Photo: Ben Alkire
It is still winter in Indiana with snow on the ground but Spring will be here soon. Many gardeners bring plants indoors for the winter and set them outside during the summer. The outdoor plants can have insects on them and can lead to surprises. A friend sent me this picture of a Pipevine Swallowtail that emerged in his house in March. It is too cold to release outside it is unlikely to live long enough to find a mate in late spring. Last Fall, the house plants were resting in a garden near garden rue, a host plant for Pipevine Swallowtails. The fully developed caterpillar likely left the rue and pupated on one the plants that was brought indoors. Swallowtails enter diapause that does not break until both temperatures warm and daylight increases. Those conditions were obviously met for this butterfly. Some insect surprises are not as pleasant as this one.
One animal’s refuse is another animal’s resource. The yellow-spined bamboo locust, Ceracris kiangsu, has been observed drinking from puddles of human urine. Human urine contains nitrogen waste in the form of urea and excess salts. The locusts drink the urine to obtain nitrogen and salt. However, the locusts are unable to use urea as a source and urea is repellent. Why do the locusts drink urine?
When the urine is heated by sunlight on hot summer days, the urea is converted to ammonium bicarbonate with the help of microorganisms. The locusts are able to use ammonium bicarbonate to synthesize amino acids and ammonium bicarbonate has proved to be an attractant. Thus, the locusts will not drink fresh urine. They only drink after it is baked in the sun and the urea converted to ammonium bicarbonate.
Moebius Strip I I
Humans are social animals with social rules governed by a malleable culture. Obedience to norms and rules is optional. People who think they have the best rules spend their time trying to convince others to follow their rules. Animals, including insects, have often been used to teach moral lessons to human society. Social insects, such as ants are lauded for the relentless hard work, their foresight for storing food to survive winter, obeying their “ruler” and their cooperative spirit. However, comprehensive study of ants finds these character traits are not as true as popularly believed. Lectures by scientists often result in fingers in ears and people clinging to beliefs. Comedians may have more success, but not much. Leave it to American humorist Mark Twain to try to disabuse people of false notions about insects. In A Tramp Abroad, Mark Twain writes:
Science has recently discovered that the ant does not lay up anything for winter use. This will knock him out of literature, to some extent. He does not work, except when people are looking, and only then when the observer has a green, naturalistic look, and seems to be taking notes. This amounts to deception, and will injure him for the Sunday schools. He has not judgment enough to know what is good to eat from what isn’t. This amounts to ignorance, and will impair the world’s respect for him. He cannot stroll around a stump and find his way home again. This amounts to idiocy, and once the damaging fact is established, thoughtful people will cease to look up to him, the sentimental will cease to fondle him. His vaunted industry is but a vanity and of no effect, since he never gets home with anything he starts with. This disposes of the last remnant of his reputation and wholly destroys his main usefulness as a moral agent, since it will make the sluggard hesitate to go to him any more. It is strange beyond comprehension, that so manifest a humbug as the ant has been able to fool so many nations and keep it up so many ages without being found out.
Underside of Immature Bed Bug
An alert teacher at Luzerne County High School in Pennsylvania found a bed bug and reported it to the administration. The students were moved to another room so the room could be inspected. Rumors of bed bugs at the high school quickly spread inducing panic among parents who took their children home from school early. A further inspection of the school found no more bed bugs. The one bed bug likely traveled to the school in a backpack of a student or other type of bag.
The school superintendent says the panic reaction is overblown. Is he correct? Bed bugs are nocturnal and primarily move at night. They are unlikely to leave their harborage during the day. Since the students are only present during the day when lights are bright, the likelihood of a student bringing home an infestation is quite low. Additionally, the school was inspected and treated to eliminate bed bugs as a precaution. The missed class time is harmful to students and disruptive of the school. The administration wants the students to return immediately and threatened to punish students who stayed home due to the bed bug panic.
The unreported question: How did the bed bug get to school? It most likely came with a student or employee of the school. That person probably has a substantial infestation that needs elimination. Finding the source of the bed bug infestation and eliminating it would be most helpful to prevent future bed bugs at the school. Bed bugs are a public health problem and if treated as such, can be greatly reduced or eliminated locally. Treating bed bug infestations as a sign of a personal failure of poor housekeeping or bad sanitation is counterproductive.
The American cockroach, Periplaneta americana, feeds on a low protein diet and stores uric acid in special cells of the fat body. These cells contain a symbiotic microorganisms: Blattabacterium. The cockroach uses Blattabacterium symbionts to help regulate its balance of nitrogen with other diet components. Blattabacterium convert amino acid nitrogen into uric acid and uric acid into amino acids depending on the needs of its cockroach host. If fed on a diet enriched with protein, the cockroach will excrete some of the excess nitrogen as ammonia. About 90% of the nitrogenous waste from American cockroaches is in the form of ammonia. Scientists don’t know how the ammonia arrives in the hindgut. It may be filtered from the blood and flow into the hindgut through the Malpighian tubules or bacteria and other microorganisms present in the hind gut may produce the ammonia within the hindgut. We do know that some of the bacteria in the cockroach hindgut have the ability to fix nitrogen from the atmosphere. These bacteria fix more nitrogen when dietary protein is low. The nitrogen fixing bacteria of the hindgut work in concert with the Blattabacterium to regulate nitrogen balance.
Brown Plant Hopper
The brown planthopper, Nilaparvata lugens is a pest of rice, feeding on phloem and transmitting plant viruses. Phloem is rich in sugars but poor in amino acids and proteins. The amino acids in the plant sap are not balanced in the proportions needed by the planthopper. The plant hopper consumes excess of some amino acids. The nitrogen from those amino acids is processed into uric acid. Unlike other insects that eliminate the uric acid as waste, the plant hopper stores uric acid.
Nilaparvata lugens hosts symbionts that can metabolize uric acid. In periods of starvation, the symbionts can metabolize the uric acid to release ammonia used in the synthesis of amino acids.
M.J. O’Donnell and Andrew Donini. Nitrogen Excretion and Metabolism in Insects. In: Acid-Base Balance and Nitrogen Excretion in Invertebrates pp 109-126.
Photo: Thierry Heger
Blood feeding insects such as the “kissing bug”, Rhodnius prolixus create a high volume of oxygen radicals when the blood meal is metabolized. Oxygen radicals can damage cell membranes if in high enough concentration and must be neutralized. The neutralization process involves the reaction of the oxygen radical with an oxygen scavenger.
Mammalian blood contains copious amounts of the protein hemoglobin. Metabolism of the protein creates nitrogenous waste that can be excreted in the form of uric acid but some is retained. Uric acid is a scavenger of oxygen radicals. Rhodnius maintains high levels (about 5 mM) of uric acid in its hemolymph. Uric acid is responsible for neutralizing almost all of the oxygen radicals. The product of the reaction of oxygen with uric acid can be excreted. Using uric acid for protection against oxygen radicals makes certain that not all goes to waste.