- Author: Ben Faber
It might seem like common sense that a starving animal is more likely to take dangerous risks to obtain food than one with a full belly. But new research from UCLA shows that groups of Argentine ants, who forage boldly when they're well fed, exercise far more caution when they've been deprived of carbohydrates and the risks from competitors are high.
This counterintuitive foraging strategy might contribute to the success of these insects, known as Linepithema humile, an invasive species that displaces native ant populations in California and elsewhere and has become a significant agricultural pest, the researchers said.
Their findings, published in the journal Current Zoology, suggest that the unwillingness of Argentine ants to expose themselves to danger when weakened by hunger could possibly give them a competitive edge over other species by helping to preserve their colonies' foraging capabilities.
“While not foraging may lead to a reduction in food stores when those stores are already low, foraging in a high-risk environment exposes the colony to potential loss of foragers,” said the study's senior author, Noa Pinter-Wollman, a UCLA professor of ecology and evolutionary biology. “So reduced foraging could be interpreted as individual foragers not taking unnecessary risks.”
To support the energetic requirements of daily life, all ants require carbohydrates, which they obtain from a variety of plant and animal sources. They also need protein, which they generally get from dead animals, to nourish their larval offspring. Ant colonies adjust their foraging strategies according to the availability of these food sources, the presence of competing ant species, and the threat of predators or other dangers. Well-fed ants will forage for carbohydrates even in the presence of other ant species or danger cues.
First author Bryce Barbee, who conducted the research as a UCLA undergraduate, expected that starving Argentine ants of either carbohydrates or protein would only increase their willingness to forage for those foods in high-risk environments because they had little to lose and everything to gain.
Together with Pinter-Wollman, Barbee designed a series of laboratory experiments that involved feeding ants normally, depriving them of either carbohydrates or protein, and depriving them of both, then allowing them to forage as they normally would in either low-risk or high-risk environments.
The researchers created the impression of high-risk environments with formic acid, a chemical marker produced by ants, to signal the presence of competitors.
When the risk was low, starving ants did indeed forage more vigorously for the food of which they had been deprived. But when the risk was high, starving ants surprised the researchers by becoming more cautious, not less, in their foraging strategies.
In both high- and low-risk foraging scenarios, the ants were more willing to forage for carbohydrates than protein, which they only need to raise their brood. Since no eggs or pupae were present in the laboratory colonies, this finding might not be surprising, but it could also indicate that starving ants put their own energetic needs ahead of raising offspring, the researchers said.
Scientists who study animal behavior have advanced two ideas to explain foraging strategies. The first, known as the asset-protection principle, holds that hungry animals have less to lose than satiated animals and will therefore behave more assertively to get food. The second, the state-dependent safety hypothesis, holds that animals in good condition are more likely to take risks because they are more likely to survive dangers they encounter.
“Our work upheld the state-dependent safety hypothesis but not the asset-protection principle,” said Barbee, now a doctoral student at UC Santa Barbara. “The findings suggest that factors such as activity level and energetic costs of starvation are important for Argentine ant foraging decisions.”
The work points toward an avenue of research that could lead to better efforts to control the spread of Argentine ants and mitigate their detrimental impact on agriculture, the researchers said.
https://academic.oup.com/cz/advance-article/doi/10.1093/cz/zoac089/6825390
Ant species across five subfamilies exchange milk-like substances. Jasius via Getty Images
- Author: Ben Faber
Protecting Avocados from Frost and Then What
The long-range forecast is for no or little rain in Southern California. A dry winter often means a cold winter. A winter when frost and freeze can occur, And over the years, it seems like if there is a freeze in Chile in their winter, we can get one here, but 6 months later. Chile had a freeze this year.
The following is an outline of how a grower can prepare for cold events. Some require considerable advance preparation – plant the right variety – and some can be instituted right away – protection of young trees with palm fronds. The guidelines here are specific to avocado, but for the most part apply to lemon and other cold sensitive citrus.
Frost damage reduces tree growth and fruit yields. Thus, it presents a problem to the avocado grower who must develop and maintain high production to have a profitable business.
Before choosing frost protection equipment, however, the individual grower should ask the question: “Will the fruit and foliage saved pay for the trouble and expense of protection?” In some places, a small amount of damage may not fully justify the installation and operation of frost protection equipment. In other places, avocados can be grown only if expensive heating is done. Nearly all locations have sufficient cold to cause the grower to take into account probable frost damage, possible methods of protection, and the long-range economic effect of his frost situation.
