By: Bonnie L. Grant, Certified Urban Agriculturist
Who would consider ants as farmers? Plant pests and picnic nuisances, yes, but farmer is not a vocation naturally assigned to these tiny insects. However, it is a true circumstance in which they herd and care for aphids in order to keep a much loved food in constant supply. Aphids and ants on plants are as interdependent as peanut butter and jelly.
Aphids are sucking insects that are common on both outdoor and indoor plants. They feed on the sap of plants and secrete a substance called honeydew. This sticky resin is a favorite food of ants, who actually “milk” the aphids for it by stroking their abdomen. The relationship between aphids and ants is symbiotic in that both receive some benefit from the arrangement.
The unique relationship between these two organisms provides protection for the aphids and food for the ants. Ants protect the aphids from predators, such as lacewings and ladybugs. They have also recently been found to protect the aphids from a fungal outbreak that causes death, by removing the bodies of the infected aphids.
Anytime you see a large number of ants on a tree or plant, it is likely you have a large infestation of aphids. Not all species of ant find this arrangement beneficial, but many of the more common species do indeed farm aphids in this way.
How do aphids help ants? Aphids feed the ants and docilely allow themselves to be moved if the ants require them to relocate. It is a fascinating arrangement where aphids and ants on plants live in close cooperative proximity.
Farmed aphids supposedly produce larger drops of honeydew and more offspring. The sweet sticky stuff is a favorite food for ants, who also take it back to feed larvae. Plants where there are aphids farmed by ants may appear to be overrun by insects. This is where aphids and ant control take center stage.
Managing ants is one way of controlling the aphid population. Ant bait stations are effective because the ants take the bait and bring it back to the main colony. This destroys more of the insects at one time. With less ants to defend them, aphid numbers will drop.
A non-toxic method is to simply wrap the plant or tree with sticky tape or netting. This catches the ants and prevents them from tending to the aphids. In turn, the aphids are exposed to predators and their numbers will dwindle.
Conversely, you can focus your attention on the aphid population. Without aphids, the ants will be forced to move on for food. Horticultural soap sprays or neem oil work well for aphid control.
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When you step into your yard to relax in the evening, the last thing you want to see is a line of ants plodding along what appears to be a spontaneous ant highway. Unfortunately, our yards, gardens, and even our homes attract ants like a local park draws children — and they want to stay. Unfortunately for us, any period of time they’re around is generally too long!
While most ants don’t typically carry illnesses, they are a nuisance. They tend to live in large colonies, and an ant leaves scent trails that can indicate where its friends can follow to go acquire food or water to take home. In this guide, we’ll look at a number of ways to avoid, control, or kill ants, even if they’ve already moved in and gotten comfortable.
Listen to this post on the Epic Gardening Podcast
Aphids are small herbivorous insects that spend their entire life cycles on specific host plants. They excrete a sugar-rich substance called honeydew that is a prized resource for various ant species.
Photo via Adobe Stock
In exchange for this food source, ants provide the aphids protection from predators in the same way that humans give dairy cattle a safe environment for feeding in exchange for the milk they provide.
It has been documented that, in some particularly aggressive ant species, aphids are herded onto specific types of plants that are more productive and have positive effects on honeydew production.
Ant tending has been shown to increase honeydew production by up to 50 percent. This indicates that ants stand to realize large benefits by ensuring that their own aphids have a safe and nutritious habitat.
The aphid Chaitophorus populicola and the ant Formica propinqua exist in this mutualistic relationship. The aphids are protected by living in close proximity to the ants, while the ants gain the nutritional benefits from the honeydew.
Aphid numbers drop by 88 percent when their tree habitats are located more than six meters from an ant mound. No aphid colonies at all are found further than ten meters from an ant mound.
In other words, without protection from their tending ants, the aphid populations are much more likely to be wiped out by predators.
Photo via Adobe Stock
The aggressive ants actively remove potential predators from aphid-inhabited trees, including other herbivores and competing ant species. However, in providing the aphids with this safe habitat, the ants affect the makeup of the communities present on the plant.
Overall species richness and abundance is greater on trees without aphid-ant mutualists than on trees where they are present. When aphids were experimentally removed from trees and the aggressive ants therefore abandoned them, there were increases in overall species richness (31 percent) and arthropod abundance (26 percent). This demonstrates that ants were effectively clearing the trees of both predators and competitors, thereby decreasing biodiversity, to ensure the success of their honeydew crop.
Stomaphis yanonis being cared for by Lasius ants. Credit: Yoshiyuki Matsumoto of Shinshu University, Japan
Plant-feeding insect aphids are thought to have diversified by shifting their host plants to other closely related plant species. However, the aphid Stomaphis established not only association with host plants but also mutualistic relationships with ants. A research team examined the relative importance of host plants and mutualistic partners in their diversification and found an unusual evolutionary pattern in aphids.
One of the major objectives in biology is to understand the factors and mechanisms that have led to the diversification of species on earth. Plant-feeding insects are the most diversified group of organisms on earth, and they account for more than 40% of all insects. There have been numerous studies into the diversification patterns and driving forces seen in host plants however, interactions with other organisms have yet to be accounted for.
The study, "Evolutionary diversification of Japanese Stomaphis aphids (Aphididae, Lachninae) in relation to their host plant use and ant association," set out to understand the driving force that generated evolutionary diversification of the plant-feeding, ant-associated Stomaphis aphids through their long evolutionary history. Aphids are known to have established a mutualistic relationship with ants by providing them with honeydew in exchange for protection from their natural enemies and receiving hygienic services. Aphids are relatively large and remain sedentary due to their need to suck sap from tree trunks.
