Grasshopper Color Vision

Grasshopper

Grasshopper

Humans and insects typically perceive color through 3 types of photoreceptors present in the retina of the eye. In humans, each photoreceptor type is maximally sesitive to a different wavelength of light in the red, green and blue portions of the spectrum. The brain integrates signals from the 3 receptors types and produces the sensation of color. Many insects use a similar process but with the wavelength of light sensed shifted to detect green, blue and ultraviolet. The grasshopper, Phlaeoba, can discriminate between between red and green and other colors, even though the eye has only one type of photoreceptor pigment. How does Phlaeoba discriminate color?

The compound eyes of Phlaeoba have some ommatidia that are clear and others that contain a screening pigment. The screening pigment filters some wavelengths of light more than others. Receptors without the pigment are maximally sensitive to light at 525 nm wavelength.  Those receptors with screening pigment are maximally sensitive to light at 545 nm wavelength. Thus, a single photoreceptor pigment can function as if it were 2 distinct pigments with different sensitivities and enable the grasshopper to discriminate color.

Posted in Biomaterials, by jjneal, Vision | 1 Comment

Wasp Venom and Cancer

Wasp Stinger

Wasp Stinger

One of the reasons for preservation of biodiversity is to maintain sources for biomaterials “mining”. Stinging wasps are known for producing unique toxins that can have profound biological effects. Wasps use their venoms for defense or to immobilize prey. The venom must act on cells of the the target organism to be effective.  Medical researchers are exploring wasp venom toxins for novel agents with potential for therapeutic uses.

The Brazilian wasp, Polybia paulista, produces a toxin called Polybia-MPI that specifically affects cells containing significant titers of the lipid, phosphatidylserine (PS), on the cell surface. This lipid can be common on tumor cells but is mostly absent from the surface of healthy cells. Polybia-MPI is an antibacterial peptide that selectively affects cells with external PS. Polybia-MPI acts on the membranes of these cells, making them “leaky” and ultimately killing the cell. Desirable features of Polybia-MPI are its selectivity and mode of action. Its target site and mode of action are unique and it is an effect agent against cancer cells that become resistant to agents with different targets.

Kai-rong Wang, Jie-xi Yan, Bang-zhi Zhang Jing-jing Song, Peng-fei Jia, Rui Wang.  2009. Novel mode of action of polybia-MPI, a novel antimicrobial peptide, in multi-drug resistant leukemic cells.  Cancer Letters.  278:65-72.

 

Posted in Biomaterials, by jjneal, Health | 1 Comment

The Goldenrod Soldier Beetle

Goldenrod soldier beetle

Goldenrod soldier beetle

The Goldenrod Soldier Beetle Chauliognathus pensylvanicus is a common sight on goldenrod and other fall flowers in Indiana. These beetles spend much of their time mating or feeding on pollen in plain sight during the day. The yellow and black warning colors suggest toxicity or unpalatability.

A group of scientists* investigated the chemical defenses of these beetles. There are 9 pairs of defensive glands that secrete droplets of fluid when the beetles are disturbed. The droplets contain Z-dihydromatricaria acid a substance that is deterrent to spiders and other common predators. A robust anti-predator defense allows the beetles to spend more time feeding and mating and less time running and hiding.

* Eisner, Thomas; Hill, David; Goetz, Michael; Jain, Subhash; Alsop, David; Camazine, Scott. 1981. Antifeedant action ofZ-dihydromatricaria acid from soldier beetles. Journal of Chemical Ecology. 7:1149-1158.
http://dx.doi.org/10.1007/BF00987634

Posted in behavior, by jjneal, Environment | 1 Comment

Cannibalism and Disease

Differential Grasshopper

Differential Grasshopper

Grasshoppers are known for voracious appetites and ability to damage crops. Their appetite can extend beyond plant feeding to feeding on dead animials including cannibalism of dead grasshoppers. One downside of cannibalism is the potential spread of infectious disease.  Two common fungi that kill grasshoppers are Beauveria bassiana and Metarhizium acridum. Is it common for these fungal diseases to spread through cannibalism?

Jaronski* compared cannibalism of grasshoppers killed by freezing to those killed by fungal infections. Grasshoppers readily cannibalized all or most of the uninfected grasshoppers killed by freezing. Grasshoppers avoided cannibalizing grasshoppers killed by fungi, leaving them largely untouched except for minor feeding on the tarsi. Grasshoppers have the ability to detect fungus infections in carcasses and avoid the consumption. This behavior could reduce the spread of these fungi in natural populations.

*Jaronski ST. 2013. Mycosis inhibits cannibalism by Melanoplus sanguinipes, M. differentialis, Schistocerca americana, and Anabrus simplex. Journal of Insect Science 13:122.
http://www.insectscience.org/13.122

Posted in behavior, by jjneal, Environment | 1 Comment

Differential Grasshoppers

Differential Grasshopper

Differential Grasshopper


The differential grasshopper, Melanoplus differentialis is common in Indiana this year. Some years populations can become large and reach pest status. They are not restricted to the countryside and commonly seen in vacant urban lots with tall vegetation.

As in many species of grasshoppers, the male is much smaller than the female. Both male and female have distinctive chevrons on their hind femurs. The chevrons are part of the cryptic coloration. The grasshoppers are easy to spot when they fly but quickly disappear when they land in the weeds. One of the favorite foods of this grasshopper is the sunflower.

Posted in by jjneal, Environment | 1 Comment

Sunday Bug Jokes

AntsBabysmWhy did the ant dance on the honey jar lid?
It said “Twist to Open”.

What game do ants refuse to play with elephants?
Squash

Where did the housefly actor prefer to perch?
On the screen.

How does bee hair become sticky?
From the honey comb.

What were the starving flea’s last words?
Dog gone.

How are a pair of lice eggs like a cheap suit?
They are double (k)nits.

What slogan does Indiana Beach use to attract lady beetles?
“There’s more than cornicles in Indiana.”

Posted in by jjneal, jokes | 1 Comment

Plague Update

Plague WarningCases of Bubonic Plague are infrequent in the US but the number of incidents is higher than normal this year (2015) prompting an alert from the CDC. The alert is aimed at doctors and the public. Doctors follow CDC reports to help them diagnose diseases. The CDC report moves plague onto the Doctor’s lists of possibilities for people living in or visiting the affected area.

Plague cases average 7 per year in the US, but in 2015 so far there have been 12 cases. The most recent case from Utah, a man died from plague this August. Yosemite has had another case of plague since warnings were posted in early August. An 18 year old woman from Georgia is recovering. Prompt diagnosis and treatment is important for good patient outcomes. A Colorado boy died earlier this year, among 4 cases diagnosed from CO. The area of concern for plague is Colorado and all states at or west of that latitude.

In spite of the spike in plague cases, the risk of one person contracting plague is low.  Be aware that plague is in the western US rodent population and can be spread by fleas.  Avoid contact with dead rodents and fleas.  Pets can contract plague from fleas and put pet owners at risk.  The CDC suggests these addition precautions in areas where plague is endemic (Colorado and all States West of that latitude.

Persons engaging in outdoor activities in areas where plague is endemic should wear long pants when possible and use insect repellent on clothing and skin. Persons also should avoid direct contact with ill or dead animals and never feed squirrels, chipmunks, or other rodents. In addition, pet owners should regularly use flea control products on their pets and consult a veterinarian if their pet is ill. Rodent habitat can be reduced around the home by removing brush, clutter, and potential rodent food sources such as garbage or pet food.

Posted in by jjneal, Environment, Health | 1 Comment