Seed Bugs | Nysius spp.

 California Pest Rating for
Nysius spp.  : (Seed Bugs)
Hemiptera: Lygaeidae
Pest  Rating: NR

Initiating Event:

Nysius spp. (Seed Bugs) are frequently intercepted by CDFA’s high risk programs and at border stations. These have a temporary rating of “Q”.  A pest rating proposal is required to evaluate their pest risk.

History & Status:

Background: The insects of the Nysius spp. commonly known as seed bugs or ground bugs and these are found on every continent except Antarctica2. The Lygaeidae is a very successful family of true bugs found worldwide. Several species of this family are well-known as major economic pests of a variety of crops. Some members of genus Nysius spp. are very useful for insect studies especially, insect physiology and evolutionary ecology.2

The insects of Nysius spp. are small insect commonly found within grassy or weedy fields, pastures, and foothills. Each spring, once the plants in these areas dry up, these insects migrates to find new places to feed. This becomes a nuisance for homeowners when these bugs migrate into their landscapes and homes and can cause problems for gardeners and farmers. The problems are most serious in the year with wet and cool springs.1

Nysius species are polyphagous insects that feed on a large number of crops, fruits & weeds5. The members of this genus have been associated with both endemic and introduced plant species from sea level to over 13,000 feet3. Crops attacked by these insects include: cabbage, rape, turnip, clover, lucerne, cucumber, carrots, potato, beets, cotton, sorghum, tomatoes and all types of squash, barley, wheat and many more crops. Many fruits plants were attacked by the insects of this genus, especially soft skin fruit like strawberries, kiwifruit and apple are seriously injured. Several weeds are reservoir hosts of these bugs, particularly those belonging to the Amaranthaceae, Chenopodiaceae, Asteraceae, Euphorbiaceae, and Portulacaceae families.4, 5

Worldwide Distribution: The insects of Nysius spp. are considered among the most successful insects on earth; they are found on every continent except Antarctica.2

Official Control: Nysius spp. are listed as harmful organisms by New Zealand, Japan, the Republic of Korea, Canada and Taiwan.8

California Distribution: Nysius spp. are distributed all over California, but there are no official surveys done for these insects to confirm their presence. There are 106 described species in the genus Nysius and many of these have never been found in the environment of California.

California Interceptions: Nysius spp. have been intercepted multiple times through border station inspections, dog teams and high risk pest exclusion activities. Between January 2000 and December 2016, they have been intercepted 990 times. Many of these specimen were submitted by homeowners from all over the state.

The risk Nysius spp. (Seed bugs) would pose to California is evaluated below.

Consequences of Introduction: 

1) Climate/Host Interaction: Hosts plants of Nysius spp. are commonly grown in California and these species are expected to be established wherever the hosts are grown. It receives a High (3) in this category.

Evaluate if the pest would have suitable hosts and climate to establish in California:

Low (1) Not likely to establish in California; or likely to establish in very limited areas.

Medium (2) may be able to establish in a larger but limited part of California.

High (3) likely to establish a widespread distribution in California.

2) Known Pest Host Range: The insects of Nysius are highly polyphagous that can feed on variety of field crop and wild plants. It receives a High (3) in this category.

Evaluate the host range of the pest.

Low (1) has a very limited host range.

Medium (2) has a moderate host range.

High (3) has a wide host range.

3) Pest Dispersal Potential: The female of Nysius spp. generally lay eggs in clutches, which can range in size from 10 to over 100 eggs and may lay many clutches in their lifetime. The adults travel short distance in search of food and overwintering sites. They may move longer distances as result of hitchhiking on infested planting material or field equipment. It receives a High (3) in this category.

Evaluate the natural and artificial dispersal potential of the pest.

Low (1) does not have high reproductive or dispersal potential.

Medium (2) has either high reproductive or dispersal potential.

High (3) has both high reproduction and dispersal potential.

4) Economic Impact: Some species of Nysius considered pests of seedlings and in severe infestations they can damage young almond, pistachio, pomegranate, and citrus trees. Nysius huttoni feed on wheat grain in the milk-ripe stage with sucking mouthparts, which pierce through the glumes into the developing grain. It inject saliva that contains an enzyme, which bring changes in the flour protein makes it runny dough unsuitable for baking.4, 5  Most of the species are viewed as agricultural pests.  It might reduce the crop yield and increase crop production costs for farmers. It is not expected to change cultural practice vector other organisms, injure animals, or disrupt water supplies. Depending on the species they could receive a Low (-1) to Medium (2) in this category.

Evaluate the economic impact of the pest to California using the criteria below.

Economic Impact: A, B

A. The pest could lower crop yield.

B. The pest could lower crop value (includes increasing crop production costs).

C. The pest could trigger the loss of markets (includes quarantines).

D. The pest could negatively change normal cultural practices.

E. The pest can vector, or is vectored, by another pestiferous organism.

F. The organism is injurious or poisonous to agriculturally important animals.

G. The organism can interfere with the delivery or supply of water for agricultural uses.

Economic Impact Score: 1-2

Low (1) causes 0 or 1 of these impacts.

