Entomologists and researchers invest a lot of time studying the anatomy and diseases of butterflies. Changing climates and human activities can damage their natural habitats and increase the chances of pathogens transmission among different insects.
Can Butterflies Carry Diseases? Butterflies carry diseases caused by parasites, viruses, bacteria, and fungi. These diseases severely affect their health and growth and can cause death. However, these insects cannot transfer diseases to humans, but indirect contact with plants and living sites of infected butterflies can cause skin irritation.
The bacterial and fungal infections can be contagious for the caterpillars and lead to many health problems if they survive.
Do butterflies carry diseases?
Butterflies carry parasites, and these microorganisms lead to many diseases among these species. Habitat destruction causes more exposure to harmful parasites and pathogens because they are not familiar with the new living areas.
Various bacterial and fungal pathogens can infect many of their species if they come in contact with the surface or environment where these airborne microbes live.
The parasites live within the host body and get all essential nutrients from it to thrive and multiply into hundreds.
It poses a severe threat to the host, which leads to death or deformities in their metamorphosis stage. Hundreds of parasites can reside and infect many of their species.
The parasitoids also cause diseases, as the flies or wasps lay their eggs on caterpillars and parasitize them because the larvae feed on the host caterpillar and infect them.
They pupate inside the caterpillar and emerge from cocoons they form on the back of the caterpillar, leaving the host disabled or dead.
Parasites are tiny creatures that cause the host to face several life challenges if they multiply into hundreds. However, all parasites do not cause the host to die, and the caterpillars or adult insects recover from the disease.
What diseases and parasites do butterflies carry?
Many parasitic and other diseases can harm butterflies. One of the common and frequently observed parasites is Ophryocystis elektroscirrha, which infects the caterpillar and adult insects feeding on the specific host plant.
It severely damages the overall health and growth of the caterpillar if they get the protozoan or the spores enter their bodies.
Encephalitis affects the nervous system and brain functioning of the infected insects.
The brain tissues swell and cause severe problems for them because they cannot work without a healthy immune system.
Moreover, they can also carry Malaria, dengue fever, and Zika viruses. They face several challenges in their daily life if they get infected.
They cannot fly and forage food to long distances if the parasites affect the internal organs of their bodies.
Plasmodium parasites cause Malaria in butterflies, as it multiplies rapidly and leads to a weak immune system. They also carry many viruses and bacteria, such as Pseudomonas aeruginosa, which cause health problems in these insects and alter the wing color.
They carry Nuclear Polyhedrosis viruses (NPVs), also known as Baculoviruses, as they live in the wild and get these pathogens from contaminated surfaces or infected animals or insects.
The virus attacks the caterpillar cells and replicates inside the nuclei, which causes them to turn into a jelly or melt because the virus causes the cell to burst.
This virus is also deadly to caterpillars and sometimes alters the chrysalis into black sac-like jelly with a foul smell before pupating into an adult insect and the pupa skin raptures.
Fungal infections, such as Fungal Hyphae, are thread-like filamentous branches that infect butterflies, and the spores get inside the caterpillars to germinate and replicate inside the host. They also carry Cordyceps disease caused by Fungus Entomophthora grylli.
Moreover, Wolbachia bacteria cause several reproductive problems, such as these insects can manipulate reproduction and damage embryos. It causes the male embryos to alter into females or mating issues among these insects.
In Africa, 70-80% of White-barred Acraea are infected with this bacteria, and there is a rapid decrease in the male population due to sexual change in the growing stages. It does not cause the death of the host but affects the reproduction and mating abilities.
In addition, the Tachinid flies lay eggs on the caterpillars, and larvae bore into the host skin and grow inside their bodies to get nutrients.
