diabrotica spp description and organic pest management

Word count: 2290

Assignment #6: Organic Pest Management

For SOIL 342, ORGANIC SOIL FERTILIZATION, Professor Joann Whalen

Jane Sorensen, 119447640

Contents

Overview: Diabrotica species and economic importance ......................................................... 2

Spotted Cucumber beetle/Southern Corn Rootworm and Banded Cucumber Beetle............ 4

Life cycle................................................................................................................................ 5

Monitoring of pests ................................................................................................................ 6

Pest management with biocontrol organisms......................................................................... 7

Other pest management techniques........................................................................................ 8

Conclusion ................................................................................................................................. 9

References................................................................................................................................ 10

Jane Sorensen Thursday, November 24, 2011

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Overview: Diabrotica species and economic importance

Corn rootworms are one of the most economically destructive pests in the United States, and

therefore, a serious problem in Canada.

Diabroticina are chrysomelid beetles (Coleoptera: Chrysomelidae: Subfamily Galerucinae:

Tribe Luperini : Diabroticina) that includes two major pest genera: Cerotomites and

Diabroticites. These genera are endemic to the Americas. The 350 described species of

Diabrotica are divided into three series: virgifera, fucata and signifera. (Toepfer et al 2009)

In North America, the Virgifera group feeds primarily on corn with a few other grasses; its

species include the Northern (Diabrotica barberi), Western (Diabrotica virgifera virgifera), and

Mexican (Diabrotica virgifera zeae) corn rootworms. The Western and the Northern rootworm

species are the most devastating pests in Iowa, a major corn-growing area, and it goes to show

that these pests can affect organic sweet corn and organic commodity corn. Found throughout the

United States and southern Canada east of the Rocky Mountains, the northern populations

migrate north and south as seasons change, travelling up to 800 km in a few days. (Bradley p

262)

The Fucata group comprises important pests of horticultural and field crops of cucurbits

(melon, pumpkin, squash, and cucumber), peanuts, sweet potatoes, leafy vegetables and flowers.

This group is comprised of the banded cucumber beetle, Diabrotica balteata, and three varieties

of the Spotted cucumber beetle (a.k.a. Southern corn rootworm), D. undecimpunctata howardi,

Western spotted cucumber beetle, D. undecimpunctata undecimpunctata, and the Western

cucumber beetle, D. undecimpunctata tenella. This paper will assume these three varieties


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function as one spotted cucumber beetle, whether they are Southern or Western. (Toepfer et al

2009, Wikipedia)

Diabrotica spp. was unknown in European countries until the 1990s, when it appeared to have

entered Europe multiple times (Toepfer et al 2009) from the United States during the Yugoslav

wars. (Wikipedia, Kiss et al 2005) There has since been a lot of research and intervention of

these pests in the European context.

There is a third species of cucumber beetle (and very possibly more than that), of which this

paper does not discuss. The Striped cucumber beetle’s genus is Acalymma and its species is

vittatum. It superficially resembles the adult Western corn rootworm, and it is equally important

to D. undecimpunctata in its effects on organic vegetable production. (Toepfer et al 2009)

In the 2006 OMAFRA census1, 3.1% of Ontario farms (=1,769) grew vegetable and melon

crops, while 22.8%, or 13,056 farms, were oilseed and grain production – which means that there

will be plenty of opportunities for Diabrotica species to infest from one type of farm to another.

The 2006 Canadian total2 of certified organic farms producing fruit, vegetables, and greenhouse

products was 916, with 208 of these farms in Quebec and 174 in Ontario. 358 of these farms are

in British Columbia; there, however, the D. undecimpunctata range is not so extensive. In

addition, there are twice as many non-certified organic farms in all categories of farms across

1 http://www.omafra.gov.on.ca/english/stats/census/naics.htm accessed on 27/11/2011 7:17 PM 2 Table 1: Organic but not certified producers by product type, 2006 http://www.statcan.gc.ca/pub/96-325-

x/2007000/t/6000060-eng.htm, Table 3: Farms reporting certified organic fruit, vegetables or greenhouse products, Canada and provinces, 2006 and 2001 http://www.statcan.gc.ca/pub/96-325-x/2007000/t/6000062-eng.htm

Accessed 11/27/11 5:50 PM


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Canada. (Kendrick 2009) Wherever there are extensive cornfields or cucurbit crops, Diabrotica

will be a concern for organic farmers.

