In the Atlantic forests of Brazil resides a small orchid known scientifically as Dichaea cogniauxiana. Like most plant species, this orchid experiences plenty of pressure from herbivores. It faces rather intense pressures from two species of weevil in the genus Montella. These weevils are new to science and have yet been given full species status. What's more, they don't appear to eat the leaves of D. cogniauxiana. Instead, female weevils lay eggs in the developing fruits and the larvae hatch out and consume the seeds within. In other words, they treat the fruits like a nursery chamber.

This is where this relationship gets interesting. You see, the weevils themselves appear to take matters into their own hands. Instead of waiting to find already pollinated orchids, an event that can be exceedingly rare in these dense forests, these weevils go about pollinating the orchids themselves. Females have been observed picking up orchid pollinia and depositing the pollen onto the stigmas. In this way, they ensure that there will be developing fruits in which they can raise their young.

Left unchecked, the weevil larvae readily consume all of the developing seeds within the pod, an unfortunate blow to the reproductive efforts of this tiny orchid. However, the situation changes when parasitoid wasps enter the mix. The wasps are also looking for a place to rear their young but the wasp larvae do not eat orchid seeds. Instead, the wasps must find juicy weevil larvae in which to lay their eggs. When the wasp larvae hatch out, they eat the weevil larvae from the inside out and this is where things get really interesting.

The wasp larvae develop at a much faster rate than do the weevil larvae. As such, they kill the weevil long before it has a chance to eat all of the orchid seeds. By doing so, the wasp has effectively rescued the orchids reproductive effort. Over a five year period, researchers based out of the University of Campinas found that orchid fruits in which wasp larvae have killed off the weevil larvae produced nearly as many seeds as uninfected fruits. As such, the parasitoid wasps have made effective pollinators out of otherwise destructive herbivorous weevils.

The fact that a third party (in this case a parasitic wasp) can change a herbivore into an effective pollinator is quite remarkable to say the least. It reminds us just how little we know about the intricate ways in which species interact and form communities. The authors note that even though pollination in this case represents selfing and thus reduced genetic diversity, it nonetheless increases the reproductive success of an orchid that naturally experiences low pollination rates to begin with. In the hyper diverse and competitive world of Brazilian rainforests, even self-pollination cab be a boost for this orchid.

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Photo by I, Luc Viatour licensed under CC BY 2.0

Parrots, especially the larger species, have long been thought to be a bane to plant reproduction. Anyone that has watched a parrot feed may understand why this has been the case. With their incredible beaks, parrots make short work of even the toughest seeds. However, this assumption is much too broad. In fact, recent research suggests that entire Amazonian ecosystems may have parrots to thank.

Bolivia's Amazonian savannas are remarkable and dynamic ecosystems. These seasonally flooded grasslands are dotted with forest islands dominated by the motacú palm (Attalea princeps). These forest patches are an integral part of the local ecology and have thus received a lot of attention both culturally and scientifically. The dominance of motacú palm poses an intriguing question - what maintains them on the landscape?

The fruits of this palm are quite large and fleshy. Some have hypothesized that this represents an anachronism of sorts, with the large fruit having once been dispersed by now extinct Pleistocene megafauna. Despite this assumption, these forest islands persist. What's more, motacú palms still manage to germinate. Obviously there was more to this story than meets the theoretical eye. As it turns out, macaws seem to be the missing piece of this ecological puzzle.

Researchers found that three species of macaw (Ara ararauna, A. glaucogularis, and A. severus) comprised the main seed dispersers of this dominant palm species. What's more, they manage to do so over great distances. You see, the palms offer up vast quantities of fleshy fruits but not much in the way of a good perch on which to eat them. Parrots such as macaws cannot take an entire seed down in one gulp. They must manipulate it with their beak and feet in order to consume the flesh. To do this they need to find a perch.

Suitable perches aren't always in the immediate area so the macaws take to the wing along with their seedy meals. Researchers found that these three macaw species will fly upwards of 1,200 meters to perch and eat. Far from being the seed predators they were assumed to be, the birds are actually quite good for the seeds. The fleshy outer covering is consumed and the seed itself is discarded intact. This suggests that preferred perching trees become centers of palm propagation and they have the parrots to thank.

Indeed, seedling motacú palms are frequently found within 1 - 5 meters of the nearest perching tree. No other seed disperser even came close to the macaws. What's more, introduced cattle (thought to mimic the seed dispersing capabilities of some extinct megafauna) had a markedly negative effect on palm seed germination thanks to issues such as soil compaction, trampling, and herbivory. Taken together, this paints a radically different picture of the forces structuring this unique Amazonian community.

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