Ophiomyia phaseoli (Tryon)
(Also known as Agromyza phaseoli Coquillett and Melanagromyza phaseoli Coquillett).
Taxonomic placing: Insecta, Holometabola, Diptera, Brachycera, Agromyzidae.
Common name: Bean fly; snap bean fly.
Geographical distribution: A tropical and subtropical species that occurs in Australia, Africa, Asia and the Middle East.
Morphology: Adults about 2 mm in length with a black body and large red eyes, The maggot is white, about 3-4 mm long,
Host plants: Various legumes, especially beans and peas.
Life history: These flies lay an average of 100-200 eggs/female on the host leaves, whereon the young maggots feed. Later they enter the midrib, move into the stem and mine down to soil level, into the taproot. The feeding causes stems to form lesions wherein the maggots pupate, sometimes in small groups. Pest fecundity and longevity vary according to the specific host plant. The adult flies feed on plant secretions and on sap exuding from feeding holes. In the Middle East the pest completes several annual generations.
Economic importance: Ophiomyia phaseoli is one of the most dangerous agromyzid flies in the world. In tropical to subtropical Asia it is a major pest of most edible legumes, such as beans and peas. The extent of damage varies from crop to crop and season to season, being especially severe to seedlings. If the attacked plant survives, the effect of the injury may be manifested later, in the older plants. In severe attacks infested leaves initially hang down, then wilt and may even drop. The stems can crack and yield is low. Overall plant growth is stunted and it may die; yield losses in some east-Asian countries can come to 30-50% and even to 100%.
Management:
Monitoring: Seedlings are to be examined for pest symptoms, such as oviposition marks on the leaves, and for the small and shiny black flies with clear wings. The presence of swollen and cracked stems at the plant base also indicates pest infestation.
Horticultural methods: Destruction of crop residues with symptoms of damage and removal of any wild legumes around the crop area. Covering the seedlings with straw to protect them against oviposition by the pest. Crop rotation, using crops like maize or leek, (Allium porum L.), which are unattractive to the fly and may even repel. It.
Plant tolerance: Pest-tolerant varieties of bean and other legumes have been bred and are available at AVRDC (the Asian Vegetable Research and Development Center , now known as the World Vegetable Center). Such tolerance is associated with high trichome density on leaves and stems, purplish and smaller diameter stems, and smaller unifoliate leaves.
Chemical control: Sprays of Neem or a neonicotinoid control the pest.
Biological control: Several parasitoids attack the fly in different parts of the world where it infests various hosts. The more common enemy is the braconid Opius phaseoli Fischer, which may cause almost 90% pest mortality in some regions. Species of Sphegigaster spp. (Pteromalidae) may bring about 45% fly mortality.
References
Abate, T. 1991. The bean fly, Ophiomyia phaseoli (Tryon) (Diptera: Agromyzidae) and its parasitoids in Ethiopia. Journal of Applied Entomology 111: 278-285.
Abul-Nasr, S. and Abdel-Halin, M.A. 1966. Some ecological aspects concerning the bean-fly, Melanagromyza phaseoli (Tryon). Bulletin de la Société Entomologique d’Égypte 50: 163-172.
Bandara, K.A., Kumar, V., Ninkovic, V., Ahmed, E., Pettersson, J. and Glinwood, R. 2009. Can leek interfere with bean plant-bean fly interaction? Test of ecological pest management in mixed cropping. Journal of Economic Entomology 102: 999-1008.
Greathead, D.J. 1975. Biological control of the bean fly Ophiomyia phaseoli (Diptera: Agromyzidae) by Opius spp. (Hymenoptera: Braconidae) in the Hawaiian Islands. Entomophaga 20: 313–316.
Letourneau, D.K. 1994. Bean fly, management practices, and biological control in Malawian subsistence agriculture. Agriculture, Ecosystems and Environment 50: 103-111.
Songa, J.M. 1999. Ecology of the bean stem maggot attacking dry bean (Phaseolus vulgaris L.) in the semiarid areas of eastern Kenya. International Journal of Pest Management 45: 35-40.
Talekar, N.S., 1990. Agromyzid Flies of Food Legumes in the Tropics. Asian vegetable research and development center, Taiwan, Wiley Eastern Ltd., New Delhi. 297 pp.
Talekar, N.S., Yang, H.C. and Lee, Y.H. 1988. Morphological and physiological traits associated with agromyzid (Diptera: Agromyzidae) resistance in mungbean. Journal of Economic Entomology 81: 1352-1358.
Tengecho, B., Coulson, C.L. and d’Souza, H.A. 1988. Distribution and Effect of Bean flies, Ophiomyia phaseoli and O. spencerella, on beans at Kabete, Kenya. International Journal of Tropical Insect Science 9: 505-508.