Smithsonian Science » plants

First ever record of insect pollination captured in 100 million-year-old amber

John Barrat — Tue, 15 May 2012 13:24:47 +0000

Amber from Cretaceous deposits (110-105 million years ago) in Northern Spain has revealed the first-ever record of insect pollination. Scientists have discovered several specimens of tiny insects covered with pollen grains in two pieces of amber, revealing the first record of pollen transport and social behavior in this group of animals. The results are published in the Proceedings of the National Academy of the Science (PNAS) dated 14-18 May 2012.

Image right: Gymnosperm pollen attached to the abdomen and wing of a thysanopteran from the Alava amber (Credit: Enrique Peñalver, IGME).

The international team of scientists comprises: Enrique Peñalver and Eduardo Barrón from the Instituto Geológico y Minero de España in Madrid; Xavier Delclòs from the University of Barcelona; Andre and Patricia Nel from the Muséum national d’histoire naturelle in Paris; Conrad Labandeira from the Smithsonian’s National Museum of Natural History in Washington D.C.; and Carmen Soriano and Paul Tafforeau from the European Synchrotron Radiation Facility in Grenoble, France. The amber samples were from the collection of the Museo de Ciencias Naturales de Álava in Spain.

Today, more than 80 percent of plant species rely on insects to transport pollen from male to female flower parts. Pollination is best known in flowering plants but also exists in so-called gymnosperms, seed-producing plants like conifers. Although the most popular group of pollinator insects are bees and butterflies, a myriad of lesser-known species of flies, beetles or thrips have co-evolved with plants, transporting pollen and in return for this effort being rewarded with food.

Image left: An artist’s conception of of Gymnospollisthrips with pollen attached to the body over an ovulate organ of a gingko (Credit: Enrique Peñalver, IGME).

During the last 20 years, amber from the Lower Cretaceous found in the Basque country in Northern Spain has revealed many new plant and animal species, mainly insects. Here, the amber featured inclusions of thysanopterans, so-called thrips, a group of minute insects of less than 2 millimeters long that feed on pollen and other plant tissues. They are efficient pollinators for several species of flowering plants.

Two amber pieces revealed six fossilized specimens of female thrips with hundreds of pollen grains attached to their bodies. These insects exhibit highly specialized hairs with a ringed structure to increase their ability to collect pollen grains, very similar to the ones of well known pollinators like domestic bees. The scientists describe these six specimens in a new genus (Gymnopollisthrips) comprising two new species, G. minor and G. major.

The most representative specimen was also studied with synchrotron X-ray tomography at the European Synchrotron Radiation Facility to reveal the pollen grain distribution over the insect’s body in 3D and at very high resolution. The pollen grains are very small and exhibit the adherent features needed so that insects can transport them. The scientists conclude that this pollen is from a kind of cycad or ginkgo tree, a kind of living fossil of which only a few species are known to science. Ginkgos are either male or female, and male trees produce small pollen cones whereas female trees bear ovules at the end of stalks which develop into seeds after pollination.

Image right: Synchrotron tomography image of Gymnospollisthrips minor showing pollen. (Credit: ESRF).

Why did these tiny insects collect and transport gingko pollen 100 million years ago? Their ringed hairs cannot have grown due to an evolutionary selection benefiting the trees. The benefit for the thrips can only be explained by the possibility their larvae ate pollen. This suggests that this species formed colonies with larvae living in the ovules of some kind of gingko for shelter and protection, and female insects transporting pollen from the male gingko cones to the female ovules to feed the larvae and at the same time pollinate the trees.