How Frosts and Freeze Occur
Before considering the methods of frost protection, one should understand the conditions under which low temperatures occur. To differentiate between the two major sources of the cold, the terms local radiation frost and freeze are used.
Local radiation frost
Frosts are caused by a cooling of the objects on the earth's surface during the night. This loss of heat from the foliage and soil is called radiation. Heat accumulated from sunshine during the day is radiated to the sky during the night. The cooled objects chill the surrounding air and usually the coldest zone is near the ground surface. Air temperatures are warmer as one goes higher until a height is reached where they are at a maximum for that location. This is called the ceiling. The temperature and height of the ceiling is different for each place and situation.
When the ceiling is low, warm air is nearer the ground than when the ceiling is high. This phenomenon, occurring frequently in Southern California, is called temperature inversion and accounts for this area's ability to protect its orchards.
Colder air settles near the ground and then moves (flows) down the slope to still lower ground resulting in what is called the drift.
Terrain features and winds influence its direction and velocity. A strong drift maintains air temperatures higher than those existing when little or no drift is present.
Freeze
The other type of freezing weather occurs when a large mass of cold air moves in from the north. Fortunately, these freezes have not occurred frequently. The major ones were in 1913, 1922, 1937, 1949, and 1950. Under freeze conditions, temperatures usually go below those experienced during local radiation frosts. When this cold air moves in, high ground is no warmer than lower ground and there is little or no ceiling. Orchard protection at such time is difficult, and methods employing the addition of heat are most effective.
Measuring Temperatures
Orchard temperatures are usually measured with a specially designed self-registering minimum thermometer mounted in a standardized shelter. In this way, readings are comparable and experience allows the grower to use these air temperature readings in judging his hazard and operating his equipment. The height of the thermometer above ground should be five feet in mature orchards and two feet in nurseries and recently planted orchards.
Most orchards have areas which are colder than other areas. You should have enough thermometers to measure temperatures in each of these areas. In establishing thermometer locations in a new orchard, set up one thermometer in a permanent reference location. Move the other thermometers around every few nights until you find the cold spots. With this experience, you can locate and determine the number of thermometers needed. The range in numbers will be from a minimum of two or three for small groves to one for each three to five acres in larger orchards.
Types of Injury
Fruit damage
Fruit damage consists of frozen stems, frozen fibers inside the fruit, or frozen flesh and skin, depending on the temperatures and their duration. This damage appears slowly and is difficult to appraise accurately.
For some varieties, principally in the case of the ‘Hass', the first evidence of damage will show up as a browning on the stem a few days after a frost. If this is the only damage, mature fruit might be picked and marketed. This all depends on the packer. The problem often is assessing how extensive the damage is. Unless this fruit is harvested, it will fall from the tree. Frozen fruit of other varieties, particularly the Guatemalan types, may never show the browning but will drop anyway.
Stem Damage
Frozen fruit fibers (vascular bundles) turn black and California law prohibits the marketing of all seriously damaged fruits. Before you pick mature frosted fruit, you should call in your marketing organization representative and local agricultural inspector to help you determine how much of the fruit should be harvested. By cutting representative fruit, they can tell whether it is within the legal tolerance or not, and guide you in marketing your fruit.
Severely frozen fruit may show brown water-soaked spots in the skin, gray areas in the flesh, and may even crack or split. It is unmarketable and will drop from the tree in time.
Water soaked and frosted neck, Mary Lu Arpaia
Brown vascular bundles, Mary Lu Arpaia
Tree damage
Frozen blossoms, leaves, and twigs turn black within a few days. But larger wood, although frozen, may never turn black. Great variation occurs in the location of tree damage. In some cases, only the lower part of the tree will be frosted, while in other cases only the top part is affected. Sometimes, only a limb on one side will be frosted. Thus, it is impossible to evaluate accurately the extent of wood damage until new growth comes out the following spring and summer.
Trees suffering moderate wood damage usually will not bloom properly and will produce a reduced crop the following season. Occasionally, trees have been killed all the way to the ground by severe freezes.
Tree Resistance
The resistance of the fruit and trees to freezing temperatures helps determine whether a grove must be protected or not. Then, too, both the minimum temperature and the duration of damaging temperatures affect the amount of injury. For example, three or four hours of 29 degrees may injure an orchard more than a brief drop to 25 degrees.
Frost susceptibility varies greatly from situation to situation. Adequate appraisal of each situation should include consideration of the following variables.
Age and crowding
Young trees (up to 3 years of age) and recently top-worked trees of all varieties may be killed by temperatures which would only cause minor damage to nearby mature trees. Protection for such trees is a wise practice, even in warm locations.
