Conditioning proboscis extension

In sum, both rigorous analyses of floral odors and olfactory/behavioral assays will be required to tease apart the critical factors that underlie pollinator-flower interactions. Recent work from independent sources indicates progress in this area. For example, studies using GC-EAD and conditioned proboscis extension (Wadhams et al., 1994 Blight et al., 1997 Pham-Delegue et al., 1997) have... 

The conditioned proboscis extension response involves gustatory, olfactory, and motor functions, as well as integrative processes underlying... 

Measurements of behavioral endpoints in honey bees should provide an effective assessment of hazards caused by crop protection chemicals especially when applied to melliferous plants. Under laboratory conditions, the conditioned proboscis extension (CPE) assay provides detectable sub-lethal effects due to pesticides, and also to gene products potentially used in plant genetic engineering (see other chapters of this book). Impairment in olfactory learning abilities have been shown for chemical concentrations at which no additional mortality occurred. Thus, the use of the CPE assay as a method to evaluate the potential effect on the honey bees foraging behavior can help to assess the toxicity of chemicals in a more comprehensive way than by considering the mortality endpoint alone. The CPE procedure can be used to compare responses to different chemicals (Table... 

The acute toxicity of GNA at three concentrations (500, 800, 1000 jig/ml) was tested. No additional mortality was observed after 24 and 48 hours for any of the treated groups. Chronic toxicity of 10, 100 and 1000 jig/ml GNA-added solutions, over a 2-month period, was not significantly different from controls. Consistently, 2 weeks exposure to the protein at these concentrations did not affect bees learning responses in the conditioned proboscis extension procedure (M.H. Pham-Delegue, unpublished data). 

Figure 15.3 Percentage of conditioned responses obtained in the conditioned proboscis extension paradigm by stimulating the bees with the floral volatiles of transformed (OCI variety expressing a cystein proteinase inhibitor gene) or control (Drakkar variety) oilseed rape.

Figure 15.4 Simultaneous recordings of chemical (gas chromatography, GC) and biological (conditioned proboscis extension, CPE ) responses. The upper line shows the volatile components of control oilseed rape flowers, and the lower lines the CPE responses of bees previously conditioned either to the control or to the transformed (OCI) floral volatiles, and tested for the individual components of the blend separated at the effluent of the chromatograph. Arrows indicate the main compounds (linalool and phenyl acetaldehyde) eliciting most of the behavioral activity.

At a more subtle level, behavioral disturbances may make it more difficult for animals to find food. Pyrethroids, carbamates, OPs, and neonicotinoids can disturb the foraging activity of bees (Thompson 2003). Interestingly, effects have been shown upon the wagtail dance of bees, and this disrupts communication between individuals as to the location of nectar-bearing plants. Also, the neonicotinoid imidacloprid has been shown to adversely affect conditioned responses such as proboscis extension of honeybees (Guez et al. 2001). Nicotinoids can disturb the functioning of cholinergic synapses, which are involved in the operation of the proboscis reflex as... 

Le Mdtayer, M., Marion-Poll, F., Sandoz, J. C. el al. (1997). Effect of conditioning on discrimination of oilseed rape volatiles by the honeybee use of a combined gas chromatography-proboscis extension behavioral assay. Chemical Senses 22 ... 

Bestmann H. J., Winkler L. and von Helversen O. (1997) Headspace analysis of volatile flower scent constituents of bat-pollinated plants. Phytochemistry 46, 1169-1172. Bitterman M. E., Menzel R., Fietz A. and Schafer S. (1983) Classical conditioning of proboscis extension in honeybees (Apis mellifera). J. Comp. Psychol. 97, 107-119. Blight M. M. Le Metayer M., Pham-Delegue M.-H., Pickett J.A., Marion-Poll F. and Wadhams L. J. (1997) Identification of floral volatiles involved in recognition of oilseed rape flowers, Brassica napus, by honeybees, Apis mellifera. J. Chem. Ecol. 

Bitterman M. E., Menzel R., Fietz A. and Schafer S. (1983) Classical conditioning of proboscis extension in honeybees (Apis mellifera). J. Comp. Psychol. 97, 107-119. 

MARFAING, P., ROUAULT, J. LAFFORT, P., Effect of the concentration and nature of olfactory stimuli on the proboscis extension of conditioned honeybees (Apis mellifera ligustica). J. Insect Phys., 1989, 35, 949-955. 

The CPE assay can involve associative and non-associative phenomena. The associative nature of proboscis extension reflex conditioning can be established by demonstrating that only forward pairing of CS-US sequences are effective to establish proper conditioning, compared to various control procedures, such as unpaired CS-US presentation [52]. The effects of an imidacloprid exposure can be shown not only on the bees performances in an associative learning task [53] but also in a non-associative learning procedure such as habituation imidacloprid at sub-lethal doses alters the number of trials needed to habituate the bees... 

Sandoz, J., Roger, B. and Pham-Delegue, M.H. (1995). Olfactory learning and memory in the honeybee Comparison of different classical conditioning procedures of the proboscis extension response. C. R. Acad. Sci. Paris, Sci. Vie 318, 749-755. 

Braudes, C. and Menzel, R. (1990). Common mechanisms in proboscis extension conditioning and visual learning revealed by genetic selection in honey bees Apis mellifera capensis). J. Comp. Physiol. A. 166, 545-552. 

J.N., Poppy, G. and Pham-Delegue M.H. (1999). Olfactory conditioning of the proboscis extension in bumble bees. Entomol. Exp. Appl. 90,123-129. 

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