Liriomyza trifolii (Burgess)
Common name: Serpentine leafminer.
Geographical distribution: This pest, of North America origin, has spread around the world due to the international transport of plant material. CIE Map # 450, 1984.
Common name: Serpentine leafminer, American serpentine leafminer.
Host plants: Polyphagous, infesting plants in many families, especially the Asteraceae (Compositae), as well as various weeds.
Morphology: Adults about 1.3-2.3 mm in length, grey-black with bright yellow sides. The yellow-orange maggot is legless, 2-3 mm in length.
Life cycle: Females puncture leaf surfaces with their ovipositor to feed on the plant juices and to insert their eggs (200-400/female, depending on the host) under the epidermis of the upper leaf. The hatching larvae burrow twisting, serpentine tunnels within the leaf; thus the pest’s common name. The size of the mines increases with larval growth. The mature larvae drop to the ground and pupate there. The females live for a few weeks; the estimated threshold of development is between 9.9 and 10.7ºC. The pest prefers warm climates, being active outdoors the year around in tropical regions, infesting crops throughout the year in protected crops.
Economic importance: In the open this pest attacks ornamentals, vegetables like tomatoes and beans, and (more recently in Turkey) cotton. In greenhouses L. trifolii infests vegetables and also ornamentals, especially chrysanthemums. Injury is due to aesthetic damage from feeding punctures and tunnels, which results in leaf stippling and premature drop, opening invasion wounds for bacteria and molds and to the reduction of photosynthesis. Damage to ornamentals can be especially severe because many countries, and even retailers, will not accept plants or cut flowers with a single fly blemish.
Sampling: Counting live larvae and/or mines in infested leaves, collecting pupae, rearing adults from foliage, catching adults with a vacuum sampler and trapping adults on yellow sticky boards.
Horticultural control: Sanitation, including the removal and destruction of infested plants and weeds, as well as deep plowing crop residues. There has been limited success in using trap plants in covered crops.
Plant resistance: Research on resistant tomatoes focuses on developing plants with a high density of glandular trichomes, which physically reduce feeding and restrict oviposition sites. Other crops, such as lettuce, spinach and celery are also being evaluated for resistance.
Effect of Radiation: Low doses of gamma radiation applied to eggs or 1st-instar larvae of the pest resulted in very few flies becoming adults and the few survivors died before breeding.
Sterile insect technique (SIT): Sterilizing the males of L. trifolii significantly reduced the number of the pest’s progeny. Best results were obtained when such males were combined in an IPM programme in a chrysanthemum greenhouse with releases of the parasitoid Diglyphus isaea Walker.
Chemical control: The pest has become resistant to many pesticides. Abamectin and neem, applied in sequence, reduced pest damage to beans in Egypt. Bensulpat controlled the fly in Turkey, as did aqueous extracts from two plants. Chemica; treatments should be targeted at the young, susceptible larvae.
Biological control: About 40 species of endoparasitoids attack L. trifolii world-wide. The more important in the Middle East are the Eulophidae Diglyphus isaea (Walker), Diglyphus crassinervis Erdős and Neochrysocharis formosa (Westwood), which control the pest on various crops. In Europe some success has been achieved with entomopathogenic nematodes.
Abd-Rabou, S. 2006. Biological control of the leafminer Liriomyza trifolii by introduction, releasing and evaluation of the parasitoids Diglyphus isaea and Dacnusa sibirica on vegetable crops in greenhouses in Egypt. Archives of Phytopathology and Plant Protection 39: 439-443.
Broadbent, A.B. and Olthof, T.H.A. 1995. Foliar application of Steinernema carpocapsae (Rhabditida: Steinernematidae) to control Liriomyza trifolii (Diptera: Agromyzidae) larvae in chrysanthemums. Environmental Entomology 24: 431-435.
Civelek, H.S. and Weintraub P.G. 2003. Effects of bensultap on larval serpentine leafminers, Liriomyza tirfolii (Burgess) (Diptera: Agromyzidae), in tomatoes. Crop Protection 22: 479–483.
Civelek, H. S. and. Weintraub, P.G. 2004. Effects of two plant extracts on larval leafminer Liriomyza trifolii (Diptera: Agromyzidae) in tomatoes. Journal of Economic Entomology 97: 1581-1586.
Ferguson, J.S. 2004. Development and stability of insecticide resistance in the leafminer Liriomyza trifolii (Diptera: Agromyzidae) to cyromazine, abamectin, and spinosad. Journal of Economic Entomology 97: 112-119.
Freidberg, A. and Gijswijt, M.J. 1983. A list and preliminary observations on natural enemies of the leaf miner Liriomyza trifolii (Burgess) (Diptera: Agromyzidae) in Israel. Israel Journal of Entomology 17: 115-116.
Kaspi, R. and Parrella, M. P. 2006. Improving the biological control of leafminers (Diptera: Agromyzidae) using the sterile insect technique. Journal of Economic Entomology 99: 1168-1175.
Minkenberg, O.P.J.M. and van Lenteren, J. 1986. The leafminers Liriomyza bryoniae and L. trifolii, their parasites and host plants: a review. Agricultural University Wageningen Papers 86-2.
Mou, B. and Ryder, E.J. 2003. Screening and breeding for resistance to leafminer (Liriomyza langei) in lettuce and spinach. In: van Hintum, Th.J.L., Lebeda, A., Pink, D. and Schut, J.S.W. (Eds.) Eucarpia Leafy Vegetables, Noordwijkerhout, Netherlands, pp: 43-47.
Saad, A.S., Massoud, M.A., Abdel-Megeed, A.A., Hamid, N.A., Mourad, A.K. and Barakat, A.S. 2007. Abamectin, pymetrozine and azadirachtin sequence as a unique solution to control the leafminer Liriomyza trifolii (Burgess) (Diptera: Agromyzidae) infesting garden beans (Phaseolus vulgaris L.) in Egypt. Communications in Agricultural and Applied Biological Sciences 72: 583-93.
Yathom, S., Padova, R., Chen, M. and Ross, I. 1991. Effect of gamma irradiation on sterility of Liriomyza trifolii flies. Phytoparasitica 19: 149-152.
Phyllis G. Weintraub, e-mail: email@example.com Gilat Research Center D.N. Negev, 85280, Israel