Early resources lead to persistent benefits for bumble bee colony dynamics

Abstract

Conditions experienced early in development can affect the future performance of individuals and populations. Demographic theories predict persistent population impacts of past resources, but few studies have experimentally tested such carry-over effects across generations or cohorts. We used bumble bees to test whether resource timing had persistent effects on withincolony dynamics over sequential cohorts of workers. We simulated a resource pulse for field colonies either early or late in colony development and estimated colony growth rates during pulse-and non-pulse periods. During periods when resources were not supplemented, early-pulse colonies grew faster than late-pulse colonies; early-pulse colonies grew larger as a result. These results reveal persistent effects of past resources on current growth and support the importance of transient dynamics in natural ecological systems. Early-pulse colonies also produced more queen offspring, highlighting the critical nature of resource timing for population, as well as colony, dynamics of a key pollinator.

Flower plantings support wild bee reproduction and may also mitigate pesticide exposure effects

“…Two small B. vosnesenskii colonies, containing a queen and 17–25 workers ( M ± SD 20.7 ± 3.0) and brood in all stages, were placed at each site (Figure 1) 18 April–10 May 2017 (see Malfi et al, 2022 for details). The four colonies at paired flower planting and control sites were placed on the same day, with random allocation of colonies.…”

“…Every 10 days, colonies were weighed (Malfi et al, 2022) and pollen was collected from foragers returning to the colonies during 1 hr between 09:00–15:00, with observations alternating between morning and afternoon among sites with and without flower plantings. If fewer than 10 pollen foragers had been caught at the end of the hour, pollen collection continued until 10 pollen‐carrying bees had been caught or the total collection time reached 2 hr.…”

“…The four colonies at paired flower planting and control sites were placed on the same day, with random allocation of colonies. Colonies were raised from wild queens caught near Monterey, California during March 2017 (Permit #SC-13698; for details see Malfi et al, 2019Malfi et al, , 2022Williams et al, 2012). No other permits or licences were needed for the study.…”

Floral resource continuity boosts bumble bee colony performance relative to variable floral resources

“…While laboratory studies can provide insights into the mechanisms driving colony responses to variable resource abundance, field experiments are needed to understand how colonies respond under more natural, free‐foraging conditions where foraging energy expenditures factor into colony economics. To date, few studies address how variability in resources over time influences colony performance (but see Malfi et al, 2021).…”

“…Because bumble bee colonies are long‐lived, the continuous availability of flowers during colony establishment and growth is thought to be critical to colony success (Hemberger et al, 2020; Kevan & Baker, 1983; Schellhorn et al, 2015). For example, worker production in colonies of B. terrestris Linnaeus and B. vosnesenskii Radoszkowski are positively linked to early‐season resource availability, suggesting that shortfalls in these resources could negatively impact growing colonies, limiting their ability to produce reproductive individuals (gynes) later in the season (Crone & Williams, 2016; Malfi et al, 2021; Westphal et al, 2009; Williams et al, 2012). Additionally, late‐season mass‐flowering crops benefit queen production in B. terrestris by eliminating a late‐season resource gap (Rundlöf et al, 2014).…”