Liriomyza strigata (Meigen, 1830)
Closely related to Liriomyza huidobrensis and Liriomyza bryoniae. No morphological characters available for the separation of the adults of strigata from huidobrensis. The slight differences in the male distiphallus illustrated by Spencer are problematical. However, strigata is restricted to Europe where huidobrensis was only recently introduced. As far as known strigata occurs only outside greenhouses.
L. strigata is generally lighter than huidobrensis with the inner vertical bristle on yellow cuticle.
The species can be readily distinguished from bryoniae by the peculiar mines being associated with the midribs of the leaves.
For separating strigata from other agromyzids than the relatives huidobrensis and bryoniae the peculiar aedeagus are a good diagnostic character.
IMPORTANT CHARACTERS
Adults
Wing length: 1.8 - 2.2 mm. Third segment of antennae with a very small point. Margin of eyes black reaching the outer vertical bristles but the inner ones are situated on yellow cuticle. Anepisternum yellow with black bar which is anteriorly bent upwards.
Male terminalia
Surstyli 'normally' with 2-3 apical spines (Spencer, 1973).
Immature stages
Corresponding to the different feeding habit, the larva has a slightly more cylindrical body shape with a rather blunt frontal part. This is rather typical for stem miners. The living larva is whitish colored instead of yellowish as in bryoniae.
BIONOMICS
The egg is laid near the margin of the leaf, young larva mines initially on the lower surface to the midrib above which, now on the upper surface, the main mine is formed, with lateral offshoots into the leaf-blade, frequently following one of the subsidiary veins (de Meijere, 1925 cited after Spencer, 1973). When the larva has reached the mid rib it first mines towards the leaf-base and then turns and feeds along the midrib apically, forming offshoots of varying length into the leaf-blade but always returning again to the midrib. In this respect, the mine is similar to that of the closely related species Liriomyza huidobrensis.
HOST PLANTS
Polyphagous species, Spencer, 1990 recorded 29 plant families, which contain species known as potential hosts. The following crops may be sometimes attacked: Beta vulgaris L., Lactuca sp., Pisum sativum L. and ornamental crops. The preferred wild hosts apparently belong to the families Asteraceae, Campanulaceae and Lamiaceae (Spencer, 1976 b).
DISTRIBUTION
Widespread in Europe, the eastern border of distribution is not known (Spencer, 1973).
In BMNH many old records which should be confirmed: India, Malaya, Singapore, China.
ECONOMIC IMPORTANCE
The species appears to occur only rarely in larger populations, serious damage caused by Liriomyza strigata is so far not known. The reason could be the large number of parasitoid species. But Spencer, 1973 noted: "However, with such an exceptionally wide host range, its potential to build up populations of pest proportions should be recognized."