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.

The hoverfly Eristalinus aeneus is an important pollinator of crops and wild plants. However, there is a lack of detailed information about its foraging behaviour and its potential as a managed pollinator of mango. Given the growing economic importance of protected cultivation of mango, our aim is to study the flight activity and foraging behaviour of E. aeneus on this crop. Eristalinus aeneus displayed a bimodal daily activity, with peaks during mid-morning and mid-afternoon. The activity was maintained over a wide range of temperature (from 17.8 up to 37.4°C), light intensity (from 8.2 up to 57.4 klux) and relative humidity (from 19.0 up to 88.8%). The syrphids were active most of the time in this crop, and we observed five different types of activity: foraging (67%), resting (17%), flying (10%), grooming (4%) and walking (2%). This hoverfly visited hermaphrodite flowers more often than male flowers. On average, it visited 36.46 ± 13.92 flowers per 5 min, with a higher number of floral visits for nectar feeding. The duration of the visits to hermaphrodite and male flowers was similar but pollen-feeding visits lasted longer (6.44 s per flower) than nectar-feeding ones (5.51 s per flower). The highest number of visits to mango inflorescences was observed during the morning, but the longest visits occurred at midday. The implication of these results for the potential use of E. aeneus as a managed pollinator in protected cultivation of mango is discussed.