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Grower Notes and Pest News

Brown Marmorated Stink Bug in San Luis Obispo County

Brown marmorated stink bug adult male (Photo by: Surendra Dara, UCCE and Rodney Cooper, USDA-ARS)

Brown marmorated stink bug (BMSB), Halyomorpha halys Stål was recently found in San Luis Obispo County in an incoming shipment of household items from Pennsylvania, where it is considered as a serious pest.  Ag Commissioner's office took immediate action to eradicate this intruder by physical removal and chemical treatments.  In light of this, here is a brief note on this invasive pest.

Origin and distribution:
BMSB is native to Asia and is considered as an important pest in China, Japan, Korea, and Taiwan.  It was first reported in Pennsylvania in late 90s and is now reported in a majority of the states in the US.  However, reproducing populations may not be present in all the states it was found.  In California, Los Angeles County is the only place where populations of BMSB are known to exist.

Host range: It has a wide host range that includes about 300 species according to a report.  It feeds on a variety of hosts that include fruit trees, broadleaved trees, vegetables, field crops, and ornamental plants.  It is also a nuisance to homeowners as it looks for hiding locations in or around the houses to overwinter.



Depressions on the fruit surface normally result from late season feeding damage of BMSB (above).  Corking injury due to the necrosis of damaged tissue (below).  (Photos by Chris Bergh, Virginia Tech)

Damage: BMSB has piercing and sucking mouthparts with which it sucks plant juices from fruits, pods, or other parts and causes malformation, discoloration or cloudy spots, depressed areas, and wart-like growth depending on the plant or damaged part. Small dark spots also develop as a result of puncturing by its mouthparts and these areas can harbor secondary infections.  BMSB is also known to transmit witches' broom, a phytoplasma disease in princess tree (Paulownia tomentosa) in Japan, but such disease transmission has not been reported in the US.

Characteristic features that help distinguish the brown marmorated stink bug from other stink bugs
(Photo by: Surendra Dara, UCCE and Rodney Cooper, USDA-ARS)

Biology: BMSB belongs to the stink bug family Pentatomidae in the order Hemiptera.  It is a shield shaped bug which emits pungent odor when disturbed.  Adults are 12-17 mm long with mottled brown body.  Last two antennal segments have alternating light and dark bands which appear as a single white band.  This is a characteristic feature of this species.  Exposed margins of the abdomen (not covered by the wings) have alternating brown and white bands.  White bands are also seen on legs.  Eggs are spherical to barrel-shaped, white to pale green and deposited each week in clusters of 20-30 on the underside of leaves.  Female can lay 250-400 in its life time.  There are 5 nymphal instars which range in size from 2.4 to 12 mm.  First instar nymphs are reddish orange and second instars are black.  Later instars develop brown coloration.  Depending on temperature, egg stage lasts for 4-5 days and each nymphal instar for a week.  Adults reach sexual maturity in two weeks.

Adults mate in spring and females continue egg laying for the next few months.  Adults gather in large numbers in fall in search of overwintering places.  In warmer regions of China, BMSB has multiple generations per year.  In the US, it was initially thought to have a single generation, but recent reports indicate more than one generation per year.

Management: Hand removal or vacuuming is the best way to remove BMSB in or around homes.  Mechanical exclusion by sealing the cracks and crevices that serve as hiding locations, and using screens for doors and windows is also important.  Various insecticides are available for managing this insect in other situations.  In laboratory bioassays, pyrethroid insecticides (especially bifenthrin) were more effective compared to neonicotinoids and an organophosphate compound.  Males were less susceptible than the females to thiomethoxam (neonicotinoid).  There are no known natural enemies in the US, but an egg parasitoid [Trissolcus halymorphae Yang (Hymenoptera: Scelionidae)] is found to be very effective in China.

What to do: It is important to note that care must be taken to exclude pests in packages while moving from other areas.  If you notice BMSB in your surroundings, bring it to the attention of the Ag Commissioner or contact me at skdara@ucdavis.edu or 805-781-5940.

http://ucanr.edu/articlefeedback

References:

Bernon, G. K., M. Bernhard, E. R. Hoebeke, M. E. Carter and L. Beanland. 2004.  Halyomorpha halys, (Heteroptera: Pentatomidae), the brown marmorated stink bug; Are trees the primary host for this new invasive pest? GTR-NE-332. Proc. XV USDA Interagency Res. Forum on Gypsy Moth and Other Invasive Species 2004

Jones, J. R. and P. L. Lambdin.  2009.  New county and state Records for Tennessee of an exotic pest, Halyomorpha halys (Hemiptera: Pentatomidae), with potential economic and ecological implications.  Florida Entomologist 92: 177-178.

