Thursday, October 29, 2015

Harvester Ants

Entrance to a colony of Harvester Ants, Pogonomyrmex spp.
Harvester Ants are large ants within the genera Pogonomyrmex or Ephebomyrmex with habitats west of the Mississippi with only one exception. There are 12 species found within Texas with the Red Harvester Ant, Pogonomyrmex barbatus being the most widespread. In addition to their large size, harvester ants can be identified by their conspicuous mounds in open areas. Grass around the nest is generally cleared, pebbles line the entrance, and foraging trails are often obvious.

Foraging trail of a harvester ant colony.
While harvester ants have a nasty sting, their primarily seed feeders, but will sometimes collect dead insects. They have characteristic large heads and powerful jaws used to carry food and crack seeds. The bounty gathered is stored in neat stacks within any number of sorting chambers up to 1.8 m (6 ft) underground. As with many ant species, harvester ants are social. There is a single queen who may live up to 15-20 years, but when she dies, she is not replaced. The fertile males and females leave the colony to reproduce while sterile females remain as workers with a lifespan of up to 1 year. During that year the young workers mainly fill roles keeping them inside the nest such as nest maintenance, while the older workers are more likely to fill roles taking them outside such as foraging and patrol. Their most well-known predator is the horned lizard whose diet is up to 65% harvester ant. Unfortunately, competition with imported fire ants and indiscriminate use of insecticides are reducing the number of harvester ants who already face the difficulty of a 1% success rate of new colonies.

Tuesday, October 27, 2015

Flooding (Hiatus)

It's been a long day of work, but as almost always when not doing a normal post, I'll at least leave you with a photo or two of some sort and of something that I won't otherwise talk about. If you've heard the news, Texas has been getting some massive flooding again all over the state from far north to far south. Many places have seen over 46 cm (18.11 inches) of rain, some over a day and some within a couple of hours.

Many of the crop fields look more like rice patties down in the south and some of the roads are only now opening after days and days being underwater. Some places have been almost completely cut off. You don't always have to be from the area to be impressed and in awe of what nature might bring you.

Thursday, October 22, 2015

American Alligator

American Alligators, Alligator mississippiensis at Laguna Atascosa.
One of only two species of Alligator, the other found in China, the American Alligator thrives in the water of southeastern states from North Carolina to the Rio Grande in Texas. While most often found within the freshwater of slow-moving rivers, alligators can also be found in swamps, marshes, and lakes. They are carnivorous, reach maturity when reaching 1.8 m (6 ft) in length, and are recorded to live around 50 years in the wild and up to 80 years in captivity. The sex of hatchlings is based on the temperature of the nest with all being males if temperatures are 33.8°C (93°F), all females if at 30°C (86°F) or below, or a mix of both if the nest temperature falls between. With the help of state and federal protection, habitat preservation efforts, and a reduced demand for alligator products, the American alligator has gone from an endangered species to a thriving population of over one million as of present day.

Note: Apologies for the lack of post on Tuesday! It was not intentional, but rather an honest mistake of exactly what day it was (not Monday, as I kept thinking). Don't worry, I'm good now! ;) 

Thursday, October 15, 2015

American Beautyberry

American Beautyberry, Callicarpa americana
American Beautyberry is a perennial, many-branched deciduous shrub found within the southeastern United States down into Mexico and the West Indies. It is one of approximately 135 species of Callicarpa found throughout the world, but American Beautyberry, Callicarpa americana, is the only species native to the United States. American beautyberry can grow up to 2.7 m (9 ft) in favorable conditions of partial shade and moist soil, but averages 1-1.5 m (3-5 ft) and is drought tolerant. The pale pink flowers become trademark bright, iridescent purple berry clusters along the stems from autumn into winter, though it should not be confused with the unrelated smaller-leafed coralberry. The berries are a favorite of many species of birds and mammals and can be made into a jam for human consumption. Native Americans used the roots, leaves, and berries to treat rheumatism, fevers, malaria, dysentery, and colic, but one of the most interesting aspect of beautyberry that has gained it attention is its potential as an effective insect repellent.

Early 20th century farmers helped bring American beautyberry to light as they would crush the leaves and place them under the harnesses of their horses and mules to repel biting flies and mosquitoes. In addition, about 20 other species of Callicarpa have reported *ethnobotanical and ethnomedical uses, especially in China and South Asia. They were similarly used for digestion, fever, and rheumatism as well as for hepatitis, skin cancer, intestinal cancer, to regulate fertility, and as a fish poison. In evaluating different species of Callicarpa for biological activity, researchers discovered antibacterial, antifungal, anti-insect growth, cytotoxic, and phytotoxic activities. Amino acids, benzenoids, simple carbohydrates, lipids, diterpenes, flavonoids, phenylpropanoids, phytosterols, sesquiterpenes, and triterpenes have been detected or isolated. In Callicarpa americana specifically, the essential oils are reported to have antialgal and phytotoxic activities, many of which contribute to the mosquito bite-deterrent activity first reported. Three compounds in particular, callicarpenal, spathulenol, and intermedeol, show significant repellent activity – spathulenol from Japanese Beautyberry, Callicarpa japonica and callicarpenal and intermedeol from American Beautyberry, Callicarpa americana.

