Ophiomyia pinguis (Fallén, 1820)
Larvae of Ophiomyia pinguis can be confused with those of Napomyza cichorii which frequently occurs on the same host plant. Since both species belong to different subfamilies, the larvae of both species can be distinguished by the cephalopharyngeal skeleton (agr-phy-larva.pct, Ophiomyia gr. ceph.pct).
IMPORTANT CHARACTERS
Adults
Wing length: 1.9 - 2.3 mm. O. pinguis can be easily identified by external characters: elongated mouthparts (proboscis) in both sexes (Oph pinguis head.pct) and two additional characters found in males only: missing orbital bristles, extremely amplified, proclinate frontorbital setulae.
Immature stages
Larval mandibles rather strong, each with one hook, the left one enlarged. The shape of the cephalopharyngeal skeleton is typical for Ophiomyia.
HOST PLANTS
Cichorium endivia (endive) Cichorium intybus (chicory, witloof), also Lactuca sativa L. (lettuce), Leontodon sp.
BIONOMICS
The larvae feed mainly in the leaf nerves and in the petioles of the plants. No colored frass can be found in the mine, the mine can be very long. One larva can infest several leaves, which are entered from the petiole. Pupation takes place within the mine, the puparium subsequently develops within living or dead plant matter.
The adults emerge from end of March to mid April. In Lombardy (Italy) there are 3 - 4 generations per year. The egg hatches after about 10 days and larval feeding in the first generation lasts for 18 - 25 days (SÜss, 1971). Probably both the number of generations and the feeding time depends strongly on climatic factors. Larval feeding is usually continuing in the winter and can affect late grown lettuce and chicory. The latter is crucial since the final processing (forcing) of the chicory heads takes place in the winter. Larvae mining through the chicory heads and leaving their brownish traces can reduce the market price of the product considerably. However, the summer generations may reduce the vigor of the chicory plants and may contribute to yield reduction.
DISTRIBUTION (Spencer, 1973)
Widespread in Central Europe, also found in Russia, Tadzhikistan, Uzbekistan, India (Kashmir) (Zaka ur Rab, 1981) and Egypt.
ECONOMIC IMPORTANCE
Together with Napomyza cichorii, Ophiomyia pinguis is a serious danger for chicory and lettuce plantations, mainly since it reduces the market value of the crops.