Therefore, aphids are referred to as a secondary pest, and their importance in integrated pest management programmes is increasing. More than 20 aphid species have been identified as economically important pests on the most commonly grown fruit trees in North-Western Europe (apple, plum, pear, peach, apricot, cherry). For instance, in apple trees, where most extensive research has been carried out, 4 different aphid species present the most problematic pest after codling moth.
What are the symptoms of aphids?
The symptoms of aphids in fruit trees are resulting from their piercing-sucking feeding activity and include twisted and curled leaves (when sucking in green tissue) and formation of knots and galls (when sucking in woody tissue). This weakens the fruit trees, resulting in the production of small non-marketable fruits. Most aphids also excrete sticky honeydew which allows the growth of black sooty moulds covering foliage and fruits, retarding growth, and reducing the market value of the fruit.
What are the economic consequences of aphids?
Apple production in the EU covers 560,000 ha and pear production takes 139,900 ha. The production area of cherries in the EU is around 177,000 ha, and the production area of peaches and nectarines is around 244,000 ha. Aphids can cause economic losses of up to 80% when not controlled.
How can aphids be controlled?
Parasitoids are the most efficient enemies of aphids and all other fruit pests. They are often naturally present in commercial orchards but in general too late, as parasitoid populations build up only when aphids are present in higher numbers and are already causing damage.
Parasitoid releases have now commonly and successfully been used for aphid control in most protected crops for at least two decades. However, the technique is not yet commonly used in open field crops but some examples show that this is possible.
There are several reasons why biological control is not yet widespread. One of the reasons is the very low price of chemical pesticides. Another important reason is the lack of a complete integrated pest management programme for several specific crops. Biological control of one pest is impossible when another must be controlled with chemicals that may kill the beneficial insects.
Use of pesticides
At present, commercial orchards are sprayed with multiple insecticide treatments per season to control major pests, including several aphid species.
Some aphid species are not susceptible to a range of insecticides due to protection by shields or waxy coatings (e.g. woolly apple aphids) or resistance development. On the other hand, the use of chemical broad-spectrum pesticides can harm bees and beneficial organisms, thereby hindering integrated pest management strategies in the orchard. Another disadvantage of the use of chemical pesticides is the fact that often residues are still present on the fruits at harvest, which complicates their marketing.
BIOCOMES biological control agent
Several aphid species (like woolly apple aphids or black cherry aphid) are extremely hard to control with the currently available (chemical) control compounds and the requirements concerning maximum residue limits (often even extra-legal demands by leading retailers). BIOCOMES will develop a biological control agent (BCA) to control aphids based on parasitoids.
Current stage of the Biological Control Agent
Month 18: List of at least 10 selected identified parasitoids
Month 24: Report on fauna and crop protection practices in orchards
Month 24: Results of screening of parasitoids under laboratory conditions of at least 5 parasitoid species ranked by production efficiency and 4 species ranked by parasitism efficiency on plants
Month 36: Results on optimization and scaling up of mass rearing
Month 48: Protocol for optimized release strategy
Aphid Identification Guide
A unique tool that helps fruit growers and researchers to identify aphids appearing in almond, apricot, blackthorn, cherry plum, peach, pear, plum and cherry orchards. Pictures and clear descriptions help to identify the right aphid in just a few steps.
Have a look yourself: BIOCOMES Aphid Identification Guide.
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