Insects get sick too. We’re used to thinking about insects as vectors (transmitters) of human diseases. For example: Zika virus, malaria, and Lyme disease are all diseases carried by insects that affect humans. It is no wonder that this is what comes to mind when we think of insects and disease; diseases vectored by arthropods (insects along with spiders, millipedes, centipedes, and crustaceans) cause 1.5 million deaths every year . However, what we don’t typically think about is that, in many cases, these diseases also affect the insect itself. For example, carrying malaria increases mortality risk to the mosquito itself . Further, insects also suffer from their own diseases, which while devastating to their insect hosts, are harmless to humans. Insects can suffer from diseases caused by bacteria, fungi, viruses, parasitoids (insect parasites), protists, or nematodes . The study of such diseases and their insect hosts is called Insect Pathology. Seem obscure? While it is certainly specialized, it is a large and meaningful field of study.
Why study insect diseases?
With almost one million described species, insects make up the largest proportion of the world’s species . From the human perspective, these insect species are classified as beneficial, innocuous, or pests. The majority of insect species are innocuous (harmless) and many are directly beneficial (e.g. honeybees, silkworms, ladybugs), but pest species by far get the most attention.
Fig. 1. Estimated proportions of the different types of life on Earth today. Chordates, species with a spinal cord, includes many species we’re familiar with—fish, amphibians, reptiles, birds, and mammals. Graph from Fossil Focus by Ben J. Slater. Estimates based on data presented by Purvis and Hector 2000.
Diseases can help manage insect populations
We can use our knowledge of the insect pathogens to help aid in the management of these pest species. Pressure to minimize the use of chemical insecticides has led to increased interest in the application of pathogens to manage insect populations. This is called Microbial Control . Consider Bacillus thuringiensis, which is a particularly famous microbial control agent. You may have heard of it referred to as simply Bt. Bt is a bacterium commercially available for the control of insects, and is important for agriculture and public health. Safe for humans, Bt kills a wide spectrum of insects and other arthropods. Strains have been found to work against caterpillars, true bugs, ants, grasshoppers, lice, mites, nematodes, and more. Another famous microbial control story involves the fungal pathogen Entomophaga maimaiga. From Japan, the fungus can effectively control outbreak populations of Gypsy Moths . Gypsy moth is an invasive insect from Europe, which denudes trees. Microbial control can also be used for fruit pests. Codling moth is considered the most serious insect pest of the apple production worldwide  and apple production has a reputation of being heavily reliant on harmful pesticides. However, researchers discovered a virus beneficial in controlling the effect of codling moth on apple and pear production .
Fig. 2. Resting (overwintering) spores of Entomophaga maimaiga_, _a Japanese fungus used in the successful management of the invasive insect, Gypsy moth. Photo credit: Wikimedia Commons
More than just killing pests
Insect Pathology has implications for understanding and controlling pest species, but also has important applications for protecting beneficial insects. We use products from or supported by beneficial insects every day. About a third of our food crops depend on pollinators to reproduce; these pollinators include an array of bees, butterflies, moths, beetles, and other insects . Honey and beeswax comes from honey bees, silk is produced by silkworms, and in many countries insects are commonly eaten as a valuable source of protein. There is currently great concern about bee Colony Collapse Disorder, the rapid die off of overwintering bee colonies. Over the winter of 2006 to 2007, some beekeepers reported losses of 30-90% of their hives . While die off has been a bit lower the last few years and progress is being made to understand the cause, there is still much to know about this issue. Insect Pathology has been key to understanding and improving this situation to protect the insects that support important products and our food supply.
Fig. 3. A honeybee. Recently, there have been massive die off of honeybees. It appears that multiple causes are to blame, but collectively the die-off is referred to as Colony Collapse Disorder. Photo credit: Wikimedia Commons
Insect diseases teach us about human disease
If the two above reasons to study Insect Pathology—to manage pest insects and to protect beneficial insects—aren’t enough, another reason to study insect diseases is because they it can aid in our understanding of human diseases. Disease in insects exhibits similar interactions, complexities, and patterns as those found in mammalian hosts and thus can be used a model system . By studying insect pathology, we can learn a lot about human diseases.
In a nutshell: insect pathology is important for managing pest species, protecting beneficially species, and as a model system. Insect pathology may have seemed obscure at first, but hopefully I have shown a few of the very relevant applications.
Hill, C.A., F.C. Kafatos, S.K. Stansfield, and F.H. Collins, Arthropod-borne diseases: Vector control in the genomics era. . Microbiology, 2005. 3: p. 262-268.
Schwartz, A. and J.C. Koella, Trade-offs, conflicts of interest and manipulation in Plasmodium–mosquito interactions. Trends in Parasitology, 2001. 17(4): p. 189-194.
