Butterfly assemblages are frequently seen in museums, their vibrantly colored wings and distinctive patterns captivating the attention of onlookers. Although these mounted specimens are remarkable by themselves, a recent investigation by the University of Georgia examined how museum specimens can assist in monitoring the dissemination of diseases.

Ophryocystis elektroscirrha (OE) is a protozoan parasite that can impede a butterfly’s development and ability to fly. Caterpillars may contract the infection by consuming spores located on the surfaces of plants, and the subsequent infection may continue into adulthood.

OE seldom directly causes death in its hosts, as it relies on adult butterflies to disseminate its spores. Nonetheless, it is estimated that countless monarchs do not survive their yearly migration due to this infection.

“Many individuals do not consider butterflies as being capable of falling ill, but butterflies and other insects can host microorganisms that pose issues for them,” stated Sonia Altizer, Martha Odum Distinguished Professor at UGA’s Odum School of Ecology and a co-author of the research. “It’s akin to having a debilitating lifelong condition that complicates your ability to travel and work, yet it does not necessarily lead to immediate death.”

The scientists examined nearly 3,000 butterfly specimens from five museums in the United States and internationally, including the Georgia Museum of Natural History. Among the 61 butterfly species they studied, five were discovered to be infected, with instances dating back to 1909, 60 years prior to the first documented descriptions of OE in monarchs and queens. This research also features the initial documented cases of infection in Jamaican monarchs.

Widespread Infection Distribution

The butterfly specimens were sourced from various regions globally and collected between 1832 and 2019. Due to the delicacy of the specimens, the researchers had to employ a specialized method to prevent damage.

When butterflies are infected with OE, the spores of the parasite manifest on the exterior of their bodies. The researchers collected samples by gently twisting a fiber swab against the butterfly’s body and gathering the scales. Those scales can then be placed onto a glass slide for microscopic examination.

This research concentrated on milkweed butterflies, as they can be found worldwide, and monarchs and queens are already recognized as susceptible to the disease. This name originates from their consumption of milkweed and the absorption of the plant’s toxins to safeguard themselves against predators.

Using this group, the researchers found traces of infection across the Americas, Europe, Asia, Africa, and Oceania. However, the locations where butterflies contracted infections varied, even within the same species.

“There were numerous regions where these species were sampled with no infections, even though some other areas showed positive results,” Altizer noted. “There was considerable geographic diversity within each species regarding where infections were noted.”

Infection Restricted to Specific Types of Butterflies

Despite OE being evident across the globe, the number of species impacted was minimal. Only five species — lesser wanderers, monarchs, plain tigers, queens, and Jamaican monarchs — tested positive for OE. All these species belong to the Danaus genus.

This raises the question of why OE appears to infect only a limited group of closely related species.

This phenomenon may partly stem from the specialization of the parasites; the spores derived from monarchs were typically darker and larger than those identified from the other four species.

A companion study led by Maria Luisa Müller-Theissen, who conducted this research as part of her Ph.D. studies in ecology at UGA in 2024, further investigated the potential for cross-infection between monarchs and queens. While monarchs could be afflicted by parasites affecting both species, queens were solely influenced by parasites that specifically target queens. Monarchs also appeared to suffer more severely from the disease in comparison to infected queens.

“When you place monarchs and queens side by side, the monarchs typically have the upper hand over queens in terms of food acquisition,” Altizer remarked. “The queens adapt by developing greater resistance to parasites and being more resilient in other aspects.”

Museum Collections Essential for Research

While uncertainties persist concerning the dynamics between OE and its hosts, the museum collections remain invaluable for forming a clearer understanding of infection trends in natural settings.

“No single person could travel globally and observe all these distinct species within a feasible timeframe and budget,” Altizer expressed. “However, by visiting a museum, we can access samples from around the world that date back decades or even further and glean important information from these organisms.”

Considering the detrimental impacts OE can impose on butterflies, improving the understanding of parasite distributions and other hazards could aid in shaping conservation initiatives for monarchs and the preservation of additional species.

The study was published in Ecological Entomology with lead author Maria Luisa Müller-Theissen and co-authors Paola Barriga, Katie Yan, and Nicole Gottdenker.

The article Museum collections unveil the global spread of butterfly disease first appeared on UGA Today.