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Posts Tagged: biocontrol
UCCE researchers target sugar-feeding ants, a key to controlling citrus pests, disease
Sugar-feeding ants protect pests that infect trees and damage the fruit they bear. Insecticides are often a go-to solution, but may kill beneficial insects in the process, too. Thankfully, Mark Hoddle, University of California Cooperative Extension entomologist and biological control specialist at UC Riverside, together with UCR colleagues in chemical engineering, developed a biodegradable hydrogel baiting system that targets ant populations, which protect sap-sucking pests from their natural enemies. Control of ants allows beneficial parasitoids and predators to greatly reduce pest populations.
Deciding to expand Hoddle's research was a “no-brainer” according to David Haviland, UC Cooperative Extension farm advisor in Kern County.
Haviland is investigating active ingredients that can be effectively used in hydrogel baiting systems. His research builds on Hoddle's use of alginate gels, also known as water beads, soaked in sugar water to control Argentine ants.
“What we're doing in California can benefit places like Florida, Texas, Mexico and beyond,” Haviland said.
The Hoddle lab conducted two years of orchard research showing that when ants are controlled, the amount of citrus flush infested with Asian citrus psyllid (ACP), a mottled brown insect that vectors the pathogen causing citrus greening, decreases by 75%. Citrus flush refers to newly developed leaves.
“But benefits are not restricted to just ACP with Argentine ant control, as natural enemies destroy colonies of other sap-sucking pests too,” said Hoddle. “For example, citrus mealybug infestations on leaves were completely eliminated by natural enemies, 100% control, while densities of fruit infested by mealybugs were reduced by 50%.”
The Hoddle lab's success inspired Haviland to consider how this approach will fare in different regions of the state where there are different crops, different pests and different ant species.
Haviland has worked for many years on solid baits that are effective and affordable for ants that feed primarily on protein, like fire ants in almonds, but successful control measures for sugar-feeding ants that drink their food have been elusive.
“Therefore, we're using hydrogels to essentially turn a liquid bait into a solid, making it effective and commercially adoptable,” Haviland said. He and his team are assessing whether active ingredients that undoubtedly work against ants, like thiamethoxam, maintain their effects in a hydrogel system.
Unlike Hoddle's biodegradable alginate gels, Haviland is relying on acrylamide gels that are similar to the absorbing material you would find in a diaper. These gels are not organic, but are currently accessible on a commercial scale, and have been shown to be effective in wine grapes on the North Coast by a Cooperative Extension advisor in Napa County, Monica Cooper. Haviland's current research efforts are focused on citrus, table grapes and wine grapes in the San Joaquin Valley, and on lemons on the coast.
The primary challenge now is navigating pesticide regulations and registration.
“This is cutting-edge research,” Haviland said, and manufacturer labels for the products being used need to be updated to include hydrogels as an approved use. This process takes time. Additionally, adding new product uses needs to make economic sense for the manufacturer.
Hoddle and Haviland's research can provide data for adding these methods to the product labels.
“If we can show that this tech works against lots of pests, lots of ant species, in lots of different crops across California, hopefully we'll achieve a critical mass of benefits that motivates product manufacturers to make modifications to their labels,” said Haviland.
Haviland is hopeful about the process, and said he believes that UC ANR is in a prime position to lead innovation for an issue that requires collaboration among specialists, advisors and the industry.
Let's Hear It for Biocontrol, Integrated Pest Management
Let's hear it for biocontrol. You've seen lady beetles, aka ladybugs, preying on aphids. But have you seen an assassin bug attack a spotted...
An assassin bug drills a pest, a spotted cucumber beetle. (Photo by Kathy Keatley Garvey)
A lady beetle, aka ladybug, snares an aphid. (Photo by Kathy Keatley Garvey)
A crab spider munches on a stink bug. (Photo by Kathy Keatley Garvey)
A great blue heron engages in a little pest management: it catches a rodent, a meadow vole, at Bodega Bay. (Photo by Kathy Keatley Garvey)
The great blue heron gets its prey, a meadow vole, in position before swallowing it whole. (Photo by Kathy Keatley Garvey)
Alfalfa YouTube Finalist
We are excited to announce that our Alfalfa IPM YouTube video titled, “Identification of parasitized alfalfa caterpillars and armyworms”,...
YouTube video showing how to identify parasitized caterpillars in alfalfa fields
Sesame seed-size insect is victimizing trees in Southern California
Akif Eskalen, UC Cooperative Extension plant pathology specialist at UC Riverside, wants to contain this invasive bug before it spreads throughout Southern California.
"If we can't control them," Eskalen said, "they are going to wipe out all our trees."
Box elders, sycamores, American sweetgum, maple and coast live oaks are susceptible to polyphagous shot hole borer attack. In urban and suburban areas, the dead and dying trees can pose fire and limb falling dangers. In the agricultural sector, avocado trees could face huge financial losses. In the fight against the pest, the California Avocado Commission has provided Eskalen $800,000 to broaden his investigation into this mysterious species of ambrosia beetle.
In March, Eskalen and his colleagues - UC Riverside entomologist Richard Stouthamer and Huntington Library curator of woody collections Tim Thibault - spent two weeks in Vietnam, where PSHB originates, searching forests and fields for natural enemies of the fungus spread by the pest. They collected a host of possible allies, whose DNA is now being analyzed in the lab.
"I am very hopeful that we are going to find some solutions to control this fungus," Eskalen said. "We have to."
Invasive meltdown
Ants can be a huge nuisance in and outside our homes, particularly if you have food lying around. But now, it turns out, they’re unwelcome, too, on citrus trees.
A year ago, UC Riverside entomologists released Tamarixia, a parasitoid wasp and natural enemy of the Asian citrus psyllid (ACP) imported from Pakistan, into a biocontrol grove in Riverside, Calif. Tamarixia can serve as an excellent biocontrol agent against ACP, a citrus pest first detected in 2008 in Southern California that is capable of spreading citrus greening disease, or Huanglongbing.
Female Tamarixia can kill psyllids also by “host-feeding.” They use their ovipositors as daggers to stab psyllid nymphs numerous times until the nymphs start to bleed. As bodily fluids ooze out of the nymph, Tamarixia sucks up this rich protein needed for developing more eggs.
An excellent way then to control ACP populations! Yes, but only until the ants come marching in. Argentine ants are threatening to disrupt the biocontrol of ACP by battling it out with Tamarixia on citrus branches. While not quite a Vader-Skywalker lightsaber duel on a precarious walkway, an “invasive meltdown” begins when the ants gang up to protect the nymphs.
“ACP nymphs produce a white, sugary waste product called honeydew, a good carbohydrate source for the ants,” explains Mark Hoddle, the director of the Center for Invasive Species Research at UC Riverside, whose research team has released Tamarixia into several Southern California citrus groves. “The ants, therefore, will protect the nymphs from Tamarixia. We have seen ants chase female Tamarixia off the psyllids, and even catch and eat them!”
“If you kill off the ants, Tamarixia can play the role of the biocontrol agent it was cast to do on citrus trees,” Hoddle says. “We’re seeing that the ants are impacting Tamarixia in two ways: they are preventing Tamarixia’s establishment in some areas; and, where Tamarixia is already established, the ants are not allowing these parasitoids to reach their full biocontrol potential.”
