2 What is Oe? Ophryocystis elektroscirrha (Oe) Protozoan parasite that infects Monarch butterflies in NZ
3 What 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
4 Obligate 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)
5 Oe 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
6 Oe 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.
7 Oe 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
8 Oe 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.
9 Oe SporesAt 400xHere is a picture of Oe spores at 400X.
10 Life cycle of Oe is closely related to the life cycle of the Monarch butterfly.
11 Oe 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
12 Oe 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
13 Oe 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)
14 Oe 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
15 Oe 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
16 Spores 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
17 Adult 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
18 Parasitised 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
19 Where 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.
20 Where 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
21 Monarchs in North America Summer Ranges and Migratory Routes Eastern migratorypopulationThere are three Monarch populations in North America. Two populations migrate and the third one, which is in South Florida, does not migrate. The Rocky Mountains separate the two migratory groups of Monarchs.2. Western migratorypopulation3. South Florida residentpopulation
22 Eastern Migratory Monarchs The eastern migratory population is the largest and most famousThese Monarchs spend the winter in the transvolcanic mountains of central MexicoTransvolcanic Mountains
23 Monarchs Overwintering in Oyamel Fir Trees in the Mountains of Central Mexico
24 Eastern Migratory Monarchs Spring: After mating, migrate north to their summer breeding grounds in the United States and CanadaSummer: Several generations of Monarchs inhabit lands east of the Rocky Mountains from Alberta to Maine
25 Eastern Migratory Monarchs Fall: tens of millions of Monarchs return to Mexico in a spectacular migration
26 Western Migratory Monarchs Shorter, less dramatic migration to their roosting areas on the coast of CaliforniaOverwinter in much smaller groups than the ones in MexicoSpring: migrate north and eastRocky MountainsSummer Range for Western MonarchsOverwintering Sites for Western Monarchs
27 Monarchs of South Florida Do not migrateMilkweed plants grow here all year round, the butterflies do not need to leave the areaResident Monarchs reproduce throughout the entire yearMonarch larva feeding on tropical milkweed, a common but non-native host plant species in S. Florida
28 How common is Oe in North America? 1. Eastern migratorypopulation– Less than 10%heavily infected3. South Florida resident population– Over 70% heavily infectedOe is found throughout North America, but the prevalence (fraction of the population infected) varies dramatically among populations. Fewer than 10% of Monarchs in eastern N. America re heavily infected, about 30% of Monarchs on the west coast are infected, and over 70% of Monarchs in S. Florida are heavily infected.2. Western migratorypopulation– 30% heavily infected
29 Differences between populations have persisted for many decades Western migratoryBy examining historical collections of Monarchs, scientists have found that differences in prevalence between populations have persisted for up to 30 years. This graph shows the % heavily infected Monarchs for each year where collections were available from the 3 populations, including samples from the most recent 5 years. Despite the inter-annual variations, the eastern migratory population has been less than 8% infected for the past 30 years, with a sign of some recent increases in the past 5 years, whereas more limited data suggests that the western population has been 30% infected, and the S. Florida population near Miami has had high parasite loads, % heavily infected.Eastern migratory
30 Do my Monarchs have Oe? What are the symptoms? Butterflies can become sick for many different reasonsMonarchs infected with Oe have a variety of symptomsCaterpillars may have damage to their gut wallsInfections may be fatalMonarch caterpillars often turn brown within a few hours of death.
31 Damage to the pupaInfected pupae may develop dark spots or blotches 2-3 days before the butterfly emergesThese abnormal dark areas are parasite sporesSpores form on the eyes, antennae, wing veins, but mostly on the abdomenYou can see the spores through the outside layer of the pupa a day or two before pigments that color the butterfly normally darken the pupa
32 Dissected pupa Showing Oe Spores The dark spots are Oe sporesHeadAbdomenInfected pupabefore dissectionBefore a butterfly emerges from the chrysalis, pigments are laid down coloring the scales that cover the butterfly. This normal change in the color of the pupa is symmetrical. The color change of an infected Monarch happens earlier and does not create a balanced pattern on the pupa.WingsDissected pupa
33 Damaged Adult Monarchs Heavily infected adults are weak and often have difficulty emerging from the chrysalisSome Monarchs die before emergingOthers emerge, but are too weak to cling to the pupal caseThey fall to the ground before fully expanding their wingsThese severely deformed Monarchs do not survive long
34 Mild infections also harm butterflies Infected adults are often smaller than healthy MonarchsThey weigh less and have smaller wings and shorter lifespans than normal MonarchsParasites also damage the cuticle or outside layer of the Monarch’s abdomenThis causes the butterfly to dry out and lose weight faster than normal.Especially a problem if there is a shortage of nectar or water
35 Parasite infection hinders Monarch flight ability Studies have shown that Monarchs infected with Oe can not fly as far or as long as healthy butterfliesFlight millA flight mill is used to measurea Monarch’s flight endurance
36 Monarchs with mild infections can transmit disease Infected adults that survive to reproduce will pass the infections on to their offspring
37 Many infected Monarchs look the same as healthy butterflies These are all symptoms of Oe, but many infected Monarchs look healthyThey emerge normally and are not deformedThe only way to really know if your Monarch is infected is to check for parasite spores on its body.Easy way to test for infections: swabbing
39 Use sterile protocols when handling Monarchs Oe spores are difficult to destroyUse latex, nitrile or vinyl gloves when touching butterfliesSterilise all tools and surfaces that contact Monarchs (counter tops, rearing containers) with 20% bleach solution
40 Can You Tell Which Monarchs are Infected with Oe?
41 Can You Tell Which Monarchs are Infected with Oe? ALL OF THEM!Admittedly, the one in the lower right had a mild infection.
42 Adapted with thanks from an original presentation of the Monarch Health Project, Odum School of Ecology, University of Georgia Athens, GA, USA.
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