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Why study Biting Midges?

There are numerous reasons to study biting midges. Primarily, in a world where we have become acutely aware that natural environments are under huge duress and that species are becoming extinct at an unprecedented rate, it is critically important that we explore the details of our ecosystems. Scientists have become increasingly aware that such ecosystems are primarily sustained by a wealth of small organisms which are represented by millions of different species (worldwide). Although there have been major extinctions in the past, these have primarily involved large organisms such as vertebrates. In large measure, smaller organisms, such as insects, have not experienced catastrophic extinctions. For example, at the end of the Cretaceous when dinosaurs and many other large organisms went extinct, most groups of insects more or less came through unharmed. In other words, ecosystems have been sustained for a long, long time by such small organisms as biting midges. It is only recently, through the impact of humans, that they disappearing at such a rate. We have very little idea what will be the outcome of grossly modifying ecosystems when we remove these players by the truckload; there is a good possibility that the result could be catastrophic, not only for the species that are permanently removed from the planet but, ultimately, for us. It is vital, therefore, to know the species that are present in nature and to better understand their roles in ecosystems.

One might think that a group that bites humans and domestic animals and transmits many diseases would be well known but unfortunately this is not the case. Even in Canada, with a reduced fauna, there are species which bite humans which are unnamed. In the tropics, it is obvious that the majority of the species are unnamed (and there are thousands!). First of all, therefore, there is a great need to describe and name the different species present. This will provide at a minimum, an estimate of patterns of biodiversity (i.e. where are the species found and where are areas of high endemism), and allow for further ecological, behavioural and other biological studies.

From what we do know, and as described in more detail elsewhere, biting midges do play an important ecological role in the environment. Particularly in regard to humans, the adults of two genera, Leptoconops and Culicoides, with many species, transmit diseases and parasites to a variety of vertebrates (from frogs to birds to mammals) and others possibly do the same for a number of insects. And as outdoor people know, they can be miserable biters of humans; they do the same to a number of domestic animals (including horses, cattle, sheep, dogs, and poultry). Although often thought of in negative terms, the adults are also important pollinators of some commercial trees such as cacao (we wouldn’t have chocolate without them!) and rubber and also for numbers of other plants. The larvae are important predators in aquatic systems of all sizes, from tiny treeholes and the water held by tropical flowers, to large rivers and lakes. In the tropics and in some temperate areas, they form a large component of arboreal aquatic systems (such as in bromeliads and treeholes).

The description of species and their distribution is just the first step in understanding biodiversity. It is also important to know the evolutionary history of the species we study. An understanding of evolutionary relationships provides a framework to organize all biological information. When we understand how species are related to one another, we have powerful tools to interpret the nature of adaptations (that is how we know whales evolved from land mammals) and have critical information about how communities have been put together, of where species originated and why they are distributed the way they are on the planet.

The biting midges are a wonderful group to study evolutionary relationships because of three outstanding features. First, they are diverse in numbers of species. Generally, when a group is speciose, there are intermediate species or groups present which provide good clues on the direction of evolutionary change. Second, the biting midges have three very different stages (larva, pupa, adult) each of which have diversified structurally. Unlike many other groups (a caterpillar is more or less a caterpillar!), the immatures of biting midges have evolved in many different morphological directions. Therefore, it is possible to compare conclusions about relationships based on one stage against the conclusions based on a different stage. Obviously, there is only one evolutionary tree and the results of study of the different stages must come to the same conclusion (as they most often do in practice). Third, the biting midges have an incredible fossil record in amber (fossilized resin) that has been investigated in some detail. There are now 11 major deposits ranging from 17 to 128 million years of age, with thousands of specimens to study. The fossil biting midges are largely in excellent condition and most taxonomic features can be studied in detail. These fossils provide an excellent gauge as to the accuracy of our interpretation of evolutionary relationships based on living species and are an incredible window into the past lives of these midges. We even have strong evidence that some bit dinosaurs long ago.

The best reason for studying biting midges is that they are incredibly beautiful and wonderful creatures. As we get to know more about this fascinating group, we’ve been discovering the important ecological roles they play, their complex behaviours, some amazing adaptations, their striking structural features, their remarkable history on the planet and all of that packed into those small bodies! To know them is to love them!