More than one hundred million years ago, flowering plants started to diversify enormously, eventually replacing conifers as the dominant species. “This is the oldest direct evidence for pollination, and the only one from the age of the dinosaurs,” says Carmen Soriano, who led the investigation of the amber pieces with X-ray tomography at the ESRF. “The co-evolution of flowering plants and insects, thanks to pollination, is a great evolutionary success story. It began about 100 million years ago, when this piece of amber fossil was produced by resin dropping from a tree, which today is the oldest fossil record of pollinating insects. Thrips might indeed turn out to be one of the first pollinator groups in geological history, long before evolution turned some of them into flower pollinators.” –Source: European Synchrotron Radiation Facility

New invasive species database allows public to ID marine invaders with a home computer

John Barrat — Mon, 12 Mar 2012 14:53:42 +0000

Mitten crabs, zebra mussels and rock vomit: These and hundreds of other non-native species have invaded coastal regions throughout the United States, often causing dramatic changes to coastal ecosystems and significant economic costs. The Smithsonian Environmental Research Center has now created NEMESIS (National Estuarine and Marine Exotic Species Information System), an online public database to provide key information about the non-native marine species throughout the nation.

Image right: Tunicate Botryllus planus. Colonial tunicates like this one are made of hundreds of tiny zooids that act as a single organism. (Photo: Rosana Rocha, Universidade de Federal de Paraná, Brazil)

The rate of new marine invasions along U.S. coasts has risen sharply in recent decades due to human-aided introductions, often unintentional. Organisms can attach directly to the hulls of ships or be taken up and transported in ballast water (water used by large ships to provide stability and trim during sailing). They can also be introduced with imports of seafood, bait and packing materials. In addition, some species have been deliberately introduced to create new fisheries, though this practice is now very rare. As trade and globalization have increased, so has the opportunity for invasions.

No part of the country is untouched by non-native species. Although most people recognize a few of the common and conspicuous invaders in nearby waters, the full scope of invasions that lurk beneath the water often go unnoticed.

Image left: Chinese mitten crab.

NEMESIS aims to provide comprehensive and synthetic information on hundreds of individual marine species in the continental United States. Created by SERC’s marine invasions lab, the database includes information on how and when invasions occurred, distribution maps and what is known about their impacts. For example, the tunicate Didemnum vexillum (commonly known as D. vex or “rock vomit”) has created serious problems on the West and East Coasts of the United States. This mat-like species grows rapidly and can completely cover aquaculture nets, shellfish beds and sensitive marine environments. The database also includes an interactive map of the U.S., where visitors can search for invaders impacting their own coastlines.

NEMESIS launched March 5 with tunicates, a group that includes the destructive rock vomit. Tunicates, also known as ascidians or sea squirts, are filter feeders that grow on hard surfaces such as docks, rocks or sandy marine sediments. Information for other groups of species will become publicly available over the next year as NEMESIS continues its rollout, starting with crabs, shrimp and crayfish.

Photo right: Tunicate Styela clava, the club sea squirt. It has caused major headaches in Canada, where fouling of fishing and aquaculture equipment cost anywhere 34 to 88 million Canadian dollars per year. (Photo: Melissa Frey, Royal BC Museum, Canada)

NEMESIS was designed in partnership with the U.S. Geological Survey. NEMESIS focuses on invasions in marine and estuarine waters, while the USGS Nonindigenous Aquatic Species database focuses on invasions in freshwater habitats of the U.S. The complementary databases were designed to be compatible, allowing for joint syntheses across marine and freshwater habitats in the U.S.

The NEMESIS database is a long-term and dynamic program that will continue to grow over time. Records are updated regularly as new species are discovered and new research becomes available. For more information on NEMESIS or recent updates, visit the NEMESIS home page and the NEMESIS Interactive Invasions Map.

Cool science is being carried out on a Smithsonian island in the Panama Canal

John Barrat — Mon, 06 Dec 2010 13:47:45 +0000

Smithsonian scientists to help identify and eradicate invasive species in Alaskan waters

John Barrat — Thu, 02 Dec 2010 16:00:28 +0000

The Smithsonian Environmental Research Center in Edgewater, Md., and the Alaska Sea Grant Program of the University of Alaska, Fairbanks, were recently identified as the recipients of a $400,000 grant from NOAA’s National Sea Grant College. The money will be used by the two collaborating organizations to create an early detection and rapid response system for invasive marine species in Alaska. A key element of the detection system will be observations from volunteer “citizen scientists.”

