First report of an unknown Contarinia species on Alstroemeria in the Netherlands
During summer 2016, unusual damage was noticed in a glasshouse producing cut flowers of Alstroemeria (hybrid ‘Granada) in the municipality of Kaag en Braassem in the province Zuid-Holland, the Netherlands. In 2 compartments of the glasshouse (of 0.1 ha each), large numbers of Alstroemeria flowers and flower buds were malformed. As a consequence, no cut flowers could be harvested from these plants. Damage had initially been observed by the grower who notified a diagnostic laboratory, which in turn notified the Dutch NPPO. The NPPO received a sample for diagnosis and the glasshouse concerned was subsequently visited to assess the impact of the problem. In July 2016, the entomologist of the National Reference Centre found gall midge larvae when opening affected flower buds. These larvae were confirmed to belong to the family Cecidomyiidae (Diptera) and were tentatively identified as Contarinia sp. on the basis of preliminary molecular DNA comparisons. The rearing of adults remains necessary to pursue further research and confirm the identification at least at genus level. The possibility that the infestation involved Contarinia quinquenotata, which is known to infect Hemerocallis in the Netherlands, has been excluded. The origin of this finding is unknown. Given the large impact of the pest on the marketability of cut flowers and the conspicuous damage, it is assumed that the gall midge infestation is recent. No link could be established with imports of cut flowers or plants for planting. The native range of Alstroemeria spp. is South America which might also be the most likely origin of the midge species. Interestingly, the NPPO of Japan has intercepted Contarinia larvae in Alstroemeria flowers imported from Australia and New Zealand (Iwaizumi et al., 2007), but it is not known whether this concerns the same pest species as in the Netherlands. The grower has volunteered to destroy all flowers and flower buds over a 5 week-period to remove all potential sites for egg laying. In addition, plants will be sprayed weekly to eliminate adult midges. The NPPO will monitor the situation during this period, and surveys will be carried out in spring 2017 when the new flower production cycle starts.
The pest status of this unknown Contarinia species in the Netherlands is officially declared as: Transient: actionable, under surveillance.
NPPO of the Netherlands (2016-08).
Iwaizumi R, Tokuda M, Yukawa J (2007) Identification of gall midges (Diptera: Cecidomyiidae) intercepted under plant quarantine inspection at Japanese sea-and airports from 2000 to 2005. Applied Entomology and Zoology 42(2), 231-240.