Foraging behavior of individual workers and foraging dynamics of colonies of three Sumatran stingless bees

Abstract

SummaryThe foraging behavior of three stingless bees, Trigona (Tetragonula) minangkabau, T. (Trigonella) moorei and T. (Heterotrigona) itama, was studied to describe patterns of resource harvest in disturbed forest areas in Sumatra, Indonesia. Average daily total number of foraging flights per colony was 1200 in T. minangkabau, 2400 in T. moorei and 7000 in T. itama and it was proportional to colony population size. Foragers collecting nectar, pollen or plant resin were respectively 70–80%, 10–20% and <10% in the three species. Pollen was collected most in the morning. Nectar collection peaked in midday in T. itama but continued almost evenly until dusk in T. minangkabau and T. moorei. Resin was collected evenly throughout day. In all the three species the volume of a nectar load carried by a returning forager did not decrease until 1600, followed by slight decline. In the morning the sugar concentration of nectar was almost constantly 30%, and in the afternoon its maximum value reached 60% although some remained 30%. As a result, the mean sugar weight in a nectar load gradually increased until dusk. In T. minangkabau, resin was collected by specialized foragers. Nectar foragers switched to collect pollen and vice versa. There were two types of foraging: “exploitatory” flights, the repitition of short, rather constant flights bringing back full resource loads, and “exploratory” flights, prolonged flight and/or reduction in amount of resources carried. Exploitatory flights followed the exploratory flights which led to discovery of rich sources. Mean duration of exploitatory flights was 7 min during nectar collection, 12 min for pollen and 23 min for resin. Sites of exploited flowers were estimated to be 84–434 m distant from the nest site. Mean duration of flights for nectar collection was 13 min in the morning and 6 min in the late afternoon.

Effect of food availability on individual foraging specialisation in the stingless beePlebeia tobagoensis(Hymenoptera, Meliponini)

“…We found support for this hypothesis in the stingless bee Plebeia tobagoensis where 71% of the foragers focussed on the collection of one food commodity when the commodity was always available. Lower percentages of specialists were found in other studies on foraging task specialisation in stingless bees and other social bee species (30-70% specialists (Ribbands, 1952;O'Donnell et al, 2000;Biesmeijer and Tóth, 1998;Inoue et al, 1985)). Those other studies were performed on foraging bees in their natural habitat where food availability fluctuates.…”

“…In bumble bees 30-40% of the foragers are specialists (O'Donnell et al, 2000). In the stingless bee Melipona beecheii about 50% of the foragers specialised on one food commodity during their foraging career (Biesmeijer and Tóth, 1998), while more than 70% of Melipona favosa (Sommeijer et al, 1983) and Trigona minangkabau (Inoue et al, 1985) foragers collected only one type of material over a sequence of days.…”

“…Variability in food availability and colony state are probably the most important factors affecting the degree of task specialisation of individual foragers. Although previous studies described the presence of specialised and flexible foragers in social bee colonies (Ribbands, 1952;Sommeijer et al, 1983;Inoue et al, 1985;Biesmeijer and Tóth, 1998;O'Donnell, 2000), nothing is known about proportional changes in specialised and flexible foragers resulting from changes in food availability.…”

An unusually large and persistent male swarm of the stingless bee <i>Tetragonula laeviceps</i> in Thailand (Hymenoptera: Apidae: Meliponini)

“…Additional males probably have come from more than the 23 nests we found in the study area. The flying range of the workers of the large Melipona fasciata Latreille was 2.1-2.5 km (Roubik & Aluja, 1983) and of the small T. minangkabau (Sakagami & Inoue) was less than 0.5 km (Inoue et al, 1985), hence that of T. laeviceps, somewhat larger than the latter, must be somewhere in between the two. But the flying range of males is assumed to be several times that of workers which, unlike the males, have to return to their nests each time with the collected forage.…”

Impacto da precipitação pluviométrica sobre a atividade de vôo de Plebeia remota (Holmberg, 1903) (Apidae, Meliponini)

“…Nos últimos anos, a atividade de vôo das abelhas sem ferrão tem sido estudada em vários aspectos, verificando-se que ela pode ser influenciada por fatores climáticos, tais como: temperatura, intensidade luminosa, umidade relativa, chuva e vento (Fowler 1979, Mouga 1984, Inoue et al 1985, Azevedo 1996, Contrera et al 2004, Souza et al 2006. Além disto, outros fatores, separados ou em conjunto, também podem afetar a atividade de vôo, como as condições internas da colônia (Hilário et al 2000, Fidalgo & Kleinert 2007), a divisão de tarefas (Biesmeijer & Tóth 1998, Nunes-Silva 2007, a fisiologia e o tamanho das abelhas (Imperatriz-Fonseca et al 1985), a temporização interna das abelhas (Mohammed & Starr 1999, Bellusci & Marques 2001, Hilário et al 2003, a diapausa reprodutiva (Pick & Blochtein 2002), a recompensa calórica do néctar (Roubik & Buchmann 1984), a disponibilidade de recursos florais na natureza (Nagamitsu & Inoue 2002, Pierrot & Schlindwein 2003 ou em estufa (Bruijn et al 1991, Bruijn & Sommeijer 1997) e a sazonalidade (Heard & Hendrikz 1993, Hilário & Imperatriz-Fonseca 2002, Borges & Blochtein 2005, Cortopassi-Laurino et al 2007.…”