Characterizing Honeybee Cuticular Hydrocarbons During Foraging

Honeybees (Apis mellifera) adjust their time and effort during foraging activity. Their metabolic rates together with body temperature rise while gathering profitable resources. These physiological changes may result in a differential cuticular profile, which in turn may bear communicational value. We evaluated if sucrose concentration of collected food affects the cuticular chemistry of honeybees during foraging. We trained bees to artificial feeders with high (2 M) and low (0.5 M) sucrose concentrations, and captured the active foragers for surface extraction of cuticular compounds. We sampled foragers just after feeding, before taking-off towards the hive, and upon landing at the hive entrance, before entering the hive. Through gas chromatography-mass spectrometry analysis of cuticular extracts, we identified and quantified 48 compounds, including cuticular hydrocarbons (CHCs) and volatiles associated with exocrine glands. We found that higher sucrose concentrations resulted in increased amounts of alkanes and alkenes in the surface extracts of foragers captured at the hive entrance, but not at the feeding site. Our results suggest that the differences that have been reported for CHCs in waggle-dancing honey bees can be already found once they return to the hive from profitable food sources.

Chemical disguise as particular caste of host ants in the ant inquiline parasite Niphanda fusca (Lepidoptera: Lycaenidae)

The exploitation of parental care is common in avian and insect ‘cuckoos’ and these species engage in a coevolutionary arms race. Caterpillars of the lycaenid butterfly Niphanda fusca develop as parasites inside the nests of host ants ( Camponotus japonicus ) where they grow by feeding on the worker trophallaxis. We hypothesized that N. fusca caterpillars chemically mimic host larvae, or some particular castes of the host ant, so that the caterpillars are accepted and cared for by the host workers. Behaviourally, it was observed that the host workers enthusiastically tended glass dummies coated with the cuticular chemicals of larvae or males and those of N. fusca caterpillars living together. Cuticular chemical analyses revealed that N. fusca caterpillars grown in a host ant nest acquired a colony-specific blend of cuticular hydrocarbons (CHCs). Furthermore, the CHC profiles of the N. fusca caterpillars were particularly close to those of the males rather than those of the host larvae and the others. We suggest that N. fusca caterpillars exploit worker care by matching their cuticular profile to that of the host males, since the males are fed by trophallaxis with workers in their natal nests for approximately ten months.