Whats causing the decline in monarch butterfly populations?

March 27, 2020 by  
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Monarch butterflies  are amongst North America’s majestic wildlife. They fascinate with their vibrant allure and migratory prowess. Yet these beauties are under serious threat, as evidenced by drastic population reduction throughout North America. What factors are causing monarch butterfly numbers to dwindle? Habitat loss For monarchs,  habitat  entails food, water and shelter, says the  National Wildlife Federation (NWF)  and the  World Wildlife Fund (WWF) . Specific to monarchs is their habitat corridor, a trek of thousands of miles from Central America’s warm regions, where they overwinter, to areas across the United States and southern Canada, where they stay for spring and summer.  In recent decades, population surveys reveal monarchs declining because of  deforestation  in Mexico, loss of grasslands in the Great Plains’ Corn Belt — which the  Center for Biological Diversity  calls “the heart of the monarch’s range” — and loss of native milkweed plants in the U.S. Such habitat losses negatively impact monarch populations as they breed, migrate and overwinter.   Habitat loss  stems mainly from the deforestation of overwintering areas,  climate change ‘s fluctuating weather patterns, developmental sprawl, plus the conversion of U.S. grasslands into ranches and farmlands. This conversion to farmland for corn and soy has spurred the Center for Biological Diversity’s admonishment against the overuse of  herbicides . These harmful chemicals poison a key player in monarch habitats, their host plant, the milkweed.  Problems with milkweed Milkweed is vital to monarchs. They are host plants, upon which females lay eggs. Once hatched, caterpillars enjoy milkweed as a food source while they grow and develop into adulthood, a process that happens in the first month of a monarch’s lifespan. And, as adults, the  butterflies  feed on milkweed nectar. Several generations of offspring spawn on milkweed during spring and summer months before migration to overwintering sites even begins. According to the NWF, “Monarch caterpillars feed exclusively on the leaves of milkweed, the only host plant for this iconic butterfly species. As such, milkweed is critical for the survival of monarchs. Without it, they cannot complete their life cycle and their  populations  decline.” Interestingly, milkweed has the toxin cardenolide, which accumulates in caterpillars feeding on milkweed . When these caterpillars become adults, the cardenolides remain, protecting them from predation. Birds and predators veer away, signaled off by the toxin’s presence in the monarchs’ bright wings. Unfortunately, milkweed loss is increasing in the destabilized landscape. Milkweed has lost considerable ground to urbanization, shifting land management practices, climate change and even herbicide misuse, like that of Roundup.  Alarming still are reports by  Science  magazine and  Entomology Today  that well-meaning gardeners have been planting the wrong species of milkweed. There are over 100 milkweed species, and not all are good for monarchs. Sadly, the tropical milkweed species  Asclepias curassavica  is heavily marketed because it is easier to obtain. But this invasive species is not well-suited for monarchs, yet remains the species good-intentioned gardeners are planting rather than the native milkweed species the monarchs are better adapted to. This invasive milkweed is now recognized by the  Ecological Society of America  as an ecological trap for monarch butterflies.     What dangers do these “wrong” species of milkweed pose for monarchs? For one, they harbor parasites, such as the protozoan parasite  Ophryocystis elektroscirrha  (OE), that are harmful to the monarch butterfly. These parasites debilitate monarchs, weakening them via “wing deformities, smaller body size, reduced flight performance, and shorter adult lifespans,” Entomology Today explained. Should these issues with milkweed persist unmitigated, their repercussions would continue to exacerbate the monarch butterfly population crisis.    Pesticide, insecticide and fungicide misuse While media attention has spotlighted herbicides as a culprit, equally important is the fact that monarch butterflies are also vulnerable to  pesticides ,  neonicotinoid  insecticides and fungicides. For instance, a Purdue University Department of Entomology  study , published last summer 2019 in  Frontiers in Ecology and Evolution , revealed that non-target pesticides, insecticides and fungicides have wreaked havoc on monarch butterflies, even at their larval stage. As the study elucidated, “agricultural intensification and a corresponding rise in pesticide use has been an  environmental  concern” that adversely affects beneficial  pollinators , like the monarch butterfly. Exposure to these pesticides, insecticides and fungicides, can be from “direct contact with contaminated surfaces or spray droplets, residues remaining on the soil, and consumption via food resources such as leaves, nectar or pollen.” Just as vexing are pesticides, insecticides and fungicides “applied by aircraft.” The study emphasized the “evidence of lower abundance and/or diversity of butterflies.” Climate change The  WWF  affirms that “monarchs are highly sensitive to  weather  and climate. They depend on environmental cues (temperature in particular) to trigger reproduction, migration, and hibernation.” Their decline is also attributed to “the effects of an increasing frequency of extreme weather events such as drought and severe storms, and extremes in hot and cold temperatures.” No wonder then that the  Environmental Defense Fund ‘s Director of Conservation Studies, David Wolfe, has lamented that “The iconic and beloved North American monarch butterfly is one of the species that has difficulty adjusting to our new climate-stressed world. Its population has declined 95 percent in the last 20 years Yet another way  climate  change adversely affects monarch butterflies is by disrupting their migration. These butterflies can travel between 50 and 100 miles a day, but when extreme weather sets in during  migration , the entire cluster or roost is vulnerable.  “Every year, a new generation of these butterflies follows the same path forged by generations before them. The only thing guiding them on this migration is temperature telling them when they need to travel – like a biological trigger setting them in flight,” Wolfe explained. “But in recent years, the monarch’s fall south migration from Canada has been delayed by as much as six weeks due to warmer-than-normal temperatures that failed to trigger the butterflies’ instincts to move south. By the time the temperature cooled enough to trigger the migration, it’s been too cold in the Midwest and many monarchs died on their trip south.” Even more worrisome, the  Xerces Society , a nonprofit environmental group focused on invertebrates, has reported that warmer temperatures from climate change increase the toxicity of tropical milkweed by increasing cardenolide concentrations. Monarch caterpillars are only tolerant up to a threshold.  EcoWatch  explained, “warmer temperatures increase the cardenolides in  A. curassavica  [the tropical milkweed species] to the point where they poison monarch larvae, delaying larval growth and stunting adult forewings. Native milkweed is not similarly impacted.” Hence, as  invasive  milkweed persists, they further harm monarch populations as temperatures rise in our current  climate crisis .  Diseases, parasites and fungal pathogens Emory University  emphasizes that climate change affects pathogen development, parasite survival rates, disease transmission processes. What would monarch populations be susceptible to? Bacterial and viral infections — like bacillus thuringiensis (BT), pseudomonas, the nuclear polyhedrosis virus (NPV) — are not unheard of, often turning an infected caterpillar or chrysalis into a darkened or black hue. Parasite attacks can come from tachinid flies or wasps (chalcid, trichogramma). Plus, fungal pathogens in the genus  Cordyceps  also attack. Each of these factors cause harm to monarch butterfly populations.

