Comparison of insecticidal efficacy of four natural substances against granary weevil (Sitophilus granarius [L.]) adults: does the combined use of the substances improve their efficacy?

Laboratory tests were carried out to evaluate the insecticidal efficacy of different natural inert dusts (diatomaceous earth, wood ash, quartz sand) and the leaf powder of Azadirachta indica A. Juss. against granary weevil (Sitophilus granarius [L.]) adults. The efficacy of the substances was tested individually and in combination with each other. The substances were applied at different concentrations, and bioassays were carried out at four different temperatures (20, 25, 30 and 35°C) and two different relative humidity (RH) levels (55% and 75%). The adult mortality was recorded after the 7th, 14th and 21st days of exposure. The progeny production of individuals exposed to different combinations was also assessed. Wood ash proved to be the most efficient inert dust in our research. We detected 100% mortality in the treatment exposed to a higher concentration (5 w%) of wood ash at 35°C and 55% RH after 7 days of exposure. A lower RH level had also a negative impact on the progeny production. We can conclude that wood ash can be efficient in controlling granary weevil adults as a single substance or in combination with other substances. Further surveys should focus on the impact of the wood ash dose rates. Due to the high percentage of area covered with forest in some European countries, the main ingredient is present locally, but additional surveys are needed to help improve the practical use of wood ash

Twelve years (2005-2017) of scientific and professional work in the field of stored products pests protection in Slovenia: Poster

Scientific and professional work in the field of stored products pests protection in Slovenia began in 2005, when we tested the efficacy of entomopathogenic nematodes against the granary weevil (Sitophilus granarius) and the sawtoothed grain beetle (Oryzaephilus surinamensis) adults under laboratory conditions. In 2007, we participated as partners in the project SEE-ERA.NET “Development of a non-toxic, ecologically compatible, natural-resource based insecticide from diatomaceous earth deposits of South Eastern Europe to control storedgrain insects pests” (coordinated by C. Athanassiou), and we thus became acquainted with the research work in the field of investigation the efficacy of diatomaceous earth in controlling beetles from the Sitophilus genus. We have continued the research of different aspects of diatomaceous earth (the influence of geochemical composition and abiotic factors on its efficiency, the effects of individual and combined application, the effects on various harmful insect pests, etc.). In search for comparable substances to diatomaceous earth (regarding the efficacy), we have studied insecticidal effects of quartz sand and entomopathogenic nematodes from Slovenia, plant powders and essential oils on various harmful beetles. In the recent years, our research work has been mainly dedicated to studying the efficacy of wood ash and zeolites as natural insecticides, which have demonstrated sufficient efficiency in suppressing Sitophilus beetles. In the same period, we studied the seasonal dynamics of the Indian mealmoth (Plodia interpunctella), the Mediterranean flour moth (Ephestia kuehniella) and the Angoumois grain moth (Sitotroga cerealella) in cereal stores, where we were also searching for possible indigenious natural enemies of stored product insects pests. We have confirmed the occurrence of two parasitoids, Anisopteromalus calandrae and Dibrachys microgastri. In 2017, we have organized the 11th Conference of the IOBC/wprs Working Group on Integrated Protection of Stored Products (Ljubljana, 3-5 July), which was attended by 136 participants from 25 countries. We also transfer knowledge to Slovenian agricultural specialists about the harmfulness and possible ways of controlling stored products insects pests. In 2014, we have organized a workshop on this topic (“From Technological Maturity to Storing of Cereals and Legumes“). In 2015, we have hosted C. Athanassiou as an invited lecturer at the 12th Slovenian Conference on Plant Protection with international participation in Ptuj. In recent years, we have been working with experts from other countries with the aim of studying the efficacy of environmentally acceptable insecticides (spinosad, spinetoram) and the influence of cereal production technologies on grains’ susceptibility to attack by Sitophilus beetles. Furthermore, we participate in the research regarding the efficiency of new formulations of insecticidal preparations. The paper presents the chronology of activities in this area of our work.Scientific and professional work in the field of stored products pests protection in Slovenia began in 2005, when we tested the efficacy of entomopathogenic nematodes against the granary weevil (Sitophilus granarius) and the sawtoothed grain beetle (Oryzaephilus surinamensis) adults under laboratory conditions. In 2007, we participated as partners in the project SEE-ERA.NET “Development of a non-toxic, ecologically compatible, natural-resource based insecticide from diatomaceous earth deposits of South Eastern Europe to control storedgrain insects pests” (coordinated by C. Athanassiou), and we thus became acquainted with the research work in the field of investigation the efficacy of diatomaceous earth in controlling beetles from the Sitophilus genus. We have continued the research of different aspects of diatomaceous earth (the influence of geochemical composition and abiotic factors on its efficiency, the effects of individual and combined application, the effects on various harmful insect pests, etc.). In search for comparable substances to diatomaceous earth (regarding the efficacy), we have studied insecticidal effects of quartz sand and entomopathogenic nematodes from Slovenia, plant powders and essential oils on various harmful beetles. In the recent years, our research work has been mainly dedicated to studying the efficacy of wood ash and zeolites as natural insecticides, which have demonstrated sufficient efficiency in suppressing Sitophilus beetles. In the same period, we studied the seasonal dynamics of the Indian mealmoth (Plodia interpunctella), the Mediterranean flour moth (Ephestia kuehniella) and the Angoumois grain moth (Sitotroga cerealella) in cereal stores, where we were also searching for possible indigenious natural enemies of stored product insects pests. We have confirmed the occurrence of two parasitoids, Anisopteromalus calandrae and Dibrachys microgastri. In 2017, we have organized the 11th Conference of the IOBC/wprs Working Group on Integrated Protection of Stored Products (Ljubljana, 3-5 July), which was attended by 136 participants from 25 countries. We also transfer knowledge to Slovenian agricultural specialists about the harmfulness and possible ways of controlling stored products insects pests. In 2014, we have organized a workshop on this topic (“From Technological Maturity to Storing of Cereals and Legumes“). In 2015, we have hosted C. Athanassiou as an invited lecturer at the 12th Slovenian Conference on Plant Protection with international participation in Ptuj. In recent years, we have been working with experts from other countries with the aim of studying the efficacy of environmentally acceptable insecticides (spinosad, spinetoram) and the influence of cereal production technologies on grains’ susceptibility to attack by Sitophilus beetles. Furthermore, we participate in the research regarding the efficiency of new formulations of insecticidal preparations. The paper presents the chronology of activities in this area of our work

