In combing through my recent email last week, I found news about a potential weapon against a dangerous bee disease and ants that decorate their nests with the skulls of an enemy.
New weapon against infectious bee disease
Bill Chappell, a writer and producer on NPR’s Newsdesk, reported on Dec. 7 that an edible vaccine has been developed “aimed at helping struggling honeybee populations.” It’s the first vaccine to be developed for any insect. It targets the disease American foulbrood, an infectious disease that “devastates hives and can spread at a calamitous rate,” Chappell writes. The disease “works by bacteria feeding on larvae — and then generating more spores, to spread further.” Scientists looking for a way to combat AFB have continually run into a morphological wall because insects’ immune systems do not have antibodies, which means they essentially lack a “memory” for fighting diseases.
The Finnish research team that developed the vaccine report that it can be delivered to the queen via a sugar patty. As Chappell writes, “the idea of a potential new weapon to fight AFB has generated excitement in the beekeeping community, along with some skepticism about the claim of a vaccine — which remains in the testing phase.” While a hive can be treated with antibiotics after the disease has invaded, there is no cure and the colony invariably dies or must be destroyed to keep the AFB from spreading. (For more, go to tinyurl.com/wi-bee-vaccine.)
Headhunter and kidnapper ants
A recent Science Magazine article summarizes recent research on why the “headhunter” ant (Formica archboldi) — a small, red ant — has “the macabre habit of decorating its nests with the severed heads of larger, predatory trap-jaw ants” (Odontomachus genus). The headhunter, which is native to the southeastern United States and only ranges as far north as South Carolina, apparently subdues its larger foe with toxic acid sprays and then harvests the heads and body parts. Researchers hypothesize the headhunters may use the scent from the heads to camouflage themselves, either in defense against other ant predators or to sneak up on prey.
I’m a big fan of ants, and in finding our more about the headhunters, I was happy to discover AntWiki, a website for ant biologists to share their knowledge. That led me to AntMaps.org, which has maps showing distribution of ant species and higher taxonomic classes. Both are worth a visit for anyone wanting to know more about these fascinating social insects. They both are good complements to my favorite myrmecological reference, “The Ants,” a fantastic, coffee-table-sized book by Bert Holldobler and Edward O. Wilson (available in the Rappahannock County Public Library’s Conservation Collection).
In my research, I also came across an interesting 2015 article in the journal Insectes Sociaux about ants that enslave other ant species, which is not a common behavior among ants. The enslaving ants kidnap young ants from the other species’ nest and rears them. Depending on the slave-maker species, the slaves are either “vital for colony survival” or increase the colony’s workforce.
The researchers also found extensive, but often-overlooked, evidence in historical and recent literature that some enslaved ants engage in various forms of “so-called slave rebellions.” Such activities of enslaved ants fall into four categories, according to the researchers: acts of physical aggression directed by slaves to slave-makers; attempts by slaves to reproduce within a slave-maker colony; “sabotage” by slaves through activities that weaken the slave-makers’ colony and population; and slave emancipation, the partial or complete self-liberation of slaves from slave-maker colonies.
In a National Geographic article, another researcher explains that “slave-making” ant species are now more generally referred to as “dulotic ants,” kidnapper or pirate ants. These ants, for example, Amazon ants (Polyergus genus), sometimes use scent as a cloaking device to take over headhunter colonies. The Amazon ant queen invades a headhunter ant colony by sneaking in and murdering the incumbent queen. The Amazon queen then soaks in the headhunter queen’s bodily fluids and uses this “newly acquired scent profile to avoid detection while she pumps out a bunch of eggs.” The generation of workers that emerges from the eggs then captures more headhunter ants.
This is why I like social insects, including ants and bees — few other insect species have more more intriguing behaviors and a lot of these behaviors are similar to those of another social animal, Homo sapiens.
© 2018 Pam Owen