Honeybee (Apis cerana) Foraging Responses to the Toxic Honey of Tripterygium hypoglaucum (Celastraceae): Changing Threshold of Nectar Acceptability

Abstract

To investigate honeybee foraging responses to toxic nectar, honey was collected from Apis cerana colonies in the Yaoan county of Yunnan Province, China, during June, when flowers of Tripterygium hypoglaucum were the main nectar source available. Pollen analysis confirmed the origin of the honey, and high-performance liquid chromatography showed the prominent component triptolide to be present at a concentration of 0.61 mug/g +/- 0.11 SD. In cage tests that used young adult worker bees, significantly more of those provided with a diet of T. hypoglaucum honey mixed with sugar powder (1:1) died within 6 d (68.3%) compared to control groups provided with normal honey mixed with sugar powder (15.8%). Honeybees were trained to visit feeders that contained honey of T. hypoglaucum (toxic honey) as the test group and honey of Vicia sativa or Elsholtzia ciliata as control groups (all honeys diluted 1:3 with water). Bees preferred the feeders with normal honey to those with toxic honey, as shown by significantly higher visiting frequencies and longer imbibition times. However, when the feeder of normal honey was removed, leaving only honey of T. hypoglaucum, the foraging bees returned to the toxic honey after a few seconds of hesitation, and both visiting frequency and imbibition time increased to values previously recorded for normal honey. Toxic honey thus became acceptable to the bees in the absence of other nectar sources.

Honeybees and nectar nicotine: Deterrence and reduced survival versus potential health benefits

“…This is a common finding in studies of the response of pollinators to nectar SM (Singaravelan et al, 2005;Tadmor-Melamed et al, 2004;Tan et al, 2007); and Singaravelan and colleagues (2005) found that low concentrations of nicotine and caffeine elicited a significant feeding preference in honeybees. Partial repellence by SM has implications for plant fitness: moth and hummingbird pollinators removed more nectar from nicotine-silenced N. attenuata plants than from control plants with nicotine-containing nectar (Kessler and Baldwin, 2006).…”

“…While nectar SM may be harmless when honeybees can forage on a variety of plants, detrimental effects are observed when the choice of flowering plant species is limited. Post-ingestive effects of nectar SM on honeybees include negative effects on foraging behaviour , interference with social communication (Barron et al, 2009;Gao et al, 2010), and an increase in mortality Reinhard et al, 2009;Tan et al, 2007). However, the consumption of SM may also be beneficial, as it has been shown to reduce the pathogen and parasitoid load of tobacco hornworms, fall armyworms and bumble bees (Barbosa et al, 1986;Manson et al, 2010).…”

Investigating the importance of altitude and weather conditions for the production of toxic honey in New Zealand

“…In support of this, Tan et al (2007) observed Indian honey bees (A. cerana) to prefer non-toxic nectar to the toxic nectar of the Chinese plant Tripterygium hypoglaucum. When the non-toxic nectar was removed, the bees readily accepted the toxic nectar (Tan et al 2007). In this case however, the toxic nectar had a poisonous effect on honey bees, whereas honeydew from tutu is harmless to bees (Palmer-Jones 1947).…”

Honeybee Nests

“…Fine details on the chemistry and biology of nectar in relation to honeybees and other animals is given by Nicolson et al (2007), but the information is not directly related to comb-building. The quality of 'nectar' is even more difficult to judge.…”