Insects are quite remarkable creatures and we have identified in the region of 1 million species with estimates of the number of unidentified species ranging from 5 million to 8 million 2. Insects exist all over the world and survive in some of the harshest environments on earth; it is believed that they - in terms of numbers - outnumber all other animal species combined 3.
Learn more about zoologist careers , parasitologist careers , and parasitology. It may seem like a simple question, but there is some confusion over what is and what is not an insect.
There are certain criteria by which we define which creatures are insects. For starters, they must have an exoskeleton - this is common to all arthropods. In order for the arthropod to be an insect, the specimen must have six legs - this is generally what separates them from other arthropods. They also have three distinct body parts broken down into the head, abdomen and thorax. They may or may not have wings, or antennae, or both 4 and they may live on land, in the air or in bodies of water though there are not many marine species as these environments are dominated by other types of arthropods.
Most insects have compound eyes that are large relative to their bodies, though some are eyeless 5 and many have ocelli sensors that fulfill some functions of eyes in other species 6, p Combined, the compound eyes, antennae and ocelli perform most sensory functions of the insect.
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Sensory hairs on the bodies of many insects tell them the direction the wind is blowing, so if they smell food, they know what direction to fly or crawl to find it. Some type of beetles for example such as the subfamily Omaliinae of the Staphylinidae do have ocelli while most beetle types do not. Nelson, Professor of Geology, Colby College. Learn more about how to become an entomologist. Humans have always been interested in insects for one reason or another; ancient cultures have examined, farmed and even venerated them.
Ancient Egyptians worshipped a large species of dung beetle, or Scarab, that would gather balls of dung and bury them.
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The female would lay eggs on the dung, and then weeks or months later, new beetles would emerge from the ground - seemingly reborn from nothing and thus representing the renewal of life. Many Roman writers discussed insects and Aristotle and Pliny the Elder both had a strong fascination in which they published their observations of insects in books on natural history. The true scientific study of insects did not development until the Renaissance and through to the Enlightenment era - with the greatest expansion of the subject seeming to be the s.
Three strands of study grew up in a very short space of time: first there were the researchers who wanted to depict nature's beauty through producing highly detailed image. This wasn't just useful for art's sake, these highly detailed sketches were useful to researchers wanting to understand the insects' physiology. The second group concerned itself as many natural sciences did with classification, dividing for the sake of convenience and ease of study - still a common practice today and we still use the division method in classification of new species, even where and when we realise that not all species of anything fit neatly into boxes.
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The third group focused largely on examining the biological processes of insects - life cycle, reproduction, habitats and other elements. This developed through the course of the 18 th century and by the 19 th century most major universities were studying the world's insects and major scientific institutes began a systematic programme of research and investigation.
In North America and in Europe, the Victorian era saw the greatest expansion of interest of insects 8 firstly through the amateur research of the well to do gentleman researcher, and later into more academic study leading to the formalised science that we have today. There is no greater work with such a wide scope for this third group, than the four volumes published in the early 19 th century by William Kirby and William Spence 9 and it is still considered a seminal work today. For the most part, this 19 th century research into insects was driven by medical science and a need to understand and combat diseases carried by insects such as malaria and yellow fever 10 , their causes and how they spread.
It was important to the colonialism and the growing market economy of nations spreading their influence and building markets in developing countries. That's not to say that study for study's sake was not an issue as it was with so many other 18 th and 19 th century naturalists, because it was.
As humans we are driven to examining and understanding the world around us. The 20 th and 21 st centuries led to the more discoveries of insect species, and how they live and reproduce, than ever before. Now we can visit very remote areas far more easily than we could before - new species turn up every day. We have also discovered that the study of insects has uses outside of entomology. The subject does not exist in a bubble where it is useful only to itself; it is part of a wider environmental study of our natural ecology and human geography - insects are affected by the climate and results of studies can tell us much about what is going on in the world around us.
We discover new uses for studies in entomology all the time and there are already several established disciplines where insects and insect remains are a powerful type of evidence. Insects are a vital part of forest biodiversity and as they are particularly sensitive to changes in the climate and the patterns and seasons of regional flora cover, entomology provides evidence for general forest health 11 as well changes in the cover.
The arrival of a new pest or the sudden decline of a well-established native species can indicate many things, such as the effects of deforestation, or a change in the types of arboreal cover, CO2 concentration, persistent ecological issues such as drought or flooding. They can tell us much about the types of trees, shrubs and flowers that grow there especially pollinating insects such as butterflies 12, p and any changes.
The Arctic Circle has a very delicate ecosystem and this is one area where researchers in many fields rely heavily on entomology, particularly of the relationship between insect groups, between insects and the environment, between insects and other animal species; evidence from population numbers and density is often used to examine specific environmental indicators Similarly, and as archaeology moves more into the realm of environmental science, insect population and remains are becoming more important in the interpretation of archaeological sites and landscapes.
One of the hallmarks of research in my lab is a focus on linking detailed biochemical and physiological measurements to their life history and fitness consequences. Biochemical and physiological techniques are often low-throughput, limiting their application in ecological and evolutionary studies that frequently require large sample sizes and multiple treatment groups. We overcome this challenge by first doing the careful and slow biochemistry and physiology across multiple levels of the biological hierarchy from molecules, cells and organs to tissues and whole organisms , and then using the results to develop and validate high-throughput assays that recapitulate the phenotype of interest.
This approach has enabled me to discover links between genotype and physiological phenotype, and understand how those links are mediated through the biochemistry of metabolic pathways. Another hallmark of my research approach is the analysis of evolutionary change in the plasticity of physiological traits. Unlike morphological traits that are frequently fixed during development, physiological traits are labile over the entire lifetime of an organism, responding almost instantly to changes in environmental conditions with changes in their rates and intensities.
Thus, most physiological traits are best described as curves or functions that describe their environmental sensitivity. Climate change research historically focused on summer, and winter climate change was considered mostly beneficial due to amelioration of damaging cold. My research is shifting this paradigm, and illustrating how sub-lethal performance consequences of variation in winter conditions drive responses of terrestrial organisms to climate change. I have shown that winter warming negatively impacts many insects by increasing metabolic rates and energy drain, which can reduce subsequent reproduction.
Selective pressures imposed by warm winters can lead to changes in the thermal sensitivity of metabolism, leading to better performance over winter and in the subsequent growing season. Using field- and lab-based reciprocal transplant experiments, I demonstrated that winter conditions drive local adaptation of insect populations, suggesting that changes in winter conditions may cause population declines across the range.
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I have shown that cold adaptation increases metabolic costs due to increased flux through central metabolic pathways, allowing cold hardy flies to synthesize protective molecules more rapidly. This suggests a mechanism through which cold stress shapes evolution of metabolic pathways, possibly contributing to large-scale biogeographic patterns in life histories previously attributed to selection on growing season performance.
Together, this work illustrates how profoundly winter conditions shape ecology and evolution of ectothermic animals.
I am currently investigating how snow drives ecology and evolution of insects.