The biological control is based on the release of natural enemies, to control harmful organisms of the crops. In particular, the biological control looks for the reduction of pests to levels that are economically justified and that guarantee the survival of natural enemies.
There are different types of biological control:
- Classic: The introduction of exotic species to control pests. The aim of this technique is to establish the exotic species permanently becoming them autochthonous.
- Augmentative: The biological control agents are produced in laboratories and then, they are released several times each year.
- Conservative: It is based on the modification of the surrounding and the existing practices in order to protect and enhance natural enemies that can be found in the surrounding.
Among the natural enemies there are predatory arthropods, parasitoids and other entomopathogenic organisms (bacteria, fungus, nematodes and virus). Some information about different families of auxiliary fauna is collected bellow:
- Predatory bugs:
There are two important families inside this group: miridae and antocoridae.
The family Miridae is very polyphagous. They have thin body and long extremities. They feed on Cabbage whitefly nymphs and also small larvae, aphids and trips. Macrolophus are an example of Miridae.
The family Antocoridae is also very polyphagous. They are characterised by its small size and its black colour. They are used to control pear sucker, red spider mite and trips, but they also feed on small larvae and aphids. One example of Antocoridae is the genus Orius.
Figure 6. Adult of Orius niger in a flower of pepper
Lady beetles are perhaps the most familiar insect predators in most agricultural crops. They are usually red-orange with black spots on the wing covers. Adults and larvae of this family feed on aphids.
Figure 7. Larvae of Coccinella septempunctata
Pale green insects, with big transparent wings can be found within the family. Larvae are predators of aphids, while adults feed on nectar and pollen. Chrysoperla carnea is an example of Crysophidae.
Figure 8. Crisopa (Chrysoperla carnea) in peach tree
It is a group of families of small wasps, dark in color. The females put their eggs within an egg, larva or pupa of a host insect. The resulting larvae feed on the host insect and leave it when it is an adult. Adults feed on nectar and pollen.
This family consists of small to medium flies, which have yellow and black striped bodies. Adults feed primarily on nectar and pollen, while larvae prey on aphids.
Figura 9. Episyrphus balteatus
Natural enemies require nutritional and habitat resources that are often not found in conventional agricultural fields, so it is recommended to use this technique with strategies that allow conserving them (flower stripes, fences, banker plants…),
Implementation of this measure in LIFE AGROintegra project:
This technique has been applied in two of the demonstrations that have been done with fruit trees. In apple tree Amblyseius californicus and Phytoseilus permisilis were released to control red spider mite (Panonychus ulmi) (Figure 10). In pear tree Anthocoris nemoralis were released to control pear sucker (Cacopsylla pyri).
Figure 10. Release of phytoseiids in apple tree
Furthermore, biological control has been applied in more experiences during the second campaign of the project. Thus, releases of Macrolophus sp. and Nesidiocoris sp. have been done in different horticultural crops (tomato, chard, borage, thistle…).