Nielsen A. L, P. W. Shearer, G. C. Hamilton. 2008. Toxicity of insecticides to Halyomorpha halys (Hemiptera: Pentatomidae) using glass-vial bioassays. J. Economic Entomol. 101: 1439-1442.

Yang Z., Y. Yao, L. Oiu , Z. Li. 2009. A new species of Trissoltus (Hymenoptera: Scelionidae) parasitizing eggs of Halyomorpha halys (Heteroptera: Pentatomidae) in China with comments on its biology. Annals of the Entomological Society of America 102: 39-47.

Additional resources:

http://edis.ifas.ufl.edu/in623

http://ento.psu.edu/extension/factsheets/brown-marmorated-stink-bug

http://entnemdept.ufl.edu/creatures/veg/bean/brown_marmorated_stink_bug.htm

http://pestthreats.umd.edu/content/documents/BMSBFactSheet_10-2010_000.pdf

http://www.aphis.usda.gov/plant_health/plant_pest_info/bmsb/index.shtml

http://www.entsoc.org/PDF/Pubs/Periodicals/AE/AE-2009/Spring/Hamilton-sym.pdf

Posted on Thursday, November 3, 2011 at 10:04 PM

European pepper moth: A pest of many host plants

Life stages of the European pepper moth, Duponchelia fovealis.  Eggs (top left, photo credit: Lance Osborne, University of Florida), larva (top middle, photo credit: Bryan Vander Mey, UCCE), pupa in an opened cocoon (top right, photo credit: James Hayden, Florida Department of Agriculture and Consumer Services, Division of Plant Industry) and adult male (left) and female (right) moths (bottom, photo credit: James Hayden)

European pepper moth (EPM), Duponchelia fovealis Zeller is an invasive pest in the US.  It was first discovered in San Diego County in 2004 and again in July, 2010.  EPM has a CDFA pest rating of C, which means it is currently widespread in California.  APHIS, National Plant Board, and industry stakeholders have established an EPM task force to address the pest issue.  I have been invited to be a part of the Technical Working Group along with my UCCE colleagues, James Bethke and Steve Tjosvold to work on research and outreach related to this pest.  Information on the economic impact of this pest in California or in the US is unknown, but here is some general information about this pest.

EPM belongs to the family Crambidae.  Crambids are known as grass moths or close-wing moths.  Older literature classifies this pest under the family Pyralidae.  Some sources also refer to EPM as southern European marshland pyralid.  Peppered moth, Biston betularia (Common name: measuringworms, Family: Geometridae, Order: Lepidoptera) from Europe is not related to this species.  It can be confusing when the name European peppered moth also appears in some sources, but verifying the scientific name helps confirm the identity.

Origin and Distribution: EPM is a pest native to the Mediterranean region and the Canary Islands.  It is also reported to be an important greenhouse pest in the Netherlands for the past two decades.  It is an established pest in many European countries, the Middle East and Africa.  EPM is now reported to be present in several central and southern California counties and in Arizona, Colorado, Oklahoma, Texas, Georgia and Florida.  EPM was also reported in a southern Ontario, Canada greenhouse in 2005.

Host range: EPM is a polyphagous pest and has a very wide host range that includes several crop plants like corn, peppers, tomatoes, squash, and strawberries and ornamental plants like azalea, begonia, geranium, and poinsettia.   Due to its feeding behavior and preference to infest foliage and plant parts near or below the soil line, crops that have such plant structure may be more vulnerable to this pest.

Biology: Eggs are oval, 0.5-0.7 mm long, whitish-green initially and turn bright red as they mature.  Females can lay up to 200 eggs either individually or in batches of 3-10 in a roof-tile pattern.  Larvae are creamy white to brown with dark spots on their body and have a dark head capsule.  They measure up to 20-30 mm when they are fully developed.  Pupa is 9-12 mm long, yellowish to light brown initially and turn dark with maturity.  A cocoon is spun around the pupa with silk, frass, and soil particles under the foliage, below the soil line or attached to the pots.  Adults have brown to grey wings with a wing span of about 20 mm.  Adults are good fliers.  Males have a long, slender abdomen that is turned upwards.  Length of the life cycle depends on temperature, but varies from 6-8 weeks.  Egg stage lasts for 4-9 days, larval stage for 3-4 weeks, pupal stage for 1-2 weeks, and adult stage for 1-2 weeks.  They produce multiple generations especially in greenhouses (up to 8 to 9) or in warm areas such as California and southeastern US.  They can be limited to greenhouses in cooler regions or during cooler seasons of the year and seen in the fields under ideal conditions.