Vega, F.E. and H.K. Kaya. Insect Pathology. 2012; 2nd:[Available from: http://www.sciencedirect.com/science/book/9780123849847
Numbers of Insects (Species and Individuals). Encyclopedia Smithsonian [cited 18; Available from: https://www.si.edu/Encyclopedia_SI/nmnh/buginfo/bugnos.htm
Entomophaga maimaiga – The caterpillar killer Cornell Mushroom Blog 2009; Available from: https://blog.mycology.cornell.edu/2009/03/18/entomophaga-maimaiga-the-caterpillar-killer/
Lacey, L.A., D. Thomson, C. Vincent, and S.P. Arthurs. Codling moth granulovirus: a comprehensive review. Biocontrol Science and Technology 2008 [cited 18 7]; 639-663]. Available from: https://www.researchgate.net/publication/43272872_Codling_moth_granulovirus_A_comprehensive_review
Insects and Pollinators. [cited 2016 17 July 2016 ]; Available from: http://www.nrcs.usda.gov/wps/portal/nrcs/main/national/plantsanimals/pollinate/.
Colony Collapse Disorder. [cited 2016 17 July 2016]; Available from: https://www.epa.gov/pollinator-protection/colony-collapse-disorder.
Insect Pathology. Department of Entomology [cited 2016 17 July 2016 ]; Available from: http://entomology.umd.edu/insect-pathology.html.
More From Thats Life [Science]
- If Only There Were a U.S. Census Question About Biodiversity…
- How An Invasive Plant Helped Fuel The Largest Wildfire You’ve Never Heard Of
- Human Eye Structure Makes No Sense…Or Does It?
- The Price of Pigment on Your Immune System
- Midnight Snacks Could Be the Death of You
- Lobster Fight Club
- Making a Murderer - A Matter of Biology?
- Got Lactase? Breaking Down the Enzyme
- Why Do I Shiver When It’s Cold?
- Crap you didn’t really need to know
- You Can't Observe A Lot Just By Watching
- What Do You Do When It's Too Hot to Move?
- 5 Fun Facts about Hormones
- Death stinks - literally
- Why the sea salt fad could be very bad
- Henry's Pockets: A Poem
- Henry's Pockets: A Poem
- Biology Superpowers: X-Ray Vision
- How to Expand Your Senses by Reading a Blog Post
- What's up with bat echolocation?
- Seeing is Believing - How Can We Visualize Tiny Colorless Bacteria?
- Saving water is no longer a matter of how short our showers are · Water balance in a man-made world
- Double Digestion in Rabbits · Why Does Mopsy Eat Her Own Poop?
- Should I say sex or gender? Pt. 2
- Should I say sex or gender? Pt. 1
- How To Catch Hard-to-Catch Fish?
- Finding the Perfect Partner
- Is your gut trying to kill your resolve? · Mind over microbe
- Why Do Mothers Mother?
- GMO! The Places You'll Go!
- New-Fangled Paleontology · Really Old Fossils, Really Strong Predators, and Cool New Tech
- A Brief History of Evolutionary Thought, part III
- Saving face: transplanting our most distinctive features
- A Brief History of Evolutionary Thought, part II
- DNA as a solution for data storage · DNA - Nature’s Hard Drive
- A Crash Course in the Coolness of Mitochondria · Mitochondria: The Underrated Organelles
- A Pollinator’s Job Description and Why We Should All Care About Them · Pollination 101
- You May Say I’m Biased, But I’m Not the Only One
- The evolution of one of the greatest medical discoveries in history. · The Path of Least Resistance: Our Relationship with Antibiotics
- Mother Nature’s History Book · Estimating the Age of Life Long-Gone
- Proprioception as a vital sense · Know Your Limb-its
- Man’s Best Artificially-Selected Friend · Your Dog is a GMO Wolf
- Better Safe Than Sorry: The Pesticide Industry is Getting a Revamp
- Sometimes scientists have to get creative in order to effectively do science – especially on a budget. · The Bizarre Shopping List of a Determined Scientist
- Insects Get Sick Too: The Study of Insect Pathology
- Our teeny tiny friends and their huge potential · Employee of the Month - Hire a Microbe to Do Your Work
- A Brief History of Evolutionary Thought - Part I
- The Effects of Custom Build Paradise · Artificial Islands
- To B(PA) Or To Not B(PA): Regulating Endocrine Disruptors
- Bioluminescence truly looks like it is nothing short of sorcery, and although this naturally occurring phenomenon is well studied and explained, that does not take away from its beauty. · Fireflies of the Ocean: Lighting up the Dark with Science
- Part II - Cases of altruism in the animal kingdom · Charity cases in nature - when are animals more likely to be altruistic?
- Part I - Why true altruism is a rare behavior in the animal kingdom · Being selfish means staying alive
- Penguins and other strange things we study from space
- Pseudoreplication and the Art of Biological Statistics
- What is wrong with my tomatoes?...And other plant disease questions · Why did orange prices increase?
- How fecal microbiota transplants can improve lives and possibly save them · The Wonders of Fecal Transplants
- The scientific facts behind the safety and efficacy of childhood vaccines · Calling the Shots - Discussing Vaccines
- 3D Printing for Fun and Science
- What is wrong with my tomatoes?...And other plant disease questions · What is Phytopathology?
- Medical Mysteries Still Surrounding Zika Virus
- More ›