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Author Topic: Here’s how to attract good garden bugs to fight the bad ones causing citrus gree  (Read 174 times)

A.T. Hagan

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Photo courtesy of Linda Richards
A hoverfly, which has been found to be effective against the Asian citrus psyllid and other pests, is on a brittlebrush plant in Linda Richards’ garden in Redlands.


http://www.redlandsdailyfacts.com/2017/09/11/there-is-such-a-thing-as-good-bugs-in-the-garden-heres-how-to-invite-them/

By Contributed Content |
PUBLISHED: September 11, 2017 at 12:21 pm | UPDATED: September 12, 2017 at 12:13 pm

By Linda Richards

Add plant diversity to your gardens and make sure you have flowering plants year round. Those are key recommendations of ecologists for enlisting insect natural predators to combat pests in our gardens and orchards.

These tips can even help ward off pests such as the Asian citrus psyllid, which is, alarmingly, moving into our citrus trees in Southern California.

Nicola Irvin, a specialist in biological control (using natural enemies to manage pests) at UC Riverside, began work 15 years ago with the sharpshooter insect that was devastating the grape industry. Her research today is focused more on the Asian citrus psyllid.

California Department of Food and Agriculture agricultural technician Maritza Paredes collects Asian citrus psyllid nymphs from a tangerine tree in the backyard of a home in Riverside on Tuesday, Aug. 1, 2017. The California Department of Food and Agriculture announced last week that Huanglongbing, a deadly citrus greening disease, has been found in Riverside. (Photo by Watchara Phomicinda, The Press-Enterprise/SCNG)

This article won’t go into all the amazing aspects of beneficial insects that not only help in pollination but also kill pests. What’s important to know is that thousands of overlooked native insects play vital roles. Some work by parasitizing the pest, that is, they lay eggs in them so their hatched larvae then feed on the pest. Others just eat the pests outright.

To understand how beneficial insects work, it is important to know that they and most pests go through many forms or instars, much like the monarch caterpillar. For example, the Asian citrus psyllid goes through five forms, or instars, before it’s an adult that can carry the bacterium that causes citrus greening disease.

Irvin explained that having many types of predators and parasitoids can prevent the pest from achieving its adult size, because these natural enemies will attack the pests in their various forms.

Native flies and wasps are particularly disregarded insects that are receiving more notice these days. For example, many adult female wasps perform double duty. They parasitize the host pests by laying eggs in them, and they kill hosts, such as scales and whiteflies, by feeding on them.

It’s important to note that none of these native wasps sting people, and they don’t build group nests. Some are tiny — the smallest is the size of a grain of sand — while medium-sized ones such as tachinid flies get mistaken for houseflies.

Irvin carries out research at UCR investigating the benefit of native flowering plants on the survival of parasitoids of the Asian citrus psyllid.

“When I planted some red California buckwheat in my yard, I also noticed it attracted a lot of hoverflies. Hoverflies eat scales, thrips, aphids and even the larvae form of ACP (Asian citrus psyllid). They’re generalists, so will eat many soft-bodied pests, and are very ravenous,” she said.

While lady beetles seem to provide the most control of the Asian citrus psyllid in Florida, this is not mirrored in Southern California.

“Hoverflies and lacewing have been identified as the most important predator of ACP nymphs in California. Their combined effect can kill 86 percent of ACP nymphs,” Irvin said.

Other natural predators of pests include spiders, beetles, predatory mites and a group called true bugs. Then there are natural predators such as birds, reptiles and even mammals such as the opossum.
Aphids among the peskiest pests

Irvin views aphids, mites and caterpillars as the most prevalent pests for backyard gardeners in the inland areas of Southern California, adding that mites can be particularly problematic in our dusty environments.

“However, if you forcefully spray the leaves with water and keep the dust down, that will help reduce mite populations. Be sure to provide adequate irrigation, as water-stressed trees and plants are also less tolerant of mite damage,” Irvin said.

For cutworms, loopers and hornworms, three common types of caterpillar, Irvin recommends Bacillus thuringiensis, commonly called Bt, a targeted organic insecticide that affects only caterpillars. Remember, however, that the despised tomato hornworm turns into the beautiful sphinx moth.

Adding diversity and year-round flowering plants

Irvin said the most important thing you can do to attract beneficial insects is add different types of plants to your yard.

“Increasing plant diversity in your garden attracts more beneficial insects by providing a wider variety of habitats and alternative foods to predators, parasitoids and pollinators,” Irvin said. “Introduce lots of native plants if you can, because they are adapted to the environment and require less water. They also attract native birds and insects, like native beeflies and robber flies, that will reduce mosquitos and insect pests.”

