Straight talk on bees, silkworms and human survival

In his theory of evolution, Charles Darwin described how natural selection changes species over time. But later in life, his attention turned to domestication — artificial selection used to change plants and animals in ways that benefit people.

That’s to say, how the wolf gave rise to the pug, the wildcat gave rise to the tabby, and bees became producers of grocerystore honey.

“Everyone knows Darwin and natural selection, but he was among the first to write extensively about the hereditary factors involved in artificial selection — an inspiration for him to come up with natural selection,” said May Berenbaum, a noted University of Illinois biologist.

“Rapid diversification among species and the human manipulation of plant and animal reproduction, people don’t talk much about that.”

Ms. Berenbaum will deliver the keynote address — “Unnatural Selection: How Humans Affect Insect Evolution Without Even Realizing It” — at 7 p.m. Thursday during Duquesne University’s annual celebration

of the life and works of Charles Darwin.

The Darwin Day event, free and open to the public, will be held in the Charles J. Dougherty Ballroom of the university’s Power Center, 1015 Forbes Ave., Uptown.

Ms. Berenbaum, who holds a doctorate in ecology and evolutionary biology, has published more than 300 scientific works and 35 book chapters. Her focus has been on “the chemical mechanisms underlying interactions between insects and their host plants” and ways to develop “sustainable management practices for natural and agricultural communities” of insects, including bees.

“Dr. Berenbaum is and has been a leader in the field of insect evolution for decades,” said David Lampe, the Duquesne University biologist who organizes the Darwin Day event.

“She is also very prominent in the area of bringing insects to the attention of the public. Insects run the planet, something most people don’t know, and they are in real trouble. If they go, they’re taking us with them.”

Mr. Lampe, who holds a doctorate, was a student of Ms. Berenbaum in graduate school. She said she’s generally overwhelmed by requests to speak and turns down most of them. But not in this case.

“It’s hard to turn down an invite from an alumnus I personally know and have nothing but fond memories of,” she said. “I’m proud of him.”

People long have used artificial selection to develop new breeds of dogs, pigeons and livestock; to make flowers grow faster, last longer and look more beautiful; and to generate grains, fruits and vegetables that are tastier, plumper and produce higher yields.

But those processes also can put species in danger by making them fully dependent on humans for survival.

“Humans have obliviously exerted selection pressures on insects in diverse orders and changed their distributions, abundances, life histories, and physiology, with consequences ranging from increasing their ability to cause us harm to bringing their populations to the brink of extinction,” the Darwin Day promotion states.

While Ms. Berenbaum’s research has concentrated on managed honeybees, other insects have been domesticated or semi-domesticated, she said, including scarab beetles, fruit flies and singing crickets.

“Probably the only one truly domesticated insect is the silkworm that is not able to live without human care,” she said, explaining that their survival skills have been bred out of them.

Western honeybees, which are not a native species of North America, continue struggling for survival in the new century, in part due to characteristics bred out of them.

For example, honeybees now have less ability to produce propolis, or bee glue, which they use to fill cracks in hives. Its stickiness caused so many problems for beekeepers that it led to development of bees that make less of it.

But propolis now has been shown to protect bees from pathogens. Their reduced ability to make it may be contributing to colony collapse disorder, which has plagued bees and beekeepers since 2006.

“We created houses for them to occupy without understanding their needs,” Ms. Berenbaum said. “We’ve failed them by semi-domesticating them.”