{"id":7649,"date":"2020-11-11T15:22:22","date_gmt":"2020-11-11T15:22:22","guid":{"rendered":"https:\/\/www.nnyagdev.org\/?p=7649"},"modified":"2020-11-11T15:22:34","modified_gmt":"2020-11-11T15:22:34","slug":"persistent-biocontrol-nematodes-what-why-how-when-and-where-to-get-them","status":"publish","type":"post","link":"https:\/\/nnyagdev.org\/index.php\/2020\/11\/11\/persistent-biocontrol-nematodes-what-why-how-when-and-where-to-get-them\/","title":{"rendered":"Persistent Biocontrol Nematodes: What, Why, How, When and Where to Get Them"},"content":{"rendered":"

Note: <\/strong>The use of biocontrol nematodes for the management of alfalfa snout beetle, and the depth of science behind it, was pioneered by Dr. Shields and Tony Testa with long-term funding support from the farmer-driven Northern New York Agricultural Development Program. The NNYADP was committed to finding a science-based solution for the most destructive alfalfa pest that was impacting alfalfa production and the related milk production for NNY dairy farms.<\/em><\/p>\n

Are Persistent Biocontrol Nematodes (Entomopathogenic) an Economic Benefit for Your Northern NY Farm?
\n<\/strong>By Elson Shields and Tony Testa, Department of Entomology, Cornell University, Ithaca , NY<\/p>\n

\"Adult
An adult alfalfa snout beetle. Photo: Tony Testa<\/em><\/figcaption><\/figure>\n

What are Biocontrol Nematodes?
\n<\/u><\/strong>Biocontrol nematodes are microscopic round worms in the soil which only attack insects in the soil or on the soil surface.\u00a0 These are different nematodes from the plant parasitic nematodes which attack crops.\u00a0 The biocontrol nematodes discussed here are native to our NNY soil where they were original collected.\u00a0 The nematode insect infective stage (called the Infective Juvenile or IJ) moves about in the soil in search of insect hosts, finding the insect using CO2 gradients and other chemical attractants.\u00a0 When an insect host is located, the IJ enters the insect through a breathing opening called a spiracle and enters the insect body cavity.\u00a0 Once inside, the nematode releases a bacteria which kills in insect.\u00a0 The nematodes then molt to adults and produce offspring on the nutrition provided by the dead insect.\u00a0 When the insect resources are consumed, a new set of IJs are released into the soil to search additional insect hosts.\u00a0 An average sized insect larvae will produce between 100,000 and 200,000 new IJs.<\/p>\n

What Do These Biocontrol Nematodes Attack
\n<\/u>Alfalfa Snout Beetle:<\/strong>
\nThis entire technology was developed to reduce snout beetle populations to sub-economic levels within NNY.\u00a0 This insect is costly to the dairy farmer, commonly killing out alfalfa in a single year.\u00a0 The economic costs of this insect on dairy farmers is very high and often hidden.\u00a0 Dairy farms are impacted with the high cost of replacing alfalfa fields and the high cost of purchasing replacement feed to replace the lost alfalfa production.\u00a0 Estimates of these dual costs exceed $30,000 per 100 cows on the farm annually.\u00a0 To date, more than 150 NNY farms have applied biocontrol nematodes to >25,000 acres to successfully reduce snout beetle to a sub-economic level and increase stand life back to 3-5 years.<\/p>\n

Corn Rootworm:<\/strong>
\nDuring the research developing this technology for snout beetle, it was discovered that biocontrol nematodes applied in alfalfa for snout beetle control also carryover to attack corn rootworm when the field is rotated to corn.\u00a0 Not only are the biocontrol nematodes completely compatible with all of the Bt-RW traits, killing the Bt toxin survivors, but in NY, the biocontrol nematodes appear to be capable of being used alone if the farmer chooses to grow non-Bt-RW traited corn.\u00a0 Research has shown that after 4 years of corn, the populations of biocontrol nematodes in the field are high enough to attack snout beetle when the field is rotated back to alfalfa.<\/p>\n

