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Insects that are harmful to plants

While some insects are essential for plants, others can be detrimental to their health and destroy gardens, forests, wood and crops. In view of climate change and increased international trade, it is vital to identify and manage the multitude of new insects that could potentially become established in France. ANSES is the National Reference Laboratory for the identification of harmful insects.

Every year, three to four new insect species are detected in France and more than 20 species in Europe. Insects that are harmful to plants can be divided into two categories: pests and disease vectors. Some insects damage plants directly by feeding on them, while others carry pathogens and spread them from plant to plant.

Insect pests of plants

Some insects feed on plants, and can damage or even kill them.

Some examples of insect pests:

The red palm weevil: this beetle is native to South and South-East Asia but has been established in the south of France since the early 2000s. Infested palm trees die within two to five years.

Pine and oak processionary caterpillars: these insects can cause significant leaf loss, stunted pine growth and can weaken infested trees making them vulnerable to other insect pests. As well as threatening plant health, their stinging hairs are problematic for both human and animal health.

The Japanese beetle: this insect, native to Japan, is already found in Switzerland and Italy and could arrive in France. It can feed on more than 400 different plant species, over a hundred of which are found in metropolitan France. These include plants grown for food: plums, apples, vines, maize, soya, beans, asparagus, etc. 

Insect vectors of plant diseases

Other insects act as vectors, transmitting bacteria that are pathogenic to plants.

Some examples of pathogens and insect vectors:

 Xylella fastidiosa: this bacterium is transmitted by a small insect, the meadow spittlebug. It can have an impact on major agricultural crops such as vines, citrus, almonds and olives.

The pinewood nematode is a microscopic worm transported by a beetle. A single insect can carry several hundred nematode larvae. Because the insect vector is already present in maritime pine forests in the Landes region, it represents a risk factor for the spread of the nematode.

Huanglongbing: this disease, which threatens citrus crops, is also transmitted by insects, the Asian citrus psyllid (Diaphorina citri) and the African citrus psyllid (Trioza erytreae). The latter is already found in Portugal and Spain and could spread the disease across Europe.

National and European Reference Laboratory

ANSES is the National and European Union Reference Laboratory for insects and mites. In this role, it analyses the insects intercepted at plant transport and sales points before they can spread. Over 2000 samples are analysed each year. The laboratory has an insect library containing thousands of reference insects used for identification.