Is a combination of different natural substances suitable for slug (Arion spp.) control?

In a laboratory study we investigated the contact and barrier efficacy of different natural substances (wood ash, sawdust, hydrated lime, and diatomaceous earth) against slugs of the genus Arion, an important agricultural pest. Natural substances were tested individually and in combination with each other. The experiment was carried out in plastic petri dishes and in glass insectaria. Moistened tampons and fresh leaves of lettuce were placed into both experimental arenas. The slugs were starved for 48 hours prior to the experiment. Six categories of behaviour were identified for slugs in the presence of the natural substances: (1) slug survived the experiment, (2) slug died during the experiment, (3) slug crossed the barrier, (4) slug did not cross the barrier, (5) slug fed on the lettuce, and (6) slug did not feed on the lettuce. The effect of different treatments (natural substances) was significant. The results of our study have shown that hydrated lime had the best contact efficacy on slugs (the mortality of slugs was 100%), both individually and in combination with other substances. The treatments with hydrated lime also proved to be the most efficient barrier preventing slugs from feeding on lettuce. Hydrated lime shows great potential in Arion control in our investigation; however, further research is needed to investigate the practical value (how to avoid the problem when the substance becomes wet), safety and economics of hydrated lime used in this way

About Previous Investigations Regarding the Role of Glucosinolates in Controlling Brassica Insect Pests in Slovenia

The chapter presents previous field and laboratory investigations of cabbage flea beetles (Phyllotreta spp.) and cabbage stink bugs (Eurydema spp.) interactions with different Brassica crops in Slovenia. The special emphasis is given to an influence of different glucosinolates on injuries caused by mentioned economically important two genera of insect pests. In the study, we found out that the content of glucosinolates differs between different Brassica species, as well as between individual plant organs of the same species. The content of glucosinolates is conditioned also by environmental influences. Among the analysed glucosinolates, glucobrassicin was presented in all plant species. In almost all plant species, it inhibited the feeding of cabbage flea beetles, except in oil rape, where it had stimulative effects. We have established that the influence of individual glucosinolate on Phyllotreta spp. and Eurydema spp. is not identical as it differs between individual plant species. Because of the variability of glucosinolates as well as different preferences of the studied groups of harmful pests in regard to the plant species, one of the options for diminishing the damage caused by cabbage stink bugs and cabbage flea beetles is the use of mixed Brassica crops for trapping the pests in the growing season. In the future, glucosinolates should be employed to a greater extent in environmentally acceptable ways of food production, one of which is also the use of trap crops in order to reduce harmful effects of cabbage stink bugs

