Determination of Flower Constancy in Bombus atratus Franklin and Bombus bellicosus Smith (Hymenoptera: Apidae) through Palynological Analysis of Nectar and Corbicular Pollen Loads

Abstract

The flower constancy (the visit to a single plant species during a foraging trip) in pollinator insects is a theme widely discussed in behavioral ecology and has an important implication in the evolution of angiosperms. This behavior was studied in the bumblebees Bombus atratus Franklin and Bombus bellicosus Smith through palynological analysis of the nectar and pollen loads of individuals captured while foraging in a restricted area. In both species, there were more individuals with constant flights than with non-constant ones, although in the nectar loads of B. atratus there were no significant differences between individuals with each flight types. It was verified that the nectar loads of the individuals that made either constant or non-constant flights did not differ in the number of pollen grains they contained. Considering this measurement as an estimate for flight duration, the results would indicate that the probability of changing between plant species during nectar collection is independent of the foraging trip duration. In both species, most individuals who collected nectar and/or pollen from more than one plant species visited just two plant species. In these cases, the pollen of one plant species was predominant. In the bumblebees in which it was possible to analyze nectar and pollen loads, the botanical origin of both resources was the same or they shared the principal species (with the exception of two individuals), showing that bumblebees do not often use a botanical source in an exclusive way to collect nectar and another to collect pollen.

Past, present and future distributions of bumblebees in South America: Identifying priority species and areas for conservation

“…(B. transversalis) and Cucurbita spp . (B. morio, B. bellicosus and B. pauloensis ), among others (A.B.E.L.H.A., 2020; Camillo & Garófalo, 1989; Cavalcante, Maués, & Freitas, 2012; Rossi, Santos, & Salvarrey, 2015). Among the studied species, B. morio , B. pauloensis and B. transversalis are classified as of ‘least concern’ by the International Union for Conservation of Nature (IUCN), while there are insufficient data for classification of B. bellicosus , B. brasiliensis and B. brevivillus .…”

When should bees be flower constant? An agent-based model highlights the importance of social information and foraging conditions

“…Why do bee species vary in their degree of flower constancy? Social bees, in particular, are often highly flower constant (Cholis et al, 2020; Free, 1963; Heinrich, 1976, 1979; Hill et al, 1997; Kozuharova, 2018; Pangestika et al, 2017; Rossi et al, 2015; Slaa et al, 2003; White et al, 2001; but see Martínez-Bauer et al, 2021), while flower constancy seems to be less pronounced in solitary bees (Bateman, 1951; Campbell & Motten, 1985; Eckhardt et al, 2014; Jakobsson et al, 2008; Pohl et al, 2011; Smith et al, 2019; Waser, 1986; Williams & Tepedino, 2003). Smith et al (2019), for example, studied pollen composition of 56 bee species and found that individual social bees showed a higher degree of specialisation during a foraging bout than solitary species.…”

Distribución de las especies del género Bombus Latreille (Hymenoptera, Apidae) en Uruguay

“…Por otro lado, se ha reportado la presencia de Bombus terrestris (Linnaeus) en Uruguay como consecuencia de su propagación espontánea luego de su introducción en América con fines comerciales (Dafni et al, 2010). Sin embargo, en los últimos 10 años sólo B. pauloensis y B. bellicosus han sido encontrados en el país (Arbulo et al, 2011(Arbulo et al, , 2015Salvarrey et al, 2013;Rossi et al, 2015). El objetivo de este estudio es constatar las especies de abejorros presentes en Uruguay y su distribución geográfica en el territorio del país.…”