Heliconius erato

Heliconius erato, or the red postman, is one of about 40 neotropical species of butterfly belonging to the genus Heliconius. It is also commonly known as the small postman, the red passion flower butterfly, or the crimson-patched longwing. It was described by Carl Linnaeus in his 1758 10th edition of Systema Naturae. H. erato exhibits Müllerian mimicry with other Heliconius butterflies such as Heliconius melpomene in order to warn common predators against attacking, which contributes to its surprising longevity. It also has a unique mating ritual involving the transfer of anti-aphrodisiacs from males to females. Recent field work has confirmed the relative abundance of this butterfly. H. erato is a neotropical species, found from southern Texas to northern Argentina and Paraguay, and resides on the edges of tropical rainforests. It is philopatric, having a particularly restricted home range. In areas of dense population in Trinidad, some home ranges are only separated by 30 yards, but H. erato rarely travels to neighboring home ranges. Larvae feed on the host plant, first consuming the terminal bud. After they have exhausted the resources of the plant they have hatched on, later instars may move to another plant. H. erato is a pollen-feeding species, collecting from the Lantana camara flower. They do not spend much time or energy collecting nectar (only remaining for a few seconds). Instead, they collect pollen in a mass on the ventral side of their proboscis. They then agitate the pollen by coiling and uncoiling their proboscis in order to release its nutrients. H. erato is then able to extract nitrogenous compounds in a clear liquid, including amino acids like arginine, leucine, lysine, valine, proline, histidine, isoleucine, methionine, phenylalanine, threonine, and tryptophan. Females typically carry larger loads of pollen than males as females require more amino acids for egg production. Previous studies have shown that host plants, such as Passiflora, have coevolved with Heliconius butterflies. Passiflora plants are usually found in low densities with even less plants in fruiting or flower conditions due to caterpillar feeding. To increase chances of survival and cross-pollination, Passiflora plants synthesize toxins in leaves to deter Heliconius. Passiflora species produce different toxins, leading to different preferences for oviposition among Heliconius species. This leads to a lower chance of herbivore damage for individual Passiflora species and thus helps protect Passiflora plants. Chemical composition of toxins in such plants have not been studied widely. Studies have identified cyanogenic glycosides and alkaloids as potential chemicals that drive distasteful reactions among Heliconius. Toxin variation among Passiflora is one of the reasons for host specificity among Heliconius butterflies.   Studies have shown that H. erato species that feed on specific Passiflora species tend to spend more time on the host plant and are thus exposed to the toxins for a longer period. Accumulation of toxins such as cyanogenic glycosides leads to a low survival rate among H. erato larvae. Increasing exposure to parasitoids due to longer time spent on the host plant also contributes to the high mortality rate. One recent study showed that mortality increased among H. erato larvae which fed on cyanide-releasing Passiflora. Survived butterflies were capable of excreting higher levels of cyanides, suggesting a defense mechanism in H. erato. H. erato species with more mechanisms to detoxify and secrete ingested toxins are the result of genetic differences among H. erato subspecies.  Toxin excretion, from previous studies, results in changes in wing pattern and body size. Consequences include decreased fecundity, egg size, and survival rate.