Nectar collecting in honeybees: How do changes in the relative food source profitability exploited by individual bees affect the social foraging activity?

PÍREZ, N.; DE MARCO, R.J.; FARINA, W.M.

Foz do Iguaçu, Brasil

Congreso; XXI International Congress of Entomology; 2000

International Congress of Entomology

When a foraging group of honeybees (Apis mellifera ligustica) exploits a floral patch, the recruitment mechanisms displayed inside the hive as well as the number of bees arriving at the feeding place change according to the actual food source profitability. However, bees returning from a constant profitable food source could modify their recruitment behaviors according to changes in the social context of the hive, a fact that could incidentally affect recruitment levels in hive mates exploiting other feeding places. With the aim to study this problem, interactions between an individual forager returning from a constant profitable rate-feeder and a group of bees exploiting an alternative feeder that fluctuated in terms of sugar solution flow were analyzed in a flight enclosure. We used two rate-feeders offering an unscented sugar solution of 1.8 M. The first one was located at the end of a one-meter corridor that measured 100 x 15 x 15 cm (1) while the other was inside a flight enclosure of 6 x 3 x 2 m (2). Only one (individually) trained bee was allowed to forage at the rate-feeder that delivered 5 ul/min of sugar solution. At the rate-feeder (2) we used a decreasing profitability program presenting a sugar solution flow rate of 90 ul/min at first and 3 ul/min after four foraging cycles performed by the trained bee collecting sugar solution from feeder (1). At the same time the number of bees foraging per min in the flight enclosure was quantified, we also recorded the dancing and trophallactic behavior performed in the hive by the individual bee returning from rate-feeder (1). When the sugar solution flow rate offered at the flight enclosure was decreased, the number of foraging bees showed an oscillatory response. In such cases, some of these increasing fluctuations were positively correlated with a previous permanence in the hive by the individual bee that foraged at the constant profitable feeder (1). On the other hand, when the sugar solution intake rate of the colony was artificially reduced, we also observed an increase either in the number of dancing events performed or in the trophallactic giving contacts by the same trained bee. Thus, the size of a group of foragers exploiting a fluctuating profitable food source can instantaneoulsy increase in response to changes in the recruiting behavior of individual foragers which actually exploit other sources in the surrounding environment.