2What is Oe? Ophryocystis elektroscirrha (Oe) Protozoan parasite that infects Monarch butterflies in NZ
3What is Oe? Protozoans: single celled organisms Share many characteristics with animals (often called animal-like protists)Protozoans are single celled organisms, living things that have many of the same characteristics as animals. In fact, protozoans are often called animal-like protists.This slide has several protozoans pictures at the bottom that you may be familiar with. The first two are ‘free living’ protozoans called Euglena and a ciliate called Paramecium. The third is a parasitic protozoan called Plasmodium – this is a blood parasite that causes Malaria in humansEuglenaParameciumPlasmodium
4Obligate parasite: must live within a host to grow and multiply. Monarch (and queen butterflies overseas) are the only known hosts of OeMonarch Butterfly (Danaus plexippus)Queen Butterfly (Danaus gilippus)
5Oe produces spores on the outside of Monarchs Highly Magnified ImageSpores: dormant cells that can resist harsh environmental conditionsFound on the outside of infected MonarchsBetween infections Oe survives as spores that are resistant to extreme environmental conditions.Photo of Oe spores is a scanning electron micrograph taken by Chip Taylor.Oe sporesMonarch scales
6Oe SporesGreatest concentration of Oe spores is on the abdomens of infected MonarchsAbdomenThese tiny spores are sandwiched in between the scales that cover a butterfly’s body.
7Oe Spores Spores are ~ 100x smaller than Monarch scales Need to view under x powerSpores are much smaller than scales. In fact, a Monarch scale is about 100 times larger than an Oe spore. You must use a light microscope set at 40 to 100X to see a spore. This slide shows a researcher using a stereomicroscope at 60 times magnification to examine Oe spores from an infected MonarchLooking for spores using a microscope
8Oe Spores Spores appear as small, brown or black lemon-shaped objects. Monarch scalesOe SporesEven at this magnification spores look like small, brown or black lemon-shaped objects.
9Oe SporesAt 400xHere is a picture of Oe spores at 400X.
10Life cycle of Oe is closely related to the life cycle of the Monarch butterfly.
11Oe Life Cycle Oe can only reproduce inside living Monarchs Infected females pass the parasite to their offspring when they lay eggsDormant spores on the outside of the female’s abdomen are scattered on the eggs and milkweed leavesInfected femaleslay eggs andscatter Oespores on eggsand leavesDark spots are Oe spores
12Oe Infects the Caterpillar When a caterpillar emerges, its first meal is the egg shellIt ingests Oe spores along with the shell and milkweedNewly emerged caterpillarA caterpillar eating the egg shell andany Oe spores on the shell’s surface
13Oe Moves to the MidgutThe dormant spores move through the larva to the midgutDigestive chemicals break open the spores releasing the parasitesThe parasites then pass through the intestinal wall to the hypoderm (underneath caterpillar’s skin)
14Oe Reproduces in the pupa Most damage to the butterfly happens during the pupal stageWhere Oe reproduces asexuallyEach Oe parent cell divides many times, greatly increasing the number of parasitesThe Oe parasite then goes through sexual reproduction, followed immediately by meiosis
15Oe cells in the pupa Merozoites: vegetative, replicating stage of Oe Single parent cell many hundreds of daughter cellsOe merozoites in the hemolymph of a 5-day old Monarch pupa
16Spores Form in the pupae About three days before the adult emerges from the pupa, Oe spores begin to formSpores allow Oe to survive outside of the Monarch’s bodyThe spores can be seen through the integument or outside layer of the pupaOe Spores
17Adult Emerges with Spores Infected adults emerge covered with sporesOnce butterflies are infected, they do not recoverBy the time adults emerge with parasite spores, all physical damage by the Oe parasites has been doneThe parasites do not grow or reproduce on the adultsThe spores are inactive or dormant until they are eaten by another caterpillar
18Parasitised emerging Monarchs Monarchs that are heavily infected with Oe can have difficulty emerging from their pupal casesInfected Monarchs are covered with millions of tiny Oe spores
19Where in the World do you Find Oe? Monarchs have a wide geographic rangeOe occurs in all Monarch populations examined to dateMonarch geographic range:N. AmericaCentral and S. AmericaCaribbean IslandsPacific IslandsAustraliaNew ZealandOe was first discovered infecting Monarch and queen butterflies in Florida in the late 1960s. Since then this parasite has been found in all other Monarch populations world-wide. Monarchs and Oe have an extensive range that currently includes North America, Central America, central South America, Cuba and other islands of the Caribbean, Bermuda and Canary Islands of the Atlantic. During the 1800s, Monarchs were introduced to New Zealand, Australia, Philippines, south Pacific Islands, and Hawaii. Because Oe parasitises Monarchs all over the world, all indications are that this parasite has coevolved with Monarchs.
20Where in the World do you Find Oe? Prevalence of OePopulationEasternNARockhampton,AustraliaNorthernS AmericaWesternSydney,S Floridan = 27n = 25n = 39n = 1103n = 717n = 152Prevalence: Measures proportion of Monarchs infected with Oe# infected / total # sampled (n)To see what fraction of Monarchs in different populations were actually infected, researchers have done extensive sampling of Monarchs collected throughout NA both in recent years and from past historical collections dating back to the early 1970's. An important measure of infection for any population is the fraction or proportion of animals that are infected. This is called prevalence. This graph shows the prevalence of Oe in 6 different wild Monarchs populations. Researchers went out, caught the butterfrlies, and examined them for Oe. …What they found is that the prevalence of this parasite is highly variable among populations, and declines with increasing host migration distances. As you go from L to R in this graph, you are seeing populations that go from migrating the longest distance to those that migrate short distances or are resident breeders. Highest prevalence in pops that breed continuously in the same area (such as Florida and Hawaii) and lowest in Eastern NA.To understand what might be going on here requires some working knowledge of Monarch butterfly migration