How ants can be “good” in ag production systems
By: Madison Sankovitz, UCR Entomology, Ph.D. Candidate, Purcell Lab, UC Riverside
Ants are often underappreciated in the United States for their natural benefits to agriculture. Organized as predatory superorganisms, ants often play an important role in pest management. Further, their influence extends beyond their pest control abilities; many ants live in soil and play a crucial role in maintaining soil fertility. Although recognized for their aphid-protecting tendencies and thus disliked by many growers, many traits of ants make them not only beneficial insects in agricultural settings but possibly a significant solution for sustainable food production moving forward.
The ability of ants to suppress pest species in an efficient way has been known since the year 300 A.D., and farmers continue to conserve and promote ant populations in agricultural systems in many regions of the world (Drummond & Choate 2011). They eat the larvae and eggs of pests and also disturb them during feeding and oviposition (e.g. López & Potter 2000). Weaver ants Oecophylla spp. (which live throughout Asia and Australia) are arguably the most well-documented ant genus used in biological control, but similar effects may occur in ants worldwide. Weaver ants share beneficial traits with nearly 13,000 other ant species and are unlikely to be unique in their properties as control agents (Offenberg 2015). For example, all ants can store protein in the form of trophic eggs and brood that can be cannibalized (Nonacs 1991), making their colonies stable and predictable service. Similar social and morphological traits in other ant species suggest great potential for the use of native California ants in the control of arthropod pests, weeds, and plant diseases in orchards and arable crops.
In addition to pest control, ants are important soil agents in agricultural systems because they contribute to aeration and fertilization, leading to higher soil quality. Aeration is the creation of pockets of air in soil, which help nutrients, water, and fertilizers seep into the soil and reach a greater extent of root systems throughout an agricultural plot. Ants aid in this process by digging a labyrinth of tunnels within the soil. Furthermore, ants introduce outside nutrients (e.g. seeds and insects) to the aerated soil through their foraging; food sources brought into the nest by worker ants decay and fertilize the surrounding plants, especially in no-till plots (Lange et al. 2008). For example, one field experiment showed that ants and termites increase wheat yield by 36% from increased soil water infiltration due to their tunnels and improved soil nitrogen (Evans et al. 2011). This result suggests that ants and termites have similar functional roles to earthworms (often regarded as the most important agents of soil turnover in many regions of the world). Additionally, they may provide valuable ecosystem services in dryland agriculture, which will become increasingly crucial for agricultural sustainability in arid climates, as is the case in some parts of California (Evans et al. 2011).
Ants as Indicators
The presence of ants alone can be beneficial for growers; ants have been suggested as effective bioindicators of soil quality, especially in low-income areas that do not have access to expensive soil monitoring equipment (De Bruyn 1999). Growers are being pressured to rectify the issues of land degradation by reforming their management techniques; however, there are few tools to monitor soil health that can reliably inform farmers of the wholistic state of their soil. If ants could be further investigated as accurate bioindicators, they would be valuable tools for use in agricultural practices worldwide.
Through changes in management practices such as tillage and other manipulations of vegetation and crop structure, beneficial ant populations can be conserved in a variety of agroecosystems. However, there is still much research to be done to determine the extent of agricultural services ants provide. Some ant species succeed in defending specific cropping systems, whereas others are damaging and yet others play dual roles. A future challenge is to determine positive and negative ant–crop pairs and to develop management practices that facilitate the positives and remove the negatives. Another possibility for research is to focus on the development of barriers that keep ants in soil and off of crops; this would allow them to carry out their soil services while not tending phloem-feeding insects. Additionally, there is a need for better documentation of ant biodiversity in agricultural soils in many regions of the world, including California. This data will allow for evaluation of ants as bioindicators of soil quality and predictions of the vulnerability of ant species under future changes in land use and climate. If we can better understand species patterns and the multitude of roles ants play in agricultural systems, they can be utilized for more sustainable food production in the future.
De Bruyn, L. L. (1999). Ants as bioindicators of soil function in rural environments. In Invertebrate Biodiversity as Bioindicators of Sustainable Landscapes (pp. 425-441).
Drummond, F., & Choate, B. (2011). Ants as biological control agents in agricultural cropping systems. Terrestrial Arthropod Reviews, 4(2), 157-180.
Evans, T. A., Dawes, T. Z., Ward, P. R., & Lo, N. (2011). Ants and termites increase crop yield in a dry climate. Nature communications, 2, 262.
Lange, D., Fernandes, W. D., Raizer, J., & Faccenda, O. (2008). Predacious activity of ants (Hymenoptera: Formicidae) in conventional and in no-till agriculture systems. Brazilian archives of Biology and Technology, 51(6), 1199-1207.
