Resources or landmarks: which factors drive homing success in Tetragonula carbonaria foraging in natural and disturbed landscapes?

Abstract

To date, no study has investigated how landscape structural (visual) alterations affect navigation and thus homing success in stingless bees. We addressed this question in the Australian stingless bee Tetragonula carbonaria by performing marking, release and re-capture experiments in landscapes differing in habitat homogeneity (i.e., the proportion of elongated ground features typically considered prominent visual landmarks). We investigated how landscape affected the proportion of bees and nectar foragers returning to their hives as well as the earliest time bees and foragers returned. Undisturbed landscapes with few landmarks (that are conspicuous to the human eye) and large proportions of vegetation cover (natural forests) were classified visually/structurally homogeneous, and disturbed landscapes with many landmarks and fragmented or no extensive vegetation cover (gardens and plantations) visually/structurally heterogeneous. We found that proportions of successfully returning nectar foragers and earliest times first bees and foragers returned did not differ between landscapes. However, most bees returned in the visually/structurally most (forest) and least (garden) homogeneous landscape, suggesting that they use other than elongated ground features for navigation and that return speed is primarily driven by resource availability in a landscape.

Radiofrequency identification (RFID) reveals long-distance flight and homing abilities of the stingless bee Melipona fasciculata

“…Accordingly, foraging distances and habitat area are not species-specific traits, and smaller homing distances may be recorded in unfamiliar (i.e., unexploited) habitats (Van Nieuwstadt and Iraheta 1996;Guédot et al 2009). The only study that investigated influence of surrounding landscape structure on stingless bee Flight distance in Melipona fasciculata foraging verified that Tetragonula carbonaria was more successful in returning from homogenous landscapes (forest) than more heterogeneous ones (e.g., gardens; landmarks conspicuous/prominent to the human eye), indicating a complex navigation system that may be similar to one of the honey bees (Leonhardt et al 2016). This may explain why bee return rates at distances of 1600 and 3000 m at Embrapa (forest-urban mosaic; Experiment 1) were lower than those from the release points of equivalent distance in Carajás (preserved forest landscape; experiment 2) ( Table II).…”

“…However, we found great variability in the return time of the foragers (Table II). This variation may be the result of several factors, such as the initiation of foraging on the way back to the nest (Leonhardt et al 2016), the presence of Figure 6. Analyses of the duration of bee return from the distances of release (experiment 2).…”

“…Besides size, foraging distance in bees is also related to their homing ability, i.e., ability of individuals to relocate the nest, which occurs through the integration of several systems, e.g., vision, odor, magnetic fields, and memory (Menzel et al 1998(Menzel et al , 2006. Several factors can influence the homing ability of bees, including the presence of landmarks and other distinctive habitat features (Southwick and Buchmann 1995;Leonhardt et al 2016), pesticide loads (Stanley et al 2016), diseases (Li et al 2013;Wolf et al 2014) and pests (Kralj and Fuchs 2006), and experience (Capaldi and Dyer 1999;Rodrigues and Ribeiro 2014). However, most studies are from honey bees (Southwick and Buchmann 1995;Menzel et al 2006;Pahl et al 2011;He et al 2013;Li et al 2013;Wolf et al 2014), and temperate bee taxa (Turner 1908;Rau 1929;Goulson and Stout 2001;Guédot et al 2009;Stanley et al 2016), and rarely involve non-Apis bees in tropical regions (Rodrigues and Ribeiro 2014;Leonhardt et al 2016).…”

“…Most studies use bee homing ability as a proxy of flight distance, as a common method involving displacing bees from the hive (translocation), rather than actual observations of foraging activities (Janzen 1971;Roubik and Aluja 1983;van Nieuwstadt and Iraheta 1996;Menzel et al 1998;Gathmann and Tscharntke 2002;Guédot et al 2009;Rodrigues and Ribeiro 2014;Leonhardt et al 2016;Campbell et al 2019). Translocation experiments are time-consuming, because the observer needs to monitor the nest until a marked individual returns, and in the case of social bees, several foragers can return at the same time, meaning it is possible that the observer loses track of marked foragers returning to the hive.…”

Stingless bees (Meliponini): senses and behavior

“…In case that two or more species arrive simultaneously at a food patch, the presence of competitors, their aggressiveness and number might limit a colony's access to this specific resource (Keppner and Jarau 2016). Here, a high abundance of food sources in the environment allows the colonies to switch to alternative patches, to collect more efficiently, and to return more quickly to the nest (Leonhardt et al 2016). An elevated resource abundance and quality of food sources within the foraging area, moreover, stimulates the colonies to raise their foraging effort, therewith increasing the food intake rate into the nest .…”