In general, older trees of a given variety are more resistant, except in orchards where they are crowded. Where the soil is shaded during the day, it cannot absorb the sun's heat and thus has little heat to give off during the night. Crowding also restricts the drift through the grove and increases the difficulties of orchard heating. For these reasons, thinning groves is often advisable to reduce their frost hazard.
Health
Weak trees are more subject to frost damage than healthy ones. Be sure your trees go through the whole year with an adequate supply of moisture; withholding irrigation water in the fall to “harden them up” can actually weaken trees and make them more susceptible.
Growth flush
Occasionally avocado trees are in a growth flush (a period of rapid new growth) when freezing temperatures occur. This is not usual, but unseasonably warm weather may stimulate a tree into abnormal growth in the winter. To avoid stimulation, pruning should be delayed until early spring. When tender growth occurs in the winter, growers may have to provide additional protection or sustain damage.
Size of crop
Trees with large crops are more susceptible to frost. To save this fruit, temperatures would have to be maintained one or two degrees higher than would otherwise be necessary.
Varieties of avocado
A wide range of susceptibility occurs among avocado varieties. To classify them according to their resistance is difficult because of the variations already mentioned. But the races of avocados do exhibit differences and can be used as frost resistance indicators.
The Mexican race is the most resistant, and is able to withstand temperatures about as well as orange trees.
The Guatemalan race is the most susceptible grown in California. Some varieties are slightly more resistant than others, so the race can be divided into tender and very tender classifications. Because the fruit is immature during the winter, the crop may be lost while the trees will suffer only minor damage. Lower temperatures will seriously damage trees and affect their future productivity.
The hybrids, as typified by the Fuerte, are intermediate in their frost resistance, and are in about the same class as lemon trees. Because of the Fuerte's importance, it has become the standard measure of frost resistance. Protection is usually provided to save the Fuerte crop since the fruit is mature in the winter months.
As a guide to inexperienced growers, Table I gives a basis for establishing frost protection practices. The critical temperatures listed are for mature healthy trees. Other tree conditions might move these figures one or two degrees higher. Also, the duration of the damaging temperatures would affect the degree of injury. It is still not clear how much cold ‘GEM' variety can handle.
|
Table I – Variety Frost Resistance |
||
|
Race |
Typical Varieties |
Critical Temperature Below Which Fruit and/or Trees are Subject to Damage |
|
Mexican |
Duke, Topa Topa, Mexicola, Zutano, Bacon |
25 Degrees F |
|
Hybrids |
Fuerte, Puebla |
28 Degrees F |
|
Guatemalan (Tender) |
Ryan, Hass, MacArthur, Nabal, Edranol, Rincon, Lamb Hass, Sir Prize |
29 Degrees F |
|
Guatemalan (Very Tender) |
Anaheim, Dickinson, Carlsbad, Challenge, Hellen |
30 Degrees F |
Need for Protection
Frost protection is an expensive and disagreeable job which requires careful consideration by all growers. Each grower must determine his own needs. No one can predict accurately the frost hazard for a given location. Information can be obtained by installing the proper thermometers on the property. Observing adjoining orchards and talking with neighbors will give good background information.
The topography of the orchard and the surrounding land enters into the evaluation. Land on hillsides with steeper slopes is usually warmer than lower valley land. Locations with strong prevailing drifts, or exposed to winds, usually are warmer than sheltered areas having little air movement. Tall dense windbreaks can make a grove one or two degrees colder, but the lower branches of the windbreak can be trimmed to overcome this. Coastal areas usually have less frost hazard because the relative humidity is higher, and ceilings are lower than in interior areas.
As mentioned in the beginning, your final evaluation should answer this question: “Will the fruit and foliage I save pay for the trouble and expense of protection?” Often it is possible to take some damage every few years and still have a more profitable orchard than if equipment were purchased and operated. On the other hand, an investment in equipment, if properly operated, will save your trees and crops. The decision should be based on a long-range economic estimate, balancing the money lost by damage against the costs of protection. This same evaluation will determine the type of protection to provide, if needed.
In some counties and communities, smoke ordinances regulate the type of equipment and methods of operation to reduce smoke output. When you purchase new orchard heater equipment, it should be the most smokeless available in order to comply with possible future expansion or tightening of these ordinances. The trend toward eliminating smoky orchard heaters in most areas will affect the grower's choice of equipment.