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Whats causing the decline in monarch butterfly populations?

UN releases World Water Development Report 2020

March 23, 2020 by  
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Climate change further challenges the world’s overstretched water resources, ultimately threatening all aspects of human life, according to the latest UN World Water Development Report. Most human needs revolve around water, so energy production, industrial development, food security, human and animal health and housing are also vulnerable to climate change impacts. The report states that the reliability of available water will decrease as the climate becomes more variable, amplifying floods, droughts and other water-related problems. Places already stressed from insufficient water sources will suffer more, while places that have so far been unaffected will feel the pain, too. Related: IPCC landmark report warns about the state of the oceans, polar ice content and the climate crisis Over the last century, global water use has increased by a factor of six. Between population increase, economic development and explosive human consumption, this growth continues at about 1% per year. Groundwater depletion doubled from 1960 to 2000. Some experts predict that 40% of the world will face a water deficit by 2030. “If we are serious about limiting global temperature increases to below 2°C and achieving the Sustainable Development Goals by 2030, we must act immediately,” said Gilbert F. Houngbo, chair of UN Water. “There are solutions for managing water and climate in a more coordinated manner and every sector of society has a role to play. We simply cannot afford to wait.” The UN report acknowledges that while most countries recognize water as a crucial issue, few have specific action plans about adapting policies to protect this resource. The report suggests that climate change funds be used more for adaptation and mitigation of water issues. Adaptation includes social and institutional measures, plus natural, technological and technical steps to lessen climate change-related damage. Mitigation refers to the actions humans must take to reduce greenhouse gas emissions. Wastewater treatment generates a high amount of emissions. Some countries — such as Peru, Mexico , Thailand and Jordan — have already harnessed the methane in untreated wastewater as biogas, which provides enough energy to run the treatment process. The UN report also mentions wetland protection, conservation agriculture techniques, reusing partially treated wastewater for industry and agriculture and fog capture as possible water management interventions. + UN World Water Development Report 2020 Image via Alex Hu

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UN releases World Water Development Report 2020

Infographic: Water & Global Climate Crisis — What Can You Do?

March 20, 2020 by  
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This year on March 22, World Water Day focuses on … The post Infographic: Water & Global Climate Crisis — What Can You Do? appeared first on Earth911.com.

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Infographic: Water & Global Climate Crisis — What Can You Do?

What it takes to be a corporate climate leader

March 20, 2020 by  
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Making sustainability core to business strategy and aligning corporate sustainability and government relations teams helps companies deal with short-term crises such as the novel coronavirus (COVID-19).

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Earth911 Inspiration: What Kind of Difference Will You Make?

March 20, 2020 by  
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Renowned scientist and conservationist Jane Goodall reminds us that we … The post Earth911 Inspiration: What Kind of Difference Will You Make? appeared first on Earth911.com.

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Earth911 Inspiration: What Kind of Difference Will You Make?

World Water Day 2020: The role of innovation in creating abundance

March 20, 2020 by  
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We are now beyond business-as-usual approaches for water, which is critical for watersheds such as the Colorado River Basin.

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World Water Day 2020: The role of innovation in creating abundance

COVID-19 and climate change: A healthy dose of reality

March 16, 2020 by  
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Consider the global health crisis currently upon us as a warm-up act for a climate-changing world.

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COVID-19 and climate change: A healthy dose of reality

Heeding the lessons of ‘sustainability vets’

March 16, 2020 by  
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What happens to all that knowledge after a corporate sustainability executive retires?

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Heeding the lessons of ‘sustainability vets’

Trend: Nutrient diversity goes beyond meatless meat

March 16, 2020 by  
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The potential of lab-grown and plant-based protein as a solution to climate change and world hunger has already generated a great deal of buzz.

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Trend: Nutrient diversity goes beyond meatless meat

Trend: Nutrient diversity goes beyond meatless meat

March 16, 2020 by  
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The potential of lab-grown and plant-based protein as a solution to climate change and world hunger has already generated a great deal of buzz.

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Trend: Nutrient diversity goes beyond meatless meat

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