Scientists have long thought that diversity was a result of aphids shifting their host plants to other closely related plant species. Or did they diversify through a shift of mutualistic partners such as body guard ants? Some aphid traits, morphological (structural) and behavioral have evolved to serve their relationship with ants better. For example, the shape and color of aphid bodies are known to suit the type of ant they have a symbiotic relationship with. Aphids and their mutualistic relationship with ants is so ingrained to their lives they cannot survive without them. The question is, which had a stronger influence on the aphids' diversification? The host plants, or mutualistic ants? The relative importance of host plants and mutualistic partners in structuring evolutionary diversification of a group of insects had yet to be fully investigated.
The research group lead by Tetsuya Yamamoto and Takao Itino of Shinshu University studied 160 Stomaphis aphid colonies at 34 sites in Japan to find out. Currently there have been 33 species and 4 subspecies of Stomaphis aphids described world-wide. Most are specific to one plant species or genus. The researchers searched for known host plants and followed Lasius ant trails to find the aphid colonies. The researchers then examined their mitochondrial DNA using a Bayesian information criterion—a method of interpreting probability, through which scientists gain insight into the most likely lineages based on mitochondrial and nuclear DNA sequences.
The scientists were able to identify 38 haplotypes of the aphids by using molecular phylogenetic analysis. They found that evolutionary diversification of Stomaphis aphids was generated primarily through host plant shifts, rather than associated ant species because there was a high degree of specificity between each lineage and haplotype of Stomaphis aphids to their host plant species with no overlap, while almost all lineages of Stomaphis aphids were associated with two or more ant species.
Although the group showed that Stomaphis aphids evolutionarily diversified through host plant shifts, the remarkable finding that came as a surprise was that Stomaphis aphids had not shifted between closely related plant species, but between very distantly related host plant taxa—even to different plant orders, from oaks to pine trees! It is very unusual to observe such insect host shifts between very distantly related host plant taxa.
The group hopes to continue research to find the factors responsible for the host specificity of Stomaphis aphids. They hypothesize that the dependence of Stomaphis on long-lasting Lasius ant colonies situated in temperate deciduous forests where Lasius is the dominant ant genus may have led the aphids to shift to distantly related but spatially adjacent host tree species so they can potentially feed on both. Their ultimate goal is to better understand the role of ants and plants that shape plant-feeding insect evolution.
When I blogged about experiences I had with ants earlier this summer (Discrimination Opportunity and Watch, Wait and Wonder), one of my blogging friends, Hariod at contentedness.net told me that ants and aphids have a symbiotic relationship. I was fascinated by his description of the process so decided to learn more about it.
Ants play the role of protector in the ant-aphid relationship. They do that in exchange for the honeydew that the aphids express when the ants stroke the aphids’ bodies with their antennas. I found some videos that show those behaviors.
In the first part of this video, you will see the ant stroking the aphid, the honeydew being expressed, and the ant drinking it.
The next video, shows how ants protect aphids from lady bugs (I was surprised to learn that in other parts of the world lady bugs are called lady beetles, lady birds, or lady cows! Ladybugs is a North American term.)
As I continued exploring the YouTube videos, I found an incredible one which shows ants protecting aphids from an aphid lion, which is actually the larva form of a Green Lacewing. The video also reveals that there are some creatures which ants allow to stay near the aphids.
The ants are very much in charge of the relationship. Some of the articles say that ants “farm” the aphids. When an ant finds a group of aphids, it leaves a trail of pheromones for worker ants to follow. The ants then enslave the aphids. They slow the aphids down by drugging them with a tranquilizing chemical from their feet. They may also bite off the aphids’ wings to prevent them from flying away.
The ants protect and take care of the aphids in ways other than saving them from predators. They may move the aphids to parts of a plant that have the best sap. When it rains the ants may take the aphids to a more sheltered place, bringing the aphids back to the plant after the rain shower is over. Ants may even carry aphid eggs to the storage chamber of their own nest in order to help them survive a cold winter.
Nature is so amazing. Both ants and aphids are such common creatures, but I would never have guessed that they were so interconnected.
Since aphids do not have much of a shell or armor to protect them, you can get rid of or slow this pest down in some natural ways.
These are all the natural methods in which you can use to get rid of aphids or prevent them from overtaking your garden, whether it is a vegetable garden or a flower garden.
Stray aphid soon to be brought back to the herd.
Aphids are a Landscape and Garden pest while ants are both indoor and outdoor pests. If your garden is overrun by aphids, you’ll need to get rid of their protectors – the ants.
Treating your plants and shrubs on a regular basis will keep both aphids and ants away. There are do-it-yourself methods of controlling aphids such as spraying them with dish soap but that doesn’t necessarily get rid of the ants.
Farmer ants will set up business, down the shrub a little ways, where they’re sure to find a couple of stray aphids to herd and corral under a different set of leaves. …
Hearts Pest Management to the rescue! We have a wonderful landscape pest management service that utilizes Green / Organic Pest Control.
Get rid of the farmer ants and the aphids at the same time and enjoy a healthy, beautiful garden!
Call today for more information on our organic pest control services at 800-986-1006. You’re also welcome to complete the form below and a caring Hearts Pest Management representative contact you shortly.