Natural products in plant protection

Natural products can be used to control pests and diseases in crops. These products include anorganic compounds, but also a variety of plant extracts. In the beginning of this century active microbial extracts were discovered as well. Synthetic crop protection chemicals were developed from about 1940 onwards and sustained progress in modern agriculture. The first generation chemicals have aspecific modes of toxic action and are in many instances deleterious to the environment. The second generation chemicals have specific modes of action and meet modern environmental requirements. A disadvantage of these chemicals is the potency of target organisms to acquire resistance. This condition urged agrochemical industry to develop chemicals with new modes of action. Such chemicals can be developed by using natural bioactive products as leads in synthesis programmes. This paper decribes the progress that was made in the development of natural bioactive compounds in pest and disease control.     

Natural products in plant protection

Natural products can be used to control pests and diseases in crops. These products include anorganic compounds, but also a variety of plant extracts. In the beginning of this century active microbial extracts were discovered as well. Synthetic crop protection chemicals were developed from about 1940 onwards and sustained progress in modern agriculture. The first generation chemicals have aspecific modes of toxic action and are in many instances deleterious to the environment. The second generation chemicals have specific modes of action and meet modern environmental requirements. A disadvantage of these chemicals is the potency of target organisms to acquire resistance. This condition urged agrochemical industry to develop chemicals with new modes of action. Such chemicals can be developed by using natural bioactive products as leads in synthesis programmes.This paper decribes the progress that was made in the development of natural bioactive compounds in pest and disease control.     

Principles of efficacy evaluation for microbial plant protection products

Specific scope

This standard describes the principles for determining the requirements for an efficacy evaluation (effectiveness and crop safety) of plant protection products containing micro‐organisms in a registration procedure.

Specific approval and amendment

First approved in 2012–09.     

Authorization requirements for organisms as plant protection products in Austria

In Austria, beneficial arthropods and entomopathogenic nematodes ('macrobials'), as well as micro-organisms and viruses, are classified as active substances of plant protection products, according to the Federal Law on Transactions with Plant Protection Products which entered into force in 1991. Therefore, naturally occurring organisms, intended for use in the field of plant protection, must be authorized as plant protection products before they are permitted to be sold. Requirements for the authorization of macrobials, micro-organisms and viruses and the authorities involved are presented. The legislative regulations for the use of macrobials, micro-organisms and viruses as plant protection products are described. At the beginning of 1996, 35 plant protection products containing 21 different organisms have been authorized in Austria for use in agriculture, horticulture and forestry.     

Guideline for the evaluation of side-effects of plant protection products

This guideline is concerned with the evaluation of the side-effects of plant protection products on Encarsia formosa in the glasshouse. E.formosa is used for biological or integrated control of glasshouse whitefly, Trialeurodes vaporariorum (TRIAVA). Because field-testing is laborious and costly, this guideline includes a sequential testing scheme involving three laboratory tests, which may serve to classify many products as definitely harmless or harmful without having recourse to field tests. In particular, the very stringent residual toxicity test on adults (the most sensitive stage) allows products to be classed as definitely harmless, since experience has shown that no product so classed by this test is ever harmful in field tests. The direct contact test on pupae (the most insensitive stage) makes it possible to exclude as definitely harmful products which exceed a certain threshold. Products which are not harmful to pupae in this test could still kill adults after emergence if they are sufficiently persistent. So a 3-day persistence test makes it possible to exclude further products as too persistent. Finally, only products which appeared potentially harmful in the first test, but were harmless to pupae and non-persistent, have to be field tested, and compared with harmful and harmless reference products, in order to decide on the final rating. This is further illustrated by the scheme in Fig. 1.
The tests were developed according to the standard guidelines (Hassan, 1985) of the Working Group on 'Pesticides and Beneficial Organisms' of IOBC/WPRS (West Palaearctic Regional Section of the International Organization for Biological Control). An earlier version of the guideline was published (Oomen, 1985), before passing through the full EPPO guideline approval procedure.