Detection and Learning of Floral Electric Fields by Bumblebees

Neonicotinoid insecticides can impair bee learning and memorycognitive features that play a key role in colony fitness because they facilitate foraging. For example, the commonly used neonicotinoid imidacloprid reduces honey bee olfactory learning. However, no studies have previously determined whether imidacloprid can impair aversive associative learning, although such learning should enhance bee survival by allowing bees to avoid dangerous foraging sites. To mimic attempted predation of foragers, we developed an electro-mechanical predator that consistently attacked foragers with a pinching bite at a fixed force and elicited aversive olfactory learning in a sting extension response (SER) assay. We show that chronic exposure to a sublethal concentration of imidacloprid (25.6 µg l −1 =20.8 ppb) over 4 days (mean of 1.5 µg per bee day −1 ), significantly impaired aversive short-term learning and memory retention. Imidacloprid treatment reduced short-term learning by 87% and memory retention by 85% in comparison with control bees. Imidacloprid therefore impairs the ability of honey bees to associate a naturalistic predation stimulus -biting -with floral odor compounds. Such learning should enhance bee survival, suggesting that xenobiotics could alter more complex ecological interactions such as predator-prey relationships.

Section: Introductionmentioning

confidence: 99%

A neonicotinoid, imidacloprid, impairs honey bee aversive learning of simulated predation

Zhang

Nieh

2015

“…For example, bees optimize foraging efforts by assessing a variable floral market and learning and remembering the stimuli that characterize more profitable flowers, which are preferentially visited (Menzel, 1985). Floral features used by bees include colors (Daumer, 1956;von Frisch, 1967;Menzel, 1985;Galizia et al, 2012), odors (von Frisch, 1967;Galizia et al, 2012;Giurfa and Sandoz, 2012), shapes (Gould, 1985), textures (Kevan and Lane, 1985;Erber et al, 1998), temperature (Whitney et al, 2008), and electrostatic charge (Clarke et al, 2013). Experimentally, perception of floral features can be quantified by conditioning of the proboscis (tongue) extension reflex (PER) of individually restrained bees that are unharmed but prevented from flight.…”

Section: Introductionmentioning

confidence: 99%

Color dependent learning in restrained Africanized honey bees

Jernigan

Roubik

Wcislo

et al. 2013

Associative color learning has been demonstrated to be very poor using restrained European honey bees unless the antennae are amputated. Consequently, our understanding of proximate mechanisms in visual information processing is handicapped. Here we test learning performance of Africanized honey bees under restrained conditions with visual and olfactory stimulation using the proboscis extension response (PER) protocol. Restrained individuals were trained to learn an association between a color stimulus and a sugar-water reward. We evaluated performance for 'absolute' learning (learned association between a stimulus and a reward) and 'discriminant' learning (discrimination between two stimuli). Restrained Africanized honey bees (AHBs) readily learned the association of color stimulus for both blue and green LED stimuli in absolute and discriminatory learning tasks within seven presentations, but not with violet as the rewarded color. Additionally, 24-h memory improved considerably during the discrimination task, compared with absolute association (15-55%). We found that antennal amputation was unnecessary and reduced performance in AHBs. Thus color learning can now be studied using the PER protocol with intact AHBs. This finding opens the way towards investigating visual and multimodal learning with application of neural techniques commonly used in restrained honey bees.

“…Hence, the employment of any electrostatic charge to establish the thread's structure can be excluded. Being charged could actually counteract the purpose of the capture threads as insects can sense electric fields (Clarke et al, 2013;Greggers et al, 2013;Sutton et al, 2016). Hence, a charged capture thread would be detected and avoided by potential prey.…”

Section: Discussionmentioning

confidence: 99%

Nanofibre production in spiders without electric charge

Joel

Baumgärtner

2017

Technical nanofibre production is linked to high voltage, because nanofibres are typically produced by electrospinning. In contrast, spiders have evolved a way to produce nanofibres without high voltage. These spiders are called cribellate spiders and produce nanofibres within their capture thread production. It is suggested that their nanofibres become frictionally charged when brushed over a continuous area on the calamistrum, a comb-like structure at the metatarsus of the fourth leg. Although there are indications that electrostatic charges are involved in the formation of the thread structure, final proof is missing. We proposed three requirements to validate this hypothesis: (1) the removal of any charge during or after thread production has an influence on the structure of the thread; (2) the characteristic structure of the thread can be regenerated by charging; and (3) the thread is attracted to or repelled from differently charged objects. None of these three requirements were proven true. Furthermore, mathematical calculations reveal that even at low charges, the calculated structural assembly of the thread does not match the observed reality. Electrostatic forces are therefore not involved in the production of cribellate capture threads.