Cornell researchers find glyphosate herbicide unlikely source of Monarch butterfly decline

Print Friendly, PDF & Email
Screen Shot at AM
Photo by Tony Hisgett

The GLP aggregated and excerpted this blog/article to reflect the diversity of news, opinion and analysis.

In the face of scientific dogma that faults the population decline of monarch butterflies on a lack of milkweed, herbicides and genetically modified crops, a new Cornell University study casts wider blame: sparse autumnal nectar sources, weather and habitat fragmentation.

“. . . [W]e have pieced together the monarch life cycle to make inferences about what is impacting the butterflies,” said Anurag Agrawal, Cornell University professor of ecology and evolutionary biology and senior author on the new paper, to be published April 25 in the journal Oikos.

. . . .The study finds that a “lack of milkweed, the only host plant for monarch butterfly caterpillars, is unlikely to be driving the monarch’s , as the problem appears to occur after they take flight in the fall,” said Agrawal.

. . . .

. . . .Yes, said Agrawal: “The consistent decline at the overwintering sites in Mexico is cause for concern. Nonetheless, the population is six times what it was two years ago, when it was at its all-time low.” Agrawal credits the population rebound to improved weather and release from the severe drought in Texas.

Related article:  EU bans neonic insecticide thiacloprid after 2020, citing threats to human reproductive health, bees

Agrawal said that a persistent decline caused by lack of nectar sources or other threats such as habitat loss or insecticide use can conspire with large annual population fluctuations – mostly due to weather – and may eventually push monarchs to dangerously low numbers.

“Given the intense interest in monarch conservation, the blame being put on herbicide use and the national dialog about potentially listing monarchs under the endangered species act, we have to get the science right,” said Agrawal.

Read full, original post: Beyond milkweed: Monarchs face habitat, nectar threats

Outbreak Daily Digest
Biotech Facts & Fallacies
GLP Podcasts
Infographic: Trending green and going great — Every state in the US seeing decreased cases of COVID

Infographic: Trending green and going great — Every state in the US seeing decreased cases of COVID

The U.S. averaged fewer than 40,000 new cases per day over the past week. That’s a 21% improvement over the ...
News on human & agricultural genetics and biotechnology delivered to your inbox.
glp menu logo outlined

Newsletter Subscription

* indicates required
Email Lists