Heliconius charithonia

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Zebra Longwing
Dorsal view - feeding from a sage flower
Ventral view
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Lepidoptera
Family: Nymphalidae
Genus: Heliconius
Species: H. charithonia
Binomial name
Heliconius charithonia
(Linnaeus, 1767)
Synonyms
  • Papilio charithonia
  • Heliconius charithonius
  • Apostraphia charithonia Dyar, 1903

The Zebra Longwing or Zebra Heliconian (Heliconius charithonia) is a species of butterfly belonging to the subfamily Heliconiinae of the Nymphalidae.[1][2]

The caterpillars are white with black spots and have numerous black spikes along their body. Adult butterflies are monomorphic of medium size with long wings. On the dorsal side, the wings are black with narrow white and yellow stripes, with a similar pattern on the ventral side, but paler and with red spots. The wingspan ranges from 72 to 100 mm.[3]

Adults roost in groups of up to 60 individuals on a nightly basis, returning to the same roost every night. These roosts provide protection to adults, the large groups deterring predators and retaining warmth.[4]

The caterpillar feeds on Yellow Passionflower (Passiflora lutea), Corky-stemmed Passionflower (Passiflora suberosa), and Two-flower Passionflower (Passiflora biflora). The adults are unusual among butterflies in that they eat pollen as well as sip nectar. This ability contributes to their longevity—the Zebra Longwing can live up to 6 months as an adult.[5]

Adults exhibit pupal mating in which males wait for a female to emerge from her pupa. Upon emergence, two or more males may fight in order to win a copulation. The winner mates with the females and prevents other males from doing so through a chemical transfer.[2][4]

During mating, the male passes a nutrient-rich spermatophore to the female that, in addition to providing her valuable proteins, is also thought to reduce the attractiveness of the female to other male mates.[6]

Distribution[edit]

It is found in South America, Central America, the West Indies, Mexico, south Texas and peninsular Florida. Adults sometimes migrate north to New Mexico, South Carolina, and Nebraska during the warmer months. It was declared the official butterfly for the state of Florida in the United States in 1996.[1][2]

Migration[edit]

It was theorized that H. charithonia did not migrate or disperse over a wide territorial range due to its home range behavior, suggesting that the butterfly stayed near its natal area its entire life, displaying high fidelity to its nightly roost and using specific foraging routes, thereby returning daily to specific sites of adult host plants to collect nectar and pollen and larval plants to mate and lay eggs. Although the butterfly does display some hone range behavior, due to the lack of genetic variation over a wide range of territory, it has been determined that the amount of migration and dispersal in the butterflies was highly underestimated. Therefore, the butterflies do in fact move between territories.[7]

Butterflies with Mexican origins migrate north into Texas due to temperature changes, following the retracting temperature gradient. Rainfall has no effect on migration patterns. Arrival dates and duration of stay at certain locations depends on the distance travelled (the longer the distance travelled, the shorter the duration of stay).[8]

Habitat[edit]

H. charithonia is found in tropical hammocks, moist forests, edges, or fields.[2]

Roosts[edit]

Predatory defense[edit]

Roosts are formed to avoid attacks from predators since it has been found that there are higher numbers of predatory attacks on solitary individuals versus on those individuals that roost. This follows the prey dilution effect, which states that the probability of an attack on an individual decreases with increasing numbers of individuals in a group. Solitary individuals, or very small roosts, avoid exhibiting proper warning signals so as not to attract predators. On the other hand, too large of groups are overly conspicuous to a predator.[9]

Pre-roosting interactions, which consist of sitting near one another, chasing each other briefly while fluttering, or basking,[10] occur between butterflies from separate roosts, indicating that the butterflies are aware of other roosts in their home range. Despite this, the Zebra Longwing butterflies choose to form smaller aggregations, despite the availability of a substrate to create larger ones. In fact, the optimal or minimum roost size in which predator deterrence is most effective is 5 individuals. However, roost size is also influenced by resource availability and foraging. Aposematism is when prey warn predators of their unprofitability, such as toxicity or unpalatibility, via coloration or patterning. H. charithonia roosts in order to display collective aposematism, thereby deterring predators by displaying their unpalatable taste in a more conspicuous way.[9]

