Biology and ecology of Tephritomyia lauta (Diptera: Tephritidae) in Lebanon -

Abstract

The flower-head infesting tephritid, Tephritomyia lauta, is a specialist on globe thistle, Echinops species. The fly emerges from May to October at different elevations in Lebanon. The fly is closely associated with the phenology of its host plant reducing their host reproductive capacity as larvae feed and destroy seeds. The biology of this species is not well documented, and the immature stages have not been described. In this study, we aim to shed light on the life cycle, resource utilization, and ecology of T. lauta, as well as determining the extent of intraspecific variations within its different populations in Lebanon. Flower head dissection of Echinops spp. showed that the eggs are deposited singly on the inner side of the bracts surrounding the seeds. As the larvae hatch, they tunnel and feed inside one achene each. The pupa occupies all of the inner space of the achene while tightly adhering to the inner seed coat. Because larvae and pupae are concealed within individual achenes, detection requires dissection of individual achenes. Third instar larvae from E. viscosus are significantly larger than those associated with the relatively smaller flower heads of E. gaillardotii. The larger flower heads of E. viscosus can sustain more larvae per flower head (average of 13 vs. 6) than those of E. gaillardotii. The larvae suffer mortality by the ectoparasitoid, Pteromalus sp. and the observed percent parasitism was around 42percent in all collected samples. Morphometric studies on T. lauta adults, using two head and four wing measurements, revealed that the length of dm vein, second radial vein R₂₊₃ and length of third radial vein R₄₊₅ are significantly longer in adults reared from E. viscosus. This reflects that T. lauta flies can reach a larger size when reared in larger flower heads, as the length of dm vein is often correlated to body size in the Tephritidae. Nevertheless, the ovipositor length do not differ in females reared from both Echinops species. Females of T. laut