SUMMARYThe frequency and incidence of A. flavus and A. niger on barley, maize, soybean, sunflower and wheat grain, the abundance of European corn borer (Ostrinia nubilalis) moths and their interaction depending on weather conditions in the 2008-2012 period were studied. Under the agroecological conditions of Serbia, the species A. niger is more frequent than A. flavus, and concerning the crop species, its frequency is highest in kernels of sunflower, than soybean, maize, barley and wheat. A. flavus was extremely dominant on all plant species in 2012 regarding its frequency: 100% on soybean, 95.3% on maize, 65.2% on barley, 57.1% on sunflower and 45.8% on wheat. Furthermore, the incidence of A. flavus was higher in 2012 than in previous years. The uncommonly high frequency and incidence of A. flavus infestation of maize grain in 2012 were caused by extremely stressful agrometeorological conditions, high temperatures and drought over the period from flowering to waxy maturity of maize. The precipitation factor (Pf = precipitation sum / average monthly temperature) showed that 2012 was extremely arid in June (Pf = 0.57), July (Pf = 1.45), August (Pf = 0.15) and September (Pf = 1.42). European corn borer (ECB) was a second factor causing intensive occurrence of A. flavus on maize grain in 2012. The maximum flight of ECB moths was recorded as early as in July (5,149) and, as a result of this, high damage and numerous injuries were detected at harvest. Those injuries were covered by visible olive-green powdery colonies typical of A. flavus. In the chronology of A. flavus occurrence, these are the first data on its very high frequency and incidence under the agroecological conditions of Serbia. As intensive infections with A. flavus were rare in the past 50 years, the level of aflatoxins in maize grain was low.

No abstract

SUMMARyA total of 41 species of fungi were isolated from seed samples of barley, maize, soybean, and sunflower collected at different locations in Serbia. The majority of detected species occurred on barley (35 of 41 species or 87.8%) comparing to soybean (17 of 41 species or 41.5%), sunflower (16 of 41 species or 39.0%) and maize (15 of 41 species or 36.9%). Species belonging to genera Alternaria, Chaetomium, Epicoccum, Fusarium, Penicillium and Rhizopus were present on seeds of all four plant species. Alternaria species were dominant on soybean, barley and sunflower seeds (85.7%, 84.7% and 76.9%). F. verticillioides and Penicillium spp. were mainly isolated from maize seeds (100 and 92.3% respectively), while other species were isolated up to 38.5% (Chaetomium spp. and Rhizopus spp.). F. graminearum, F. proliferatum, F. poae and F. sporotrichioides were the most common Fusarium species isolated from barley (51.1-93.3%), while on the soybean seeds F. oxysporum (71.4%), F. semitectum (57.1%) and F. sporotrichioides (57.1%) were prevalent. Frequency of Fusarium species on sunflower seeds varied from 7% (F. equiseti, F. graminearum, F. proliferatum and F. subglutinans) to 15.4% (F. verticillioides). Statistically significant negative correlation (r = -0.678*) was determined for the incidence of F. graminearum and Alternaria spp., as well as, Fusarium spp. and Alternaria spp. (r = -0.614*), on barley seeds. The obtained results revealed that seedborne pathogens were present in most seed samples of important cereals and industrial crops grown under different agroecological conditions in Serbia. Some of the identified fungi are potential producers of mycotoxins, thus their presence is important in terms of reduced food safety for humans and animals. Therefore, an early and accurate diagnosis and pathogen surveillance will provide time for the development and the application of disease strategies.

The paper describes in vitro model for evaluation of natural mineral adsorbents ability to adsorb mycotoxins. Bentonite, diatomite and zeolite were prepared in the Institute for Technology of Nuclear and Other Mineral Raw Materials, Belgrade. A total of six mycotoxins: aflatoxin B1 (AFL), ochratoxin A (OTA), deoxynivalenol (DON), zearalenone (ZON), diacetoxyscirpenol (DAS) and T-2 toxin were tested in vitro. For adsorption experiments crude extracts of mycotoxins, produced in the Department of Microbiology of Bio-ecological Center in Zrenjanin, were used. The ability for binding mycotoxins was evaluated in the electrolyte 0.1 M K2HPO4 which pH value was adjusted to 3.0 and 6.9, respectively. Mass ratio of individual mycotoxin and natural mineral adsorbent was 1:5000. The experimental mixtures were incubated for 1 hour on a rotary shaker (185 rpm) at room temperature (22-25oC). After incubation the extractions of unadsorbed mycotoxins from the filtrates were performed with organic solvents, and their quantifications were done by thin-layer chromatography (TLC). By the use of TLC method it was noted that bentonite, diatomite and zeolite binded more than 95% of applicated AFL. In the case of OTA only diatomite adsorbed that toxin - adsorption index was 66.67%. Binding of DON has been observed only at pH 3.0 of electrolyte. Its adsorption index varied from 25.00 to 50.00% depending on the type of mineral adsorbent. Effect of electrolyte pH value on the binding of ZON was not so expressed. Its adsorption index ranged from 12.20 to 37.00%. In the case of type A trichothecenes (DAS and T-2 toxin) bentonite, diatomite, and zeolite binded only T-2 toxin. The amount of adsorbed T-2 toxin ranged from 16.66 to 33.33%. The obtained results point out the need for activation or processing of natural mineral adsorbens, especially bentonite and zeolite, in order to increase the efficiency of adsorption of the wider spectrum of mycotoxins.

Obtained results indicate the significantly higher concentrations of Alternaria toxins in hulls than in dehulled kernels which implicate the possible protective effect of spelt wheat hulls.