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How to Find a Bug the Size of a Grain of Rice in Tahiti’s Dense Tropics

Above, our study species, and below, the landscape in which these bugs hide.
Above, our study species, and below, the landscape in which these bugs hide.

National Geographic grantee  Nik Tatarnic is taking a closer look at the traumatic sex lives of Tahiti’s tiny bugs. Follow Nik’s expedition on Explorers Journal as he investigates the bizarre sexuality of the genus known as Coridromius.

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In less than a week we head to Tahiti to hunt for bizarre little bugs known for their violent mating system called traumatic insemination. Given that these bugs, called Coridromius, are no more than 2 to 3 mm in length, finding them and documenting their behavior is no simple task.

Luckily, there is a knack to finding these impossibly small bugs.  You see, like most members of the plant bug family Miridae, Coridromius feed on specific host plants. For example, in Australia, C. monotocopsis lives on the coastal shrub Monotoca elliptica, while C. chenopoderis – another Australian native – lives almost exclusively on chenopods, a type of flowering plant. Thus, if you can find the host plant, you can generally find the bugs.

In Tahiti, C. tahitiensis and C. taravao (see photo above) have both been found living together on two plant species: the tree, Metrosideros collina, and the invasive shrub Schinus terebinthifolius, aka Brazilian pepper. (Regarding the latter, as a biologist it’s comforting to know that at least some native species have found a use for this weed.) In any case, this co-habitation on the same host is of particular interest, as usually closely related animals with similar needs end up segregated due to competition. In plant feeding insects, this is characterized by different species specializing on different plants. Apparently not so for these critters.

So how do a pair of evolutionary biologists with a shaky understanding of tropical plants go about finding these host plants? This is where the help of our Tahitian collaborator, local botanist Jean-Yves Meyer, will be essential. Jean-Yves has over 25 years’ experience studying the terrestrial biodiversity of French Polynesia, and is our go-to for searching out potential field sites. It seems he knows where just about every track on the island and where each species of plant can be found.

Once we find the bugs, then the tricky work begins. When we get to Tahiti I’ll show how we catch the insects, and how we use tricks of documentary filmmaking to record and study their behavior.

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