Following a report from a breeding company in North Holland, the NVWA has found the spider mite Eotetranychus lewisi in poinsettias Euphorbia pulcherrima. At a pot plant company in Gelderland, the NVWA also found Eotetranychus lewisi in poinsettias grown from material from the breeding company.
This spider mite is an EU quarantine organism. This means that EU member states are obliged to prevent the introduction and spread of this organism and to control this spider mite if it is found. The spider mite is not harmful to humans and animals.
Photos of the Netherlands, left in Noord-Holland and right in Gelderland. More pictures in the pest report of the NVWA. Photos via National Plant Protection Organisation.
Originally, this organism was found in America, but through trade in plants it has also ended up on other continents. Because of its very limited occurrence in the EU, the spider mite Eotetranychus lewisi is included in the EU regulations in the list of IIA quarantine organisms. For IIA q-organisms, eradication is immediate.
In the Netherlands, the spider mite can develop well in greenhouses and cause damage, for example to poinsettias. Eotetranychus lewisi resembles the bean spider mite (Tetranychus urticae) and it is difficult to distinguish the two.
Symptoms
Eotetranychus lewisi and bean spider mite cause similar symptoms, such as sucking damage and small yellow dots on the leaves which eventually turn completely yellow/brown. In case of a severe infestation, you will see spider mites around the growing points. Since the organism is very small and the symptoms are similar, it is very difficult to notice an infestation with this quarantine species in time. This spider mite cannot survive outside in the Dutch climate. More information about host plants, symptoms, and identification of E. lewisi is shared by the NVWA here.
Control
The NVWA has imposed measures on both companies in accordance with the elimination scenario whereby heavily infected batches must be destroyed, and for lightly infected batches a control regime with chemical crop protection agents is prescribed.
Tracking
The NVWA is carrying out a tracing investigation and is trying to trace the source of the contamination through information requested from the companies. They are also investigating the possible spread of the spider mite through the trading of cutting material.
More details on the findings can be found in a pest report from the NVWA. Photos are also shared there.