The Role of Volatile Substances Emitted by Cultivated Plant\u27s Roots in Indirect Defense Against Soil Herbivores

Plants in nature have developed many defense mechanisms to defend themselves against attacks by harmful organisms; these mechanisms are indirect and direct. When attacked by a harmful organism, many plant species release volatile substances that attract natural enemies of herbivores. Volatile substances have an important role in the tritrophic system consisting of a plant, a herbivore, and its natural enemy. They function as a kind of chemical signal (semiochemical) which directly influences both harmful pests and their natural enemy. Some of these substances appear on damaged as well as undamaged plants, while other substances are released in the case of mechanic damage or feeding of a particular herbivore species. Volatile substances may repel a herbivore. Harmful pests have an important role in attracting natural enemies, as they also emit chemical signals that function as kairomones for natural enemies. In order to increase our knowledge in the field of indirect plant defense we studied chemosensation of four entomopathogenic nematode species (Steinernema, Heterorhabditis) to compounds released by insect (wireworms and grubs) damaged and undamaged potato and carrot roots, and mechanically damaged maize roots. The aim of our research was (1) to study the effect of different EPN foraging strategies (ambush, intermediate, or cruise) toward the tested volatile compounds, (2) to determine whether chemotaxis is species-specific, and (3) to assess whether the volatile compounds from damaged and undamaged roots have any behavioral effects on the EPNs studied, and (4) if volatile compounds are a part of an indirect plant defense. Our results indicate that all of the tested EPN species exhibited attraction (or repulsion) to volatiles, irrespective of their foraging strategy, and suggest that responses to distinct volatile cues are a species-specific characteristic. These results expand our knowledge of volatile compounds as cues, which may be used by EPNs to find hosts and for other aspects of navigation in soil

The effect of different entomopathogens on white grubs (Coleoptera: Scarabaeidae) in an organic hay-producing grassland

In 2011, a field block trial examined the biological control of white grubs of June beetle (Amphimallon solstitialis), margined vine chafer (Anomala dubia) and garden chafer (Phyllopertha horticola) on a permanent cut grassland in Gotenica (SE Slovenia). The efficacy of Beauveria brongniartii, Beauveria bassiana, Bacillus thuringiensis var. kurstaki and Heterorhabditis bacteriophora in the form of water suspension and infested grain was tested against a control treatment. The initial number of white grubs (April 12; 39 white grubs/m2) was reduced with all tested entomopathogens up until the third evaluation (May 26; 32 white grubs/m2). However, the studied treatments were not sufficient to reduce the white grub population in the soils below the economical threshold (20 individuals/m2). The average number of white grubs was affected mostly by the treatment where the active ingredient was B. thuringiensis var. kurstaki. With one application in April, only the abundance of overwintered white grubs was reduced. To decrease the summer generation of white grubs, an application of biological agents is also required at a later time. The 8% higher dry matter yield at the first cut (June 10) compared to the second cut (September 6) provided evidence for the prior statement

Seasonal dynamics of three lepidopteran stored grain pests in Slovenia

In the period 2004-2006 seasonal dynamics of Mediterranean flour moth (Ephestia kuehniella), Indianmeal moth (Plodia interpunctella) and Angoumois grain moth (Sitotroga cerealella) was studied in the mills and grain warehouses in central Slovenia. For this purpose pheromone traps were used from April until December, and the males of all three lepidopteran pests were counted in two week intervals. The three insect pests under investigation developed two peaks in capture per year that might represent two distinct generations per year. In the maize open air storage Ephestia kuehniella was the most numerous, while Plodia interpunctella was more frequent in the closed storage in mills and warehouses, Sitotroga cerealella was slightly less common in these latter closed warehouses. Keywords: Monitoring, Lepidoptera, Stored grain pest, Pheromones, Sloveni