Conspecific recognition[edit]

H. charithonia adults form communal roosts on a nightly basis. Communal roosting occurs when individuals aggregate at a particular site for more than a few hours. H. charithonia typically begin roosting as early as 3 hours before sunset and usually leave within two hours after sunrise.[9] Due to the timing of the communal roosting, H. charithonia need to be able to see at low light levels because it helps them navigate when searching for roost sites, either when looking for twigs, tendrils, and dry leaves to land on in order to start a roost or when searching for conspecifics that are already roosting.[11] Their eyes also help them to recognize color patterns in conspecifics. UV rhodopsins in the eye help them to distinguish between 3-OHK yellow pigments, or ultraviolet colors, and other yellow pigments, which to the human eye is undistinguishable.[12] At shorter distances, the butterflies recognize conspecifics via chemical cues.[11] These chemical cues include volatile and nonvolatile substances. The significance of this chemical communication remains largely unknown for Heliconius in general. However, in H. melpomene, (E)-?-ocimene was found to attract males and females in diurnal situations.[13]

Feeding[edit]

Pollen Feeding[edit]

It is thought that the behavior of pollen-feeding facilitated the evolution of aposematism and mimicry. Those butterflies that feed on pollen are more distasteful to predators, more brightly colored, and show superior mimetic diversity to those that do not feed on pollen.[14]

Adult butterflies choose their home ranges based on collections of pollen plants. They collect pollen by inserting their proboscis into the flower while making particular movements so that there is secure adhesion to the pollen grains. Digestion occurs immediately after ingestion when the pollen makes contact with saliva and amino acids are dissolved.[15] Optimal amino acid intake occurs via abundant saliva production and gentle and slow mastication.[16] During the night, the butterflies digest pollen since optimal nutritional resources are obtained while resting or sleeping.[15]

Pollen feeding is correlated with higher overall fitness. Individuals who exhibit pollen feeding have a longer lifespan than those who feed only on nectar or sugar water. Females carry more pollen than males since pollen supplies the nutrients necessary for egg production. Amino acids essential for egg development transfer from the pollen to the butterfly eggs. Therefore, oogenesis is greatly affected by pollen intake. When pollen is absent in the diet, oviposition rates decrease and lifetime fecundity, or the number of eggs produced, drops significantly.[15]

Pollen feeding also correlates with the unpalitibility of the butterflies to predators. The amino acids collected from pollen are used as precursors to synthesize cyanogenic glycosides that can be stored in larval and adult tissues, accounting for their toxicity.[14] When pollen availability is low, adults are able to scrounge for nitrogen reserves where there are stored cyanogens. Furthermore, the butterflies are able to recycle the cyanogenic glycosides that they have synthesized previously. With less expectation of pollen quality, females will reallocate their cyanogensto reproductive input since larvae have been seen to benefit the most from cyanogenesis and a lack of amino acids in adult diet does not necessarily correlate with reduced cyanogenic defense.[17]

Passiflora Feeding[edit]

Larvae regulate their nutritional input to an equal protein-carbohydrate ratio.[18] They feed on the Passiflora plants on which their mother laid their eggs. Passiflora plants have trichomes, which are meant to reduce herbivore attack through physical and/or chemical means. H. charithonia larvae have developed capabilities in order to avoid the effects of the trichomes. They are able to physically free themselves from the entrapment of a trichome by pulling their legs from the hold of the trichome hook and they lay silk mats on the trichomes, providing a surface so that leaf anatomy can be navigated more easily, and they remove the tips of the trichomes by biting them. Therefore, trichome tips are found in the faeces of these individuals. Furthermore, larvae often try to avoid areas where trichome density is highest by staying on the under surface of the leaves.[19]

