Cecid flies, also known as Gall Midges, are considered a high risk pest to the Australian mango industry. The damaging fly species attacks the leaves of mango trees, impacting flowering, fruit set and fruit quality.
A number of cecid fly species are found across South East Asia and may be creeping closer to the mango production regions of Australia, with one species recently invading Torres Strait and the northern tip of Cape York.
Cecid flies may be spread by wind currents and if this pest were to become established in Australia, it could have devastating consequences for the Australian mango industry.
Researchers are currently working in the Philippines and Cambodia where the cecid fly is widespread, to develop management practices to limit the risk to the Australian mango industry.
Department of Agriculture and Fisheries’ Senior Entomologist and project leader of the Philippines project, Dr Ian Newton said that it makes sense to study the pest in countries where it is already established.
“Cecid fly is a high priority emergency pest for the Australian mango industry. We want to learn as much about this pest as we can so we know the best way to manage it if it ever makes its way to the mango production regions of Australia. This includes looking at existing biological controls in the Philippines and developing management practices so we will be well equipped to manage an incursion,” he said.
“Although the project is in the early stages, it has already uncovered some interesting findings. The species of cecid fly that recently invaded Cape York appears to be one of those found in the Philippines. We have identified some of the pest’s natural enemies and documented the population dynamics of the species that show patterns of annual occurrence. This information will help time insecticide applications and the design of integrated pest management programs,” Dr Newton said.
The cecid fly is responsible for substantially decreased mango yields in many areas of the Philippines. Cecid flies lay their eggs on young mango leaves, stems, flowers or fruit, causing fruit to fall from the tree. Fruit that remains has brown scab-like spots, affecting quality and return price. Wart-like galls form quickly on leaves, which can curl up and drop off prematurely, causing dieback of whole branches.
Cambodia is an ideal location to study cecid fly, although the species found in this country are not as damaging as those found in the Philippines as they do not affect mango fruit. Leader of the Cambodian project, Dr Mark Hickey, said that the more that is known about all species of cecid fly, the more robust management strategies will be.
“Researchers have a solid understanding of the species of cecid fly found in Cambodia following extensive surveys of mango production regions. The work our team undertakes will add to the body of knowledge about cecid fly and increase the ability to protect Australian mangoes from this pest. By understanding of the damage cecid fly causes we can develop strategies to manage them,” he said.
Current management tools include pruning after harvest to reduce infestations because cecid flies are sensitive to sunlight. Cecid flies often reside on vegetation near mango orchards and clearing or spraying surrounding areas can reduce populations. Infested leaves and fallen fruits should be collected, burned, or sprayed with insecticide to prevent the spread. Likewise, bagging of fruits from 55 days to 60 days after flower induction could help prevent damage.
Future research will look at the ecology of the cecid fly to gain a greater understanding of the pests, their interactions with their environment and the most effective management and control techniques.
These research projects are co-funded by the Australian Centre for International Agricultural Research (ACIAR), the Queensland Department of Agriculture and Fisheries and the New South Wales Department of Primary Industries. ACIAR fund international and domestic research to improve the productivity and profitability of agricultural systems in partner countries as well as providing benefits to Australian agriculture. Research and development of integrated crop management for mango production in the southern Philippines and Australia is managed by Dr Ian Newton from the Queensland Department of Agriculture and Fisheries. Building a resilient mango industry in Cambodia and Australia through improved production and supply chain practices is managed by Mark Hickey from the NSW Department of Primary Industries.