Friday Cat-erpillar Blogging: A Wooly Problem

Clothes moth larva

Clothes moth larva
Photo: Guido Gerding

Wool has a long life and wears well because it is refractory to digestion by most animals. Wool proteins have many disulfide linkages. As long as the linkages are intact, proteases of insects and other animals (such as trypsin and pepsin) cannot hydrolyze (metabolize) the proteins. Treatment of the wool with strong reducing agents breaks the disulfide linkages and allows the proteins to be digested by protease enzymes.

The clothes moth, Tineola bisselliella, has a region of the its gut that has strong reducing conditions. Wool entering the digestive system of the clothes moth is little changed in the foregut and the anterior region of the midgut. Only upon passing into the reducing region of the gut do visible changes to the wool occur. Insects that digest fur or feathers such as clothes moths, dermestid beetles or bird lice all share a digestive system that contains a strong reducing region in the range of -100mV to – 300mV. The majority of insects have a gut reducing potential that is slightly positive. The ability to break disulfide bonds allows the clothes moth to readily feed on an abundant resource that is unusable by most potential competitors.

Posted in Biomaterials, by jjneal, Caterpillar Blogging | Leave a comment

Bison, Lupine & Karner Blue

Karner Blue

Karner Blue
Photo: FWS

Bison once roamed North America in large numbers. Bison, because of their large size and density, had profound effects on the prairie ecosytem. Bison grazed and trampled young trees, creating disturbed areas that favored grasslands. Bison left wallows, areas where Bison would roll in the mud, compact the soil and deposit hair, body secretions and buffalo chips. At one time, large herds of Bison were abundant, but they were hunted to low numbers in the 1800s. Development and agricultural improvements have maintained Bison populations in low numbers.

The Sandhill Wildlife Area in central Wisconsin contains a small herd of American Bison in order to maintain the oak savanna ecosystem. It also contains protected populations of the endangered Karner Blue Butterfly. Its larval host is wild blue lupine. The butterfly is found in a few open areas such as oak savannas or barrens. Both the lupine and the Karner Blue are species of “disturbed” areas. Much of the habitat has been developed and has shrunk to a handful of areas in Great Lakes and northeastern US.

A team of scientists* studied the Sandhill Wildlife Area and butterfly species found in different habitats. They were especially interested in the habitat preferences of the Karner Blue. Female Karner Blues were most abundant in areas that contained bison wallows. This suggests that the disturbances caused by the bison are important to the Karner Blue and that loss of Bison has led to loss of disturbed areas and reduction of habitat. As a management strategy, it may be possible to enhance Karner Blue populations by creating artificial wallows.

*Anna N. Hess, Robert J. Hess, Joy L. M. Hess, Beverly Paulan, Julie A. M. Hess. 2014. American bison influences on lepidopteran and wild blue lupine distribution in an oak savanna landscape. Journal of Insect Conservation. 18:327-338.

Posted in by jjneal, Endangered Species, Environment | Leave a comment

Neonicotinoids In Water

Carpenter Bee

Male Carpenter Bee Landing on a Flower

The overuse of neonicotinoids has led to increased levels of enviromental contamination. Several studies have found neonicotinoid contamination in ground water (well water). How does it get there? Two major routes for groundwater contamination are “Point Source” and “Non-Point Source”. Examples of point source contamination include a pesticide directly entering the ground water through and open well or a spill of concentrated chemical that moves as a plume that overwhelms the capacity of the soil to absorb the chemical and the soil microorganisms to degrade it. Non-Point Source pollution is limited to those chemicals that are sufficiently soluble in water, persistant in the soil and a density typically much greater than water. Given the water solubility and density of neonicotinoids (the density of Thiamethoxam is 1.57) neonicotinoids can sink in the water column and continue a downward journey. Once below the biotic zone of the soil, the persistance of a chemical can increase because of lack of metabolism.

Huseth and Groves* studied the movement of neonicotinoids and found that thiamethoxam is capable of moving through a soil lysimeter (column of soil). In experiments in potato fields, they found increased movement of insecticide after the potato vines were killed. This was true for both foliar treatments and timed release soil treatment. In furrow treatments produced the most leachate prior to vine kill. When the vines are killed, neonicotinoid present in leaves may be released to the soil and the root zone moves much less water and insecticide from the soil making more available for leaching. Their study supports non-point source as a contamination mechanism.

Ideally, pesticide contamination is minimized to low levels. This can sometimes be managed with proper formulation or changes in application. This and other studies raise questions about biological impact of these chemicals in ground water.

