Biology and Control of agapanthus gall midge


HNS PO 199 - Biology and Control of agapanthus gall midge

Start Date: 
Completion Date: 
Project Leader: 
Hayley Jones, Royal Horticultural Society
HNS PO 199

Industry Representative: Patrick Fairweather, Fairweather's Nursery

AHDB Horticulture Cost: £24,519

SummaryThe agapanthus gall midge is a newly emerged, undescribed 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.

As this pest is undescribed minimal information on its biology is available and no research on control methods has yet been carried out. Work is urgently needed to find effective and efficient strategies to control the midge. This project proposes to determine the pest’s life cycle and biology in order to help target control. Differences in susceptibility of Agapanthus varieties will be tested in the field. Experiments under controlled and field conditions will determine which of the currently available pesticide and biological control products give effective control. The knowledge gained from this project will be communicated to growers promptly and effectively.

Aims and Objectives

(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 IndustryThere 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. These estimates were generated by Patrick Fairweather and Charles Carr. Currently the only control option for growers is to remove infested flower heads, and to experiment with potential control methods. If control is ineffective the plants cannot be sold until the following year.

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. The results of the project will be communicated promptly to growers via AHDB Horticulture, RHS and ADAS communication channels.