López, R., & Potter, D. A. (2000). Ant predation on eggs and larvae of the black cutworm (Lepidoptera: Noctuidae) and Japanese beetle (Coleoptera: Scarabaeidae) in turfgrass. Environmental Entomology, 29(1), 116-125.
Nonacs, P. (1991). Less growth with more food: how insect-prey availability changes colony demographics in the ant, Camponotus floridanus. Journal of Insect Physiology, 37(12), 891-898.
Offenberg, J. (2015). Ants as tools in sustainable agriculture. Journal of Applied Ecology, 52(5), 1197-1205.
Rüppell, O., & Kirkman, R. W. (2005). Extraordinary starvation resistance in Temnothorax rugatulus (Hymenoptera, Formicidae) colonies: demography and adaptive behavior. Insectes Sociaux, 52(3), 282-290.
UC Riverside is testing whether a sesame seed-sized wasp can control a pest that could seriously damage California crops including wine, walnuts, and avocados.
The pest, a sap-sucking spotted lantern fly, is originally from China and was first detected five years ago in Pennsylvania. Since then, large populations have spread rapidly to grape vines, apple trees, and other plants in New York, Delaware, New Jersey, Maryland, and Virginia.
Experts believe the lantern fly is likely to make its way to California soon.
“It secretes copious amounts of “honeydew,” a waste product that encourages black, sooty mold and damages a plant's ability to grow,” he said. The honeydew also attracts undesirable insects such as ants and hornets.
The impacts could extend well beyond California. According to industry reports, the state is the world's fourth-largest wine producer, selling an estimated $35 billion domestically and exporting $1.5 billion annually.
Around 44% of nonnative insects arriving in California were first established elsewhere in the U.S. Given the speed with which the spotted lantern fly has spread, Hoddle realized the state needed a proactive approach to this predictable problem.
“Normally, when a bug shows up, we try to contain and eradicate it,” Hoddle said. “But by the time the population is found, it tends to already be widespread and hard to handle.”
The state Department of Food and Agriculture recently granted Hoddle $544,000 to test whether a tiny parasitic wasp, also originally from China, could be the solution to the looming problem. Hoddle explained that the wasp has a needle-like appendage it uses to lay its own eggs inside the lantern fly's eggs. While developing, the wasp larvae eat and kill their hosts, and then emerge after chewing escape holes through the lantern fly eggs.
These wasps pose no threat to plants or people, but before they can be used to control the lantern fly, Hoddle must prove they won't cause unnecessary harm to other native insects. “We can't just release a Chinese parasite into the wild in California,” Hoddle said. “Chances are low it will harm the wrong targets, but we have to be sure.”
Safety testing will be conducted in a highly secure quarantine facility at UC Riverside. Native lantern flies, the subjects of safety testing, will be collected from natural areas in California and southern Arizona this summer.
Though the wasp is now being evaluated as a biological control on the East Coast, populations of lantern fly there have already grown large enough to cause significant concern for the grape industry, Hoddle said.
A spotted lantern fly's wingspan is about 1.5 inches, and at most they can fly a few hundred feet at a time if they're assisted by the wind. The lantern fly has spread so fast in part because the females lay eggs on nonbiological materials, such as train cars, motor homes, wooden pallets, and trucks that inadvertently move them into new territories.
“Anyone on the East Coast driving to California should be especially vigilant about checking their vehicle for egg masses before they make the journey,” Hoddle warned. “Failing to notice them could have serious consequences.”
Hoddle's testing will take roughly three years, and he estimates that this may be around the time when the wasps will be needed in California. “We hope to be ready to release these wasps immediately when the spotted lantern fly shows up, giving us a really strong head start on the invasion,” he said.
reposted from: https://news.ucr.edu/articles/2019/06/17/looming-insect-invasion-threatens-california-wine-and-avocados
Great video of Lantern Fly life stages from Penn State
Photo: Lantern fly egg mass
Biological control is the management of pests and their damage by the beneficial action of parasites (parasitoids), pathogens, and predators. These beneficial organisms, collectively, are named natural enemies.
Conserving (or protecting) and releasing natural enemies are important components of integrated pest management (IPM). In most situations, employing practices that conserve natural enemies is more effective, and less expensive and time consuming, than purchasing and releasing them.
Learn about the specific situations where purchasing and releasing parasites and predators can increase the effectiveness of biological control. Before purchasing natural enemies, consult the University of California (UC) IPM Pest Management Guidelines for that crop to learn whether UC research has shown that releasing them is effective. Some natural enemies on the market have never been demonstrated to effectively control any agricultural pest in California.
