Of midge and men
In this section I will try to write new posts, though not every day but often, to introduce you to a genus or species of Chironomidae. I will also, do my very best to keep the information basic and understandable for the general public. If you are lucky that day my post will contain an accompanying picture(s). I think most people including me are visual. However, before writing about Chironomidae species I think it is necessary to talk a bit about their importance, as a family of insects, for human. This, I would think will set the stage for the future posts. So let’s start.
Traditionally, Chironomidae species don’t have common names. The family is collectively referred to as non-biting midges or blood-worms. The non-biting midge refers to the adults’ lack of mouth parts and this distinguishes them from their biting relatives, the Ceratopogonidae. The word "blood worm" is quiet popular among the anglers and fly fishermen, and it refers to those larvae Chironomidae, specifically in the tribe Chironomini, that possess hemoglobin and are red in color. I could only assume that the reason for the lack of common names usage for different species of Chironomidae, especially their usage among anglers, is partially due to the small size of both adults and immature. It is much easier to identify patterns on nymph or adults of, let say, a stonefly that measure more than 1-2 cm in length than a chironomid larva that only measures up to 4mm. This; however, won’t prevent anglers and fly fishers not to use larvae and adults of Chironomidae as live baits to catch fish.
Speaking of fish, here is one reason why Chironomidae are important. They constitute a large portion of fish and other aquatic species diet, both as larva and as pupa. Adults also make a substantial portion of diet for many larger insects such as dragonflies, which in turn the latter will be consumed by fish again. This means that economically these organisms play a vital role for fish industries. In addition to fish diet, in agricultural wetlands, such as rice fields, chironomids can make up a significant portion of wetland’s birds diet and contribute to the health of wetland birds populations. Some chironomid species are also pest in rice fields.
I can only think of two ways in which Chironomidae could be of some nuisance to human. Their swarms may cause allergic reaction in some human, though rarely. Also, some water ticks and mites can use chironomids for piggy back ride for traveling to different bodies of water. Chironomids are not vectors of diseases. Beside the food source their ubiquitous nature makes them ideal organisms for monitoring the health and conditions of freshwater. Traditionally environmental monitoring programs refer to these organisms as tolerant of environmental pollution. However, based on many past and present research investigations we know that individual species, even within the same genus, show large variation in their tolerance to different environmental factors. This variation can in turn be used to detect environmental changes in freshwater.
But what factor(s) contribute to this variation? Well, partially this is due to the fact that this family of insects tend to be very diverse in terms of number of species, many still to be discovered. So, it only makes sense that with diversity in species, variations to environmental response happens (i.e., niche and habitat segregation due to speciation). One might ask how they then can be used for monitoring. Well, let say that we have a pristine cold water stream in a forested catchment. This stream has naturally larger proportion of cold loving (i.e. cold stenotherms) species of Chironomidae. Now, if a power plant extends its operation or a dam is build upstream, runoffs from the plants or change in water flow due to dam gradually increase the water temperature in the stream. This means that gradually cold loving species get replaced with warm loving species of Chironomidae. Now naturally if we monitor this stream for a specific period of time we can detect the changes in the assemblage of species and change in the stream water temperature in turn. As simple as that.
You might then ask why chironomids are so diverse. Although, opinion varies, production of silk has been contributed as a major reason for these insects diversity. Silk can be used for overwintering larvae and to produce cocoons, and hence to inhabit cold waters. Silk is also used in production of case. Chironomid cases can be attached to substrate or vegetation for the purpose of filtering water and to obtain organic matters. Cases can be portable that can help in collection and gathering of material attached to substrates. Also, cases of Chironomidae, just like those of caddisflies, can be used for anti-predatory purpose.
In my next posts I will explore some interesting facts about their biology. This will include their vast global distribution and variety of habitat they inhabit.
In this section I will try to write new posts, though not every day but often, to introduce you to a genus or species of Chironomidae. I will also, do my very best to keep the information basic and understandable for the general public. If you are lucky that day my post will contain an accompanying picture(s). I think most people including me are visual. However, before writing about Chironomidae species I think it is necessary to talk a bit about their importance, as a family of insects, for human. This, I would think will set the stage for the future posts. So let’s start.
Traditionally, Chironomidae species don’t have common names. The family is collectively referred to as non-biting midges or blood-worms. The non-biting midge refers to the adults’ lack of mouth parts and this distinguishes them from their biting relatives, the Ceratopogonidae. The word "blood worm" is quiet popular among the anglers and fly fishermen, and it refers to those larvae Chironomidae, specifically in the tribe Chironomini, that possess hemoglobin and are red in color. I could only assume that the reason for the lack of common names usage for different species of Chironomidae, especially their usage among anglers, is partially due to the small size of both adults and immature. It is much easier to identify patterns on nymph or adults of, let say, a stonefly that measure more than 1-2 cm in length than a chironomid larva that only measures up to 4mm. This; however, won’t prevent anglers and fly fishers not to use larvae and adults of Chironomidae as live baits to catch fish.
Speaking of fish, here is one reason why Chironomidae are important. They constitute a large portion of fish and other aquatic species diet, both as larva and as pupa. Adults also make a substantial portion of diet for many larger insects such as dragonflies, which in turn the latter will be consumed by fish again. This means that economically these organisms play a vital role for fish industries. In addition to fish diet, in agricultural wetlands, such as rice fields, chironomids can make up a significant portion of wetland’s birds diet and contribute to the health of wetland birds populations. Some chironomid species are also pest in rice fields.
I can only think of two ways in which Chironomidae could be of some nuisance to human. Their swarms may cause allergic reaction in some human, though rarely. Also, some water ticks and mites can use chironomids for piggy back ride for traveling to different bodies of water. Chironomids are not vectors of diseases. Beside the food source their ubiquitous nature makes them ideal organisms for monitoring the health and conditions of freshwater. Traditionally environmental monitoring programs refer to these organisms as tolerant of environmental pollution. However, based on many past and present research investigations we know that individual species, even within the same genus, show large variation in their tolerance to different environmental factors. This variation can in turn be used to detect environmental changes in freshwater.
But what factor(s) contribute to this variation? Well, partially this is due to the fact that this family of insects tend to be very diverse in terms of number of species, many still to be discovered. So, it only makes sense that with diversity in species, variations to environmental response happens (i.e., niche and habitat segregation due to speciation). One might ask how they then can be used for monitoring. Well, let say that we have a pristine cold water stream in a forested catchment. This stream has naturally larger proportion of cold loving (i.e. cold stenotherms) species of Chironomidae. Now, if a power plant extends its operation or a dam is build upstream, runoffs from the plants or change in water flow due to dam gradually increase the water temperature in the stream. This means that gradually cold loving species get replaced with warm loving species of Chironomidae. Now naturally if we monitor this stream for a specific period of time we can detect the changes in the assemblage of species and change in the stream water temperature in turn. As simple as that.
You might then ask why chironomids are so diverse. Although, opinion varies, production of silk has been contributed as a major reason for these insects diversity. Silk can be used for overwintering larvae and to produce cocoons, and hence to inhabit cold waters. Silk is also used in production of case. Chironomid cases can be attached to substrate or vegetation for the purpose of filtering water and to obtain organic matters. Cases can be portable that can help in collection and gathering of material attached to substrates. Also, cases of Chironomidae, just like those of caddisflies, can be used for anti-predatory purpose.
In my next posts I will explore some interesting facts about their biology. This will include their vast global distribution and variety of habitat they inhabit.