Medium (2) causes 2 of these impacts.

High (3) causes 3 or more of these impacts.

5) Environmental Impact: The insects of Nysius spp. are not expected to lower biodiversity, disrupt natural communities, or change ecosystem processes. It may effect sensitive species of Brassicaceae such as Caperfruit tropidocarpum (Tropidocarpum capparideum), Santa Cruz Wallflower (Erysimum teretifolium), Tiburon jewel flower (Streptanthus niger) and Metcalf canyon jewel flower (Streptanthus albidus ssp. Albidus). However, no significant documented impact occurs from native species on sensitive species. It would not be expected to disrupt critical habitats. If pest species were established then would it very likely trigger new treatment programs by farmers and residents who find infested plants unsightly. Depending on species  it would a receive Low (-1)  to  High (3) in this category.

Evaluate the environmental impact of the pest on California using the criteria below.

Environmental Impact:  B, D

A. The pest could have a significant environmental impact such as lowering biodiversity, disrupting natural communities, or changing ecosystem processes.

B. The pest could directly affect threatened or endangered species.

C. The pest could impact threatened or endangered species by disrupting critical habitats.

D. The pest could trigger additional official or private treatment programs.

E. The pest significantly impacts cultural practices, home/urban gardening or ornamental plantings.

Environmental Impact: Score:  1-3

Low (1) causes none of the above to occur.

Medium (2) causes one of the above to occur.

High (3) causes two or more of the above to occur.

Consequences of Introduction to California for Nysius spp. (Seed bugs): Low -High (11-14)

Low = 5-8 points

Medium = 9-12 points

High = 13-15 points

6) Post Entry Distribution and Survey Information: There are 106 described species of Nysius and many of them are established in California. They receive a High (-3) in this category.   Nysius not established in California receive a Not established (0) in this category.

This genus receives a Not Established (0) to High Established (-3) in this category.

Evaluate the known distribution in California. Only official records identified by a taxonomic expert and supported by voucher specimens deposited in natural history collections should be considered. Pest incursions that have been eradicated, are under eradication, or have been delimited with no further detections should not be included.

Not established (0) Pest never detected in California, or known only from incursions.

Low (-1) Pest has a localized distribution in California, or is established in one suitable climate/host area (region).

Medium (-2) Pest is widespread in California but not fully established in the endangered area, or pest established in two contiguous suitable climate/host areas.

High (-3) Pest has fully established in the endangered area, or pest is reported in more than two contiguous or non-contiguous suitable climate/host areas.

Final Score:

The final score is the consequences of introduction score minus the post entry distribution and survey information score: Low (8) to High (14).


Uncertainty is high as the species are hard to identify and they vary substantially in their current status and risk to CA.

Conclusion and Rating Justification:

There are many species of Nysius that have not been found in the environment of California.  New species could have significant economic and environmental impacts. Examples of species of Nysius that are not found in California and would be likely to have significant impacts here include Nysius nemorivagus from Hawaii3 and Nysius vinitor from Australia.  While on the other hand there are lot more species which are commonly found in California and are not expected to have significant economic and environmental impacts to California. Example of these species are Nysius raphanus Howard & Nysius tenellus Barber.

It is not possible combine pest rating all 106 species in one proposal. Pest ratings can be lawfully proposed for each individual species versus the whole genus. Non-native Nysius species can have significant impact on California agriculture whereas native species are already present in the state and are being monitored for spread and growth. Considering these facts, a “NR” rating is justified this genus.

  1. R. Haviland, W. J. Bentley, 2016   UC IPM.   Accessed on 2-08-17.
  2. R. Burdfield – Steel, David M Shuker. 2014. The evolutionary ecology of the Lygaeidae.  On line NCBI.  Accessed on 2-08-17.
  3. Jayma L. M. Kessing, Ronal F.L. Mau. 1993. Crop knowledge master Hawaii.    Accessed on 2-08-17.
  4. Brambila. 2007.  USDA- APHIS – PPQ   Invasive Arthropod workshop. Accessed on Feb, 6 2017.
  5. Baker, R. Cannon. 2006.  CSL pest risk analysis for Nysius huttoni Accessed on 2-08-17.
  6. Pest and Damage Record Database, California Department of Food and Agriculture, Plant Health and Pest Prevention Services.
  7. Pest Information wiki. Online   Accessed on 1-31-17.
  8. USDA Phytosanitary Certificate Issuance & Tracking System (PCIT) Phytosanitary Export Database (PExD). Accessed on 1-31-17.


Responsible Party:

Javaid Iqbal,  California Department of Food and Agriculture; 1220 N Street, Sacramento, CA 95814; Tel. (916) 403-6695;[@]

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Consequences of Introduction:  1. Climate/Host Interaction: [Your comment that relates to “Climate/Host Interaction” here.]

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Pest  Rating: NR

Posted by ls