Survival strategies of stingless bees (Melipona subnitida) in an unpredictable environment, the Brazilian tropical dry forest

Abstract

-Unpredictable environments are a challenge to highly eusocial bees because unreliable food availability, owing mainly to seasonally unpredictable precipitation rates, renders the maintenance of permanent colonies difficult. Here, we investigated the strategy of the stingless bee Melipona subnitida to cope with elevated temperatures and extended, irregular periods of drought in the Brazilian tropical dry forest. We found a high association between colony behaviour (pollen foraging and brood production) and environmental parameters (abiotic factors and availability of pollen sources), suggesting that colonies tightly adjust their activities to the respective environmental conditions. This minimises unnecessary costs related to foraging and brood rearing when forage availability is low. Additionally, M. subnitida selectively foraged at the most lucrative pollen-sources (massflowering trees, plants with poricidal flowers), which indicates that the colonies maximise their food intake as soon as resources are available.Caatinga / floral resources / pollen foraging / brood-cell construction

Newly emerged workers of the stingless bee Scaptotrigona aff. depilis prefer stored pollen to fresh pollen

“…Pollen availability is seasonal in many tropical and subtropical areas (Aleixo et al 2014), so long-term pollen storage could be advantageous. Moreover, this process is even more important in regions with severe scarcity of pollen during some periods of the year (Maia-Silva et al 2015). Several studies provide evidence for the preservative properties of fermentation, including its use in the industry, such as in food preservation (Gilliam 1997).…”

“…For colony growth and development, forager bees collect pollen as main protein source (Michener 1974). To ensure a constant food supply and, consequently, increase the colony's chances of survival during events of resource scarcity, bees store pollen and nectar (carbohydrate source) in the nest (Roubik 1982;Maia-Silva et al 2015).…”

“…Our results suggested that fermented pollen attracted more bees potentially due to innate preference of young bees, higher levels of attractant substances present in fermented pollen, or due to associative learning reminiscent from larvae feeding habits. To ensure a constant food supply and, consequently, increase the colony's chances of survival during events of resource scarcity, bees store pollen and nectar (carbohydrate source) in the nest (Roubik 1982;Maia-Silva et al 2015).During pollen collection on flowers, foragers agglomerate pollen grains in their corbicula using nectar or salivary secretions. This process facilitates pollen adhesion to the corbicula (Herbert and Shimanuki 1978;Leonhardt et al 2007).…”

“…Our results suggested that fermented pollen attracted more bees potentially due to innate preference of young bees, higher levels of attractant substances present in fermented pollen, or due to associative learning reminiscent from larvae feeding habits. To ensure a constant food supply and, consequently, increase the colony's chances of survival during events of resource scarcity, bees store pollen and nectar (carbohydrate source) in the nest (Roubik 1982;Maia-Silva et al 2015).…”

Nectar profitability, not empty honey stores, stimulate recruitment and foraging in Melipona scutellaris (Apidae, Meliponini)

“…Serious shortage of floral resources may be found in deserts and semideserts. Although Melipona does not occur in true deserts, a few species do occur in tropical semi-arid regions (Zanella 2000;Camargo 2013;Maia-Silva et al 2015). These species could indeed provide us with answers to the question whether periodically reoccurring long periods of floral scarcity shape the regulation of food storage in a particular way.…”