Age-stage two-sex life table analysis ofEristalinus aeneus(Diptera, Syrphidae) reared with two different larval media

Abstract

Eristalinus aeneus (Scopoli, 1763) is a suitable candidate for artificial rearing due to its pollination efficiency and subcosmopolitan distribution. However, the high mortality found at the larval stage of this species needs to be overcome. In this research, two different larval media were used to study the life cycle of E. aeneus: brewery spent grain (BSG) from a local craft-beer factory and soaked oat grains (SOG). The age-stage, two-sex life table method was used to analyze the results, which were compared using the paired bootstrap test. The greatest mortality was found at the larval stage with both media. Individuals fed on SOG presented a shorter preadult developmental time (22.05 days) than those reared with BSG (26.97 days). This fact had a direct impact on the total preoviposition period, it being shorter with SOG (34.36 days) than BSG (38.29 days), although the second provided a larger total number of eggs (19,242 eggs) and a faster adult maturation (10.67 days). The population parameters indicated that both populations will display a positive growth under the studied conditions, being the mean generation time (T) significantly shorter when using SOG (38.71 days) than BSG (45.95 days). Despite the preadult results pointing to SOG being a more efficient medium, the promising fecundity values provided by BSG, as well as it's lower cost and ecological benefits, suggest that this second medium could be improved and used as an alternative to SOG in the near future.

Different Sensitivity of Flower-Visiting Diptera to a Neonicotinoid Insecticide: Expanding the Base for a Multiple-Species Risk Assessment Approach

“…Fecundity of individual E. aeneus females was assessed daily for 7 days. To promote egg laying, we provided a substrate of decaying soaked oat grains [69,70] for each individual female. The substrate was prepared with organic oat and distilled water (200 g per 175 mL) and left for 24 h at room temperature in complete darkness.…”

Episyrphus balteatus symbiont variation across developmental stages, living states, two sexes, and potential horizontal transmission from prey or environment

“…Tens of thousands of migrating E. balteatus were previously reported dead on a strandline in the south of France without any warning (Fisler and Marcacci, 2022). In addition, high mortality also existed at the larval stage of some hoverfly species such as Eristalinus aeneus (Campoy et al, 2022). It is speculated that the establishment, maintenance, and refreshing of symbiosis with bacteria for hoverflies are important and dynamic.…”