Image right: Didemnum vexillum, a sea squirt species believed to have originated near Japan that was recently discovered in Sitka, Alaska. (Photo courtesy USGS)

The grant is one of five regional grants totaling $2 million awarded by the National Sea Grant College program to prevent and control aquatic invasive species. “Invasive species in our waterways are threatening ecosystems from coast to coast — from tunicates on the West Coast and Australian spotted jellyfish on the East Coast to the round goby in our Great Lakes,” NOAA Sea Grant Director Leon Cammen said. “These grants will help to reduce the great ecological and economic costs of aquatic invasive species.”

This video shows D. vexillum tendrils hanging from a float in Orleans, Mass. (Courtesy USGS)

A non-native species, Didemnum vexillum, was discovered in Sitka, Alaska, earlier this year during a Marine Invasive Species Bioblitz organized by the Smithsonian Environmental Research Center, Alaska Department of Fish and Game, Alaska Sitka Tribe, University of Alaska, NOAA and San Francisco State University. A notorious fouling organism on boats, fishing nets, docks, and buoys, D. vexillum (also known as the carpet sea squirt) is of major concern because it grows rapidly and can completely cover aquaculture nets, shellfish beds and sensitive marine environments. Believed to have originated near Japan, the species spreads through both sexual reproduction and fragmentation, which aids in its ability to colonize new areas rapidly.

Image left: Sitka harbor, Alaska (Photo by Robert A. Estremo)

D. vexillum could have been introduced to Alaska through ballast water, fouled commercial and recreational boat hulls, relocating fouled piers and docks, fishing equipment and aquaculture gear. Now that it has been identified in Sitka, it is important to keep D. vexillum from spreading to other parts of Alaska. Several agencies are now working in conjunction with the Smithsonian to develop a rapid response plan for D. vexillum and efforts are underway to determine the extent of its distribution.

Potential biofuel pest, the switchgrass moth, under renewed scrutiny of entomologists

John Barrat — Mon, 29 Nov 2010 13:45:41 +0000

Scientists are learning more about the life stages and biology of an insect that may compete with humans for the energy crops of the future—an insect some scientists are calling the switchgrass moth.

Image left: A switchgrass moth adult (Photo by Paul Johnson)

In an recent article in the journal Zootaxa, researchers from the Smithsonian Institution, South Dakota State University and the University of Nebraska, for the first time described the immature stages of the insect species Blastobasis repartella, first described in scant detail from two male specimens of the adult moth collected in Denver, Colo., in 1910. The article re-describes the adult insect far more closely and discusses some aspects of its biology in relation to its host plant, switchgrass. Blastobasis repartella bores into the stems of switchgrass.

The insect has gain come to the attention of agricultural scientists because native grasses like switchgrass are being considered as candidates for the large-scale production of cellulosic ethanol, a next-generation biofuel.

Image right: David Adamski

Already in May 2004 at the Dakota Lakes Research Farm of South Dakota State University, professor Arvid Boe, a forage and biomass grass breeder, and postdoctoral research associate DoKyoung Lee estimated that up to 40 percent of new tillers of a few scattered plants of switchgrass were lost to the caterpillar of the switchgrass moth.

Paul Johnson, curator of SDSU’s Severin-McDaniel Insect Research Collection and a research associate in the Entomology Department of the Smithsonian’s National Museum of Natural History in Washington, D.C., collected adult moths using simple emergence traps in 2008, and estimated their population densities. SDSU scientists first suspected the stem-borer might be a new species. But David Adamski, entomologist with the USDA’s Agricultural Research Service, research associate at the Smithsonian, and a specialist in small moths, ultimately identified the insect.