Mature European pepper moth larva in the potting soil below the surface 
(Photo credit: Lyle Buss, University of Florida)

Damage: EPM larvae feed on roots, stems, foliage, inflorescences and fruits.  They can also feed on the organic matter in the soil. Although they have a preference for feeding at the plant base, damage can be inflicted higher in the plant.  Sometimes, larvae emerging from the eggs laid on the top of the foliage can burrow their way down through the stem.  Damage ranges from holes in the foliage, wilting, defoliation, girdling of the stem to stem collapse.  Damaged areas are also exposed to fungal diseases like Botrytis.  Larvae prefer moist conditions and hide under the foliage that is in contact with soil, just below the soil line or in the tunnels formed by spinning the leaves together.  In potted plants where the foliage is not in contact with the soil, larvae can be found in webbing near the edges of the pots.

Stem girdling of peppers by larval feeding of the European pepper moth.  Photo credit: Bryan Vander Mey, UCCE.

Management: Sanitation to remove debris and infestation sites like lower leaves in contact with the soil and use of drier potting medium appear to help reduce the infestation.  Biological control with Bacillus thuringiensis, predatory mites (Stratiolaelaps milesHypoaspis miles and H. aculeifer), predatory beetle (Dalotia coriaria), parasitoid wasps (Trichogramma evanescens and T. cacoeciae), and entomopathogenic nematodes (Heterorhabditis bacteriophora and Steinernema sp.) are reported to be effective.  Chemical control can be difficult with contact insecticides as the larvae hide in protected areas.  However, control with acephate, azadirachtin, chlorpyrifos, emamectin, imidacloprid, pyrethrins, and spinosad was found to be effective in areas where they are registered to be used.

What to do:
If you notice EPM damage on your crop, please contact me at skdara@ucdavis.edu or 805-781-5940.

Additional details about EPM and more photos can be found at the below sources.

http://ucanr.edu/articlefeedback

References:

Bethke,  J. and B. Vander Mey.  2010. Duponchelia fovealis. Pest Alert, University of California Cooperative Extension, San Diego.

Brambila, J. and I. Stocks.  2010.  The European pepper moth, Duponchelia fovealis Zeller (Lepidoptera: Crambidae), a Mediterranean pest moth discovered in central Florida.  Pest Alert, Florida Department of Agriculture and Consumer Services, Division of Plant Industry.

Messelink, G. and W. Van Wensveen.  2003.  Biocontrol of Duponchelia fovealis (Lepidoptera: Pyralidae) with soil-dwelling predators in potted plants.  Comm. Appl. Biol. Sci., Ghent University 68: 159-165.

http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1000&context=systentomologyusda

http://entnemdept.ufl.edu/creatures/veg/leps/european_pepper_moth.htm

http://mrec.ifas.ufl.edu/lso/dupon/dupon.html

http://nationalplantboard.org/docs/spro/spro_duponchelia_2011_08_05.pdf

http://www.freshfromflorida.com/pi/pest_alerts/pdf/duponchelia_fovealis.pdf

Posted on Monday, September 26, 2011 at 1:47 PM

Twospotted spider mite and Lewis mite: A comparison

Life stages twospotted spider mite and Lewis mite.  Notice the similarities between twospotted spider mite female (top right) and Lewis mite (bottom).  Photos by Surendra Dara

A few species of spider mites infest strawberries grown on the California coast.  The twospotted spider mite, Tetranychus urticae Koch is a common species and considered a major pest.  Lewis mite or Lewis spider mite, Eotetranychus lewisi (McGregor) is another spider mite species that feeds on a variety of host plants was recently found causing heavy infestations in strawberries and raspberries in Ventura County.  Both species look very similar in general appearance except that when adult females are compared, Lewis mites are smaller than twospotted spider mites and have several small spots on their body while twospotted spider mites have a single dark spot on either side of the body.  Below are some details to compare these two mites.

http://ucanr.edu/articlefeedback

Posted on Wednesday, September 14, 2011 at 4:22 PM

Japanese dodder, an exotic and noxious weed found in Santa Barbara County

Japanese dodder, Cuscuta japonica recently found in Lompoc, Santa Barbara Co. 
(Photo by: Matt Victoria, Santa Barbara Ag Commissioner's Office)


Japanese dodder is an exotic parasitic weed which is a high priority noxious weed in California.  It was recently detected in a natural wooded area in Lompoc.  It is the first time it is reported in Santa Barbara Co and the Ag Commissioner's office is taking an immediate action.

