MELON FLY (Bactrocera cucurbitae (Coquillett))
Female melon fly (Photo: S. Wilson) DISTRIBUTION: Native to tropical Asia and widespread as far west as Pakistan. It is present and common all over Papua New Guinea (but still absent on Manus and less common in the Highlands than at lower elevations). It was discovered in Solomon Islands in 1984, and is now widespread in all provinces, except Makira, Rennell-Bellona and Temotu. It has been introduced and occurs in Hawai'i (first detected in 1895), Guam (detected in 1936), Commonwealth of Northern Mariana Islands (detected in 1943, eradicated by sterile insect release in 1963, but reestablished, from neighboring Guam, in 1981), and Nauru (detected in 1982 and eradicated in 1999 by male annihilation and protein bait spraying, but re-introduced in 2001). It is also present in some parts of Africa (Kenya, Tanzania, Mauritius, Réunion).
HOST PLANTS: Over 125 species of hosts have been recorded for this species, based on extensive host surveys in Asia and Hawai'i. Plants in the family Cucurbitaceae are, however, the usual hosts. In southeast Asia, it has been reared from 42 host species, in 26 genera and 12 families (Allwood et al, 1999). Nine species of cucurbit hosts have been recorded in the Pacific. There are numerous records from other plant families, many requiring confirmation. Some of the non-cucurbit hosts recorded in Asia and Hawaii include, among others, beans (Vigna unguiculata and Phaseolus vulgaris) and papaya (Carica papaya). Host species recorded in surveys in Papua New Guinea, Solomon Islands, Nauru and Northern Mariana Islands (published in Wong et al, 1989) are: Detailed host list.
BIOLOGY: Adults mate at dusk. Female flies start laying eggs 11-12 days after their emergence from pupae. Females lay eggs primarily on cucurbits, but can infest a wide range of other fruits and fleshy vegetables. Over 125 hosts have been recorded in Hawaii. Eggs are laid in batches of 1-40 eggs in young to ripe fruits, but also on flowers, buds and even leaf stalks and stems of host cucurbits. One female may lay over 1000 eggs during her life. Oviposition peaks occur in the morning and late afternoon. Eggs hatch in about 24 hours.
Development time varies from 4 to 17 days (larva) and 7-13 days (pupa), depending on temperature and host. In Solomon Islands, development from egg to adult takes 13 days at 29°C. Adults are long-lived, typically up to 150 days, but 240-460 days under cooler temperature. This species is uncommon in the forest.
This species is kept in laboratory colonies in Solomon Islands and in Papua New Guinea. Heat tolerance studies were done in Hawaii.
ECONOMIC IMPORTANCE: Melon fly causes considerable damage to all cucurbit crops everywhere it occurs. In Papua New Guinea, 95% of bitter gourd fruits are infested and destroyed. In Solomon Islands, it attacks over 90% of snake gourds and 60-87% of pumpkins.
MALE LURE: Cue-lure.
QUARANTINE SURVEILLANCE: Cue-lure trapping and regular host fruit surveys of Cucurbitaceae.
OPTIONS FOR RESPONSE (If newly discovered in a country): Increased trapping, increased host fruit sampling, restriction of fruit movement, protein bait spraying, male annihilation (see Nauru page), sterile insect technique (see Northern Marianas page).
CONTROL: Protein bait spraying, destruction of fallen and overripe fruits, early harvest of mature green fruits.
REFERENCES: (Does not include papers from Asia and Hawaii).
Allwood, A.J., Chinajariyawong, A., Drew, R.A.I., Hamacek, E.L., Hancock, D.L., Hengsawad, C., Jinapin, J.C., Jirasurat, M., Kong Krong, C., Kritsaneepaiboon, S., Leong, C.T.S., and S. Vijaysegaran. 1999. Host plant records for fruit flies (Diptera: Tephritidae) in South-East Asia. The Raffles Bulletin of Zoology. Supplement 7. 92 pp. (Complete host list in Asia).
Drew, R.A.I. 1989. The tropical fruit flies (Diptera: Tephritidae: Dacinae) of the Australasian and Oceanian regions. Memoirs of the Queensland Museum. Volume 26. 521 pp. (Description and illustration).
Eta, C.R. 1985. Eradication of the melon fly from Shortland Islands (special report). Solomon Islands Agricultural Quarantine Service, Annual Report. Ministry of Agriculture and Lands, Honiara.
Hollingsworth, R., Allwood, A.J. 2000. Melon fly. SPC Pest Advisory Leaflet. Draft. 2pp.
Hollingsworth, R., Vagalo, M., Tsatsia, F. 1997. Biology of melon fly, with special reference to Solomon Islands. pp. 140-144 in: Allwood, A.J., and Drew, R.A I., Management of fruit flies in the Pacific. ACIAR Proceedings No 76. 267pp. (Host list, seasonal abundance).
Johnson, V. 1988. Survey of melon fly in the Solomon Islands, final report. Internal report, Agricultural Quarantine Service, Solomon Islands Government.
Mitchell, W.C. 1980. Verification of the absence of Oriental fruit and melon fruit fly following an eradication program in the Mariana Islands. Proceedings, Hawaiian Entomological Society. 23: 239-243.
Steiner, L.F., Harris, E.J., Mitchell, W.C., Fujimoto, M.S., Christenson, L.D. 1965. Melon fly eradication by overflooding with sterile flies. Journal of Economic Entomology. 58: 519-522.
Tsatsia, F., Hollingsworth, R. 1997. Rearing techniques for Dacus solomonensis and Bactrocera cucurbitae in Solomon Islands. pp. 157-160 in: Allwood, A.J., and Drew, R.A I., Management of fruit flies in the Pacific. ACIAR Proceedings No 76. 267pp.
Wong, T.Y., Cunningham, R.T., McInnis, D.O., Gilmore, J.E. 1989. Spatial distribution and abundance of Dacus cucurbitae (Diptera: Tephritidae) in Rota, Commonwealth of the Northern Mariana Islands. Environmental Entomology. 18: 1079-1082.
Download Pest Advisory Leaflet on Melon Fly in English (192 Kb)
Page updated on: 12 November, 2002