Heliconius hecale zuleika, Costa Rica – Maris Pukitis
Introduction
The tribe Heliconiini, colloquially known as Longwings, includes 71 species, all confined exclusively to the neotropics. The Heliconiini includes the genera Heliconius, Podotricha, Dryas, Agraulis, Dione, Dryadula, Eueides, Neruda, Laparus and Philaethria.
The 39 Heliconius species are much studied by geneticists and taxonomists. Many of them produce a staggering variety of colour forms – Heliconius erato e.g. produces no less than 29 geographical forms, each of which corresponds almost exactly in colour and pattern to a “sister” subspecies of Heliconius melpomene flying in the same area.
All Heliconius species have long black wings bearing simple but striking patterns, typically featuring streaks or patches of red and cream, or blue and cream. Several including hecale have subspecies which mimic ‘tiger complex’ orange and black Ithomiines. Heliconius hecale zuleika for example is a mimic of the Cream-spotted Tigerwing Tithorea tarricina, while another subspecies zeus mimics its congener Tithorea harmonia. Likewise ithaca is a near-perfect mimic of another Ithomiine Melinaea marsaeus. In fact every one of the 29 hecale subspecies mimics an Ithomiine species that inhabits the same area. The Ithomiines in all cases are toxic or unpalatable to birds. Studies have provided strong evidence that birds which eat the Ithomiines suffer from nausea and vomiting. Consequently they avoid eating similarly coloured butterflies, whether they be other toxic Ithomiines, or palatable mimics such as Heliconius hecale.
Heliconius hecale is distributed from Mexico to Bolivia. The illustrated subspecies zuleika is found in Central America, from Mexico to Panama.
Habitats
The butterfly is found in forested areas at altitudes between sea level and about 1400m.
Lifecycle
To be completed.
Adult behaviour
Heliconius butterflies are characterised by having a very delicate fluttering flight, particularly when hovering around flowers. They commonly nectar at Hamelia, Lantana and Palicourea.
Unlike other butterflies, Heliconius females feed on pollen as well as nectar. Studies of ethilla have shown that females deprived of pollen can only produce about 15% of the number of eggs laid by females that have access to it. This probably applies equally to other Heliconius species including melpomene. The pollen from Psiguria, Anguria and Gurania flowers provides amino acids that can’t be obtained from nectar or other sources, and contributes greatly to the longevity of the butterflies – some Heliconius species are known to live for up to 9 months as adults.
Studies have shown that Heliconius butterflies have home ranges within which they can memorise the locations of nectar and pollen sources, host plants and communal roosting sites. They are able to plan the most efficient route by which to visit all nectar / pollen sources in the vicinity by using simple calculations akin to what mathematicians call the “travelling salesman algorithm”. Erlich & Gilbert demonstrated that individual butterflies memorise the location of particular Psiguria plants, which they visit daily, following a predefined circuit through the forest.
In the genus Heliconius most species rely entirely on airborne chemicals to locate mates. Males of hecale, ismenius and cydno are attracted by pheromones to the pupae of conspecific females. The day before emergence a female pupa will usually have several males in close attendance. A frantic battle takes place the instant she hatches, as the males all struggle to copulate with her, not even allowing her time to expand and dry her wings. In some other Heliconius species such as hecalesia, hewitsoni, erato, charithonia and sara the males don’t even wait until the female emerges. Instead they physically break open her pupa and copulate as soon as her genitalia are accessible.