Spotted Cucumber beetle/Southern Corn Rootworm and Banded Cucumber Beetle

D. undecimpunctata, the spotted cucumber beetle, causes much economic damage in Canada,

but in the United States alone, current estimates show that 30 million acres (120,000 km²) of

corn, out of 80 million acres (320,000 km²) grown, are infested with corn rootworms, and the

number of infested acres is expected to grow over the next 20 years3. Larvae of these insects feed

on roots of corn, often killing young plants; older plants are weakened and stalks topple easily.

D. balteata, the banded cucumber beetle, is nearly omnivorous, and in addition to attacking

numerous plants, injures all parts of the plant: damage may occur to foliage, blossoms, corn silk,

kernels and grains. Adults feed on leaves and sometimes petals of cucumber, squash, beet, bean

and soybean, pea, sweet potato, okra, corn, lettuce, onion, and cabbage, other vegetable crops,

and flowers, and seem to prefer plants from the family Cucurbitaceae, Leguminoseae, and

Crucifereae:. Rosaceae fruits are also susceptible. (Capinera 2007)

D. undecimpunctata adults are greenish yellow, 5 to 6 mm in length, with 11 black spots or

three transverse bands across the elytra (wing covers), and also can have a red head and black

thorax, and a thin green band running down the center of the insect's back. The banding pattern is

variable, and sometimes almost absent. (Capinera 2007) Compare the image on the left of

D. undecimpunctata with that of the banded cucumber beetle, D. balteata, on the right:

3 Source: http://en.wikipedia.org/wiki/Diabrotica


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Larvae are white, ½ inch grubs with brown heads and brown patches on first and last

segments.

Both larvae and adults can transit cucumber mosaic virus and bacterial wilt. (Bradley p 262)

Larval feeding might increase the incidence and severity of Fusarium wilt. (Capinera 2007)

Life cycle

Overwintering adults emerge from under

crop residues in spring. (Bradley p 262) Adult

longevity is 17 to 44 days, but averages 26

days. About six days after adult emergence

(from overwintering or pupae), copulation

occurs, with egg deposition beginning about

16 days later. Oviposition takes place at two

to three day intervals, for two to eight weeks.

Females normally deposit two to 15 egg

clusters of up to 100 eggs each. A female can produce a total of 850 eggs (Capinera 2007). The

eggs are yellow or orange in color, oval in form, and measure about 0.6 mm in length and 0.35

mm in width. Banded cucumber beetle (D. balteata) eggs are deposited in cracks in the soil

12-spotted cucumber beetle (Diabrotica undecimpunctata howardii) larva, pupa and adult http://keys.lucidcentral.org/keys/sweetpotato/key/Sweetpotato%20Diagnotes/Media/Html/TheProblems/Pest-Root&StemInsects/Wireworm/wireworm.htm


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(Bradley et al 2009), and spotted cucumber beetles (D.

undecimpunctata) lay orange egg masses on the underside

of leaves. 4

Eggs require five to nine days to hatch. The larval

development time is usually 11 to 17 days and is

temperature dependent. For instars 1 to 3, the range is about 4-8, 3-11, and 4-15 days

respectively. Pupation, of four to six days, occurs in the soil. (Capinera 2007)

D. balteata does not enter diapause. It remains active as long as the weather remains

favorable. Under optimal conditions, D. balteata’s life cycle can be completed in 45 days.