Image left: Arvid Boe in a switchgrass plot maintained by South Dakota State University. (Image courtesy South Dakota State University)

Adamski is the lead author of the journal article. Professors Paul Johnson and Arvid Boe, both of South Dakota State University, are co-authors, along with J.D. Bradshaw of the University of Nebraska-Lincoln and Alan Pultyniewicz of Columbia, Md.

The journal article notes that while some Blastobasis species feed on various grasses, Blastobasis repartella “appears to be restricted to switchgrass.”

If farmers grow switchgrass as a biomass crop in the future, Johnson says, it is very likely that switchgrass moth populations will increase along with the acres devoted to the grass. This means it is very likely that agricultural producers will want researchers to develop insect control regimens to limit damage to energy crops.

Image right: Paul Johnson with insect traps in a field of switchgrass. (Image courtesy South Dakota State University)

The journal article notes that switchgrass larvae are presumably inactive during the coldest months. They were found to be active in South Dakota when plants were brought into the greenhouse in early spring and forced into early growth. In the field, mature larvae are commonly found actively feeding in late May.

Adults of Blastobasis repartella are nocturnal with a peak of activity during the pre-sunrise hours. In eastern South Dakota, adult activity occurs primarily from mid-July to mid-August. Seasonal peak adult activity related to reproductive behavior was measured by the frequency of arriving males (40–50 males per night and occasionally exceeding 75 males per night) at cages containing calling females.

There is no evidence to suggest the occurrence of a second generation or overlapping cohorts in either South Dakota or Illinois populations, the researchers say. This is consistent with the single per year growth of switchgrass and appears to correlate with geographic variations in growing season differences of switchgrass, Boe said.–Lance Nixon, South Dakota State University

Fossil reveals 48-million year history of zombie ants

John Barrat — Wed, 10 Nov 2010 12:42:43 +0000

A 48 million-year-old fossilized leaf has revealed the oldest known evidence of a macabre part of nature – parasites taking control of their hosts to turn them into zombies.

The discovery has been made by a research team led by David Hughes of the University of Exeter in England, who studies parasites that can take over the minds of their hosts; Conrad Labandeira from the Smithsonian’s National Museum of Natural History; and Torsten Wappler, from the Steinmann Institute in Germany.

Image right: An ant killed by a fungal parasite is shown here biting into a leaf vein. The fungal growth can be clearly seen issuing from the ant’s head. (Photo by David P. Hughes)

All manner of animals are susceptible to the often deadly body invasion, but scientists have been trying to track down when and where such parasites evolved.

“There are various techniques, called a molecular clock approach, which we can use to estimate where and when they developed and fossils are an important source of information to calibrate such clocks,” Hughes says.

“This leaf shows clear signs of one well documented form of zombie-parasite, a fungus which infects ants and then manipulates their behavior.”

The fungus, called Ophiocordyceps unilateralis, appears to take over the mind of infected ants – causing them to leave their colonies and head for a leaf which provides the ideal conditions for the parasite to reproduce.

Image left and below: This 48-million-year-old leaf fossil from Messel clearly bears the tell-tale scars of ants that have been infected with the mind-controlling fungal parasite. (Photo by Torsten Wappler)

When the ant gets there it goes into a ‘death grip’– biting down very hard on the major vein of a leaf. This means that when the ant dies, its body stays put so the fungus has time to grow and release its spores to infect other ants.

The death grip bite leaves a very distinct scar on the leaves. This prompted Hughes, Labandeira and Wappler to search for potential evidence of the fungus at work by studying the fossilized remains of leaves.

After studying leaf fossils from the Messel Pit, a site on the eastern side of the Rhine Rift Valley in Hesse, Germany, they found clear evidence of the death grip bite in a 48 million-year-old leaf specimen.

“The evidence we found mirrors very closely the type of leaf scars that we find today, showing that the parasite has been working in the same way for a very long time,” Hughes explains.

“This is, as far as we know, the oldest evidence of parasites manipulating the behaviour of their hosts and it shows this parasitic association with ants is relatively ancient and not a recent development.

