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by Susan Holloway | Bio

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Ants! Friend or foe?

4 Jan 2022 8:22 AM | Anonymous
Oh, hello there! May I sample your holiday cookie crumbs?


   
Just when it seemed like it was never going to rain again, the skies have opened and the streams, lakes, and reservoirs are nearly full. This is of course great but let’s mention one small downside — home invasion by waterlogged ants. Ants are at once the coolest of creatures and the biggest of pests. How do we live with them?


What are these tiny black ants doing in my kitchen?

It may come as no surprise to you that, excluding bacteria, there are more ants on this planet than any other animal. Estimates put the number at about ten billion billion (i.e., a one with 18 zeros), compared to seven billion human beings. There are 13,000 species of ants sprinkled across the globe. California is home to more than 270 species. The most common one in urban and suburban areas of Northern California is the non-native Argentine ant, whereas native ants are dominant in wild areas of the state.

Argentine queen ant and worker ant  

Why are some of these billion billion ants trying to gain entry to your house? In the summer, they come inside to find food and water. In the winter, heavy rains such as those we are experiencing may drive them out of their underground nest. They are searching for a place to take shelter. In other words, contrary to the children’s song, the ants are marching out of — not into — the ground to get out of the rain!

This is an ordinary phenomenon, but how do ants actually undertake the monumental task of coordinating a campaign to retrieve bagel crumbs from your kitchen counter, much less that of moving an entire colony after a flood? 


Ants: Taking Care of Business

  Images of fire ants by Lisa Vertudaches
   

Ants are highly social but have few ways of communicating with each other. They have very poor eyesight and can’t hear, although they can detect vibrations associated with sound. Their superpower is a highly developed sense of smell. Each ant generates chemicals that create an aroma unique to that ant. One ant uses her antennae to sniff the aroma of other ants, which in turn gives her information about what the others are doing.

Let’s look at some of the basic features of an ant colony. Bear in mind that there are many differences across the 13,000 species, so I am just giving you the big picture here.

Ants live in a caste system, so the ants’ responsibilities depend on the caste to which they belong. The queen is the founder of the colony, and her role is to lay eggs. Being the queen may sound good, but she is basically confined to an underground chamber where she does little but lay eggs.  

Then there are the male ants, called drones. Male ants have cool wings, but they stay in the nest and do little besides eat, have sex once with the queen, and then die. Their lives are over in as little as one week.  

Deborah Gordon
And finally you have the worker ants, all of whom are female. Their tasks include caring for the queen and the young, scouting out and foraging for food, policing conflicts in the colony, and disposing of waste. These sterile workers will most likely never have their own offspring. But at least they live for a year or so and get to travel outside the nest.

Each type of ant is genetically predisposed to do what is necessary for the nest to function properly. Although, as I have mentioned, they can communicate by smell, no one ant has knowledge of the big picture or acts as a coordinator of the others. How do they get things done? Check out this video in which Dr. Deborah Gordon, a professor of biology at Stanford, answers this important question.

 

Do Ants Help Anyone Outside Their Own Colony? 

Ants with an eliaosome
and seed
Ants tending
aphids


  Ants can also make a tasty snack

One amazing contribution ants make to the plant world is through a special kind of seed dispersal. Some ants are attracted to certain plants whose seeds are connected to a little packet of tasty (to the ants) nutrients. The ants carry the seeds with the packets, called elaisomes, back to the nest. They feed the elaisomes to the ant larvae and toss out the seeds, which then have an opportunity to germinate at some distance from the parent plant. This plant-ant interaction is true mutualism in the sense that it benefits the ants and the plants equally.

A second contribution of ants derives from their attraction to honeydew, a sugary excrement produced by many sap-sucking insects including caterpillars and aphids. Ants defend these insects from their natural enemies in order to protect the delicious honeydew. This “tending” behavior benefits the sap-sucking insects, including the endangered Mission Blue butterfly for example, but can pose a problem for gardeners who don’t want aphids on their plants.


E. O. WILSON: The Ant Man

“I honestly cannot understand why most people don’t study ants.E.O. Wilson

  E. O. Wilson
 
   
On December 26 of 2021 we received the sad news of the death of Dr. Edwin O. Wilson, lifelong myrmecologist (studier of ants) and ardent environmentalist. Dr. Wilson became obsessed with the social lives of ants at an age when most youth are trying to navigate the social structure of middle school. By age 13 he had already discovered the first known colony of imported ants in the United States. In high school, he conducted a survey of all the ant species in Alabama, and from there leapt from one achievement to the next with remarkable speed. He earned a PhD in biology from Harvard in 1955 and spent most of his professional life at Harvard’s Museum of Comparative Zoology.

In terms of research on ants, his most important work was showing through both observational and experimental studies how ants function as an organized community. One of his main findings was that ants communicate through the release of chemicals called pheromones. For instance, ant scouts leave a pheromone trail that leads their foraging friends right to sources of food. 

Wilson’s intensive study of the social organization of ant colonies led him to formulate the field of sociobiology, which addresses the biological basis of social behavior in animals. Sociobiology is based on the premise that some behaviors (not just physical traits) are at least partly inherited. Animals whose behavior helps the survival of the group (not just that of the individual) are particularly likely to survive and breed, thus ensuring the continuation of the predisposition to be a team player. Although the theory has been well received with respect to less complex animals like ants, it remains quite controversial when applied to humans.

As an environmentalist, Wilson was an untiring advocate of strategies for addressing climate change and for preserving biodiversity. His 2016 book “Half-Earth, Our Planet’s Fight for Life” argues for conserving half the land and seas for biodiversity in order to prevent mass extinction at the level last experienced by the dinosaurs 65 million years ago.

“If we allow the living part of the environment to disappear, for me, it would be by future generations regarded as one of the most catastrophic, even evil periods in human history, for our descendants to look back and say, they wiped out half or more of all of the rest of life on Earth, the variety of life on Earth.” E.O. Wilson


  Alison Hermance
   
Controlling Ants

Some people think ants are disgusting, but I think they are relatively unobjectionable insects. I feel bad wiping them out with a wet sponge as they trudge across my kitchen countertop. I do so anyway, taking some comfort in the scientific consensus that they feel neither pain nor fear.

Other than physically squashing them, how else can we control them in the home? In a recent essay Alison Hermance, a writer affiliated with WildCare, made a strong case against using pesticides and rodenticides, arguing that these poisonous substances always affect animals other than those being targeted.

“Because the thing about rodenticides — and pesticides in general — is that the person using the poison thinks on some level that they are the only ones putting out poison…People don’t realize that every other person has come to the same conclusion, and that in fact, these poisons are everywhere.” Alison Hermance 


Uncle Milton and his ant farm
There are many ways to control pests that do not entail poisoning them. Here are a few ideas:
  1. Prevent them from getting inside. Seal entry points with caulking or petroleum jelly.
  2. Don’t tempt them with treats. Store food in sealed containers and keep the floors and counters free of crumbs. Wipe surfaces with soapy water to get rid of sticky remnants.
  3. Put out things they hate. Spray surfaces with 50:50 solution of vinegar and water. Sprinkle cayenne pepper, cinnamon, scented talcum powder, red chili powder, coffee grounds, or ground black pepper at entry points of large infestations.
  4. Befriend some Daddy-Long-Legs spiders; they make their webs along the ant entry points.
  5. Learn more about them and they may bother you less. If you have children, or are young at heart, consider getting an ant farm or make one of your own.


That’s it for this post of the EFM Notebook! Special thanks to Dr. Paul da Silva for his helpful comments and suggestions.


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