Mating System[edit]

Mating cues[edit]

Male butterflies exhibit a preference for visual, olfactory, tactile, and auditory cues during mating so that females are made more obvious.[20] In H. charithonia, certain host plants provide these cues to males, thereby influencing the time and location of reproduction. This happens because as larvae damage the plant upon eating it, green-leaf volatiles, six carbon alcohols, aldehydes, and acetates, are released. They give olfactory cues to the male, thereby indicating the location of the pupae (mate). Since these pupae have camouflaged coloring and lack strong sexual pheromones, the olfactory cue given off from the damaged plant is necessary for the male to find a mate. Furthermore, the odors given off from the plant not only signal the location of pupae but also provide a trigger that induces learning the location of the plant for future copulations. This is possible due to the fact that the butterflies have a sophisticated spatial memory, as exhibited by their tendency to have specific nocturnal roosting locations and regular visitations of sites with abundant adult resources.[21]

A common problem amongst all butterflies is the ability of mates to discriminate mating with conspecifics and heterospecifics (other butterfly species).[22] Although mistakes do occur, they are quite uncommon and males are able to distinguish, more often than not, between the emissions produced upon the larvae and other herbivores eating the plant. It has been shown that the zebra longwing also uses larval coloration and odors to find mates. Chemical analysis has demonstrated that the larvae release volatiles that are similar chemically to those emitted by the plant.[21]

H. chartihonia also demonstrates pleiotropic mating cues, particularly in regards to mimicry. Pleiotropic mating cues have been simultaneously ecologically and sexually selected. Mimetic patterns have been used in cues to mate-finding as well as in predatory protection, leading to the coevolution of mate choice and assortative mating, a nonrandom mating pattern in which individuals choose mates with similar genotypes and/or phenotypes to themselves.[23] Polymorphism exists in mimetic patterns due to the fact that each morph mimics a different model.[24]

Pupal mating[edit]

Pupal mating arose once during the evolution of Heliconius, and these species form a clade on the evolutionary tree. Although pupal mating is observed quite frequently in insectaries, it is rarely seen in nature.[25] Males perform precopulatory mate guarding behavior, in which males find and perch on pupae, followed by copulation with the female.[21]

Upon reaching the pupae, males often have to compete to copulate with the female, who is teneral (freshly emerged). Typically, a male visits the same pupa for at least a week, during which time he periodically swarms it, fighting with other males over positioning. Fights consist of males fending off other males that attempt to land on the same pupa by opening their wings. If this does not work, the male tries to throw the intruder off with the pressure of his head and antennae. If more males attempt to swarm the pupa, the two original males will work together to attempt to fend off the others by simultaneously opening their wings, momentarily forgetting that they were originally competitors. Fights usually last one or two hours, but continue throughout the pupa’s development.

The act of pupal mating consists of the male inserting his abdomen into the pupa. If a second male appears, he will fend off other males for the first male by opening his wings while the first male copulates, rather than attempting to mate with the female himself by inserting his abdomen. After two or three hours of mating, the female comes out during which copulation stills occurs for another hour. During the process, females remain relatively still, with the exception of the spreading of their wings and the discharge of meconium. As copulation proceeds, fewer males attempt to approach the female. However, if this does occur, the copulating male continues to fend them off by opening his wings. After copulation is done, the male and female sit side-by-side for some time. During this brief period, no other males attempt to mate with the female.[25]

Nuptial gifts in the form of the spermatophore[edit]

Males transfer a protein-rich spermatophore to females upon mating. Spermatophores are thought to be nuptial gifts, which serve a number of different functions. One of these is to provide chemicals (cyanogens) that protect the mother and future offspring from predators so that female and egg survival are enhanced. For females, this is beneficial because egg-laying causes a depletion of protein and her defensive chemicals. Among nine Heliconius species studied, Heliconius chartihonia had the highest average cyanide concentration in its spermatophores.[26]