“Hopefully we can now find more fossilised evidence of parasitic manipulation. This will help us shed further light on the origins of this association so we can get a better idea of how it has evolved and spread.”

The paper, Ancient death-grip leaf scars reveal ant-fungal parasitism, was published in a recent edition of Royal Society journal Biology Letters. –Research News, University of Exeter

Smithsonian ecologist John Parker discusses his work with white-tailed deer and invasive plant species

John Barrat — Mon, 04 Oct 2010 14:06:59 +0000

Study reveals hazards of the high-wire life for bromeliads

John Barrat — Fri, 10 Sep 2010 13:19:45 +0000

A common epiphytic plant that pulls the nutrients it needs to live out of thin air has been conducting a high-wire act in Panama. Wind-born seeds of the bromeliad Tillandsia flexuosa have long been lodging, sprouting and appearing to thrive in the grooves of aluminum-wire wrapped electric power lines. These plants grow unprotected in the blazing tropical sun using a thick layer of water- and nutrient-absorbing scales to pull sustenance from the air. Their roots hold them fast to the cable.

Right and below: T. flexuosa growing on power lines in Panama (Photos courtesy Gerhard Zotz)

Recently, botanists Gerhard Zotz of the Smithsonian Tropical Research Institute and Stefan Wester of the University of Oldenburg in Germany decided to take a closer look at these high-wire bromeliads. They were interested to find out how the growth and survival rates of these plants on electrical cables compared to the growth and survival of plants of the same species growing in trees–their natural environment.

During a two-year study the pair surveyed some 1,400 T. flexuosa specimens living on 1250 meters of electrical cable, as well as nearby plants of the same species growing on tree limbs. The cables were 8.25 millimeters in diameter and consisted of multiple aluminum wires woven around a single steel cable, giving them a rough surface upon which the seeds and plants can cling. Before their study the scientists observed that most of the cable-growing T. flexuosa lived on cables near roads, leading them to theorize that the dust kicked-up by cars and other vehicles provided adequate nutrients for the plants to flourish.

Although the high-wire T. flexuosa appeared to be thriving, Zotz and Wester found the cables were actually a hostile environment for the plants. T. flexuosa on power lines grew slowly, suffered a high mortality rate and were not very successful in establishing new recruits. On electric cables the death of established plants greatly exceeded the recruitment of new plants from seeds.

For these bromeliads the primary problem with cable-life, the scientists found, is a lack of water. While individuals growing on both cables and trees utilize rainwater, the zero water-absorbing properties of an aluminum cable combined with greater exposure to the sun and wind, make cable life for bromeliads highly risky. Even though dust from cars should provide an abundance of nutrients to the cable-living bromeliads, lack of water prevented them from taking advantage of this benefit.

In addition, the scientists found that even though the cables had a rough surface, the plants had a difficult time anchoring themselves to the cable. Many of the plants disappeared during the course of the study, dislodged from the cables by wind and other natural forces.

The study, the first to examine the growth and survival of electric-cable growing bromeliads, was published recently in the Journal of Tropical Ecology. –John Barrat

Smithsonian entomologist Gary Hevel gives information and advice about stinkbugs in your home

John Barrat — Thu, 09 Sep 2010 11:59:55 +0000

Video: Smithsonian horticulturalist Janet Draper discusses the pollination of the pelican flower

John Barrat — Tue, 07 Sep 2010 15:30:27 +0000

Flowers are usually associated with butterflies, but not the Dutchman’s Pipe (Aristolochia grandiflora). This deciduous vine, native to Brazil, has large flowers that emit an odor of decaying flesh, which attracts flies and beetles. The insects then have to navigate the twists and turns of the flowers throat, which is covered with hairs that trap the insects inside. It is only when an insect removes the pollen sack that the hairs collapse, releasing the insect which will likely be fooled by another pelican flower into pollinating it.