The tarsal taste of honey bees: behavioral and electrophysiological analyses

Abstract

Taste plays a crucial role in the life of honey bees as their survival depends on the collection and intake of nectar and pollen, and other natural products. Here we studied the tarsal taste of honey bees through a series of behavioral and electrophysiological analyses. We characterized responsiveness to various sweet, salty and bitter tastants delivered to gustatory sensilla of the fore tarsi. Behavioral experiments showed that stimulation of opposite fore tarsi with sucrose and bitter substances or water yielded different outcomes depending on the stimulation sequence. When sucrose was applied first, thereby eliciting proboscis extension, no bitter substance could induce proboscis retraction, thus suggesting that the primacy of sucrose stimulation induced a central excitatory state. When bitter substances or water were applied first, sucrose stimulation could still elicit proboscis extension but to a lower level, thus suggesting central inhibition based on contradictory gustatory input on opposite tarsi. Electrophysiological experiments showed that receptor cells in the gustatory sensilla of the tarsomeres are highly sensitive to saline solutions at low concentrations. No evidence for receptors responding specifically to sucrose or to bitter substances was found in these sensilla. Receptor cells in the gustatory sensilla of the claws are highly sensitive to sucrose. Although bees do not possess dedicated bitter-taste receptors in the tarsi, indirect bitter detection is possible because bitter tastes inhibit sucrose receptor cells of the claws when mixed with sucrose solution. By combining behavioral and electrophysiological approaches, these results provide the first integrative study on tarsal taste detection in the honey bee.

Transcriptomic identification of chemoreceptor genes in the red palm weevil Rhynchophorus ferrugineus

“…With the exception of the antennal location, some of the identified GRs are highly expressed in the head, thorax, and abdomen. This is consistent in that gustatory sensilla are not restricted to the region around the mouth but are usually distributed over different regions of the body surface and appendages such as the antennae, mouth parts, leg tarsi, and margins of the wings (de Brito Sanchez et al, 2014). In particular, comp17518_c0 was predominantly enriched in female heads.…”

Israeli acute paralysis virus associated paralysis symptoms, viral tissue distribution and Dicer-2 induction in bumblebee workers (Bombus terrestris)

“…Although, it remains to be determined if this behaviour is to avoid transmission of the virus through the entire colony, it is known that the contacts of networks are important for parasite transmission dynamics within bumblebee nests, with bee contact rate being a significant predictor of Crithidia bombi transmission (Otterstatter & Thomson, 2007). The forelegs are able to provide food-related information to the nerve system of worker bees and are an important sensor organ (de Brito Sanchez et al, 2014;Mommaerts et al, 2013). This could explain our observations that bees with crippled/immobilized forelegs seem to 'ignore' the sugar water feeder.…”

Morphological and electrophysiological analysis of tarsal sensilla in the medfly Ceratitis capitata (Wiedemann, 1824) (Diptera: Tephritidae)

“…Oregon grape and barberry); quercetin is a flavonol present in Citrus fruits (Drewnowski & GomezCarneros 2000); PROP is a compound found in Cruciferous plants (Fox 1932;Guo & Reed 2001); nicotine is an alkaloid present in tobacco (Ling et al 2014). In honey bee, bitter substances, applied after proboscis extension induced by sucrose stimulation, do not cause proboscis retraction; in fact, this insect does not show a specific bitter-taste receptor in the tarsi even if indirect bitter detection is possible (De Brito Sanchez et al 2014). In Phormia regina, using a tip-recording technique, Ouyang et al (2009) observed that strychnine evoked a response only from D-chemosensilla located specifically in the fourth and fifth tarsomeres, while no activity was shown by the remaining D-sensilla.…”

“…All substances were purchased from Sigma-Aldrich (St. Louis, MO, USA) and their solutions were prepared using distilled water. Since a high sensitivity to 0.1 mM potassium chloride (KCl) in tarsal sensilla response was reported in the honey bee (De Brito Sanchez et al 2014), 10 mM NaCl was used as a control stimulus and was added to fructose and to bitter solutions to ensure adequate electrical conductance.…”