Posts Tagged: predators

Insectary Plantings, Think About Them.

Home is where the habitat is: This Earth Day, consider installing insectary plants

—Stephanie Parreira, UC Statewide IPM Program

Help the environment this Earth Day, which falls on Sunday April 22 this year, by installing insectary plants! These plants attract natural enemies such as lady beetles, lacewings, and parasitic wasps. Natural enemies provide biological pest control and can reduce the need for insecticides. Visit the new UC IPM Insectary Plants webpage to learn how to use these plants to your advantage.

The buzz about insectary plants

Biological control, or the use of natural enemies to reduce pests, is an important component of integrated pest management. Fields and orchards may miss out on this control if they do not offer sufficient habitat for natural enemies to thrive. Insectary plants (or insectaries) can change that—they feed and shelter these important insects and make the environment more favorable to them. For instance, sweet alyssum planted near lettuce fields encourages syrphid flies to lay their eggs on crops. More syrphid eggs means more syrphid larvae eating aphids, and perhaps a reduced need for insecticides. Similarly, planting cover crops like buckwheat within vineyards can attract predatory insects, spiders, and parasitic wasps, ultimately keeping leafhoppers and thrips under control.

Flowering insectaries also provide food for bees and other pollinators. There are both greater numbers and more kinds of native bees in fields with an insectary consisting of a row of native shrubs planted along the field edge (called a hedgerow). Native bees also stay in fields with these shrubs longer than they do in fields without them. Therefore, not only do insectaries attract natural enemies, but they can also boost crop pollination and help keep bees healthy.

Insectary plants may attract more pests to your crops, but the benefit is greater than the risk

The possibility of creating more pest problems has been a concern when it comes to installing insectaries. Current research shows that mature hedgerows, in particular, bring more benefits than risks. Hedgerows attract far more natural enemies than insect pests. And despite the fact that birds, rabbits, and mice find refuge in hedgerows, the presence of hedgerows neither increases animal pest problems in the field, nor crop contamination by animal-vectored pathogens. Hedgerow insectaries both benefit wildlife and help to control pests.

How can I install insectary plants?

Visit the Insectary Plants webpage to learn how to establish and manage insectary plants, and determine which types of insectaries may suit your needs and situation. If you need financial assistance to establish insectaries on your farm, consider applying for Conservation Action Plan funds from the Environmental Quality Incentives Program (EQIP) offered by the Natural Resources Conservation Service.

Sources:

• Flower flies (Syrphidae) and other biological control agents for aphids in vegetable crops. (PDF)
• Good news for hedgerows: no effects on food safety in the field.
• Hedgerow benefits align with food production and sustainability goals.
• Habitat restoration promotes pollinator persistence and colonization in intensively managed agriculture. (PDF)
• Reducing the abundance of leafhoppers and thrips in a northern California organic vineyard through maintenance of full season floral diversity with summer cover crops.

insectary plants

Support Biocontrol Program

Harry S. Smith, was born in 1883 to a poor farming family in Nebraska. He was trained in Biological Control in the northeast U.S.A. where he worked on the biological control of gypsy moth with the USDA. Upon his appointment to Sacramento in 1913 to work on biological control issues important to California, Smith brought recognized entomological training in biological control to California for the first time.

The phrase “Biological Control” was first used by Smith in August 1919 at the meeting of Pacific Slope Branch of the American Association of Economic Entomologists at the Mission Inn in downtown Riverside.

Based on his experiences on biological control of forest and pasture pests, Smith brought caution and tempered exaggeration about biological control in California as he worked with citrus growers and other commodity groups.

In 1923, Smith and four colleagues moved from Sacramento to the University of California Riverside Campus which had evolved from the Citrus Experiment Station (est. 1915) and he formed the Division of Beneficial Insect Investigations which was a unit distinct from the Division of Entomology. Prof. Harry, as he was
 affectionately known, is fondly remembered by his students as a patient and generous supervisor who encouraged research and work on applied and
practical aspects of biological control.

Smith went on to create the Department of Biological Control which offered the only graduate training in Biological Control in the world. The Department of Biological Control became the Division of Biological Control in 1969 which then merged into Department of Entomology at UC Riverside in 1988. Prof. Harry had two sons, both trained to be entomologists. Instead of pursuing biological control they went into the pesticide industry and Sam Smith died accidentally from pesticide poisoning. Prof. Harry passed away in 1957 and left UC Riverside $15,000 to develop a scholarship fund to support training and education in biological control. This fund has grown to approximately $45,000 today, but is insufficient to provide meaningful support to students wanting to be trained in biological control.