Methods of Protection
Mature orchards
Only two general methods of protecting avocado groves have proved satisfactory – heaters and wind machines. A combination of these two also is used. Many makes and designs of heaters and wind machines are offered for sale and they must be compared on the basis of protection provided and cost of installation and operation. This publication is limited to their general application in avocado groves. Their actual operation is discussed in other available publications of the University of California.
Orchard heaters
Experience has shown that a large number of small fires burning throughout the orchard provide better protection than a few large fires concentrated in spots. The value of heaters is noted below to provide a basis for selecting the general type of protection needed.
Their advantages are:
- They usually furnish more adequate protection than wind machines. However, in extremely cold conditions they, too, can be inadequate.
- Only enough heaters to maintain safe temperatures need to be lighted.
- Additional heaters and oil can be stored in the field for emergency conditions.
- They distribute heat to all parts of grove.
Their disadvantages are:
- Smokiness. However, certain types have low smoke output when properly operated.
- Relatively high costs of investment and operation (Table II).
- Fire hazard due to mat of leaves beneath the trees.
- Trouble and work of operation and maintenance.
- High labor requirements.
For colder locations and positive protection, orchard heating is the only proven method. Pie line heaters, using either heater oil or natural gas under pressure from permanently installed pipelines, are efficient but very expensive. Economical and effective heating is provided by heaters with 9-gallon capacity bowls and improved designs of stacks burning a low grade of diesel oil. Usually 45 to 90 heaters are used per acre depending on the frost hazard.
Wind machines
In certain locations, wind machines have provided economical protection. Their effect is essentially that of a large fan which mixes the air within and above the orchard so that the average air temperature near the ground is raised.
Their advantages are:
- More economical than orchard heaters (Table III)
- Low labor requirements for operation
- Adequate protection against local radiation frosts when temperatures go only 2 or 3 degrees below the damaging point.
- Useful in increasing air movement in groves where dead air occurs.
- Increase effectiveness of heaters.
Their disadvantages are:
- Inadequate protection with freeze conditions or when temperatures go 4 or 5 degrees or more below the damaging point.
- Inadequate protection in locations where little or no ceiling occurs.
- Unequal protection throughout grove
- Less effective in young plantings.
Machines providing at least 5 horsepower per acre should be selected on the basis of cost and ease of operation. The location of the machine or machines in an orchard depends on the drift, the topography, and the other variables.
Combination heaters and wind machines
Usually 8 to 25 heaters per acre uniformly scattered throughout the grove are sufficient when used with an effectively installed wind machine. The combination provides adequate protection for even the colder locations. The wind machine will protect the grove for some of the nights by itself, but for the very cold nights, the heaters are available to add heat and thus provide positive protection. Usually the heaters are lighted whenever the wind machines cannot maintain the temperatures above the danger point.
This combination method has the advantage over heaters used alone in that it is cheaper, while providing as complete protection.
A great many other types and methods of protection have been tried but because of one or more faults in each, they cannot be recommended.
Protecting Young Trees
Orchard heaters and wind machines are less effective in protecting young trees in their first two or three years in the orchard than other methods which are usually cheaper, anyway. The first consideration in protecting newly planted trees is to have the trees as large as possible. Planting and topworking should be done in the spring so the trees will make the maximum growth during the summer and fall, before low temperatures occur in the winter.
In locations having serious frost hazard, you might try the practice of planting Mexican seedlings in place in the field and permitting them to grow for 2 to 3 years before topworking. Then if the topworking is done early in the spring, the young trees will have made enough growth to better withstand the cold of the following winter.
Protection for young trees is best accomplished by sheltering them from radiation heat loss. Shelters for this purpose are of many types. In cold locations, young trees may require several types of protection; they may be wrapped with paper, mounded with dirt, or surrounded with corn stalks.
Use of palm fronds for both sun and frost protection, Leo McGuire.
Care of Frost Damaged Trees
Determining the amount of damage is often a difficult job and cannot be done accurately for some months following the freeze. It is usually better to let the tree recover by itself.
Sunburn prevention
Exposed limbs can be badly damaged by sunburning. Whenever defoliated tree s have not grown enough new leaves to protect the limbs before hot weather occurs, you should provide protection.
Protection is best provided by spraying or painting all exposed limbs with either a cold-water white latex paint or a whitewash. The paint needs to be white enough to reflect the light, but thin enough to flow through a sprayer. With latex paint, a 2-part latex to 1 part water is usually adequate.