(Capinera 2007)

Monitoring of pests

To follow the activity of pests and beneficial insects, make regular weekly checks in the field

with a hand lens and a sweep net, inspecting the underside of foliage for the first signs of insect

activity. Using these tools as well in cover crops, field edges, and adjacent crops to help

determine which beneficial insect species or pests may have potential to move into the crop.

(Fouche et al 2000) Alternatively, or in addition to inspection, use sticky traps to monitor

populations. For example, in the late 1990’s, in response to the invasion of Western corn

rootworm (D. virgifera), a permanent monitoring/trapping for containment and control program

on became operational in Hungary, Croatia, Romania and Bosnia-Herzegovina. It used

Hungarian pheromone traps to capture males, and Multigard™ yellow sticky traps were used to

4 http://gardening.about.com/od/gardenproblems/ig/Insects-and-Diseases-of-Plants/Cucumber-Beetle-Eggs.htm


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capture both males and females. It was hoped that this trapping method would slow down or

possibly stop the build-up of smaller isolated D. virgifera virgifera populations. (Kuhlmann &

van der Burgt, 1998)

Pest management with biocontrol organisms

The nematode Filipjevimermis leipsandra affects Diabrotica, and Hexamermis spp.

parasitizes the adults. Natural infection levels in South Carolina were reported to be in the range

of 20–40% from May through October. (Capinera 2007) Studies have indicated up to 90% of a

population of cucumber beetles being infected by the nematodes. Apply nematodes to the soil,

mulch, seed furrows and around plant roots5 on a weekly basis to control larvae (Bradley p 262),

and to kill the adults.

Except for parasitic nematodes, the natural enemies of D. balteata are not well known. Ants

have been shown to be important egg predators in the tropics, and likely are important elsewhere.

(Capinera 2007) Lacewings and ladybugs eat eggs deposited on leaves.6 Natural enemies would

be useful elements of a strategic approach to the control of Diabroticina pests, and it is suggested

to encourage Tachnid flies, soldier beetles, and braconid wasps to prevent or treat an infestation.

5 http://www.ghorganics.com/CucumberBeetles.htm accessed 11/27/11 5:50 PM



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Other pest management techniques

An Integrated Pest Management (IPM) strategy is likely to enhance the natural enemy

populations, and accelerated exploration of biological control options may provide the advances

in Diabroticina pest management that Europe, with its non-transgenic agricultural policy,

urgently needs. (Toepfer et al 2009) IPM includes the following recommendations:

Remove and destroy crop residues where adults overwinter;

Rotate garden crops with cover crops such as alfalfa;

Hand pollinate covered squash family plants;

Cover seedlings or plants with floating row cover (a spun-polyester row cover,

permeable to water and to light, which protects the crop from pests and shortens or

extends the harvest period due to its thermal properties);

Apply kaolin clay to uncovered plants, especially to leaf undersides, and reapply after

rain;

Handpick or vacuum beetles;

As a last resort, spray infested plants with pyrethrin (Bradley p 262)

Plant pest-resistant varieties, or “trap” varieties that will attract the pest away from the

crop you are growing for market

Diversify your crops as much as possible, so that if an infestation hits one crop

particularly badly, you will have other crops to sell. (Fossel 2007)

Crop rotation works very well to control larval damage. In most cases, adult damage is not

severe enough to warrant control, unless rotation of corn is not practiced in or near an organic

sweet corn field. (Caldwell)

Make sure that crops are well fertilized with compost and free from environmental and

nutritional stresses, so that should a pest stress the plant, it has a good base from which to

develop its own defenses. (Fossel 2007)


