IS THE MONARCH HEADING FOR EXTINCTION? 1

The Monarch Butterfly:
Is extinction in the near future for the Monarch?
Samuel O. Dean
Western Governors University
WGU Student ID# XXXXXXXXX

IS THE MONARCH HEADING FOR EXTINCTION? 2 Is the Monarch Heading for Extinction?
The monarch butterfly is well known and easily recognized, as it inhabits many islands and continents of the world (Bradley & Altizer, 2005). Most of the monarch populations are solitary; they remain in one basic geographical area throughout the year. The eastern North American monarch butterfly is a unique variant because it undertakes an incredible migration, spanning thousands of miles, crossing through three countries and requires three to four generations to complete this cycle every year. Throughout this journey, the monarchs breed, lay their eggs and die; it is their offspring which complete the journey. Starting in central Mexico in early spring, the monarchs traverse northward throughout a majority of the eastern United States and into southern Canada before returning to their overwintering grounds in the Transvolcanic Belt of central Mexico before winter sets in (Rudolf, Ely, Schaefer, Williamson, & Thill, 2006; Yoon, 1998; Williams, Stow, & Brower, 2007; Williams & Brower, 2007).
Over one billion butterflies migrate southward from their one million square mile breeding range, forming densely packed colonies of up to 50 million butterflies per hectare while they winter over from November through March. In fact, the third and fourth generational prodigy southward migrating butterflies will frequently return to the same areas of trees as did their ancestors (Williams et al., 2007). Why the monarchs migrate is still not known. According to an article in The New York Times (Yoon, 2002), some scientists have called this migration an endangered biological phenomenon. Sonia Altizer, Assistant Professor at the Odum School of Ecology of the University of Georgia, is recently quoted in stating "there's a very real probability that the eastern migratory population will be lost sometime in the next 50 to 100 years" (Fahmy, IS THE MONARCH HEADING FOR EXTINCTION? 3 2008, para. 14). If the migrating population vanishes, the mystery may never be solved (Yoon, 2002).
The information presented in this paper will address several pressing struggles which the monarch butterfly currently faces. First, even without human intervention, the monarch butterfly – as with most insects – is faced with many natural afflictions from parasites to predators. Second, herbicides, pesticides and other biological agents have a great deal of impact on the monarchs' life cycle. And third, development in the monarchs' northern breeding territory coupled with illegal logging in their southern wintering grounds negatively affects their ability to maintain adequate population levels. Therefore, this documentation suggests the North American monarch butterfly (Danaus Plexippus) may be nearing extinction due to a combination of natural environmental impacts, biological threats and loss of habitats from human development.
The monarch faces many perils of the natural world. These threats include severe climate change, infection by parasites and parasitoids, and attack by various predators such as spiders, ants, birds and wasps.
Severe climate changes combined with altered climate patterns can have an ill effect on the monarchs' ability to survive (Bradley & Altizer, 2005; Williams & Brower, 2007; Brower et al., 2011). For instance, in the oyamel fir forests which serve as the monarchs overwintering grounds, the area must be cool, humid and non-freezing (Williams & Brower, 2007). Yoon (2002) documents a catastrophic winter storm which killed between 220 and 270 million butterflies in mid-January of 2002. Additionally, in the spring of 2009, Brower et al. (2011) documents the occurrence of above normal temperatures in Texas which negatively affected the IS THE MONARCH HEADING FOR EXTINCTION? 4 development of first generation monarchs. That following winter, population levels at the overwintering grounds were the lowest they have been in the past 17 years (Brower et al., 2011).
Parasitoids are parasitic insects which infect their hosts, eventually killing them. Tachinid flies and braconid wasps are two types of parasitoids which commonly kill the monarch. They lay their eggs on the caterpillars to develop inside and emerge just before pupation, after they have eaten their host from the inside out (University of Georgia, 2011).
Parasites, such as the microscopic protozoan Ophryocystis elektroscirrha (Oe), infest the monarch and are transmitted to their mates and offspring (Bradley & Altizer, 2005; De Roode, Gold, & Altizer, 2006; Fahmy, 2008; UGA, 2011). Oe is an obligate parasite which affects worldwide populations of monarchs. A study conducted by Bradley and Altizer in 2005 shows that monarchs infected with Oe had decreased stamina and lost body weight at a faster rate than healthy, non-infected monarchs. As a result of these findings, they were able to show that heavily infected butterflies would most likely not survive the southern migration, but that lightly or moderately infected butterflies were able to complete the migratory cycle and would then pass the parasites to their offspring and mates during the next season. poptextThe monarch is a food source for many other creatures as well. According to the University of Georgia (2011), spiders, ants, birds and wasps are the most common predators. Other predators such as fire ants will kill and eat the monarch eggs and caterpillars, while some birds and wasps feed on the adults. poptextPesticides, poptextherbicides and genetically modified crops have been shown to kill or displace monarch butterflies and caterpillars. Herbicides used in crop management kill milkweed and other nectar sources in and around crop fields (Williams, & Brower, 2007; Brower et al., 2011). IS THE MONARCH HEADING FOR EXTINCTION? 5 The herbicides kill all of the native plants such as milkweeds, while the crops – an increasing number of which are genetically engineered to be herbicide resistant – are unaffected. While the monarchs encompass a breeding range of nearly 1 million square miles, the majority is located in the agricultural states of Kansas, Nebraska, Iowa, Missouri, Wisconsin, Illinois, Michigan, Indiana and Ohio. This is soybean and corn country according to Yoon (1998). The monarch depends on the native milkweed plants to survive, as these are the only food sources of the developing caterpillars. Brower et al. (2011) has concluded that because of the wide spread use of glyphosate herbicide on genetically modified crops, milkweeds will disappear almost completely from crop lands.
