Is Nocturnal Foraging in a Tropical Bee an Escape From Interference Competition?

Abstract

Temporal niche partitioning may result from interference competition if animals shift their activity patterns to avoid aggressive competitors. If doing so also shifts food sources, it is difficult to distinguish the effects of interference and consumptive competition in selecting for temporal niche shift. Bees compete for pollen and nectar from flowers through both interference and consumptive competition, and some species of bees have evolved nocturnality. Here, we use tropical forest canopy towers to observe bees (the night-flying sweat bees Megalopta genalis and M. centralis [Halictidae], honey bees, and stingless bees [Apidae]) visiting flowers of the balsa tree (Ochroma pyramalidae, Malvaceae). Because Ochroma flowers are open in the late afternoon through the night we can test the relative influence of each competition type on temporal nice. Niche shift due to consumptive competition predicts that Megalopta forage when resources are available: from afternoon into the night. Niche shift due to interference competition predicts that Megalopta forage only in the absence of diurnal bees. We found no overlap between diurnal bees and Megalopta in the evening, and only one instance of overlap in the morning, despite the abundance of pollen and nectar in the late afternoon and evening. This supports the hypothesis that Megalopta are avoiding interference competition, but not the hypothesis that they are limited by consumptive competition. We propose that the release from interference competition enables Megalopta to provision cells quickly, and spend most of their time investing in nest defense. Thus, increases in foraging efficiency directly resulting from temporal shifts to escape interference competition may indirectly lead to reduced predation and parasitism.

Thermal tolerance varies with dim‐light foraging and elevation in large carpenter bees (Hymenoptera: Apidae: Xylocopini)

“…In addition, our analysis of temporal niche overlap showed that X. olivieri did not overlap significantly with X. violacea and not at all with X. iris (Table ). Thus, our observations suggest a temporal niche partitioning as a result of interspecific interference competition, as previously proposed for X. olivieri (Gottlieb et al ., ) and other nocturnal bees (Smith et al ., ). However, we conducted our observations on the foraging pattern of these species in a narrow temporal window (2 days in the middle of the summer) and at a single location.…”

Light intensity regulates flower visitation in Neotropical nocturnal bees

“…For twilight periods with higher initial light intensity levels, such as during clear moonlit nights, nocturnal bees can start to www.nature.com/scientificreports/ forage earlier. This light-dependent foraging activity is likely related to a combination of factors, such as visual challenges imposed by dim light levels 31 and ecological demands to access resources before the onset of visits made by massive numbers of diurnal bees 35 . It makes sense that light intensity controls nocturnal bee activity because dim light environments represent an extreme situation for bees, which are equipped with apposition compound eyes that are better adapted for brighter conditions 4,32 .…”

“…Nonetheless, foraging during twilight and at night, despite these challenges, does have its advantages. Firstly, there is less competition, since most foraging bees are day-active 9,35 . Secondly, many plants bloom only at dawn or at night as a water-saving adaptation 28 .…”

The first gynandromorph of the Neotropical bee Megalopta amoena (Spinola, 1853) (Halictidae) with notes on its circadian rhythm

“…In bees and other pollinators, modifications of circadian rhythms may allow insects to coordinate their foraging with the timing of floral resource availability (Bloch et al 2017). The genus Megalopta has a bimodal foraging period, occurring in two narrow temporal windows of approximately 90 minutes after sunset and before sunrise, when it is nearly dark (Kelber et al 2006, Smith et al 2017.…”