Posts Tagged: insects

Chestnut Hill, Mass. (1/10/2018) - Visiting a colleague in Germany in 2012, Boston College Research Professor Paul K. Strother was examining soil samples for pollen, spores, pieces of plants and insect legs - organic debris that might otherwise have been considered "pond scum" when it was trapped in sediment during cataclysmic earth events 200 million years ago.

The slides of rock samples drilled in the German countryside included some material that looked familiar to Strother, a Department of Earth and Environmental Sciences researcher at Boston College's Weston Observatory, who studies the origin and early evolution of land plants. What he saw were features similar to those found in insect wings.

The wrinkle was that these types of moths and butterflies - known as Lepidoptera - were long posited to have evolved 50 to 70 million years later, during the Cretaceous period when the first flowering plants emerged as their prime food source.

"The consensus has been that insects followed flowers," said Strother, a co-author of "A Triassic-Jurassic window into the evolution of Lepidoptera," a new report published today in Science Advances. "But that would be 50 million years later than what the wings were saying. It was odd to say the least, that there would be butterflies before there were flowers."

Five years later, Strother and colleagues from natural history museums in Germany and a university in the Netherlands have developed a scientific case showing the Lepidoptera evolved earlier than previously established - emerging during the Jurassic period.

Absent flowers, the researchers report, primitive moths and butterflies, known as the Glossata, developed the physical attributes - namely the sucking proboscis - to find nutrition by drawing off water droplets from the tips of immature gymnosperm seeds.

"What we've found is that these butterflies and moths with mouth parts were feeding on pollen droplets of gymnosperm seeds - from conifers related to pines, seed plants without fruits and flowers. They were feeding off the cone-borne seeds - mainly as a source of water," said Strother.

Even Charles Darwin called the mysterious evolution of flowering plants "an abominable mystery." Scientists have reckoned that flowering plants preceded the insects that fed off of them. But researchers have gradually started to piece together evidence that moths and butterflies existed earlier than the Cretaceous period, which began 145 million years ago.

The team's findings shed new light on the classic example of co-evolution: the evolutionary interplay between pollenating insects - flies, bees, wasps, butterflies and moths - and angiosperms, or flowers, Strother said.

"Our discovery does not change this, but instead, it demonstrates that the Glossata - which gave rise to the Lepidoptera - evolved earlier by a feeding adaptation to the gymnospermous ovules, or the pollen droplets," said Strother. "These insects later transferred their feeding preference onto angiosperms, and, as a result, ended up co-evolving with flowers where they function to transfer pollen as they feed on nectar."

Developing a clearer picture of insect evolution had proved elusive because much of what is learned from ancient rock, soil and fossils comes from earth once covered by oceans, said Strother. Moths and butterflies lived over land masses. In addition, their delicate features were prone to deterioration prior to fossilization.

Utrecht University paleontologist Bas van de Schootbrugge and colleagues assembled a portfolio of samples containing fossilized remains of moths and butterflies to carefully establish the presence of Lepidoptera in earth samples from a region where the cataclysmic transition between Triassic and Jurassic is preserved in rock.

The mass extinction event 201 million years ago wiped out an estimated 35 percent of all species, which makes the survival and diversification of Lepidoptera all the more remarkable.

Assembling the evidence required a team that included Strother and van de Schootbrugee, Utrecht University's Timo van Eldijk, an undergraduate at the time, Carolien Weijst, and Henk Visscher; as well as Torsten Wappler of the German natural history museum Hessisches Landesmuseum Darmstadt, and Hossein Rajaei of Museum fur Naturkunde, in Stuttgart.

In 2012, Strother was examining the sample slides looking at algae, fungi and soil microorganisms. "These are organic extractions after you've dissolved away the minerals in the samples and you're looking at anything that is organic. There are pollen and spores. There are other things. Pieces of plant cuticles. Resistant organic material. Insect legs. Ninety-nine percent is plant debris.

"It's basically pond scum," said Strother, referring to the film of debris that can sit atop a pool of standing water. Part of what Strother saw looked similar to insects from another era, he said.

The project required linking a range of evidence, akin to a scientific detective story, said Strother.

"This is the old-fashioned science of discovery," said Strother. "We're looking at this microscopic world of things that lived hundreds of millions of years ago and we don't know what they are. The challenge is: can we figure out what they are? Part of it is piecing together the tree of life, or the evolution of organisms through time. It is more like a puzzle or a mystery."

https://www.eurekalert.org/pub_releases/2018-01/bc-is011018.php

IMAGE: Examples of the oldest wing and body scales of primitive moths from the Schandelah-1 core photographed with transmitted light (magnification 630x). The scales are part of palynological preparations and occur... view more 

Credit: Bas van de Schootbrugge, Utrecht University

RIVERSIDE, Calif. -- From their native home on the banks of South America's Paraná River, Argentine ants have conquered six continents and many oceanic islands. Their success is explained by several factors: they have more than one queen per colony, making them difficult to eradicate, and they adapt to changes in their environments by living transiently rather than building permanent nests.

Argentine ants are also highly aggressive, out-competing existing ant species for food and other resources. In a paper published today in Scientific Reports, researchers at the University of California, Riverside show how Argentine ants use chemical secretions as weapons in their interactions with harvester ants, which are native to California. The findings could help in the development of new pest control strategies.

Although they originated in a tropical ecosystem, Argentine ants are a major nuisance in California and the southern U.S., where they thrive in urban areas with artificial irrigation. They also pose natural and economic threats, competing with native ants and pollinators, and protecting plant pests such as aphids and scales in return for the sweet honeydew secretions that these insects produce.

Like many social insects, Argentine ants communicate via an assortment of chemicals that they excrete from their gaster (abdomen). During aggressive interactions, Argentine ants exhibit a behavior called gaster bending, where they place the tip of their gaster onto their opponent's body. Based on behavioral observations, researchers have long inferred that, during this interaction, Argentine ants may spray or dab irritant chemicals onto their opponent's body.

The UCR researchers confirmed this experimentally, showing that Argentine ants produce secretions containing two compounds (dolichodial and iridomyrmecin), which they apply to the surface of harvester ants during aggressive interactions. The research was led by Dong-Hwan Choe, an assistant cooperative extension specialist and assistant professor of entomology in UCR's College of Natural and Agricultural Sciences.

Choe's team investigated the effect of these compounds on harvester ants, showing they caused both irritation and disorientation. The compounds also attracted other Argentine ants to the area, allowing them to mount a larger, coordinated response to the native ant species.

"This research finding experimentally verified the long-held assumption that Argentine ants use gaster-produced compounds during aggressive interactions with other ant species. They use these compounds not only for incapacitating the opponent, but also for calling more nestmates from nearby locations for their help in combat," Choe said.

Choe said synthetic versions of these chemicals could be used to develop new pest management strategies with a greater selectivity.

"Potentially, these compounds could be used in a bait to attract Argentine ants toward a poison while at the same time acting as a deterrent to harmless native ants," he said.

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The title of the paper is "Verification of Argentine Ant Defensive Compounds and Their Behavioral Effects on Heterospecific Competitors and Conspecific Nestmates." In addition to Choe, contributors include first author Kevin Welzel, who completed his Ph.D. in Choe's lab at UCR; Shao Hung Lee, an entomology undergraduate at UCR; Aaron Dossey at All Things Bugs, LLC; and Kamlesh Chauhan, at the USDA-Agricultural Research Service.