Exploring the Role of Cognition in the Annual Fall Migration of the Monarch Butterfly (<i>Danaus plexippus</i>)

Each fall, monarch butterflies in eastern North America undergo an extraordinary long-distance migration to wintering areas in central Mexico, where they remain until returning northward in the spring. Migrants survive the overwintering period by metabolizing lipid reserves accumulated exclusively t...

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Main Author: Robert J. Gegear
Format: Article
Language:English
Published: MDPI AG 2021-08-01
Series:Insects
Subjects:
Online Access:https://www.mdpi.com/2075-4450/12/8/760
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author Robert J. Gegear
author_facet Robert J. Gegear
author_sort Robert J. Gegear
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description Each fall, monarch butterflies in eastern North America undergo an extraordinary long-distance migration to wintering areas in central Mexico, where they remain until returning northward in the spring. Migrants survive the overwintering period by metabolizing lipid reserves accumulated exclusively though floral nectar; however, there is little known about how individuals maximize foraging efficiency in the face of floral environments that constantly change in complex and unpredictable ways along their migratory route. Here, a proboscis extension paradigm is used to investigate the role of cognition during the foraging phase of monarch migration. Male and female migratory butterflies were consecutively trained to discriminate between two color and odor cues and then tested for their ability to simultaneously retain the information on the reward value of each cue in memory without reinforcement over a period of 7 days. To gain further insight into cognitive abilities of monarchs as a migratory species, a second set of captive-reared males and females were tested under harnessed conditions at the same time as wild-caught fall migrants. Results showed that male and female migrants can learn the reward properties of color and odor cues with over 75% accuracy after less than 40 s of exposure and can simultaneously retain visual and olfactory information predicting the availability of floral rewards in memory without reinforcement for at least 7 days. Captive-reared male butterflies also showed the ability to retain visual and olfactory information in long-term memory for 7 days; however, 80% of captive-reared females could not retain color cues in long-term memory for more than 24 h. These novel findings are consistent with the view that monarch butterflies, as a migratory species, have enhancements to long-term memory that enable them to minimize the amount of time and energy wasted searching for suitable nectar sources during their annual fall migration, thereby optimizing migratory performance and increasing the chance of overwinter survival. The possibility that female monarchs undergo a seasonal change in visual long-term memory warrants further empirical investigation.
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spelling doaj.art-9b93863a15784ba89185c9559177fa0d2023-11-22T08:08:10ZengMDPI AGInsects2075-44502021-08-0112876010.3390/insects12080760Exploring the Role of Cognition in the Annual Fall Migration of the Monarch Butterfly (<i>Danaus plexippus</i>)Robert J. Gegear0Department of Biology, University of Massachusetts, Dartmouth, MA 02747-2300, USAEach fall, monarch butterflies in eastern North America undergo an extraordinary long-distance migration to wintering areas in central Mexico, where they remain until returning northward in the spring. Migrants survive the overwintering period by metabolizing lipid reserves accumulated exclusively though floral nectar; however, there is little known about how individuals maximize foraging efficiency in the face of floral environments that constantly change in complex and unpredictable ways along their migratory route. Here, a proboscis extension paradigm is used to investigate the role of cognition during the foraging phase of monarch migration. Male and female migratory butterflies were consecutively trained to discriminate between two color and odor cues and then tested for their ability to simultaneously retain the information on the reward value of each cue in memory without reinforcement over a period of 7 days. To gain further insight into cognitive abilities of monarchs as a migratory species, a second set of captive-reared males and females were tested under harnessed conditions at the same time as wild-caught fall migrants. Results showed that male and female migrants can learn the reward properties of color and odor cues with over 75% accuracy after less than 40 s of exposure and can simultaneously retain visual and olfactory information predicting the availability of floral rewards in memory without reinforcement for at least 7 days. Captive-reared male butterflies also showed the ability to retain visual and olfactory information in long-term memory for 7 days; however, 80% of captive-reared females could not retain color cues in long-term memory for more than 24 h. These novel findings are consistent with the view that monarch butterflies, as a migratory species, have enhancements to long-term memory that enable them to minimize the amount of time and energy wasted searching for suitable nectar sources during their annual fall migration, thereby optimizing migratory performance and increasing the chance of overwinter survival. The possibility that female monarchs undergo a seasonal change in visual long-term memory warrants further empirical investigation.https://www.mdpi.com/2075-4450/12/8/760monarch butterflylong-term memorylearning abilitycognitionmigrationvisual system
spellingShingle Robert J. Gegear
Exploring the Role of Cognition in the Annual Fall Migration of the Monarch Butterfly (<i>Danaus plexippus</i>)
Insects
monarch butterfly
long-term memory
learning ability
cognition
migration
visual system
title Exploring the Role of Cognition in the Annual Fall Migration of the Monarch Butterfly (<i>Danaus plexippus</i>)
title_full Exploring the Role of Cognition in the Annual Fall Migration of the Monarch Butterfly (<i>Danaus plexippus</i>)
title_fullStr Exploring the Role of Cognition in the Annual Fall Migration of the Monarch Butterfly (<i>Danaus plexippus</i>)
title_full_unstemmed Exploring the Role of Cognition in the Annual Fall Migration of the Monarch Butterfly (<i>Danaus plexippus</i>)
title_short Exploring the Role of Cognition in the Annual Fall Migration of the Monarch Butterfly (<i>Danaus plexippus</i>)
title_sort exploring the role of cognition in the annual fall migration of the monarch butterfly i danaus plexippus i
topic monarch butterfly
long-term memory
learning ability
cognition
migration
visual system
url https://www.mdpi.com/2075-4450/12/8/760
work_keys_str_mv AT robertjgegear exploringtheroleofcognitionintheannualfallmigrationofthemonarchbutterflyidanausplexippusi