- Author: Ben Faber
Life in an ant colony is a symphony of subtle interactions between insects acting in concert, more like cells in tissue than independent organisms bunking in a colony. Now, researchers have discovered a previously unknown social interaction that unites the colony, linking ants across developmental stages—adults, larvae, and pupae, an immobile stage, not unlike a butterfly's chrysalis, during which ants transition from larvae to adults.
The study, published in Nature, reveals that pupae secrete a never-before observed fluid that is immediately adults and larvae immediately drink. The health of the entire colony appears to hinge on the prompt consumption of this nutrient-packed fluid—the larvae need it to grow and, if adults and larvae fail to drink it, the pupae die of fungal infections as the fluid builds up around them. "The way that ants use this fluid creates a dependency between different developmental stages," says Daniel Kronauer, the Stanley S. and Sydney R. Shuman Associate Professor at The Rockefeller University.
"It just shows to what extent ant colonies really operate as an integrated unit."
"Milk" for ant larvae
Ants operate within the bustle of a busy colony, posing difficulties for researchers trying to observe the various interactions among ants that keep the colony running smoothly. "These interactions lie at the very heart of understanding insect societies but, because of the inherent challenges, they haven't been investigated systematically," says Orli Snir, first author on the study and postdoc in Kronauer's lab. To tackle this problem head-on, Snir decided to reverse engineer the ant colony in order to identify some of the key principles that drive social interactions. To do so, she removed ants at different developmental stages from the colony and examined how social isolation affected the insects.
One of the first things she noticed was fluid building up around isolated pupae. Insects do not normally secrete fluid at the pupal stage, and such fluid had never been observed in ants either. This fluid was prone to fungal infections which eventually killed the pupae. Only when Snir removed the fluid manually did the pupae survive into adulthood. Clearly, the ant colony was somehow preventing pupal fluid from building up.
Kronauer, Snir, and colleagues conducted dye tracing experiments to figure out where the fluid was going and, when they discovered that adults and larvae were drinking it, they began exploring the fluid's composition and observing what happened to ants that did not partake.
The researchers discovered that the fluid is derived from a conserved process found in all insects called molting, in which insects shed their old cuticle to grow. While non-social insects recycle the molting fluid to conserve nutrients, ant pupae share it with their nestmates.
The fluid is rich in nutrients, the researchers found, as well as psychoactive substances, hormones, and some components found in the royal jelly that honeybees reserve for queen bee larvae. And while ants of all ages seem to enjoy the fluid, young ant larvae need it—those deprived of the fluid in their first four days of life fail to grow, and many eventually die.
"The first few days after hatching, larvae rely on the fluid almost like a newborn relies on milk," Kronauer says. "The adults also drink it voraciously and, although it's not clear what it does to the adults, we're confident that it impacts metabolism and physiology."
After conducting the initial study in clonal raider ants, Kronauer's team found the same general phenomenon among each of the five major ant subfamilies, suggesting that the strategy of co-opting molting fluid into a nutritious signaling fluid is highly conserved, Kronauer says. "It probably evolved once, early in ant evolution, or even preceding ant evolution."
Anatomy of a superorganism
The ant colony is sometimes referred to as a superorganism—one unified entity composed of many organisms working in concert. Indeed, ants relay information by swapping chemical signals in ways analogous to how cells communicate in tissue. These include pheromones, which often convey short-term information, and social fluids, which have the potential to effect long-term metabolic and behavioral changes. The discovery of the pupal social fluid and its role in connecting adults, pupae, and larvae, adds context to this understanding of ant colonies as interdependent superorganisms.
"Pupal social fluid is the driving force behind a central and hitherto overlooked interaction network in ant societies," Snir says. "This reveals a new aspect of dependency between larvae and pupae, and pupae and adults."
In future studies, the team will further explore the effects of this molting fluid on the inner workings of the colony. Kronauer is particularly interested in determining whether molting fluid plays a role in deciding the caste of ant larvae, and whether and how it affects the behavior of adults. "This study only provides a glimpse into the intricate interaction networks of insect societies," Snir says. "Our long-term goal is to gain a deep understanding of the neural and molecular mechanisms governing social organization, and how these mechanisms evolved."
https://www.nature.com/articles/s41586-022-05480-9
A nest of clonal raider ants with workers, pupae, and young larvae. The workers have placed the young larvae on the pupae, where they feed on pupal secretions.
Daniel Kronauer
- Author: Ben Faber
Role of Birds on Farms: Self-Certification
This 10 lesson virtual course teaches agricultural professionals and farmers how to support beneficial birds and manage pest birds on farms. By learning how to assess the farm's avian needs and opportunities, farms can be designed to provide for a diversity of beneficial birds. If pest birds are a problem, they can be discouraged with specific practices during the shorter periods when they cause damage. The sessions cover the latest research, tools and resources, and are given by experts in avian pest control, entomology, ornithology and conservation.
https://www.wildfarmalliance.org/role_of_birds_on_farms
This course was first offered via webinar format in early 2022. View the recordings of the lessons at your own pace and track your progress using the certificate below.
(Download your fillable certificate here)
The loss of 3 billion birds since 1970 is a crisis. Birds are indicators of a healthy, functioning ecosystem, providing important benefits such as pest control, pollination and seed dispersal.
Farmers can take advantage of these services and at the same time provide birds with habitat. It is mutually beneficial for farmers and birds.
When farmers provide habitat for beneficial birds and bring them closer to crops, they are increasing their farm's pest control services. Birds can help farmers keep pest insects, rodents and pest birds at bay.
