Behavioural differences between male and female carpenter bees in nectar robbing and its effect on reproductive success in Glechoma longituba (Lamiaceae)

The Sensory and Cognitive Ecology of Nectar Robbing

Animals foraging from flowers must assess their environment and make critical decisions about which patches, plants, and flowers to exploit to obtain limiting resources. The cognitive ecology of plant-pollinator interactions explores not only the complex nature of pollinator foraging behavior and decision making, but also how cognition shapes pollination and plant fitness. Floral visitors sometimes depart from what we think of as typical pollinator behavior and instead exploit floral resources by robbing nectar (bypassing the floral opening and instead consuming nectar through holes or perforations made in floral tissue). The impacts of nectar robbing on plant fitness are well-studied; however, there is considerably less understanding, from the animal’s perspective, about the cognitive processes underlying nectar robbing. Examining nectar robbing from the standpoint of animal cognition is important for understanding the evolution of this behavior and its ecological and evolutionary consequences. In this review, we draw on central concepts of foraging ecology and animal cognition to consider nectar robbing behavior either when individuals use robbing as their only foraging strategy or when they switch between robbing and legitimate foraging. We discuss sensory and cognitive biases, learning, and the role of a variable environment in making decisions about robbing vs. foraging legitimately. We also discuss ways in which an understanding of the cognitive processes involved in nectar robbing can address questions about how plant-robber interactions affect patterns of natural selection and floral evolution. We conclude by highlighting future research directions on the sensory and cognitive ecology of nectar robbing.

A review of plant characteristics, phytochemistry and bioactivities of the genus Glechoma

ETHNOPHARMACOLOGICAL RELEVANCE

Plants of the genus Glechoma have been abundantly used for thousands of years in China as folk treatments for cholelithiasis, urolithiasis, inflammation, and other conditions.

AIM OF THE STUDY

This review discusses the potential application of Glechoma as an herbal medicine. The plant characteristics, ethnobotanical uses, phytochemistry, and pharmacological activities of Glechoma are summarized as a guide for phytochemical and pharmacological investigations.

MATERIALS AND METHODS

Various search engines including SciFinder, Google Scholar, Scopus-Elsevier, Medline, Web of Science, and China National Knowledge Infrastructure were searched for publications on Glechoma using relevant keywords. Additionally, local records, books, and non-English journals were screened up to October 2020.

RESULTS

The phytochemistry of several Glechoma plants has been systematically studied, and over one hundred different compounds have been isolated and identified. Terpenoids, flavonoids and polyphenols are the major secondary metabolites. Crude extracts and isolated compounds have been shown to exhibit various pharmacological activities including prevention of nephrolithiasis, anti-inflammatory, analgesic, anticomplement, antimicrobial, antioxidant, depigmenting, anticancer, and antiviral activities, among others.

CONCLUSION

Glechoma species have been used as folk medicine to treat various diseases and have diverse biological activities, making them valuable starting materials for drug development. However, in most cases the pharmacological mechanisms, pharmacokinetics, toxicology, safety, and possible interactions with other drugs remain to be determined.

Nectar replenishment maintains the neutral effects of nectar robbing on female reproductive success of Salvia przewalskii (Lamiaceae), a plant pollinated and robbed by bumble bees

Background and Aims

It has been suggested that the dynamics of nectar replenishment could differ for flowers after being nectar robbed or visited legitimately, but further experimental work is needed to investigate this hypothesis. This study aimed to assess the role of nectar replenishment in mediating the effects of nectar robbing on pollinator behaviour and plant reproduction.

Methods

Plant-robber-pollinator interactions in an alpine plant, Salvia przewalskii , were studied. It is pollinated by long-tongued Bombus religiosus and short-tongued B. friseanus , but robbed by B. friseanus . Nectar production rates for flowers after they were either robbed or legitimately visited were compared, and three levels of nectar robbing were created to detect the effects of nectar robbing on pollinator behaviour and plant reproduction.

Key Results

Nectar replenishment did not differ between flowers that had been robbed or legitimately visited. Neither fruit set nor seed set was significantly affected by nectar robbing. In addition, nectar robbing did not significantly affect visitation rate, flowers visited within a plant per foraging bout, or flower handling time of the legitimate pollinators. However, a tendency for a decrease in relative abundance of the pollinator B. religiosus with an increase of nectar robbing was found.

Conclusions

Nectar robbing did not affect female reproductive success because nectar replenishment ensures that pollinators maintain their visiting activity to nectar-robbed flowers. Nectar replenishment might be a defence mechanism against nectar robbing to enhance reproductive fitness by maintaining attractiveness to pollinators. Further studies are needed to reveal the potential for interference competition among bumble bees foraging as robbers and legitimate visitors, and to investigate variation of nectar robbing in communities with different bumble bee species composition.