computer tracking system, a choice test revealed that all of the extracts have a repellent action. The highest repellent activity against the bean weevils adults was the ethanol extract of rue, whereas the highest repellent activity against the Colorado potato beetle adults was the lavender extract. We suggest that a cocktail of volatile components in the ethanol extracts was responsible for the observed repellent action. All three of the extracts have insecticidal effects on bean weevils, reducing F1 adult emergence, with no side effects on the germination of the bean plants. In contrast, the extracts did not demonstrate an insecticidal effect on Colorado potato beetles.
Laboratory experiments were done to determine the effect of geochemical composition of diatomaceous earth (DE) on insecticidal activity of DE against adults of the rice weevil, Sitophilus oryzae (L.) ...(Coleoptera: Curculionidae). Samples of DE were mined from DE-deposits in Slovenia, Greece, and Serbia. In addition, a commercially available DE formulation (SilicoSec®) was used in the tests and served as a positive control. The bioassays were carried out at temperatures 20, 25, and 30°C, relative humidity levels of 55 and 75%, and at application rates of 100, 300, 500, and 900 ppm. Adult mortality was recorded after 7, 14, and 21 days of exposure. Prior to bioassays with S. oryzae, the geochemical composition of all DEs that were used in the tests was determined by whole rock ICP geochemical analyses. Silica (in the form of SiO₂ or opal-A) was the DE ingredient that was significantly correlated with efficacy in most of the bioassays. Some weak positive correlation was observed between S. oryzae mortality and MnO or CaO content. All significant correlations between mortality and Al₂O₃, Fe₂O₃, K₂O, TiO₂, Cr₂O₃, P₂O₅, and MgO content were negative, while correlation between Na₂O content and mortality was generally not significant.