Our goal is to build the Harry S. Smith Scholarship fund to a significant level where the corpus of the fund will be able to generate enough revenue to provide substantial support to students wanting to be trained in biological control. This can only be achieved by actively soliciting donations from individuals, industries, and organizations that have benefited over the years from biological control projects that have that have been run by UC scientists, in particular entomologists at UC Riverside. If biological control is to continue to prosper in southern California we need to continue recruiting and training high quality students. To do this, we need to be able to provide substantial financial support, and the Harry S. Smith Scholarship is one way to attract excellent students to UC Riverside.

Learn more about the program and how you can push the fund over the top at:

http://biocontrol.ucr.edu/hoddle/harrysmithfund.html

 

parasitic wasp laying

Biocontrol and Timing of Augmentative Releases

TYPES OF NATURAL ENEMIES

Parasites, pathogens, and predators are the primary groups used in biological control of insects and mites (Table 1). Most parasites and pathogens, and many predators, are highly specialized and attack a limited number of closely related pest species. Learn how to recognize natural enemies by consulting resources such as the Natural Enemies Handbook and the Natural Enemies Gallery.

Parasites

A parasite is an organism that lives and feeds in or on a host. Insect parasites can develop on the inside or outside of the host's body. Often only the immature stage of the parasite feeds on the host. However, adult females of certain parasites (such as many wasps that attack scales and whiteflies) feed on and kill their hosts, providing an easily overlooked but important source of biological control in addition to the host mortality caused by parasitism.

Although the term “parasite” is used here, true parasites (e.g., fleas and ticks) do not typically kill their hosts. Species useful in biological control, and discussed here, kill their hosts; they are more precisely called “parasitoids.”

Most parasitic insects are either flies (Order Diptera) or wasps (Order Hymenoptera). Parasitic wasps occur in over three dozen Hymenoptera families. For example, Aphidiinae (a subfamily of Braconidae) attack aphids. Trichogrammatidae parasitize insect eggs. Aphelinidae, Encyrtidae, Eulophidae, and Ichneumonidae are other groups that parasitize insect pests. It's important to note that these tiny to medium-sized wasps are incapable of stinging people. The most common parasitic flies are the typically hairy Tachinidae. Adult tachinids often resemble house flies. Their larvae are maggots that feed inside the host.

Pathogens

Natural enemy pathogens are microorganisms including certain bacteria, fungi, nematodes, protozoa, and viruses that can infect and kill the host. Populations of some aphids, caterpillars, mites, and other invertebrates are sometimes drastically reduced by naturally occurring pathogens, usually under conditions such as prolonged high humidity or dense pest populations. In addition to a naturally occurring disease outbreak (epizootic), some beneficial pathogens are commercially available as biological or microbial pesticides. These include Bacillus thuringiensis or Bt, entomopathogenic nematodes, and granulosis viruses. Additionally, some microorganism by-products, such as avermectins and spinosyns are used in certain insecticides; but applying these products is not considered to be biological control.

Predators

Predators kill and feed on several to many individual prey during their lifetimes. Many species of amphibians, birds, mammals, and reptiles prey extensively on insects. Predatory beetles, flies, lacewings, true bugs (Order Hemiptera), and wasps feed on various pest insects or mites. Most spiders feed entirely on insects. Predatory mites that feed primarily on pest spider mites include Amblyseius spp., Neoseiulus spp., and the western predatory mite, Galendromus occidentalis.

AUGMENTATION

When resident natural enemies are insufficient, their populations can sometimes be increased (augmented) through the purchase and release of commercially available beneficial species. However, there has been relatively little research on releasing natural enemies in gardens and landscapes. Releases are unlikely to provide satisfactory pest control in most situations. Some marketed natural enemies are not effective. Many natural enemies are generalist predators and are cannibalistic and feed indiscriminately on pest and beneficial species, thereby reducing their effectiveness.

Only a few natural enemies can be effectively augmented in gardens and landscapes. For example, entomopathogenic nematodes can be applied to control certain tree-boring and lawn-feeding insects. Convergent lady beetles (Hippodamia convergens) purchased in bulk through mail order, stored in a refrigerator, and released in very large numbers at intervals can temporarily control aphids; however, lady beetles purchased through retail outlets are unlikely to be sufficient in numbers and quality to provide control.

Successful augmentation generally requires advanced planning, biological expertise, careful monitoring, optimal release timing, patience, and situations where certain levels of pests and damage can be tolerated. Situations where pests or damage are already abundant are not good opportunities for augmentation.

A classic example of poor timing for augmentative release of predatory mites for control of broad mite in coastal lemon or persea mite in avocado is right now. Pest populations for the most part have soared and releasing predatory mites is little help. Predatory mites need to be releases into a small growing population, so in both of these cases it would have been better to start small, frequent releases early and throughout the spring to knock their populations back.

 

Adult predatory mite, Euseius tularensis, and citrus red mite.

predatory mite

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