The conditioning proboscis extension assay

These different considerations have led us to assume that this method would be useful to investigate the behavioral effects of toxicants in preference to more natural approaches such as studies in field or semi-field conditions because it allows better control of treatment and conditioning parameters. Indeed, precise quantification of behavior is essential for determining whether a specific non-environmental variable affects the normal behavior. The sublethal effects of chemical pesticides have already been studied using restrained workers in the CPE assay [32-35]. It remains to establish whether the use of the CPE response as a measure of the sub-lethal effects of chemicals on honey bees can be a reliable indicator of the hazards associated with the exposure to sublethal doses of toxic compounds, and consequently can be included in standard screening proce- 

Complementarily, the products can be associated with the scent used as the CS to determine whether the insecticides have a repellent effect [35]. 

Post-conditioning treatment to permethrin has been conducted, before subjecting the bees to the test trials, in order to study the recovery period needed for treated bees to resume normal learning ability [33]. This aimed to examine how chemical treatment can interfere with the memory process, which gives an indication of the way foragers will be able to come back to a crop where they have been exposed to the toxic material while they were collecting food and memorizing the floral cues. 

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

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 

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