The oldest Hymenopteran fossils are in the family Xyelidae. There are 65 species of extant Xyelidae, sawfly-like wasps, that feed on the pollen and nectar of conifers. The Xyelidae are most noted for their unusual leg-like antennae. Like many Hymenoptera, they are recognizable from their wing venation. The Potrerillos Formation, Cuyo Basin of Argentina has produced a new fossil Xyelidae, Potrerilloxyela menendezi, that is known only from its wing. Insect wings are acellular and have properties that deter degradation by bacteria. Wings are the most common insect part that fossilizes.
The new fossil, described by Lara and colleagues*, is now the oldest Hymenopteran from Argentina. This fossil establishes that the Xyelidae appeared simultaneously in both the New and Old World. They were widespread during the days of supercontinents Laurasia and Gondwana.
*M. B. Lara, A. P. Rasnitsyn, and A. M. Zavattieri. 2014. Potrerilloxyela menendezi gen. et sp. nov. from the Late Triassic of Argentina: The Oldest Representative of Xyelidae (Hymenoptera: Symphyta) for Americas. Paleontological Journal. 48(2):182–190.
Wing of Fossil Xyelid Image: Lara & Colleagues*
The Halloween Pennant Dragonfly gets its name from its orange and black Halloween colors. The Pennant refers to its habit of perching on the top of tall grass or reeds where it can be seen swaying in the wind like a pennant. Halloween pennants prey on small flying insects.
October has Halloween on the 31st. The Pennant winners of the American and National League Baseball teams play in the World Series. However, the season for Adult Halloween Pennants rarely extends beyond early October.
Insects are good at avoiding collisions with stationary objects. Insects are not as good at avoiding collisions with moving objects such as car windshields. Insects also collide with and stick to the blades of wind turbines. A study in 2001
* found that insects can halve wind turbine power. The study began as an investigation of unexplained power loss. Insects fly during periods of high humidity and low wind speed. Under these conditions, insects collide with and accumulate on the blades of the wind turbine. At high wind speeds, the aerodynamic flow over the smooth leading edge of a turbine blade becomes critical to power output. Insects collected the blade present a rough surface and reduce power output at high wind speeds. Power returns once the blades are cleaned.
*Gustave P. Corten & Herman F. Veldkamp. Aerodynamics: Insects can halve wind-turbine power. Nature 412, 41-42 (5 July 2001)
The Daily Nebraskan
Jar Schepers with Insect Inspired Sculpture
Photo: Ryann Lynn
has a feature on Ceramics Professor and Sculptor, Jar Schepers. Schepers incorporates images from nature to create “Insectoid” sculptures. The sculpture in the photo contains recognizable insect parts including orthopteran jumping legs complete with realistic spines, spurs and claws. Schepers wants his work to be memorable and imposing. He makes large sculptures because small insects are not very imposing.
If you blow up the scale of any insect it’s just instantly horrifying.
Monarch Emerging From Its Chrysalis
The drastic decline of the Monarch population in the first half of this decade (the 2010s) combined with a longer term decline over the past 20 years has raised questions about land management practices. Why has the population declined? Several factors contribute including loss of habitat due to changes in land management practices and changes in climate. A petition has been made to add the Monarch to the Threatened Species List and to protect critical habitat. The overwintering site in Mexico is an obvious candidate that is on everyone’s must protect. Protecting sites for larval growth and development is under discussion.
Corn and Soybean fields have traditionally contained some milkweed, but a far smaller percent than Right of Ways or Conservation Reserve Land. However, land planted to corn has expanded with the increased use of corn to produce ethanol and Conservation Reserve Land decreased. Use of transgenic crops in combination with herbicides have reduced the milkweed population within fields. This combination has reduced the milkweed available to monarchs as land with substantial milkweed is replaced by crop land with little to no milkweed.
Efforts to increase milkweed populations would likely involve establishment of refuges, and restricting planting to the most productive lands. Limits on suburban sprawl could protect more monarch habitat. The highest density of milkweed is in the Right of Ways. Changes in management practices could have a substantial impact. If mowing is delayed until after monarchs have completed development in the fall, amount of habitat could be increased.
Monarchs also need sources of nectar on the journey south to fuel their flight. Right of Ways can be managed to produce more nectar sources for monarchs and other insects. Governments can change their Right of Way management practices if presented with a workable plan. The importance of considering impacts on the larger ecosystem increases as the percentage of managed land increases.
Alabama argillacea, Cotton Leafworm
The Cotton Leafworm, Alabama argillacea,
was at one time the most serious pest of cotton in the US
. The caterpillars eat the leaves of cotton. Early season feeding can reduce the cotton yield. Cotton Leafworm is not native to the US. In the early 1900s, cotton farmers used tons of toxic Paris Green (Lead Arsenate) to protect their crops. Prior to Paris Green efforts to control the pest were rarely successful.*
Alabama argillacea, was a mysterious pest, suddenly appearing some years & largely absent in others, due to its migratory nature. No life stage of the Cotton Leafworm can tolerate frost or freezing. Areas that experience low temperatures must be re-colonized from warmer areas every year. Populations every year migrated from South America, sometimes using cotton in Mexico as a stepping stone in their journey northward.
Alabama argillacea, has gone from as serious pest to a seldom collected moth in the US. Many areas that formerly grew cotton were planted to other more lucrative crops. Practices changed to eliminate cotton stubs post harvest to deny pests a source of food in areas where they could survive. Taken together, these practices drastically reduced the number of migrating moths that reached North America. The recent adoption of BT cotton further reduces the population.
Large populations of Alabama argillacea, were largely created by the planting of cotton, providing the species with large areas of a new source of food. Changes in practices have reduced populations in North America to levels that were likely present before cotton production was expanded.
The Mystery of Alabama argillacea. 1929. George N. Wolcott. The American Naturalist. Vol. 63, No. 684 pp. 82-87
Head of a male Culex pipiens mosquito
Image: Gareth Paul Jones
2013 Small World Image of Distinction
The end of October approaches and that means winners of the 2014 Nikon Small World Photomicroscopy Contest
will be announced. Every year, several images of insects and other arthropods compete (my favorites). The contest showcases microscopic techneques. Stacking is commonly used in insect images. Stacking corrects for the fact that 3D images viewed under the microscope always have regions that are out of focus because they are above or below the focus of the lens. To correct the focus, a series of images is collected by lowering the plane of focus in small increments to produce a “stack”. Each image in the stack has regions in focus and not in focus. Computer software merges the regions that are in focus to produce a composite image with all the parts in focus. This techniques overcomes the depth of field problems that lead to image distortion and produces beautiful images.
The deadline for 2015 is April 30, 2015.