The infected host appears with black, brown, or rust spots, while the white silky strings represent that the cocoons drop off the host body after completing the growth process, leaving the host dead.
| Type of butterflies | Disease or parasite | Disease type | Mode of transmission |
| Monarch butterflies | Ophryoscystis elektroschirra (OE) | Parasitic | Ingestion or physical contact |
| White-barred Acraea butterflies | Wolbachia bacteria | Bacterial | Maternally transmitted |
| Swallowtail butterflies | Nuclear Polyhedrosis viruses (NPVs) | Viral | Ingestion or contact with contaminated plants |
| Pink lady butterflies | Cordyceps disease | Fungal | Ingestion or pick up from plants or soil |
| Red admiral butterflies | Pseudomonas aeruginosa | Bacterial | Injuries, ingestion, or contaminated water and soil |
Can Ophryocystis elektroschirra kill Monarch butterflies?
Ophryoscystis elektroschirra (OE) is a single-cell parasite that lives and grows inside the host and is present as spores on plants and leaves. It survives in changing environmental conditions and finds a suitable host to reproduce and replicate.
It affects the milkweed plants, as they live on these plants and transfer to Monarch butterflies because they feed on this plant and lay eggs there.
The Monarch caterpillars ingest the OE spores, and the parasites grow and multiply into hundreds.
This parasite grows and depends on the host to survive when it breaks down from the spores; therefore, it rarely kills the host caterpillar and transfers from one generation to another.
However, it can cause many problems for adult Monarchs if they get infected by the milkweed plants, as they cannot fly as smoothly and as long as a healthy butterfly can, and their lifespan also shortens.
The caterpillar can die if they are heavily infested with this parasite because they do not have a well-developed immune system and end up in some cases. The protozoan can cause deformity, weakness, and eventually death.
They have crumped wigs, face difficulty emerging from pupa, and fall on the ground because they are weak enough to hang from their shells to expand their wings and fly.
How do butterflies get parasitic diseases?
These parasites are transmitted in different ways, as one of the common ways to get these parasites is that the caterpillars ingest the capsules or spores of various parasites and viruses.
Moreover, the monarch caterpillars ingest the spores on milkweed plants as they feed on their native host plant to get nutrients.
In addition, female butterflies can transmit the parasites or diseases to the eggs or larvae when they lay eggs on parasites or transfer them during reproduction.
Healthy insects can get diseases from infected species when they come in contact and transfer minor portions of parasitic infection through the spore exchange process.
According to research, approximately 80-85% of uninfected caterpillars get the parasites or OE protozoan after emerging from the pupa and coming in contact with the infected adult fellows.
Moreover, they migrate and fly longer distances, creating more chances to transmit the parasites and diseases to species in other areas.
Another research analysis says that approximately 50-60% of OE parasite transmission occurs through the spores on milkweed.
Parasitoids also cause parasite transmission because the mother lays an egg on the caterpillar, which infects the growing insects. Moreover, bacterial and fungal diseases are transmitted through the plants, soil, and contact with other insects.
Do butterflies transfer diseases to humans?
Butterflies do not transmit diseases to humans because the immune system of humans is strong.
They do not bite or attack humans, which reduces parasites or disease transfer chances, but they can infect the plants and flowers in the garden if they carry the parasites.
The spores fall on the flowers or plants and cause skin irritation or slight issues if you touch the infested plants and touch or eat something with dirty hands.
Therefore, washing your hands properly after coming from the parks, yards, or gardens is better.
No butterfly-related pathogens are reported to infect humans and cause severe health problems.
However, they cause problems with plant pollination because these insects are the pollinators of many plants.
They cannot travel and pollinate the plants to other areas, which indirectly affects the plants and their population in specific areas.
Can butterflies protect themselves against diseases?
They can defend themselves against diseases because they have immune cells like humans have platelets to fight bacterial and viral infections.
Butterflies have antimicrobial proteins inside their bodies and attach to the pathogens to reduce their effect. The hemocytes immune cells cover the parasites or foreign particles to vanish them and provide immunity against viral diseases.
Moreover, these hemocytes accumulate if the parasite is large and a single cell cannot engulf it. These aggregated cells deposit melanin pigment and dark color capsules around the large parasite.
They also show behavior defense, such as avoiding feeding on plants that cause health problems and migrating to other places to prevent viral infections.
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