Archive | September 18, 2012

Dangerous candy

Bushhopper Dictyophorus spumans from South Africa, also known as the foam grasshopper, is deadly toxic, and it tells you all about it with its bright coloration [Canon 7D, Canon 14mm]

My first visit to Africa was in 1989, when I went to visit some friends in Zimbabwe. Back then the country was still prosperous and democratic, Toni Childs optimistically sang “No more crime in your lifetime, Zimbabwe”, and nothing indicated the darkness it would soon descend into. I spent a few weeks traveling around the country, getting the first dose of what would soon become an obsession and a deep love for Africa. This was the first time that I saw elephants and other members of the “charismatics megafauna” outside of a ZOO, but the animals that made the greatest impression on me were not mammals, but big, slow-moving grasshoppers that covered nearly every bush and tree around the capital Harare. They were unafraid of me, they were colorful, and they looked …tasty. There was something about these bright, multicolored insects that just made me want to put them in my mouth; they were almost like candies.

Bushhopper Dictyophorus cuisinieri from Guinea defending herself with toxic foam [Canon 1Ds MkII, Canon 100mm macro, Canon MT-24EX twin light]

This, of course, only shows how far we humans are removed from the rest of the natural world, because to any other animal these very characteristics – the slowness, the bright coloration – spell out “you touch me and I’ll kill you!” And surely, the grasshoppers, which I later identified as bushhoppers Phymateus baccatus, were members of the family Pyrgomorphidae, which includes some of the most toxic insects known to man. They feed primarily on Apocynaceae and Solanaceae, plants loaded with toxic secondary compounds, which the grasshoppers are able to sequester and accumulate in their bodies. Among these poisonous metabolites are powerful cardiac glycosides. In very small doses these can be used to treat arrhythmia and other heart diseases, but in larger ones, such as if you ate one of the grasshoppers, will cause heart failure. In fact, there has been a number of cases of children in Zimbabwe and South Africa dying after eating these insects. (There are also known cases of dogs who perished after ingesting these insects, which, I think, shows how similar to humans they have become – to their own detriment; jackals in Africa never eat bushhoppers.)

A nymph of a bushhopper Phymateus viridipes from Mozambique can afford being slow and conspicuous thanks to the toxins in its body [Canon 7D, Canon 14mm, Canon MT-24EX twin light]

But even if you misinterpret the warning coloration, the bushhoppers give you plenty of additional warning. Many species fan their colorful wings when molested, and if this does not get the message across, they begin to squirt blood (hemolymph) through their thoracic respiratory openings, while simultaneously blowing air into it. This behavior instantly produces copious amounts of white foam, which quickly turns yellow and fills the air with acrid smell. All this means that bushhoppers are left alone by most predators who otherwise love gorging on grasshoppers, such as baboons and many birds, and can be found in huge numbers in suitable habitats. Young nymphs of many species are gregarious, and can be found in groups consisting of hundreds of individuals. Such aggregations are vividly colored, and have a much stronger warning effect than a single, small grasshopper nymph would, no matter how strikingly patterned. It is only after the hoppers reach a larger body size (many species are 3 to 4 inches long) that they begin leading a more solitary life, although in most species of the Pyrgomorphidae even the adults prefer to hang around each other.

Bushhopper Phyteumas whellani from Mozambique fans its wings as a warning sign [Canon 7D, Canon 100mm macro, 3 speedlights 580EXII]

Interestingly, close relatives of African bushhoppers are Mexican grasshoppers of the genus Sphenarium, which are not only non-toxic, but also quite tasty and nutritious. Some species of Sphenarium are serious agricultural pests in Oaxaca and other parts of the country, and the most effective way of controlling them is to turn them into delicious “chapulines asados.”

Candy-like colors of the bushopper Taphronota ferruginea from Guinea spell out a loud warning [Canon 1Ds MkII, Canon 180mm macro]