The addition of floral resources is a common intervention to support the adult life stages of key crop pollinators. Fly (Diptera) crop pollinators, however, typically do not require floral resources in their immature life stages and are likely not supported by this management intervention. Here, we deployed portable pools filled with habitat (decaying plant materials, soil, water) in seed carrot agroecosystems with the intention of providing reproduction sites for beneficial syrphid (tribe Eristalini) fly pollinators. Within 12 to 21 days after the pools were deployed, we found that the habitat pools supported the oviposition and larval development of two species of eristaline syrphid flies, Eristalis tenax (Linnaeus, 1758) and Eristalinus punctulatus (Macquart, 1847). Each habitat pool contained an average (±S.E.) of 547 ± 117 eristaline fly eggs and 50 ± 17 eristaline fly larvae. Additionally, we found significantly more eggs were laid on decaying plant stems and carrot roots compared to other locations within the pool habitat (e.g., on decaying carrot umbels, leaves, etc.). These results suggest that deploying habitat pools in agroecosystems can be a successful management intervention that rapidly facilitates fly pollinator reproduction. This method can be used to support future studies to determine if the addition of habitat resources on intensively cultivated farms increases flower visitation and crop pollination success by flies.

Global warming has the potential to affect plant growth, with changes in flowering phenology and nectar rewards that have subsequent effects on pollinating insects. Despite the importance of native vegetation for provisioning pollinating insects, few studies have evaluated the impacts of elevated temperatures on floral resource supply of native plant species, particularly in Australia. To examine the effects of warming on the flowering phenology and nectar production of 11 herbaceous plant species endemic to south-eastern Australia, we conducted a glasshouse experiment spanning the flowering season with two temperature treatments (ambient: 30°C [TA]; elevated: 34°C [TE]). We found that plant species differed widely in their responses to warming. Flowering phenology changed significantly under TE in three species and flower production was reduced in three species. While there was no significant treatment effect on the number of nectar-producing flowers and nectar sugar concentrations across species, individual flower nectar volume increased with warming in one species. Meanwhile, aboveground biomass production was reduced under TE in three species, and three species experienced a reduction in relative biomass allocation to reproductive, compared to vegetative, growth. These changes in reproductive resource allocation and floral phenology could impact floral resource availability, plant-pollinator interactions and pollination services in the future, notably for those critical resources supplied by winter flowering species, at times when overall floral resource availability in the landscape is low. This represents a risk for the long-term viability of vulnerable plant communities, including remnant native vegetation, that are already threatened due to land use change.