Irrigation
Do not irrigate frosted trees until the soil in the root zone approaches dryness. The loss of leaves reduces the use of water so the soil will remain wet longer than with unaffected trees. Careful, frequent examination of the soil is necessary to prevent excess moisture from normal irrigations. Avocado root rot occurs in soils with excessive moisture when the cinnamon fungus is present, and growers must guard against this disease following frost damage.
Pruning
Do no pruning until you know how much of the tree has been killed. New foliage will grow from the remaining live wood and the tree will recover better without pruning.
When new shoots are at least two or three feet long, you can remove the dead wood. This will usually be mid-summer, 6 to 8 months following the frost. At the same time, suckers should be thinned out to select the new limbs to replace those lost.
Care of young trees
Badly frozen young trees usually develop strong sucker growth which can be used to form a tree as good as a replanted tree. If these suckers are from above the bud union, you can develop a new top by thinning and training. On young trees frozen back to below the bud union, strong root suckers can be budded or grafted to the desired variety the following spring. If the sucker growth is weak, the tree should be removed.
Severely frozen mature trees
The handling of severely frozen mature trees where they have been killed back to the large scaffold limbs, to the trunk, or to the ground, presents many problems. Each tree should be considered separately. Often growers should topwork badly frozen trees to a more resistant or productive variety.
Whitewashed and topworked frozen tree
And a lot more information from the CA Avocado Commission
Frost and Frost Protection Source of Information
You wanted to know all about Frost, well it's all here. Emeritus Rick Snyder put it together over the years and it's at your finger tips.
English Frost Protection Training Units (videos)
Spanish Frost Protection Training Units (videos)
When to Turn Sprinklers On and Off for Frost Protection
FP001 Quick Answer—This quick answer provides information on using a psychrometer or temperature and dew point data to determine when to start and start sprinklers for frost protection.
Predicting Temperature Trends during Freeze Nights
FP002 Quick Answer—This quick answer gives a method for predicting the change in
temperature during a calm, radiation freeze night.
A Simple Method to Measure the Dew Point Temperature
FP003 Quick Answer—This quick answer provides information on how to measure the dew point for use in estimating minimum temperature and for starting and stopping
sprinklers for frost protection.
Sprinkler Application Rates for Freeze Protection
FP004 Quick Answer—This quick answer provides information on the sprinkler
application (precipitation) rates needed to protect crops from freezing.
Principles of Frost Protection
Frost Protection Training Units (videos) on measuring temperature, frost protection with water, frost protection with wind machines, and passive protection. Traning units are availble in English and Spanish .
FP005 Quick Answer—This quick answer provides information on the general principles of well-known frost protection methods. A PDF file of the WEB page can be uploaded from this Quick Answer. In addition, a shorter version is available.
Programs for Estimating Frost Night Minimum Temperatures and Temperature Trends (new 7 Mar 2007)
The FFST Excel application programs FFST_E.xls and FFST_M.xls are available from this link. The FFST application helps users to determine an empirical equation for estimating minimum temperatures during radiation frost nights. Note that the program will provide good estimates if there is little or no wind, no significant cold air drainage, and no clouds.
The FTrend Excel application programs FTrend_E.xls and FTrend_M.xls are available from this link. The FTrend application program is used for estimating changes in air and wet-bulb temperatures during a frost night. The application is useful for predicting when to start sprinklers for frost protection and for other methods as well.
Estimating Risk of Frost Damage from Climate Data (new 8 Jul 2006)
One of the programs included with the book Frost protection: fundamentals, practice, and economics. Volume 2, which is available from the UN FAO is the Frisk program. Information on how to obtain the book is presented above on this web page. Based on reader feedback, some improvements have been made to the Frisk application since the book was published. Updated versions of the application are made available to the public here. The Frisk program is an MS Excel application that is designed to help growers to make decisions on the risk of frost damage in a particular location. The user inputs the local climate data and a critical damage temperature, and the application computes the probability of temperature falling below the critical temperature on each day of the year. These data are then used to estimate the length of the growing season relative to the critical temperature by presenting a graph of the probability that the growing season will be less than a specific number of days. The application also computes the certainty that no air temperature will fall below the critical damage temperature after a selected date in the spring or before a selected date in the fall for design periods of 5, 10, …, 30 years. This certainty of no events is equivalent to the risk of having one or more events during the same time period. Although Celsius temperature was used in the example application programs, the program works equally well using Fahrenheit temperature. To obtain a copy of the application, click on FriskNH.xls for the northern hemisphere or FriskSH.xls for the southern hemisphere. Note that metric units were used in the Frisk application sample data.
Public Value: UCANR: Promoting economic prosperity in California
- 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.