Wireworm and White Grubs:<\/strong>\u00a0 Since NNY alfalfa culture usually incorporates grass into the mix, NNY fields usually have a population of wireworms and native white grubs in the field when the field is rotated to corn.\u00a0 Often, these insects then cause stand problems in 1st<\/sup> year corn.\u00a0 If the field has been inoculated with biocontrol nematodes for control of either snout beetle or rootworm, the biocontrol nematodes also attack these insects and reduce their impact on seedling corn when rotated to corn.<\/p>\n

Seed Corn Maggot:\u00a0 <\/strong>With our corn and soybean insecticide seed treatments under attack, the questions arises whether biocontrol nematodes present in the soil will be effective against seed corn maggot under NY spring conditions.\u00a0 Seed corn maggot is killed by biocontrol nematodes in the laboratory, but the question is whether the biocontrol nematodes can work fast enough in the field under the cool spring soil temperatures.<\/p>\n

Does the Soil Type Influence the Species of Biocontrol Nematode Applied?
\n<\/u><\/strong>NY research data indicates a mix of biocontrol nematode species gives better control of soil insects than a single species alone.\u00a0 The reason of these results is each nematode species has a preferred section of the soil profile where it is the most effective.\u00a0 For example, Steinernema carpocapsae<\/em> prefers the top 2-3\u201d of the soil profile and becomes the dominate species in this region.\u00a0 If S. carpocapsae<\/em> is the only nematode used, insect larvae below the 2\u201d level escape attack from S. carpocapsae.<\/em>\u00a0 A second nematode species which prefers the low portions of the soil profile complements the presence of S. carpocapsae<\/em> and gives more complete control of soil insects located below 2\u201d.\u00a0 In the lighter soils, the top 2\u201d often become too dry for a biocontrol nematode to move and attack insect larvae.\u00a0 In these soils, a nematode species mix which include S. carpocapsae<\/em> would be ineffective.<\/p>\n

\"Dr.
Dr. Elson Shields. Photo: NNYADP<\/em><\/figcaption><\/figure>\n

Our recommendations for biocontrol nematode species mixes for soil types:<\/strong><\/p>\n

Clay loam \u2013 silt loam soils:\u00a0 S. carpocapsae<\/em> + S. feltiae<\/em><\/p>\n

Sandy loams \u2013 sand soils:\u00a0 S. feltiae <\/em>+ Heterorhabditis bacteriophora<\/em>.<\/p>\n

What are the Differences between the Entomopathogenic (biocontrol) Nematodes Purchased on the Web from the Persistent NY Strains Mentioned Here?
\n<\/u><\/strong>Biocontrol nematodes purchased from commercial sources have lost the ability to persist in the soil after application for a significant length of time.\u00a0 Many commercial strains persist in the soil for only 7-30 days and require application timing to be closely match with the presence of their target host and an annual reapplication is required.\u00a0 In contrast, the NY persistent strains of Biocontrol Nematodes are carefully cultured to maintain their evolutionary ability to persist across hostile conditions such as the lack of available hosts and temperature extremes (like winter).\u00a0 Additionally, NY persistent strains are re-isolated from the field every two years so the nematode cultures do not become \u201cLab strains\u201d, but remain adapted for NY agricultural soil conditions.\u00a0 NY persistent strains are applied a single time and persist in the field for many years following application.\u00a0 Not surprising because they were isolated from NY soils where they have evolved for a few million years.\u00a0 If the NY persistent strains are cultured carelessly, they also quickly lose their ability to persist and are no better than the commercial strains purchased off the web.<\/p>\n

How are Biocontrol Nematodes Applied?<\/u><\/strong><\/p>\n

There are two major ways to apply biocontrol nematodes to NNY fields.<\/p>\n

Commercial pesticide sprayer:<\/strong>\u00a0 Thousands of acres have been inoculated using slightly modified pesticide sprayers of all sizes from 30\u2019 booms to 100+\u2019 booms.\u00a0 To use these sprayers, the following guidelines need to be followed.<\/p>\n