In most species of butterflies, pheromones play a role in courtship and mate recognition.[20] However, they can also play a role in deterring mates. Spermatophores are also thought to contain anaphrodisiacs, which are pheromones that reduce the attractiveness of the females to subsequent males, thereby indicating that anaphrodisiac evolution is driven by intrasexual selection. Because of this, they help reduce the occurrence of male harassment by already mated females. Furthermore, nonfertile sperm (apyrene) is added to spermatophores to increase the time of refractory periods. Overall, the transfer of anaphrodisiacs is a mechanism for degrading female mating choice.[6]

It has been observed that complete spermatophore degradation to an orange or yellow substance occurs in a 2-week period. Pupal-mating butterflies like Heliconius charatonia are thought to be monandrous, but spermatophore degradation could undermine this idea since spermatophores are often examined to count the number of matings a female has performed. However, upon further observation, it was found that females rarely participate in more than one mating per lifetime.[27]

Sex ratio and distribution[edit]

At eclosion, the ratio is highly female-biased, but the rest of the year the sex ratio is overall male-biased (68% males). This is due to the fact that males typically stay near their natal sites to find a mate while females move around to find oviposition or feeding sites at various Passiflora plants. Because females are very mobile, males do not mate with relatives very often, and therefore inbreeding rates are very low.[28]

See also[edit]

Gallery[edit]

References[edit]