*Huseth AS, Groves RL (2014) Environmental Fate of Soil Applied Neonicotinoid Insecticides in an Irrigated Potato Agroecosystem. PLoS ONE 9(5): e97081.
doi: 10.1371/journal.pone.0097081

Posted in by jjneal, Environment, Health, Pest Management | Leave a comment

A Malaria Vaccine

Mosquito Larvae

Mosquito Larvae Suspended in a Water Droplet
Photo: Dr. John H. Brackenbury

After many years of effort, a malaria vaccine appears closer to reality. GSK submitted a regulatory filing for a vaccine. Approval would be a step toward making the vaccine available. The vaccine is not 100% effective so it is proposed to be used in conjunction with other measures. It may be able to reduce malaria infection in young children by almost half. The development costs so far have exceeded a half billion dollars, and the final cost may well be over a 1 $Billion. GSK has been investigating a malaria vaccine for over 30 years. The cost may be high but the costs imposed by malaria on humans is even higher.

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Negatives of Neonicotinoids

Bumblebee

Bumblebee

The use of neonicotinoid insecticides was widely adopted in the 1990s as one of the few effective pesticides against sweet potato whitefly and other sucking insects. Some of the organophospates with high toxicity to humans were displaced by neonicotinoids with low toxicity to humans, greatly reducing the human health hazards.

Neonicotinoid use has grown in the last decade, especially as seed treatments. Many crop seeds are only sold treated with neonicotinoids as a “seed insurance” whether or not the grower wants it. The neonicotinoids are being used against variable insect pests that may not even be present. In such situations, harm outweighs benefit. Neonicotinoids have long residual life in the soil and are water soluble. Neonicotinoids are detectable in surface waters near agricultural areas. Plants absorb neonicotinoid from the soil and translocate it into the tissues and plant fluids such as nectar. Neonicotinoids are orders of magnitude more toxic to bees than the insecticide carbaryl, previously the chief cause of complaints from beekeepers. These are all reasons why use should be limited to only where absolutely necessary.

A group of Dutch scientists* have found a correlation between declining populations of some insectivorous birds and neonicotinoid use. They suggest that their observed effect may be due to direct effects of neonicotinoids in the bird’s diet or an indirect effect by decreasing the insect food available to birds. Correlation is not causation and the link needs more supporting evidence to be widely accepted. Aside from the new concerns about birds, there are other concerns that overuse of neonicotinoids on multiple crops will lead to pest resistance. The history of modern synthetic insecticides is filled with instances of insecticide overuse for short term gain leading to resistance and loss of sustainable value.

*Caspar A. Hallmann, Ruud P. B. Foppen, Chris A. M. van Turnhout, Hans de Kroon & Eelke Jongejans. 2014. Declines in insectivorous birds are associated with high neonicotinoid concentrations. Nature: 17 JULY 2014, VOL 511: 341-4.
doi:10.1038/nature13531

Posted in by jjneal, Environment, News, Pest Management, Policy | 4 Comments

Beeswax and Scientific Illustration

Bee Wax Scale

Bee Wax Scale

Modern scientific illustration flourished once techniques were developed to reproduce and disseminate the drawings. The early prints were made using wood blocks. Wood is limited by thickness of the lines required. Finer lines can be engraved into metal, but the process is time consuming and tedious. The invention of copper etching in the 15th century sped the process.

Glass or metal surfaces can be etched with acid. An acid resistant coating can be applied to a surface. Beeswax, that bees produce from scales on their abdomens, was adopted for this purpose. A pattern can be made by removing the beeswax with a stylus. The coated object is dipped in acid, the acid removes some of the metal from the exposed surface which is “etched”. This process leaves grooves in the metal that can be used to stamp ink patterns onto paper.

Beeswax could be mixed with other substances to produce a higher quality surface that could accommodate the finest lines. This process allowed scientific books to be illustrated with drawings that were much less ambiguous than verbal descriptions.

Posted in Art, Biomaterials, by jjneal | Leave a comment

Largest Aquatic Insect

Dobsonfly

Chineses Dobsonfly, Largest Aquatic Insect

The largest aquatic insect is now a dobsonfly that was found by Chinese villagers in Sichuan Province. Its wingspan measures 210.70 mm, displacing the South American helicopter damselfly as the largest aquatic insect. By comparison, the largest dobsonflies in the US are about 114 mm.

The Dobsonfly is sensitive to pollution and pH. It is a sentinel for water pollution. Like many aquatic insects, the majority of its life is in the larval stage. The adults live only a few day, mate. lay eggs and die. Their large size may intimidate the naive, but they do not bite or harm humans.

Posted in by jjneal, Environment | 1 Comment