First report of Hemadas nubilipennis in the Netherlands
The NPPO of the Netherlands recently informed the EPPO Secretariat of the first record of Hemadas nubilipennis (Hymenoptera: Pteromalidae - blueberry stem gall wasp*) on its territory. Its presence was officially confirmed in September 2024 in Vaccinium corymbosum grown for fruit production. However, based on the observation of old galls and earlier unofficial records made in 2019, it is presumed that H. nubilipennis has been present in the Netherlands for a longer period. In a Pest Categorization conducted for the United Kingdom by a visiting scientist in Canada, it was concluded that an introduction of the pest in the United Kingdom would not cause significant damage because of the relatively short production cycle of blueberries and the use of varieties which are not highly susceptible in the United Kingdom (CFIA, 2023). The Dutch NPPO noted that this would also apply to its particular case and added that native wild Vaccinium species in the Netherlands are not known to be host plants. As a consequence, no measures have been taken against H. nubilipennis.
The pest status of Hemadas nubilipennis in the Netherlands is officially declared as: Present.
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* EPPO note: Hemadas nubilipennis occurs in Eastern Canada and the USA where it is an occasional pest of blueberries (Vaccinium angustifolium, V. corymbosum and V. myrtilloides,). Female wasps lay eggs in young shoots, resulting in the formation of reniform galls. The development of these galls on young shoots can reduce berry production (by approximately 3%). In addition, galls can contaminate the harvested blueberries.
Sources
NPPO of the Netherlands (2024-11).
CFIA (2023) Pest categorization Hemadas nubilipennis (Ashmead) (Hymenoptera: Pteromalidae) Blueberry stem gall wasp. Canadian Food Inspection Agency. https://pra.eppo.int/pra/2a5f84bc-6796-49a1-b38a-f0401c005a81