Also, make sure you have flowering plants year round to provide them nectar and pollen. Otherwise, beneficial bugs will move off. These flowering native plants in Linda Richards' garden in Redlands attract beneficial insects. They include California poppies, ceanothus, sage and St.Catherine’s lace buckwheat (Erigonium giganteum).
“It’s especially good to plant flowering plants that are composites or from the Asteraceae family, which have shallow flowers that most natural enemies can feed from,” Irvin said.

The various varieties of California buckwheat, goldfields and tidy tips are good examples of flowering plants to attract beneficial predators. Another that Irvin mentioned is California poppies, because this heavy pollen producer attracts ladybugs, lacewings and hoverflies. Plus, they reseed and come back year after year. Sweet alyssum and common buckwheat also work well if you prefer non-native annuals.

Irvin also recommends letting herbs go to flower, such as coriander and dill, because they attract a lot of beneficial insects.

Use targeted approaches over general sprays

Ken Kupfer is a popular speaker on using biological controls for pests. His main home is in Florida, where he has witnessed the psyllid infestation. He is the developer of a targeted bait called KM AntPro for the Argentine ant, and his work with organic and sustainable growers finds him in California nearly half the year. Kupfer’s work on Argentine ants has also made him a proponent of natural remedies for pests.

“With Argentine ants, if you can take their crazy colonies away, then the natural pollinators and predators can come in,” Kupfer said.

Argentine ants form supercolonies that forage on the honeydew that is excreted by aphids, scales and mealybugs. They are so protective that they swarm and kill any natural predators in their midst.

Kupfer and Irvin said that if there is overkilling of natural predators that are present in a given environment, whether it’s by the Argentine ant or by overuse of insecticide sprays that kill anything they come in contact with, pest levels stay high or, in the case of sprays, actually rebound.

Kupfer said he hopes California can do a more reasoned approach to combating the psyllid, especially since the psyllid is showing up in public neighborhoods.

“In Florida, the use of systemic pesticides and foliar pesticides is mandated for the citrus crops. It’s really saturated the environment and it of course kills 99 percent of other bugs it comes in contact with,” he said.

Kupfer said employing the parasitoid wasp, a natural predator for the psyllid overseas, is a good idea, but he cautions that “it is like using a fighter plane in the battle, when we can’t forget about all the other predators.”

In 2011 Kupfer discovered the psyllid on his Florida property. He began a five-year study using 70 trees in the vicinity and various kinds of flowering plants to introduce large numbers of natural predators. He also knocked down the Argentine ants on his property. His positive results included minimal tree mortality and no need for spraying.

“We need to use the natural predators in Florida or California and feed them into our ecosystems. By taking a small area on your property and having some native plants, whether it’s native milkweed or buckwheat, that will usher in the assassin bugs and lacewings,” Kupfer said.

In addition to adding diversity, Irvin and Kupfer said moderation is important in biological control.

“First, if you have large diversity in your garden, it will recover more easily from pest infestations,” Irvin said.

“Second, if I find aphids and kill all the aphids by spraying them, I may have a worse outcome. Instead, get out the water hose and hose off some of the aphids, but you don’t have to get rid of them all because you want to keep some of their natural enemies around.”

Linda Richards is a member of the Redlands Horticultural and Improvement Society and lives in Redlands. Her website www.ifnaturecouldtalk.com is dedicated to speaking for the natural world. Contact her at linda@ifnaturecouldtalk.com

Millet

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California and Florida are distributing wasps for psyllid control.

cory

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AT Hagan, thank you for another interesting post.
Cory

brettay

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Great post!  Thank you.  One piece of anecdotal evidence, in the past I have had a moderate amount of citrus leaf miner activity which peaks in the late summer and fall.  This past year I planted a bunch of eriogonum species which attract a ridiculous number of native insects including hover flies and parasitic wasps.  This year I have had zero leafminer activity.  I’m sure there are many potential reasons for this but my hopes are that the eriogonum species with their ability to attract leaf miners’ natural predators had a significant impact.

A.T. Hagan

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My gosh there are a lot of eriogonum species.

Looks like at least one occurs in Florida.  I'm going to see if I can find a seed source.

Thanks for the tip.  Leafminers are a major annoyance for me.


fyliu

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Great post and worth the read! For people in a hurry, I highlighted the recommended plants.
Quote
They include California poppies, ceanothus, sage and St.Catherine’s lace buckwheat (Erigonium giganteum).
“It’s especially good to plant flowering plants that are composites or from the Asteraceae family, which have shallow flowers that most natural enemies can feed from,”

The various varieties of California buckwheat, goldfields and tidy tips are good examples of flowering plants to attract beneficial predators. Another that Irvin mentioned is California poppies, because this heavy pollen producer attracts ladybugs, lacewings and hoverflies. Plus, they reseed and come back year after year. Sweet alyssum and common buckwheat also work well if you prefer non-native annuals.

Irvin also recommends letting herbs go to flower, such as coriander and dill, because they attract a lot of beneficial insects.

 

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