Changes in food source profitability affect Nasonov gland exposure in honeybee foragers Apis mellifera L.

FERNANDEZ PATRICIA CARINA; FARINA WALTER

INSECTES SOCIAUX

BIRKHAUSER VERLAG AG

Lugar: BASEL; Año: 2001 p. 366 - 371

0020-1812

When arriving at a known artificial food source,foraging honeybees usually perform circular flights aroundthe feeding place prior to landing. During these flights beesexpose their Nasonov gland, an exocrine gland located at thebase of the 7th tergum, that releases a complex blend ofvolatiles. This behavior may continue even after the bee startsfood ingestion. The proportion of bees exposing the Nasonovgland and the duration of its exposure before and duringfeeding for individual bees were quantified. Trained beescollected sugar solution during 12 visits from a feeder locatedat 160 m from the hive. Five different reward programswere presented: three constant and two variable. The constantprograms offered 0.6, 1.2 or 2.4 M sugar for all 12 visits,while the variable programs delivered either 0.6, 1.2, 0.6 Mor 0.6, 2.4, 0.6 M, four visits for each molarity. Resultsshowed that sugar concentration changed the thresholds anddurations of Nasonov gland exposure. However, this relationshipwas found only for Nasonov exposure before beesbegan to feed. During feeding, a protruded Nasonov glandwas only observed for bees that had exposed it prior to feeding;suggesting that Nasonov gland exposure before feedingis a releaser of the during-feeding exposure. In variablereward programs, changes in sugar concentration were followedby changes in both thresholds and durations of exposure.However, Nasonov gland exposure during feeding didnot appear to decrease based on measurements of the lowprofitability during the current foraging visit. These resultssuggest that Nasonov gland exposure is programmed on thebasis of reward expectations, with the bees having acquiredthis information in