Agapanthus gall midge: a new and undescribed species found for the first time in the United Kingdom
The NPPO of the United Kingdom recently informed the EPPO Secretariat of the first record of an undescribed species of gall midge (Diptera: Cecidomyiidae) on Agapanthus spp. This insect was first reported to the advisory service of the Royal Horticultural Society in July 2014, following the reception of samples from Farnham, Surrey. These samples came from plants that had been infested for at least 3 years. An independent gall midge expert confirmed in August 2014 that that the agapanthus gall midge was a species new to science which still needed to be formally described. Following an official survey conducted in 2015, the midge has subsequently been identified on Agapanthus plants from public gardens in Devon, Essex, Somerset and Surrey; from private gardens in Surrey and West Sussex; and from nurseries/garden centres in Cornwall, Dorset, Hampshire and Surrey. So far, there are no records of this pest north of Essex, so the distribution of the pest is currently restricted to Southern England. As the agapanthus gall midge is new to science, there is very limited information about its origin and biology. So far, it has only been found on Agapanthus spp. It is a tiny fly which lays eggs on the developing flower buds. Feeding activities of the larvae inside the buds cause abnormal bud development. Infested buds are deformed and can fail to open. Occasionally, collapse of the whole flower head has been observed. Pictures of the insect and damage on Agapanthus can be viewed on the Royal Horticultural Society website: https://www.rhs.org.uk/advice/profile?PID=901
Although the agapanthus gall midge is restricted to a small industry in the United Kingdom, agapanthus plants are of high value and the impact of the pest could be severe. Phytosanitary measures are being taken on commercial premises where the pest has been detected in order to prevent its spread across the United Kingdom and its introduction into other countries. In commercial premises where the pest has been found, one the following three options has to be followed: 1) destroy infested and at risk material; 2) disbud flowers of Agapanthus and then repot, to sell or move on in this disbudded state, 3) keep Agapanthus on site over winter and treat with chemical pesticides in spring. If found free after treatment, plant material can be sold or moved.
The pest status of the agapanthus gall midge is officially declared as: Present (restricted distribution).
Sources
NPPO of the United Kingdom (2015-09).