Biology and Control of agapanthus gall midge

The agapanthus gall midge (Enigmadiplosis agapanthi) is a newly emerged, recently described pest affecting Agapanthus. It poses a risk to both containerised plants and cut flowers, as midge infestation causes flower buds to be deformed and discoloured, often failing to open. Heavy infestations can lead to entire flower heads being aborted.

The pest has a long and persistent active season and can infest many tissues of Agapanthus flower heads. Currently, only detection and destruction of infested material can be recommended to growers. Further research into biological and chemical controls is needed.

(i)     Project aim(s):

To determine the biology of agapanthus gall midge and identify control methods

(ii)    Project objective(s):

1. Determine and describe the life cycle of agapanthus gall midge
2. Confirm the distribution and host range
3. Quantify the effectiveness of potential chemical and biological controls
4. Communicate the results to the industry

Benefits to Industry: There are around 100 growers of Agapanthus plants in the UK, selling at least 1.25 million stems to the cut flower trade and 400,000 containerised plants per year. Infestation of flower heads with agapanthus gall midge makes the plants and stems unsaleable as it ruins the appearance. The cost to an infested nursery, based on estimates of £3 production cost per pot and potential crop loss of 70% in an infested nursery, is approximately £840,000.

This research aims to generate knowledge that will enable growers to implement a control strategy for the agapanthus gall midge, ideally to prevent infestation as well as to control existing infestations. Confirming the distribution, host range and varietal differences in the effects of the midge will highlight which geographic areas and commercial cultivars are most at risk, enabling growers to be informed and monitor accordingly. The experiments on chemical and biological controls will determine which commercially available products are effective. Understanding the biology and life cycle of the pest should enable targeted and timely use of control methods, so that control is efficient and cost-effective.