Friday, November 16, 2018

Meet Florida’s Skull-Collecting Ant



“Add ‘skull-collecting ant’ to the list of strange creatures in Florida,” says Adrian Smith, a scientist at the North Carolina Museum of Natural Sciences and North Carolina State University. His new research describes the behavioral and chemical strategies of a Florida ant, Formica archboldi, that decorates its nest with the dismembered body parts of other ant species.


Credit:  North Carolina Museum of Natural Sciences

“In 1958, shortly after this ant was described as a species, scientists reported something weird about it,” says Smith, the author of this study. Its nests were home to a collection of decapitated heads of trap-jaw ants. Trap-jaw ants are known as fierce insect predators, not easy prey for other ants. Since then, researchers have speculated that F. archboldi either inherits old trap-jaw ant nesting sites or is somehow a specialized predator. However, scientists had yet to study the biology of this ant in detail.

“This was a study that grew out of reading a peculiar observation in a 60-year-old research paper,” says Smith. “Odds were that these ant heads weren’t in Formica nests by chance and that there was some interesting biology behind this natural history note.” In researching this entomological oddity, Smith was surprised to find that F. archboldi chemically mimic their trap-jaw ant prey and use what is normally a chemical defense, a spray of formic acid, as a deadly weapon against trap-jaw ants.

Formica archboldi
Credit:  North Carolina Museum of Natural Sciences

Using high-speed video recordings Smith found that F. archboldi attacks involve a targeted spray of formic acid that quickly leads to an immobilized trap-jaw ant. Time-lapse video observation of the interior nest chambers of laboratory colonies found that freshly-killed trap-jaw ants are dragged into the nest like food items and dismembered. This leads to nests filled with trap-jaw ant body parts, as is found in natural colonies.

“The scientifically surprising finding of this study was that these ants chemically match or mimic the chemical profiles of two species of trap-jaw ant,” says Smith. The ants match in their cuticular hydrocarbons, a complex layer of waxes that coat the outer surface of an ant. Ants typically use these compounds as nestmate and species-specific signals. “It’s really unusual for an ant species to display this much variation in chemical signature. Also, chemical mimicry is usually a tactic used by social parasites, but there’s no evidence that F. archboldi are a parasitic species.”

“In aiming to figure out one unusual aspect of this ant’s biology, this research has turned up another in the chemical data,” says Smith. Though this study was unable to find a direct link between chemical mimicry and predatory behavior, this chemical mimicry likely hints at a long evolutionary history between these ant species. “Now Formica archboldi is the most chemically diverse ant species we know of. Before this work, it was just a species with a weird head-collecting habit. Now we have what might be a model species for understanding the evolution of chemical diversification and mimicry,” says Smith.

The paper, “Prey specialization and chemical mimicry between Formica archboldi and Odontomachus ants,” is published in the journal Insectes Sociaux.



Contacts and sources:
Jon Pishney
North Carolina Museum of Natural Sciences

Citation: “Prey specialization and chemical mimicry between Formica archboldi and Odontomachus ants,” is published in the journal Insectes Sociaux.

Sucking Your Baby’s Pacifier to Clean It May Prevent Allergies

If the thought of sucking your baby’s pacifier to clean it and then popping it in your baby’s mouth grosses you out, think again. New research being presented at the American College of Allergy, Asthma and Immunology (ACAAI) Annual Scientific Meeting suggests a link between parental sucking on a pacifier and a lower allergic response among young children.

“We interviewed 128 mothers of infants multiple times over a period of 18 months and asked how they cleaned their child’s pacifier,” says allergist Eliane Abou-Jaoude, MD, ACAAI member and lead author on the study conducted by Henry Ford Health System in Detroit. “We found the children of mothers who sucked on the pacifier had lower IgE levels.” IgE is a type of antibody related to allergic responses in the body. Although there are exceptions, higher IgE levels indicate a higher risk of having allergies and allergic asthma.”

File:Pacifier gag.jpg
Credit: PatrickValtiel / Wikimedia Commons

Of the 128 mothers completing multiple interviews, 58 percent reported current pacifier use by their child. Of those who had a child using a pacifier, 41 percent reported cleaning by sterilization, 72 percent reported hand washing the pacifier, and 12 percent reported parental pacifier sucking.

“We found that parental pacifier sucking was linked to suppressed IgE levels beginning around 10 months, and continued through 18 months,” says allergist Edward Zoratti, MD, ACAAI member and co-author of the study. “Further research is needed, but we believe the effect may be due to the transfer of health-promoting microbes from the parent’s mouth. It is unclear whether the lower IgE production seen among these children continues into later years.”

“We know that exposure to certain microorganisms early in life stimulates development of the immune system and may protect against allergic diseases later,” says Dr. Abou-Jaoude. “Parental pacifier sucking may be an example of a way parents may transfer healthy microorganisms to their young children. Our study indicates an association between parents who suck on their child’s pacifier and children with lower IgE levels but does not necessarily mean that pacifier sucking causes lower IgE.”



Contacts and sources:
American College of Allergy, Asthma, and Immunology

Citation: Association Between Pacifier Cleaning Methods and Child Total IgEAuthor: Eliane Abou-Jaoude, MD