Napaea eucharila (H. Bates, 1867) – Early stages

This Riodinid species has a widespread distribution from Mexico to Bolivia and in Colombia is found in lowland forests from the Choco region to the Amazon. They also colonize secondary forests and fragments where there are Bromeliads, the larval food plants.

                      (Click on photos for a higher resolution view in a separate tab)   Napaea_male   Napaea_female                                      male                                                                                             female          

Adults:   As seen in the photos the adults are dimorphic, the male is smaller and darker and the female has more red-orange coloration in the submarginal band of the hindwing. Males perch on tree trunks between 11am and 1pm and dart out to engage other males.

Host Plants:     Bromeliads (Bromeliaceae). Larvae were found on Aechmea angustifolia and also on cultivated Pineapple, Ananas comosus near Villavicencio, Colombia. 

IMG_8725  IMG_8565     Aechmea angustifolia (Bromeliaceae), the larval host plant. Feeding damage is seen on the right. 

Early Stages:  Larvae feed on the upper surface of the leaves, generally at night. As the larvae feed, they form longitudinal strips and leave intact the lower epidermis, the bottom layer of the leaf .  During the day they rest head down near the base of the leaf, where they are less conspicuous to predators.  No eggs or 1st instar larvae were found.               

IMG_8720a  IMG_8775               2nd instar, 5 mm in length.                                                              3rd instar, 13 mm

IMG_8907  IMG_8853                5th instar, 23-25 mm                                              A 4th instar parasitized larva underside.

IMG_8872  IMG_8813              A resting 4th or 5th instar                                                             A 5th instar feeding

Parasites:

IMG_9025  IMG_8895       Parasitoid cocoons underneath a dead larva                            Close-up of the cocoons (pupal stage)

All ten larvae found on the Aechmea plants were parasitized by a very efficient Braconidae parasitoid and never pupated. The wasp larvae emerged from the caterpillar and pupated between the leaf and the underside of the caterpillar. Healthy N. eucharila larvae that completed the cycle were found on potted Pineapple (Ananas comosus) in the plant nursery, possibly surviving because they were outside the search pattern of the wasps. The behavior of parasitized larvae differs from that of healthy larvae. Infected larvae start to wander and leave the host plant; healthy larvae never leave the plant and pupate there.

Larval Defenses:

IMG_8748a  IMG_8881                           Arrows showing the TNOs                              Here arrows indicate the liquid produced.

TNOs:  This species belongs to a group of New World Riodinidae with 5 radial wing veins. This group is divided into two tribes, the Eurybiini and the Mesosemiini. The later tribe is further divided into two subtribes, the Mesosemiina, and the Napaeina, the subtribe of our subject species. What they also have in common are larvae that possess organs used for ant-mediation, the Tentacle Nectary Organs (TNOs). Although larvae of these groups are not mymecophilous (attended by ants), the organs of several species have been observed to evert and produce a liquid when contacted by ants. The exact use and purpose of these organs in the present day Mesosemiina is not known but they were important enough to conserve during many millions of years of evolution without an ant-association.

IMG_8776  IMG_8802a     A small predatory ant probing the defense.                    The response to a simulated attack, the larva                                                                                                                          leans into the stimulus directing the setae

 Setae:  Especially the the last two instars have a dense coat of long setae which forms a barrier to predators, protecting the body. The setae break off in the mandibles of an ant and appear to be sticky causing the ant to break off the attack and try to clean its mandibles. The larvae will also roll into a perfect hairy sphere when dislodged from the leaf.

IMG_8797  IMG_9053   The larvae are water-repellent,  the setae                      This larva is floating on the water surface and had                 are hydrophobic.                                                           no problem reaching the leaf and climbing out.

Being hydrophobic is an adaptation for living on Bromeliads that have the tank system, This type of Bromeliad catches and stores rainwater in the leaf whorls for nutrient capture. A sudden rainstorm could fill the reservoirs and drown a larvae not so adapted. This condition also allows them to feed on the upperside of the leaves and not get water-logged or washed off the leaf in a rainstorm, a common event in the tropics. In Villavicencio it rains 22 to 28 days a month during the rainy season.

IMG_8938   IMG_8904aHead on view of a larva to show the relation between       Feeding damage crypsis. From a distance the      the width of the larva and the width of the damage.            larva appears to be a damaged part of the leaf.

 Crypsis:  Larvae appear either yellow or white depending on the lighting. This coloration is produced by the color of the dense setae and not the body color which is whitish with green streaks. This coloration contrasts with the dark green of the leaves but matches the color of the damaged strips produced when the larvae feed. The larvae eat a swath of leaf about the width of the larva and when feeding appear to be an extension of the damaged portion of the leaf. The setae also change the caterpillar’s body contour to a smoothly curved surface and shroud the movements of the head and legs, they appear to glide across the leaf surface when in movement.

IMG_8986  IMG_8991  Ananas comosus (Pineapple) showing feeding              Here pupae are seen head down near the base of     damage of two larvae.                                                                the leaf.                                                                 

Pupa:                           

IMG_8924  IMG_8919 Pupae measure 14-15 mm in length- day 3.

Pupation took place after a 3 day prepupal stage of the 5th instar larva. The pupation site was close to the insertion of a Ananas leaf and was head down towards the center of the plant in both cases. The female pupa was slightly larger than the male. No silk girdle was spun. The pupae have an interesting dark pigmented raised area around the last two spiracles with a circular cluster of dendritic setae. The day before eclosion a slight color change was noted and only on the morning of eclosion did the adult colors become noticeable through the cuticle of the pupa. The adults eclosed around 12 pm after 12 days for the male and 11 days for the female.

IMG_9016  IMG_8928                              Pupa- day 11                                          Raised cuticle around the spiracle on segment A8

IMG_9057  IMG_9082                         Pupa- day 12 – Eclosion day                                                             Recently eclosed female

Further information:

http://www.acguanacaste.ac.cr/paginas-de-especies/insectos/111-riodinidae/3470-i-napaea-eucharila-i-riodinidae-2

http://janzen.sas.upenn.edu/caterpillars/database.lasso

Brevignon, Christian. 1992. “Elevage de Deux Riodininae Guyanais, Napaea Beltiana Bates et Cremna Thasus Stoll.” Alexanor 17 (7): 403–13.  (download)

Schmidt, Gerold, and Gerhard Zotz. 2000. “Herbivory in the Epiphyte, Vriesea Sanguinolenta Cogn. & Marchal (Bromeliaceae).” Journal of Tropical Ecology 16 (6): 829–39. doi:10.1017/S0266467400001747.  (download)

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