Callicarpenal and intermedeol have been extensively studied in their repellent activity. Both compounds have shown significant bite-deterring activity against the yellow fever mosquito, Aedes aegypti, and a malaria-vector mosquito, Anopheles stephensi, show promise against the blacklegged tick, Ixodes scapularis, the lone star tick, Amblyomma americanum, and the Cayenne tick, Amblyomma cajennense, and are being evaluated against red imported fire ants, Solenopsis invicta, black imported fire ants, Solenopsis richteri, and a hybrid of the two species. Against I. scapularis, callicarpenal and intermedeol showed significant repellent activity equal with Deet, but against A. americanum, Deet and SS220 were less effective compared to callicarpenal and intermedeol. A low concentration of both were effective against both imported ants and the hybrid of the species, but intermedeol showed significantly greater repellency.

While studies are promising, effective isolation and production of these compounds is an obstacle. For callicarpenal, dry biomass results in a low isolation yield of 0.05-0.15%. The tedious bulk isolation and purification techniques substantially restricts the natural availability, but there is hope. One particularly efficient enantioslective synthesis of (-)-callicarpenal proceeds in 12 steps, results in a 36% overall yield from diketone, and utilizes readily available materials and reagents. In addition, studies have shown the chemical structure of the parent molecule can be simplified without significant loss of activity. Similar synthesis studies have been conducted on intermedeol and spathulenol.

American beautyberry and others of the Callicarpa genus hold promise for a range of purposes, but there is still research to be done. While it has potential for a great variety of biological activities, it has currently drawn the most interest in its insect repellent properties. It may be years or decades until it becomes available for commercial use and an effective alternative to other repellents, but it is very likely that day will come. Until then, American beautyberry makes for a lovely shrub in many yards, forests, and plains.

This post is a direct copy-and-paste from my Google+ post here including references and other links. While normally I'd embed the links, current internet limitations will leave them as are below. 

Sources and Further Reading:

Lady Bird Johnson Wildflower Center: Callicarpa americana (Native Plant Database | website)
American Beautyberry: Callicarpa americana (USDA Plant Fact Sheet | pdf)
Wildlife Resources Management Manual: American Beautyberry (U.S. Army Corps of Engineers | pdf)
Biologically Active Natural Products of the Genus Callicarpa (NCBI PMC | website)
Callicarpenal and Intermedeol... (ACS Symposium Series | website)
Repellency of two terpenoid compounds from Callicarp americana... (NCBI PMC | website)
Repellency of callicarpenal and intermedeol against… (NCBI PMC | website)
Synthesis of (-)-callicarpenal, a potent anthropod-repellent (NCBI PMC | website)

Tuesday, October 13, 2015

Texas Lantana

Texas Lantana, Lantana urticoides
Texas Lantana, also known as Calico Bush, is a spreading, perennial shrub native to the southern states. It blooms intermittently from April through October, especially during the warmer months, with clusters of red, orange, and yellow flowers, although some cultivars include blooms of purple, white, or only red. While able to grow in poor soil and in need of little maintenance, it prefers full sun. Butterflies and hummingbirds use the nectar of the flowers while other birds prefer the berries.

Thursday, October 8, 2015


Pigeonberry, Rivina humilis
A native perennial that can reach heights of 0.3 m (1 ft), Pigeonberry is found from the southern states into tropical South America. It blooms with small, pinkish flowers intermittently from March through October. The red berries that follow are a favorite food of many birds and can sometimes be seen alongside the flowers. Pigeonberry tolerates shade and a wide variety of soil types. While drought tolerant, extreme drought may cause it to go dormant until the next rainfall.

Tuesday, October 6, 2015

Gulf Muhly

Gulf Muhly, Muhlenbergia capillaris
Gulf muhly is a perennial native clump grass known for its striking pink and purple autumn blooms. It can grow between 0.5 m (1.6 ft) and 1 m (3.3 ft) with large, airy bunched seed heads making up half the height. It prefers sunny, sandy soil, but can tolerate many soil types and partial shade. Its native range includes the prairies, pine barrens, and open woodlands of the east coast down into Texas. Gulf muhly provides cover for wildlife and is known to attract ladybug beetles and other beneficial insects.