  1. ^ a b Card for charithonia in LepIndex. Accessed 3 August 2007.
  2. ^ a b c d "Attributes of Heliconius charithonia". Retrieved November 14, 2013. 
  3. ^ "Zebra Longwing". Retrieved November 14, 2013. 
  4. ^ a b "Zebra Heliconian-Florida's State Butterfly!". Retrieved November 14, 2013. 
  5. ^ Scott, JA. (1986). The Butterflies of North America: A Natural History and Field Guide. Stanford University Press.
  6. ^ a b Estrada, Catalina, Stefan Schulz, Selma Yildizhan, and Lawrence E. Gilbert. (2011). Sexual Selection Drives The Evolution Of Antiaphrodisiac Pheromones In Butterflies. Evolution 65(10):2843-854.
  7. ^ Kronforst, Marcus R., and Theodore H. Fleming. "Lack of Genetic Differentiation among Widely Spaced Subpopulations of a Butterfly with Home Range Behaviour." Heredity 86 (2001): 243-50.
  8. ^ Cardoso, Márcio Z. "Reconstructing Seasonal Range Expansion of the Tropical Butterfly, Heliconius Charithonia, into Texas Using Historical Records." Journal of Insect Science 10.69 (2008): 1-8.
  9. ^ a b c Finkbeiner, Susan D., Adriana D. Briscoe, and Robert D. Reed. "The Benefit of Being a Social Butterfly: Communal Roosting Deters Predation." Royal Society Publishing 279.1739 (2012): 2769-776. Print.
  10. ^ Sacledo, Christian. "Behavioral Traits Expressed During Heliconius Butterflies Roost-Assembly". Trop. Lepid. Res 21.2 (2011): 80-83.
  11. ^ a b Salcledo, Christian. "Environmental Elements Involved in Communal Roosting in Heliconius Butterflies (Lepidoptera:Nymphalidae)." Entomological Society of America 39.3 (2010): 907-11. Web.
  12. ^ Bybee, Seth M.; Monica D. Furong Yuan, Jorge Llorente-Bousquets, Robert D. Reed, Daniel Osorio, Adriana D. Briscoe (2012). "UV Photoreceptors and UV-Yellow Wing Pigments in Heliconius Butterflies Allow a Color Signal to Serve Both Mimicry and Intraspecific Communication". The American Naturalist. 1 179: 38–51. 
  13. ^ Sacledo, Christian. The Biology of Heliconius Night Roosting A Foundation. Thesis. UFDC, 2010. Gainesville, Fl: University of Florida, 2010. Print.
  14. ^ a b Estrada, Catalina, and Chris D. Jiggins. "Patterns of Pollen Feeding and Habitat Preference among Heliconius Species." Ecological Entomology 27 (2002): 448-56.
  15. ^ a b c Salcledo, Christian. "Evidence of Pollen Digestion at Nocturnal Aggregations of Heliconius Sara in Costa Rica (Lepidoptera: Nymphalidae)." Trop. Lepid. Res. 20.1 (2010): 35-37. Web.
  16. ^ Belatrán, Margarita, Chris D. Jiggins, Andrew V. Z. Brower, Eldredge Bermingham, and James Mallet. "Do Pollen Feeding, Pupal-mating, and Larval Gregariousness Have a Single Origin in Heliconius Butterflies? Inferences from Multilocus DNA Sequence Data." Biological Journal of the Linnean Society 92 (2007): 221-39.
  17. ^ Cardoso, M. Z. "Pollen Feeding, Resource Allocation and the Evolution of Chemical Defence in Passion Vine Butterflies." Journal of Evolutionary Biology 26 (2013): 1254-260.
  18. ^ VanOverbeke, Dustin R. "Nutritional Ecology of a Generalist Herbivore Vanessa Cardui Linnaeus Lepidotera: Nymphalidae on Variable Larval and Adult Diets." Diss. UC Riverside, 2011.
  19. ^ Cardoso, Márcio Z. "Ecology, Behavior and Binomics: Herbivore Handling of a Plant's Trichome: The Case of Heliconius Charithonia (L.) (Lepidoptera:Nymphalidae) and Passiflora Lobata (Kilip) Hutch. (Passifloraceae)." Neotropical Entomology 37.3 (2008): 247-52.
  20. ^ a b Douglas, Matthew M. (1986). The Lives of Butterflies. Ann Arbor: University of Michigan. 
  21. ^ a b c Estrada, Catalina; Lawrence E. Gilbert (2010). "Host Plants and Immatures as Mate-searching Cues in Heliconius Butterflies". Animal Behaviour 80: 231–239. 
  22. ^ Boggs, Carol L., Ward B. Watt, and Paul R. Ehrlich. (2003). Butterflies: Ecology and Evolution Taking Flight. Chicago: University of Chicago.
  23. ^ Jiggins, Chris D., Igor Emelianov, and James Mallet. (2005). Assortative Mating and Speciation as Pleiotropic Effects of Ecological Adaptation: Examples in Moths and Butterflies. Insect Evolutionary Ecology. By Mark Fellowes, G. J. Holloway, and J. Roff. Wallingford, Oxfordshire: CABI Pub., 451-73.
  24. ^ Scoble, M. J. (1995). The Lepidoptera: Form, Function and Diversity. [London]: Natural History Museum
  25. ^ a b Sourakov, Andrei. (2008). Pupal Mating in Zebra Longwing (Heliconius Charithonia): Photographic Evidence. News of the Lepidopterists' Society 50(1):26-32.
  26. ^ Cardoso, Márcio Zikán, and Lawrence E. Gilbert. (2006). A Male Gift to Its Partner? Cyanogenic Glycosides in the Spermatophore of Longwing Butterflies (Heliconius). Naturwissenschaften 94(1):39-42.
  27. ^ Walters, James R., Christine Stafford, Thomas J. Hardcastle, and Chris D. Jiggins. (2012). Evaluating Female Remating Rates in Light of Spermatophore Degradation in Heliconius Butterflies: Pupal-mating Monandry versus Adult-mating Polyandry. Ecological Entomology 37:257-68.
  28. ^ Fleming, Theodore H., David Serrano, and Jafet Nassar. (2005). Dynamics Of A Subtropical Population Of The Zebra Longwing Butterfly Heliconius Charithonia (Nymphalidae). Florida Entomologist 88(2):169-79.

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