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Heavy mulching can deter cucumber beetles from laying eggs in the ground near plant stems

and may hinder feeding by larvae migrating to fruits. Companion plant with oregano, radish,

tansy, and nasturtium,7 and also try broccoli, calendula, catnip, goldenrod, and rue, as they are

suggested to be repellent to the cucumber beetle. African, French or Mexican marigolds are

pungent and may be used to repel the insects, alternatively, common marigolds may attract them,

therefore could be used as a trap crop. 8

Conclusion

In reviewing the material for Diabrotica species, it became apparent that one organic practice

needs amending for the crops that are affected by pests: organic matter cannot be left on the field

at the end of the growing season, but instead must be thoroughly thermally composted to kill the

pupae, overwintering adults, and eggs left in the litter. The organic farmer will need to conduct a

thorough literature review and consult with his or her extension department to find out which

varieties of crops in the area are susceptible to Diabrotica, and which crops are ideal trap crop

candidates to make the job of manual monitoring and control a little easier for the farmer. The

farmer should try planting allelopathic or repellent companion plants, and report the results of

these efforts to the extension offices to promote information availability on what works, and

what doesn’t. Lastly, farmers and researchers should pay particular attention to literature coming

out of Europe regarding its new programs to contain D. virigifera and any D. undecimpunctata

co-invasions, as Europe’s agricultural practices are more akin to organic farming than North

American conventional practices that rely on genetic manipulation in favour of toxic production

7 http://www.weekendgardener.net/garden-pests/diabrotica-060806.htm accessed 11/26/11 8:24 PM



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or toxicity resistance. Research of the new invasion should yield interesting applications on an

aggressive natural response to Diabrotica cucumber beetles, within an organic context.

References

Bradley FM, Ellis BW, & Martin DL. 2009. The Organic Gardener's Handbook of Natural Pest and Disease Control: A Complete Guide to Maintaining a Healthy Garden and Yard the Earth-Friendly Way. New York, NY: Rodale

Caldwell BA, & New York State Agricultural Experiment Station. (2005). Resource guide for organic insect and disease management. Geneva, N.Y: New York State Agricultural Experiment Station. Accessed at http://web.pppmb.cals.cornell.edu/resourceguide/cmp/corn.php on 11/27/11 7:03 PM

Capinera JL. 1999. Banded Cucumber Beetle, Diabrotica balteata LeConte (Insecta: Coleoptera: Chrysomelidae) Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Latest revision: November 2007. http://edis.ifas.ufl.edu/pdffiles/IN/IN25000.pdf accessed on 11/25/11 2:36 PM

Fossel PV (2007). Organic farming: Everything you need to know. St. Paul, MN: MBI. Fouche C, Gaskell M, Koike ST, Mitchell J, Smith R. 2000. Insect Pest Management For

Organic Crops. The Organic Vegetable Production in California Series Publication 7251, available at http://anrcatalog.ucdavis.edu/ Accessed on 11/26/11 8:36 PM

Grabowski M, 2009. Diseases of Cucurbits. University of Minnesota. http://www.extension.umn.edu/distribution/horticulture/DG1172.html

Kendrick J, & Statistics Canada. (2008). Organic: From niche to mainstream. Ottawa: Statistics Canada.

Kiss JE, Berger CR, Cate HK, Cean P, Cheek M, Derron S, Festić J, Furlan H, Igrc-Barčić L, Ivanova J, Lammers I, Omelyuta W, Princzinger V, Reynaud G, Sivcev P, Sivicek I, Urek P, Vahala G. 2005. Monitoring of western corn rootworm (Diabrotica virgifera virgifera LeConte) in Europe 1992-2003. In: Western corn rootworm: ecology and management, Eds.Vidal S, Kuhlmann U, Edwards CR. CABI

Kuhlmann U & van der Burgt WACM. 1998. Possibilities for biological control of the western corn rootworm, Diabrotica virgifera virgifera LeConte, in Central Europe. BiocontrolNews and Information, 19(2):59N–68N

Toepfer S, Haye T, Kuhlmann U, et al. 2009. A review of the natural enemies of beetles in the subtribe Diabroticina (Coleoptera: Chrysomelidae): implications for sustainable pest management. Biocontrol Science & Technology, 19(1):1-65..

diabrotica spp description and organic pest management

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