Reversal Learning and Risk-Averse Foraging Behavior in the Monarch Butterfly, Danaus plexippus (Lepidoptera: Nymphalidae) (original) (raw)
Related papers
PeerJ
We aimed to examine mechanistically the observed foraging differences across two honey bee, Apis mellifera, subspecies using the proboscis extension response assay. Specifically, we compared differences in appetitive reversal learning ability between honey bee subspecies: Apis mellifera caucasica (Pollman), and Apis mellifera syriaca (Skorikov) in a “common garden” apiary. It was hypothesized that specific learning differences could explain previously observed foraging behavior differences of these subspecies: A.m. caucasica switches between different flower color morphs in response to reward variability, and A.m. syriaca does not switch. We suggest that flower constancy allows reduced exposure by minimizing search and handling time, whereas plasticity is important when maximizing harvest in preparation for long winter is at a premium. In the initial or Acquisition phase of the test we examined specifically discrimination learning, where bees were trained to respond to a paired cond...
Appetitive and Aversive Learning in Spodoptera littoralis Larvae
Chemical Senses, 2011
Adult Lepidoptera are capable of associative learning. This helps them to forage flowers or to find suitable oviposition sites. Larval learning has never been seriously considered because they have limited foraging capabilities and usually depend on adults as concerns their food choices. We tested if Spodoptera littoralis larvae can learn to associate an odor with a tastant using a new classical conditioning paradigm. Groups of larvae were exposed to an unconditioned stimulus (US: fructose or quinine mixed with agar) paired with a conditioned stimulus (CS: hexanol, geraniol or pentyl acetate) in a petri dish. Their reaction to CS was subsequently tested in a petri dish at different time intervals after conditioning. Trained larvae showed a significant preference or avoidance to CS when paired with US depending on the reinforcer used. The training was more efficient when larvae were given a choice between an area where CS-US was paired and an area with no CS (or another odor). In these conditions, the memory formed could be recalled at least 24 h after pairing with an aversive stimulus and only 5 min after pairing with an appetitive stimulus. This learning was specific to CS because trained larvae were able to discriminate CS from another odor that was present during the training but unrewarded. These results suggest that Lepidoptera larvae exhibit more behavioral plasticity than previously appreciated.
Effects of a reward downshift on the consummatory behavior and flower choices of bumblebee foragers
Physiology & Behavior, 2003
Insect foragers often exhibit flower constancy, the tendency to visit single flower types rather than sample alternative flowers that provide equal or higher levels of reward. We employed a negative incentive contrast procedure to examine whether a decrease of sucrose concentration in a regularly visited flower type affects bumblebee (Bombus impatiens) consummatory or choice behavior. Subjects were trained to enter a test arena where they foraged on a single, red, artificial flower that contained 140 ml of sucrose solution. Subjects were reinforced with a concentration of either 0.50 or 0.20 sucrose solution in 20 trials and in 12 subsequent test trials subjects were given a choice between a red and yellow flower that each contained 140 ml of 0.20 sucrose solution. Subjects that experienced a downshift of reward showed an abrupt disruption in consumption of sucrose solution from the red flower. These subjects were also significantly more likely to visit the novel yellow flower than subjects that were reinforced with 0.20 sucrose solution in red flowers in all trials. However, the effects of the downshift of reward were transient and appeared to disrupt consummatory behavior more strongly than flower preferences. These results support the idea that bumblebee foragers form expectations of reward in flowers-as is implied by the results of studies of honeybees-and suggest that unrealized expectations of reward may cause foragers to sample alternative flowers or to fly considerable distances in search of particular types of flowers. D
Southern Monarchs do not Develop Learned Preferences for Flowers With Pyrrolizidine Alkaloids
Journal of chemical ecology, 2015
Danaus butterflies sequester pyrrolizidine alkaloids (PAs) from nectar and leaves of various plant species for defense and reproduction. We tested the hypothesis that the southern monarch butterfly Danaus erippus shows innate preferences for certain flower colors and has the capacity to develop learned preferences for artificial flowers presenting advantageous floral rewards such as PAs. We predicted that orange and yellow flowers would be innately preferred by southern monarchs. Another prediction is that flowers with both sucrose and PAs would be preferred over those having sucrose only, regardless of flower color. In nature, males of Danaus generally visit PA sources more often than females, so we expected that males of D. erippus would exhibit a stronger learned preference for PA sources than the females. In the innate preference tests, adults were offered artificial non-rewarding yellow, orange, blue, red, green, and violet flowers. Orange and yellow artificial flowers were mos...
Animal Biology, 2006
Insects must detect and interpret stimuli embedded in a sensory environment of competing stimuli. While sensory environments vary in time and space, individuals may be able to learn local background characteristics, facilitating perceptual learning. This study on host search in butterflies examines the following questions in an ecologically relevant context: i) does cue learning depend on the sensory environment in which learning occurs; and ii) are background characteristics learned, such that performance on novel tasks in the same sensory environment is facilitated? Females of Battus philenor (Papilionidae: Lepidoptera) were trained to different coloured and shaped oviposition targets, against different background colours. Individuals trained to colours on a brown background but tested on a green background performed significantly worse than control individuals which were trained to the same colours but on a green background. Females pre-trained to discriminate green targets from red targets on a green background colour performed significantly better in a novel task (shape learning) involving green shapes on a green background than did individuals trained to discriminate the same colours on a brown background. These two results were unique to particular cue-background combinations, in particular cryptic conditions. Taken together, our results suggest that cue learning depends on an insect's sensory environment, and that learning characteristics of local backgrounds may confer benefits to habitat-faithful individuals.
Absence of adaptive learning from the oviposition foraging behaviour of a checkerspot butterfly
Animal Behaviour, 1995
A population of Edith's checkerspot butterfly, Euphydryas editha, laid eggs on two morphologically distinct host-plant species, one of which it had recently colonized. Search behaviour of two groups of females was compared in the field. 'Naive' females were experimentally deprived of both flight experience and host encounter, while 'experienced' females were observed without intervention. Three analyses failed to show evidence for adaptive learning that might have allowed the butterflies to increase their efficiency of host finding with experience: (1) proportions of alights on hosts were not different between the naive and experienced groups, (2) rates of alighting on hosts did not differ between the naive and experienced groups, and probabilities of alighting on hosts did not increase during searching bouts. Both groups searched efficiently for their traditional host species, Pedicularis semibarbata (dwarf lousewort), and inefficiently for the novel host, Collinsia torreyi (blue-eyed Mary). There was also no evidence for behavioural differences among individuals of either group. The distribution among individuals of alight frequencies on C. torreyi appeared Poisson, with a single mode near the frequency expected from random alighting. This finding is consistent with the hypothesis that no females recognized C. torreyi as a host in flight, and that differences between butterflies in observed alight frequencies stemmed simply from random variation in the composition of the vegetation over which they flew. Thus, the absence of adaptive learning impeded the evolutionary incorporation of the novel host into the diet. These results complement previous findings that E. editha from the same population failed to learn to accept particular hosts after alighting and are in contrast to other studies of insect foraging, all of which have shown that learning is an important component of foraging behaviour, causing search efficiency to improve with experience. It is suggested that E. editha could be a model 'non-learning' insect in comparative studies that empirically test the role of learning in resource choice.