Demography and population parameters of two species of eristaline flower flies (Diptera, Syrphidae, Eristalini)

The importance of eristaline flies (Diptera, Syrphidae, Eristalini) as pollinators in natural ecosystems and for agricultural crops is well known. However, in-depth studies on the life cycle of most of these species have yet to be carried out. The aim of this research was to study the life cycle of Eristalis tenax (Linnaeus, 1758) and Eristalinus aeneus (Scopoli, 1763) in order to improve the current rearing system employed at the University of Alicante. The results were analysed using the age-stage, two-sex life table method. As one of the main results, the mean duration of the life history of E. tenax and E. aeneus was 46.06 and 65.12 days (d), respectively. The most critical step for both species was found at the beginning of the larval stage (first instar), when the highest mortality was recorded. Population parameters were also analysed and compared. The intrinsic rate of increase (r), the finite rate of increase (lambda), the net reproductive rate (R-0) and the mean generation time (T) were 0.09 (d(-1)), 1.09 (d(-1)), 42.11 offspring and 40.97 d, in the case of E. aeneus and 0.05 (d(-1)), 1.05 (d(-1)), 23.13 offspring and 59.23 d, in the case of E. tenax. These results indicate that the current rearing system is more efficient for E. aeneus, which displays a faster population growth. However, some modifications need to be implemented to improve the production of E. tenax.