Dietary dopamine causes ovary activation in queenless Apis mellifera workers

Abstract

-Groups of young honey bee workers were fed a diet containing dopamine while confined in small cages at 34°C and 80% RH in absence of a queen for 8 to 13 days. The bees in eight pairs of cages, each pair containing an equal number of workers, received a pollen-rich diet supplemented with dopamine (10 µg/g of diet) (DOP groups), or not supplemented (controls). The rate of consumption of the diet was monitored continuously during the confinement period, after which the workers were dissected to assess follicle development in the ovaries. The results showed a significantly higher proportion (P = 0.004) of workers with activated ovaries in the DOP groups than in control groups. The number of bees surviving confinement was significantly higher in the control groups than in the DOP groups (P ≤ 0.01), possibly reflecting a deleterious effect of dopamine. The surviving bees from both groups consumed equivalent amounts of diet (P = 0.687), showing that ovary activation was not due to differential diet consumption. The results suggest a role of dopamine in the chain of events mediating changes in the reproductive status of orphan honey bee workers. Apis mellifera / honeybees / dopamine / ovary activation

The role of the queen mandibular gland pheromone in honeybees (Apis mellifera): honest signal or suppressive agent?

“…Beggs et al (2007) showed that HVA reduces dopamine levels in the honeybee's brain. Because feeding of dopamine to worker bees elevates rates of ovarian activation (Dombroski et al 2003), HVA might be a potential agent within QMP involved in regulating worker sterility. Alas, HVA alone has not been demonstrated to cause suppression of worker ovaries.…”

Expression of the dopamine transporter in the brain of the honeybee, Apis mellifera L. (Hymenoptera: Apidae)

“…Much evidence also suggests that dopamine is involved in the ovary development and egg-laying behaviors in honeybees (Brandes et al, 1990;Harris and Woodring, 1995;Nagao, 2001, 2002;Dombroski et al, 2003;Harano et al, 2005) as well as in other insects (Neckameyer, 1996;Boulay et al, 2001;Sasaki et al, 2007). However, the effects of dopamine on workers and queens seem contradictory.…”

Social dominance and reproductive differentiation mediated by dopaminergic signaling in a queenless ant

“…One reason for this is a scarcity of empirical studies that show actual physiological effects of amines on fecundity and aggressiveness. Examples are limited to a few studies: oral administration of dopamine stimulates reproduction in honeybee queenless workers (Dombroski et al, 2003) and paper wasp workers (Sasaki et al, 2009). Another difficulty comes from the pleiotropic functions of biogenic amines.…”