Tracking Disease in New Zealand's Monarch Butterflies
This page has information and resources for the sampling of disease in monarch butterflies. It is especially designed for a citizen science project examining the prevalence of a protozoan parasite of monarch butterflies in New Zealand.
What diseases occur New Zealand monarch butterflies?
There are two diseases that are sometimes seen here in New Zealand and around the world.
The first is a Nuclear Polyhedrosis Virus (NPV). This NPV is sometimes called Black Death for monarch caterpillars. Caterpillars with this infection turn black, die and then liquify. If they pupate, the chrysalis might turn black but you won’t see any wings. You’ll smell a foul smell if the skin or the pupae or dead caterpillar is ruptured.
The second disease causes adult butterflies to have crumpled and deformed wings. This disease is caused by the protozoan parasite Ophryocystis elektroscirrha or OE. These protozoa are single-celled organisms. They are obligate parasites, meaning they require a host organism in which to live and reproduce. Here in New Zealand they only attack monarch butterflies. Overseas, they will also attack queen butterflies (Danaus gilippus). No other animal (including humans!) is known to be affected by the parasite.
There are other diseases and predators of monarch butterflies, including wasps. But the NVP and OE are the most commonly observed diseases.
Symptoms of Ophryocystis elektroscirrha or OE
The disease OE is most easily seen in the adult monarch butterflies. A high level of infection causes the adult to have deformed or crumpled wings. These adults are unable to fly and will typically fall to the ground after they emerge from their chrysalis. Nothing can be done to help adults with these symptoms. The wings of uninfected butterflies are normally crumpled after they emerge, but these uninfected adults are able to fold out their wings and fly within an hour after emergence.
The picture of an adult butterfly here is an individual that could not fly or fold out its wings. Other individuals from this population had higher levels of deformity.
Many adult butterflies have lower levels of OE infection and appear normal. They have no crumpled wings. They emerge and fly, but carry spores of the parasite that will infect the next generation of butterflies. In Australia, 10-66% of butterflies are infected in this way.
It is also possible to see infections of OE on monarch butterfly pupa. The pupae have dots or dark spots that are easily seen on the pupae when it is green. With heavy infections the pupae might fail to emerge from the chrysalis or have difficulty doing so.
We’d like you to test adult butterflies for an OE Infection
Ensure you comply with COVID alert level guidelines at all times when participating in citizen science projects.
We are interested in the rates of this infection from around New Zealand. Anyone from primary school age and older can safely sample butterflies, without harm or hurt to the butterfly (or people) involved.
This video shows how to safely catch monarch butterflies without a net.
You can sample OE parasites by pressing clear Sellotape or Scotch tape on a butterfly's abdomen. The tape will pick up the OE spores and a few scales of the butterfly. All that is needed is:
- Press a piece of ultra-clear tape against the butterfly's abdomen
- Place the tape on a white piece of paper. Record the butterfly sex, the date, and the location of your sample
- Include an address (preferably e-mail) so we can contact you
- Place the sample in an envelope addressed to: Phil Lester, Monarch Disease Survey, School of Biological Sciences, Victoria University of Wellington, PO Box 600, Wellington 6140
We will count the spores in the laboratory and update this website with the results. Remember that butterflies infected with OE don’t always display any symptoms. They might fly and look fine but are still carrying the parasite.
We’d be very interested in your observations. Have you seen any diseased butterflies this summer? How many of your butterflies have you see pupate normally or look abnormal?
Video and web resources for sampling
There are some great YouTube videos and resources for help in testing sampling the butterflies for OE, including some school kids sampling for OE:
https://www.youtube.com/watch?v=jslY2GG45xs
https://www.youtube.com/watch?v=3ivNxhRKeoc
To sex a monarch butterfly adult, see:
https://www.butterflybiology.com/blog/2017/2/10/can-you-tell-the-difference-between-a-male-and-female-butterfly
https://monarchbutterflygarden.net/female-or-male-monarch-butterfly-pictures/
A great reference on monarch butterflies around the globe, including information on OE showing infection rates of between 10-66% in Australia, and 35% in Hawaii: https://www.frontiersin.org/articles/10.3389/fevo.2019.00362/full
There are also some great resources and information at the Monarch Butterfly New Zealand Trust, at: https://www.monarch.org.nz
Contact details: Phil Lester (phil.lester@vuw.ac.nz)