Obtaining Natural Enemies
Natural enemies can be purchased directly from various producers (companies that rear them) and suppliers (companies that purchase from producers and repackage and resell them). Some sources of parasites and predators are members of the Association of Natural Biocontrol Producers (ANBP). All ANBP members formally agree to a code of ethics and standardized methods.
Natural enemies purchased by users are commonly delivered via shipping services. Purchase parasites and predators only from in-state providers. It is illegal to obtain insects and other arthropods outside of California and carry or have them shipped across state lines without a permit from agricultural officials. Some pest control advisers and pest scouts will procure and release natural enemies as a service for growers.
Methods for Releasing Natural Enemies
Two methods for releasing natural enemies are inoculation and inundation:
- Inoculation—relatively few natural enemies are released. The offspring of these natural enemies provide biological control, not the individuals released.
- Inundation—large numbers of natural enemies are released, often several times over a growing season. The natural enemies released, and possibly their offspring, provide biological control.
The mealybug destroyer is an example of a natural enemy that is only released through inoculation—at relatively low numbers once per year early in the growing season. Aphytis melinus and Trichogramma parasites are released by inundation—at regular intervals over the growing season—to control California red scale and eggs of pest moths, respectively. Both inoculation and inundation can be used with predatory mites, depending on the situation.
Releasing Natural Enemies Effectively
Releasing natural enemies is most likely to be effective in situations where: 1) University of California researchers or other pest management experts have previously demonstrated success and 2) some level of pests and their damage can be tolerated in that crop. Desperate situations are not good opportunities for releasing natural enemies. Pests or their damage may already be too widespread for any release of parasites or predators to prevent economic loss of crop quality or quantity.
Increase the likelihood that natural enemy releases will be effective by
- Accurately identifying the pest and its natural enemies.
- Learning about the biology of the pest and its natural enemies.
- Releasing the appropriate natural enemy life stage and species.
- Releasing when the pests' vulnerable life stage(s) are present and at numbers that can be controlled by natural enemy releases.
Natural enemies are unlikely to be effective when released as if you were applying a pesticide. Instead, anticipate pest problems and begin making releases before pests are too abundant or economic damage is imminent.
- Remember that natural enemies are living organisms that require food, shelter, and water. Protect them from extreme conditions. For example, release them at night or early in the day during hot weather.
- Avoid applying broad-spectrum, residual (persistent) insecticides and miticides, and in some situations certain systemic or other pesticides, before or after releasing natural enemies. When needed, use pesticides selectively. For example, spot spray only where pests are abundant but localized.
Common reasons for the lack of satisfactory biological control after releases include the
- Application of broad-spectrum, residual insecticides, or in some situations systemic or other pesticides, prior to or after a release.
- Incorrect timing of release.
- Release of the wrong natural enemy for the pest situation.
- Release of a natural enemy species that is known to be ineffective.
For information on the use of biological control, see the UC IPM Pest Management Guidelines for your crop and specific pests. Most crops have a table called “Relative Toxicities of Insecticides and Miticides to Natural Enemies and Honey Bees” in the “General Information” section. Use these resources to guide pesticide selection to conserve natural enemies and improve biological pest control.
- Association of Natural Biocontrol Producers, Clovis, CA
- Grower Guide: Quality Assurance of Biocontrol Products (pdf), Vineland Research and Innovation Centre, Ontario
- Insectary Plants
- Natural Enemies Gallery
- Natural Enemies Handbook: The Illustrated Guide to Biological Pest Control
- Protecting Natural Enemies and Pollinators
- UC IPM Pest Management Guidelines
this is a repost from:
Photo: Adult Aphytis melinus parasite laying her egg in California red scale, Aonidiella aurantii. Releases are most effective when ants are controlled, dust is minimized, and broad spectrum pesticide applications are avoided. Credit: Jack Kelly Clark, UC IPM Program/h2>/h2>/h2>/h2>
It seems the humble earwig that can cause so much damage in citrus orchards in some years on some small trees can be a great boon in biocontrol. Read on:
WSU scientists unmask the humble earwig as an apple-protecting predator
By Seth Truscott,
College of Agricultural, Human, and Natural Resource Sciences
Shy, invasive omnivore
Apple trees covered in “snow”
Aphids: Earwigs' favorite food
If you hang around an orchard long enough something unusual will show up, especially when seasons change and there's more rain than usual and it's cold, but not so cold that it freezes and it's prolonged. So out of San Diego comes a request for an identification of a brown bump on avocado stems. It's a brown aphid. Is it something of concern? Likely not. Over the years there have been reports of several aphids on avocado. Check out Walter Ebeling's "Subtropical Fruit Pests" at Avocadosource.com:
These things come and go, and they don't do any damage because once the biocontrol bugs get going, they are fresh meat for them.