Summary The central issuses in organic agricultural production are related to the plant protection sector. As the use of synthetic pesticides is not allowed in the organic system of agricultural production, biopesticides are considerd a natural, safe and environmentally friendly alternative. The purpose of this study is to identify the most important biological agents used as biopesticides in organic agriculture through a review of the relevant literature. Biopesticides are compounds made from microorganisms and various natural materials of plant and animal origin. Biological protection also includes the use of extracts of different plant species (such as essential oils) that have toxic effects on plant pathogens. This paper accounts for the most important types of biopesticides based on bacteria, fungi and viruses, which are licensed for use in the Republic of Serbia according to the Law on Organic Agriculture. Their mechanisms of action, possibilities of application and efficiency are described in the present study. The bacterium Bacillus subtilis is the most studied bacterial species used in biological protection, whereas the species Bacillus thuringiensis is predominantly used for the control of harmful insects. There is no doubt about the need for alternative protection systems in the future, which necessitates further scientific research. A sound application of biopesticides in combination with preventive protection measures would meet the requirements of safe agricultural production.

On a global level and over a number of years, many researchers have been studying the effects of organic and conventional production methods on the chemical composition of plants and their products. The aim of this study was to determine the potential difference in the contents of several nutrients/phytochemicals in organically and conventionally produced buckwheat grains. Buckwheat was sown in 2016 at a site in Nova Varoš. The experimental plot covered a surface area of 1 ha. The contents of the following nutrients and phytochemicals in buckwheat grains were determined: proteins, pigments (chlorophyll a, chlorophyll b, carotenoids), soluble sugars, starch, free and bound polyphenols and flavonoids, and phytosterols. In addition, the antioxidant properties of the grains were assessed using the ABTS •+ ((2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) test (ability to inhibit ABTS •+ radical cations). There was no statistically significant difference in the contents of proteins, chlorophyll a and free phenols or in regard to the % of antioxidant capacity. On the other hand, two different production methods caused differences in the other chemical parameters. In organic grains, higher contents of carotenoids (6.998 µg g-1 dry matter (DM)), soluble sugar (6.48 mg 100 g-1 DM), starch (2.46 mg 100 g-1 DM), bound polyphenols (1034.3 mg (FAE) kg kg-1 DM), free flavonoids (1094.7 mg (QE) kg-1 DM) and bound flavonoids (1087.2 mg (QE) kg-1 DM) were detected, while in conventional buckwheat grains, there were higher levels of chlorophyll b (24.16 µg g-1 DM) and phytosterols (185.15 mg kg-1 DM). The study showed no clear influence of the production method on the examined parameters.