- Author: Ben Faber
Caught with Your Water Down
Another type of disorder which arises presumably from water stress is one of the fruit pedicel (stem) termed ring-neck. This disorder was first described afflicting the Fuerte variety by J. Elliot Coit in 1928. Horne (1934) provides a good description of this disorder:
It is a blemish, usually on the fruit-stem or pedicel, consisting of irregular areas of superficial dried tissues which become more or less separated from the living tissue. It is particularly likely to affect the thickened segment of the pedicel next to the fruit. Sometimes a complete ring of surface tissue dies,separates from the pedicel,and peels off, leaving a scar. The upper end of the pedicel is slightly fleshy and enlarged, and a small ring-neck spot sometimes occurs on it. Occasionally lesions which have somewhat the appearance of ring-neck develop on the fruit, and where extensive, may give it a grotesque appearance through curling up of the dead surface layer from the edges.
It was originally believed that ring-neck could be caused by a pathogen. Early attempts failed to identify the causal organism. Work in South Africa eliminated pathogen involvement in the development of this disorder. This shows up along the coast where extremes of temperature can occur with Santa Ana conditions. With increased plantings in the Central Valley, it has shown up, as well. Temperature extremes and changing water demand need to be watched in order to avoid this abiotic disorder.
Examples of ring-neck. A. Slight damage to the fruit pedicel. B. Note the peeling of the pedicel tissue.
C. Note that only one fruit (left) is affected with ring-neck.
- Author: Ben Faber
What is allelopathy?
Allelopathy literally means “death to others.” In its simplest sense, allelopathy is the ability of one plant species to affect the growth of another through their chemical exudates. While early researchers narrowly defined the relationship to include only the influence of living plants on other living plants, more recently the definition has been expanded to include interactions within the soil environment. Such “soil-mediated chemical interference” is arguably a more relevant definition, as roots of adjacent plants share the same soil environment. Competition for water and nutrients, soil microbial activity, and other environmental conditions should be considered separately from any possible “chemical warfare” among plants. Therefore, allelopathy is currently understood to involve living or dead plant parts that release chemicals into the soil which have an effect on other plants—positive or negative. And no allelopathic chemical is better known—and feared— than juglone.
Read this interesting treatise on juglone and its history as a bogey for poor plant performance by Linda Chalker-Scott –
Do Black Walnut Trees Have Allelopathic Effects on Other Plants?
And once you have had your myth revealed, check out these other horticultural myths that Chalker-Scott and team have worked over:
Horticultural Myths
Image: Impatiens struggling, think it's the juglone?
- Author: Ben Faber
What Are the UC Ag Experts Talking About?
For 2023
| Event Name | Date |
|---|---|
| UC Ag Experts Talk: Vegetable IPM in the Sacramento Valley | 2/22/2023 |
| UC Ag Experts Talk: Insects in the Vineyard | 4/19/2023 |
| UC Ag Experts Talk: Flatheaded borer concerns in California walnuts | 5/31/2023 |
What is involved in the webinars?
A series of usually 1-hour long webinars, designed for growers and pest management professionals, highlighting various pest management and horticultural topics for citrus, avocados, and other subtropical crops. Master Gardeners can benefit from participating, but the pest management methods presented, especially the pesticides, are not to be followed without a clear understanding of their legal use by homeowners.
During each session, a UC Expert on the subject makes a presentation and entertains write-in questions via chat during and/or after the presentation. As we develop this program, we may expand to other crops.
What are the topics and how do I register?
Register for webinars using the links above.
Vegetable IPM in the Sacramento Valley by Dr. Amber Vinchesi-Vahl (February 22, 2023)
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Dr. Amber Vinchesi-Vahl will discuss IPM on vegetables in the Sacramento Valley, with a focus on tomatoes. One DPR CE unit (other) and one CCA CE unit (IPM) are pending.
Insects in the Vineyard by Dr. Cindy Kron (April 19, 2023)
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Dr. Cindy Kron will discuss the importance of proper insect identification in IPM and discuss many insects that are beneficial in vineyards. She will also discuss economic thresholds for pests that cause damage and vector diseases and include a pest to be on the lookout for: spotted lanternfly. One DPR CE unit (other) and one CCA CE unit (IPM) are pending.
Flatheaded Borer Concerns in California Walnuts by Dr. Jhalendra Rijal (May 31, 2023)
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Dr. Jhalendra Rijal will discuss flatheaded borer and how it is an old pest but has become a new problem in California walnuts. One DPR CE unit (other) and one CCA CE unit (IPM) are pending.
Are there Continuing Education units?
When the subject discusses pest or disease management, continuing education units (CEU) will be requested from DPR (1 unit per session) and when relevant also Certified Crop Advisor (CCA) continuing education units will be requested. To qualify for the CEU make sure to
- register separately with your own email address and log in from your own device
- participate in the entire hour session
- complete and pass a final test with 70% or higher; if not passed, the test can be retaken
If you are connecting by smartphone and need CEUs, be sure that you are using the zoom app (Android, iPhone) so that you have access to the presentation and we can track your presence in the webinar.
Certificates of completion will be emailed within one week to those who meet those requirements above.
The webinars are recorded and linked from this web site for future study. However, continuing education units are awarded only to the participants who attend the live version of the webinar.
Make a gift to support UC Ag Experts webinars
Your gift furthers UC's Integrated Pest Management's mission to help California residents, growers, land managers, and other professional pest managers prevent and solve pest problems with minimal impact on people and the environment by developing and promoting the use of integrated and ecologically sound pest management programs. Make a gift and use the Comment field to specify that your gift is for UC Ag Experts Talk webinars.
Who is involved in the UC Ag Experts webinars?
This webinar series is brought to you by Ben Faber (UC ANR Ventura Advisor) and Dr. Beth Grafton-Cardwell (Emeritus Entomology UCCE Specialist) with the technical support of Petr Kosina (UC IPM Content Development Supervisor) and Cheryl Reynolds (UC IPM Interactive Learning Developer).