Non-target organisms, such as the monarch, are affected by broad-spectrum insecticides which are commonly applied on and around crop fields. These insecticides are employed to control any number of crop pests, although many non-target insects are included in the general eradication and various human health risks are associated with their application (Shelton & Sears, 2001).
In recent years, many types of commercially important plants, such as corn, cotton and potatoes, have been genetically engineered to provide their own built in insecticide (United States Environmental Protection Agency, 2002). Corn which is genetically modified to synthesize the Bacillus thuringiensis (Bt) bacterium becomes toxic to certain pest insects. It can, however, also transmit Bt through a process called pollen deposition. When Bt corn pollen is deposited on nearby milkweed plants, studies have shown that this can cause various amounts of distress to monarch caterpillars, from death to relocation (USEPA, 2002; Shelton & Sears, 2001; Koch, Hutchison, & Venette, 2003; Williams & Brower, 2007). IS THE MONARCH HEADING FOR EXTINCTION? 6 Human development is slowly eliminating the resources the monarch butterfly depends on to survive. According to the most recent study by Brower et al. (2011), illegal logging in Mexico has removed or degraded more than 50% of the monarchs overwintering habitats. Damage by illegally logging the oyamel fir forests of the monarchs overwintering grounds has been shown to destroy habitat and cause extreme climactic shifts (Williams & Brower, 2007). The illegal logging activities cause the forest canopy to become fragmented at best - or the habitat to become unsuitably destroyed at worst (Williams et al., 2007). The monarch is very sensitive to minute disturbances that allow more sunlight to penetrate the forest canopy. This causes the butterflies to warm and rapidly burn off their lipid reserves, which can become critically low over the winter (Williams et al., 2007).
Even though the Mexican government committed a protected status to the region in 1986 and further expanded it again in 2000 (Williams & Brower, 2007), and the United Nations dedicated the area as a Biosphere Reserve in 2006 (Revkin, 2008), illegal logging continues (Williams & Brower, 2007; The New York Times, 2001). Logging is done by family groups legitimately seeking fuel for cooking and heat; however, the organized groups of illegal loggers which supply the regional timber industry are the most threatening to the Biosphere Reserve. In an effort to provide incentive and local economic stimulation, the World Wildlife Foundation set up a $6.5 million fund to pay residents living adjacent to the reserves to report illegal logging. However, residents and local authorities would continue to take bribes from loggers, allowing the logging to continue (McKinley Jr., 2005; Williams & Brower, 2007).
Northward, in the breeding grounds of the United States and Canada, farm fields and other modern development currently take away milkweed and nectar resource habitat at a rate of IS THE MONARCH HEADING FOR EXTINCTION? 7 1 million hectares per year. This equates to a total habitat loss of 56 million hectares (220,000 square miles) from 1992 to 2007 (Brower et al., 2011). Additionally, modern land management practices using fire suppression techniques cause a reduction in nectar sources and milkweed habitat (Rudolf et al., 2006). In pre-European settlement times, many grasslands and forested areas would regularly burn, a natural process caused primarily by lightning, which many plant species depend on for survival. In the current modern era since the 1900's (Rudolf et al., 2006), forests and grasslands in many areas are managed in a manner that mitigates regular burn cycles and prevents the rejuvenation of many types of plant species. This has the effect of causing a denser canopy and a reduction in the biodiversity of the understory. During the northward spring migration, when milkweed is not as prevalent, the monarchs have fewer choices to lay their eggs. During the southward migration to Mexico, if nectar resources are further apart and fewer between, the monarchs expend more energy and are not able to store as much for their long winter latency. poptextThe monarch butterfly is widely known, and commonly spotted, in flower gardens and fields across the central and eastern United States; yet still little is understood about its complex multi-generational migratory behavior. Scientists have studied and identified the many parasites and parasitoids which naturally affect and inflict the monarch (UGA, 2011). Additionally, documentation has shown that the monarch is sensitive to climate and temperature change, which may at times eradicate them by the millions during a single adverse weather event (Bradley & Altizer, 2005; Williams & Brower, 2007; Brower et al., 2011; Yoon, 2002). And of course, the monarchs are a food source for many other creatures as well; particularly fire ants, birds and wasps (UGA, 2011). The monarchs' greatest challenges, however, come from human intervention. Herbicides used in crop management kill milkweed and other nectar sources in and IS THE MONARCH HEADING FOR EXTINCTION? 8 around crop fields (Williams & Brower, 2007; Brower et al., 2011). Broad-spectrum insecticides applied on and around crop fields affect non-target organisms such as the monarch. Furthermore, many commercially grown plants such as corn, cotton and potatoes, have been genetically engineered to synthesize their own in the case of the Bacillus thuringiensis (Bt) bacterium (USEPA, 2002). All the while, breeding ground continues to be lost due to fire-suppressed land management practices (Rudolf et al., 2006), agricultural use and development (Brower et al., 2011), while the overwintering sites continue to be decimated from illegal logging (Williams & Brower, 2007; The New York Times, 2001). Therefore, this documentation suggests the North American monarch butterfly, Danaus Plexippus, may be nearing extinction due to a combination of natural environmental impacts, biological threats and loss of habitats from human development.

IS THE MONARCH HEADING FOR EXTINCTION? 9 References
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