Biological pest control
Under biological control is defined as the deliberate introduction of viruses or animals by humans to maximize the population of certain ( "harmful") animals or plants to decimate ( pest ). In most cases, use is made of organisms that are known to be natural enemies (predators, parasites and pathogens) of the undesired species. It is also possible to modify individuals in such a way that they harm the population of their own conspecifics. In addition, organisms can also be used whose excretions pose a threat to undesirable species.
The often equated use of products that are only based on reducing the use of pesticides or insecticides is misleading and is more related to the term biological plant protection .
Biological pest control is not limited to agriculture , but has also been used in stock management since ancient times .
Principle of biological pest control
Biological pest control makes use of the principle that in a balanced ecosystem there are normally no pests in the sense of excessive reproduction, since a negative feedback between predator and prey numbers or predator and food plant stabilizes the overall system. However, a mass occurrence of species is also known under natural conditions (see Plague of Locusts and Lemmings ). A requirement of biological pest control is therefore the maintenance of a minimum biodiversity .
The settlement of beneficial insects is supported and / or these are bred and released in the affected area.
Examples
Cats have been bred for around 10,000 years to keep storage rooms largely free of small mammals by hunting mice.
Classic examples of biological pest control are the installation of nesting boxes for the settlement of insectivorous birds or perches for birds of prey to decimate rodents (agriculture) or songbirds (fruit growing). By using bat boxes , a population of crepuscular and nocturnal flying mammals can contribute to the decimation of mosquitoes , but also counteract a cockchafer infestation and decimate night butterflies , the caterpillar stages of which cause damage to trees.
A more modern example is the control of insect larvae living in the ground , such as the furrowed black weevil ( Otiorhynchus sulcatus ) or the garden beetle ( Phyllopertha horticola ), with nematodes of the genus Heterorhabditis bacteriophora which are pathogenic to insects . The released nematodes attack the pest larvae, after which a bacterium ( Xenorhabdus ) brought with them kills them or prepares them as food for the nematodes. Nematodes are considered to be harmless to plants and have no effects on warm-blooded animals. However, their effect on non-target organisms (non-targets) is still controversial due to insufficient investigations. Another important genus would be Steinernema .
In organic cultivation, especially in organic viticulture, ladybirds and their larvae are also used against aphids . The problem with this is that the Asian ladybird ( Harmonia axyridis ) was used worldwide for this purpose , which now threatens to displace the native species in Europe and North America.
Certain parasitic wasps (e.g. of the genus Trichogramma ) can also be specifically bred and used against some insects that are undesirable for humans . They are used in stock management and in agriculture, for example against the European corn borer ( Ostrinia nubilalis ).
Another example of biological pest control, in this case using plant ingredients , is biofumigation , which uses isothiocyanate ( mustard oil ) contained in some plants to reduce soil-borne pathogens.
In the meadows near airfields, strategies of biological pest control are often used to avoid flocks of birds.
Performance of beneficial insects
| Beneficial insects | Beneficial output per day | Beneficial performance up to pupation |
|---|---|---|
| Predatory mites | 5 spider mites | 30-50 spider mites |
| Predatory bugs ( Orius ) | 30 spider mites | 200 spider mites |
| Ball beetle | 30 spider mites | 250 spider mites |
| Ladybug | 10–50 aphids | 400 aphids |
| Lacewing | 30–50 aphids | 200-500 aphids |
| Hover fly | 10–40 aphids | 150–600 aphids |
| Blood lice wasp ( Aphelinus mali ) | up to 90% parasitization in autumn | |
| San José scale wasp ( Prospaltella perniciosi ) | 70–90% parasitization in autumn | |
| Aphid wasp | 200-1000 aphids |
hazards
Ignoring biological pests can cause immense ecological and economic damage. The settlement of the Australian continent, but also many other regions, can bear witness to this (e.g. rabbit and fox plagues in Australia). A well-known example is the introduction of the cane toad into Australia, which, originally intended to control a sugar cane pest, developed into a plague itself.
Biological pest control is always ecologically questionable if human organisms that are typical for the biotope and the region and foreign organisms there are not brought in (en masse).
See also
literature
- Jost Martin Franz, Aloysius Krieg: Biological pest control. Paul Parey Verlag, Berlin et al. 1972, ISBN 3-489-66526-0 .
Web links
- Biological plant protection
- Storage protection: rough parasite manners (specialist article Bio Aktuell 02/09; PDF file, 483 kB)
Individual evidence
- ↑ List of the Hamburg consumer center with reference addresses and a. for parasitic wasps ( memento from October 23, 2010 in the Internet Archive )
- ^ Karl Lind: Biological fruit growing . Leopold Stocker Verlag, Graz 1998, ISBN 3-7020-0833-0 , p. 145.