> Pete, as I've pointed out repeatedly, the pollen supply of those colonies was NEVER restricted to any extent. 

Pollen-reduced colonies. Bottom-mounted OAC (Ontario
Agricultural College) pollen traps were placed on colonies on
26 August to simulate an early decline in the availability of external
pollen resources. Trapping ensured that colonies had restricted
access to pollen from goldenrod (primarily Solidago
canadensis L.) and aster ( Aster and Symphyotrichum spp.),
which are the main sources of autumnal pollen in the region.

Pollen-supplemented colonies. Colonies were supplemented
with pollen patties during autumn to simulate extended availability
of external pollen resources. Pollen from the trapped colonies
was sifted to remove debris and then made into a patty mixture by
combining (w/w) two parts pollen to one part sucrose solution
(67.5% solids content in water; Lantic Sugar, Montreal, Canada).

When colonies were supplemented
with pollen during autumn, thereby masking the natural decline
in the availability of pollen resources in the environment, they
reared significantly more workers, and reared them later in the
season. 

Conversely, the development of the
population of winter bees was accelerated by early loss of pollen
resources from the environment. Pollen-supplemented colonies
produced almost half of their winter bees during October, whereas
control and pollen-reduced colonies had already produced over
three quarters of their winter bees by the end of September.

Mattila, H. R., & Otis, G. W. (2007). Dwindling pollen resources trigger the transition to broodless populations of long‐lived honeybees each autumn. Ecological Entomology, 32(5), 496-505.

* * *

But, in the new research, they propose not a direct effect of pollen reduction but that reduction causes the nurses to cut back on feeding the larvae, initiating the longer lifespan. By the way, research prior to these studies showed that colonies vary in the number of long lived bees produced. It seems to me that if the trigger was known, hives could be influenced to produce more long lived bees in fall and have better winter survival. '

In further support of this anticipatory mechanism in honey
bees, a recent study suggests that the physiology and performance of
adult honey bees are affected by the interaction between larval
nutrition and adult nutrition (Hoover et al., 2006). Our study further
demonstrates the importance of considering both developmental
and adult environments when we study stress responses.

Wang, Ying, et al. (2016). Starvation stress during larval development facilitates an adaptive response in adult worker honey bees (Apis mellifera L.). Journal of Experimental Biology, 219(7), 949-959.

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