English names: American Serpentine Leaf Miner, Chrysanthemum Leaf Miner
Nordic names: Serpentineminerfluen (DK), Floridankärpänen (FI), Floridaminérflue (NO), Amerikansk minerfluga (SE)
Major host plants
L. trifolii has been recorded from 25 families with preference shown for the Asteraceae. Hosts include several important crops both vegetable and ornamental.
Feeding punctures appear as white speckles between 0.13 and 0.15 mm in diameter. Oviposition punctures are smaller (0.05 mm) and are more uniformly round. Mines are typically serpentine, tightly coiled and of irregular shape, increasing in width as larvae mature. Larvae deposit excrements in a line inside the mines.
A map can be downloaded from EPPO's website. See instructions here.
Female puncture the leaves causing wounds which serve as sites for feeding or oviposition. The female may lay between 25 and 400 eggs, depending on the temperature, just below the leaf surface. Eggs hatch in 2-5 days. The duration of larval development is generally 4-7 days. L. trifolii usually pupariates externally, either on the foliage or in the soil just beneath the surface. Adult emergence occurs 7-14 days after pupariation, at temperatures between 20 and 30°C. At low temperatures emergence is delayed.
Adult flies are capable of limited flight. Dispersal over long distances is on planting material of host species. Cut flowers can also present a danger as a means of dispersal.
Detection and inspection
L. trifolii often produces a particularly convoluted, tightly coiled greenish-white mine, which is usually found towards the top of the leaf. The use of sticky traps, especially yellow ones, placed near host plants is a very effective method of collection and estimation of infestation. All Liriomyza species are similar and may be mistaken for each other on quick examination. Therefore, accurate identification requires laboratory examination.
Pest status and importance
L. trifolii is a major pest of a wide variety of ornamental or vegetable crops grown under glass or as protected crops in the EPPO region. It is apparently not capable of overwintering outdoors in northern Europe. As in the case of L. sativae, the damage is caused by larvae mining into the leaves and petioles. In addition to economic damage, L. trifolii is also known to be a vector of plant viruses.
Source of information
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Author: Christiane Scheel
Editor: Elise T. Yamamoto Buch