Biology:
Japanese dodder, Cuscuta japonica is a parasitic plant that belongs to Convolvulaceae family (note that older literature refers to it as a member of Cuscutaceae family).  It is a parasitic annual plant that has a slender, yellow stem with red spots and striations, and scale-like leaves.  It produces haustoria (singular hostorium), which are root-like structures that penetrate the vascular tissue of the host and absorb nutrients and water.   It can reproduce by seed and by vegetative means through fragments of the plant.  Seed can germinate in soil, but the plant has to come in contact with a host to for the young shoot to survive beyond a few days.  It appears that Japanese dodder seed produced in California is not viable and vegetative reproduction is the main source of propagation.

Host range: Japanese dodder has a wide host range that includes herbaceous annuals to woody shrubs and trees.  Crop plants like corn, cucumber, egg plant, pea, pumpkins, soybean, and tomato, and ornamental shrubs, fruit and other trees are among the hosts that are parasitized by this weed.

Damage: Depending on the extent of infestation, damage can range from stunted growth to death.  Japanese dodder growers faster and spreads to larger areas than the other dodders.

Dissemination: It is spread by equipment, birds, animals and people as seed and fragments of plant material.  Gardening activities and improper composting and infested plant material can spread the weed.  Intentional planting for medicinal purposes is thought to be a significant factor for the dissemination of this weed.

Management: Prevention of the infestation is the best way to manage Japanese dodder.  Due to its current status a high priority regulated pest, one should not attempt to control or remove Japanese dodder if detected.  It should be immediately reported to the local Ag Commissioner's office (805-681-5600 for Santa Barbara Co and 805-781-5910 for San Luis Obispo Co).

Detailed information on Japanese dodder biology, identification, and reporting the infestation can be found at the following sources.

http://ucanr.edu/articlefeedback

References:

Santa Barbara Co Ag Commissioner's Office: http://www.countyofsb.org/agcomm/wma.aspx?id=29344

UC IPM: http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7496.html

CDFA Noxious Weed Information Project: http://www.cdfa.ca.gov/plant/ipc/noxweedinfo/noxweedinfo_jdodder.htm

Center for Invasive Species and Ecosystem Health: http://www.invasive.org/eastern/other/DicCusCjO01.pdf

Posted on Thursday, September 1, 2011 at 3:17 PM

Downy mildew of basil

Basil plants that originated from a central coast nursery were recently found infected with downy mildew pathogen, Peronospora belbahri in a home and garden store in California.  This is a new pathogen that can cause serious damage to culinary and ornamental basil plants.

Symptoms include yellowing of the area between the veins on the upper leaf surface and growth of fungal mycelia and purplish grey spores on the lower surface.  Yellowing on the upper leaf surface can be confused with nutritional deficiency, so careful examination of the lower side is important.


Fungal spores on the lowerside of the basil leaf (Photo by: Heather Scheck, Santa Barbara County Ag Commissioner Pathologist)


Basil downy mildew was first reported in the United States in 2007 in Florida and in several eastern states by 2008.  It was also found in California by 2009.  Infected seeds and plants are main sources of infection.  Growers should try to obtain clean seeds.  Spores can be dispersed by wind and close spacing and overhead irrigation can also aid in the dispersal of the inoculum.

Regular monitoring of the fields for early detection of the infection and timely application of the fungicides is important for managing this disease.  Proper ventilation and temperature control in the greenhouses is also critical as prolonged leaf wetness, high humidity, and cool weather promote the disease development.

Additional information about the disease and management
guidelines can be found at: http://vegetablemdonline.ppath.cornell.edu/NewsArticles/BasilDowny.html

http://ucanr.edu/articlefeedback

Posted on Sunday, June 5, 2011 at 11:08 PM

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