Liriomyza chinensis (Kato, 1949)
In external view the three Liriomyza species feeding on Allium (cepae, nietzkei and chinensis) are untypical member of the genus and can be confused by the unusually dark appearance and black scutellum. However, the male genitalia are distinct. A further hint might be the angulate third antennal segment.
To separate the species within this group, the investigation of the male distiphallus is necessary.
IMPORTANT CHARACTERS
Adults
Wing length: 1.5 - 1.9 mm. Third antennal segment angulate. Frontorbital setulae rather strong.
Male terminalia
Only epandrium available: Very similar to Liriomyza cepae, same shape of surstyli and also with the single spine, which may be stronger than in cepae. Bacilliform sclerites well developed.
Immature stages
The larvae were described by Sasakawa, 1961 (as Phytobia cepae). To check his description of the larval mouth hooks I restudied a puparium of Liriomyza chinensis. Contrary to the drawing of Sasakawa (reproduced in Spencer, 1973) I found the mandibles clearly alternating with two mouth hooks on each mandible. The other parts of the immature stages were described correctly. The mandibles have distinct lateral sclerites, the elements of the cephalopharyngeal skeleton is generally strong and broad indicating similarities of the feeding habit of chinensis to that of true stem miners.
BIONOMICS
No details known, but probably similar as Liriomyza nietzkei and Liriomyza cepae.
HOST PLANTS
Allium cepa L., Allium bakeri Regel., A. fistulosum L., and A. odorum L. (Sasakawa, 1961) (not in host plant module); Allium porrum (leek) (Martinez, 1982), ?Allium sativum.
DISTRIBUTION
Apparently widespread in the eastern Palaearctic region. Records exist from Japan, Malaya, China and Singapore. However, the species is also present in Europe, records exist from France (Martinez, 1982) and Germany (von Tschirnhaus, personal communication).
ECONOMIC IMPORTANCE
Because of possible taxonomic confusions species records concerning leaf miner damage on onion should be handled with care, especially those from before 1973, when Spencer's book on agromyzids of economic importance appeared. The Liriomyza species causing the damage can be either Liriomyza cepae, Liriomyza chinensis (especially in the Eastern palaearctic region but also in Europe), or Liriomyza nietzkei (especially in Europe).
The larvae weaken the plants in destroying leaves. If they occur in large numbers all of these species have the potential to cause severe damage and are treated as serious pests by most authors (see literature). However, outbreaks seem to be rather intermittal and local.