|Ptocadica sp. ("fat yellow") prefers to feed on Passiflora ambigua|
The correspondences are as follows: Monomacra violacea (Blue), Parchicola d.f.1 (Black-legged Yellow), Heliconius cydno, and H. hecale are generalists, feeding on most or all Passiflora species. Passiflora ambigua (in subgenus Passiflora) hosts the specialist butterfly Heliconius doris and is the preferred host for Ptocadica sp. "yellow". P. oerstedii and P. menispemifolia host the butterfly H. melpomene, but don't host a correspondingly specialist flea beetle. In Decaloba/Astrophea, P. pittieri hosts the specialist butterfly H. sappho and the specialist flea beetle Pedilia sp "red". P. lobata hosts Heliconius charitonia (which I have not seen yet at La Selva this trip) and is the preferred host for Ptocadica sp. "red-white". P. auriculata hosts the specialist butterfly H. sara and is the preferred host for Ptocadica bifasciata, the red-brown-white flea beetle, and Parchicola d.f. 2, the Yellow-legged Yellow flea beetle. P. biflora hosts H. erato and is the preferred host for Monomacra chontalensis.
|Crematogaster ants sharing Passiflora auriculata nectary with flea beetle larva|
|Pedilia sp "red" larvae eating stem epidermis on P. pittieri|
One of the biggest differences I have seen between between flea beetles and Heliconiine butterflies is that the beetles tend to avoid plants or plant parts which produce high amounts of cyanide gas when crushed. Even Pedilia sp. that feeds on the highly cyanogenic Passiflora pittieri seems to avoid some of the cyanide (perhaps 90%) by feeding on the epidermis of the stems and leaves (see photos of feeding damage). The butterflies seem completely unaffected by the presence or absence of HCN, with caterpillars feeding and growing rapidly on plants with the highest HCN content such as P. arbelaezii and P. costaricensis. Also, preliminary measurements indicate that Pedilia sp. "red" are not themselves cyanogenic, in either the larvae or the adults. This is a strong contrast to Heliconiine butterflies and larvae, which are strongly cyanogenic. Another big difference I mentioned above: flea beetles seem unaffected by the presence or absence of ants (see photo of flea beetle larva with ants). Heliconius, by contrast, seldom survive to pupation on plants tended by the "wrong" species of ants (such as Ectatomma tuberculatum).
|P. pittieri leaf vein that has had its epidermis removed by feeding Pedilia flea beetles.|
Overall summary of project: Progress! We're having fun! Remarkably stable communities of plants and insects over the 40 year interval (thank you, La Selva!).