Regulated Non-Quarantine Projects

Two EU funded projects for the benefit of the whole EPPO region

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Justification for qualification based on EPPO PM 4 Standards
Justification for disqualification
Additional or non-conclusive information
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NAME OF THE ORGANISM: Cecidophyopsis ribis (ERPHRI)


GENERAL INFORMATION ON THE PEST

Name as submitted in the project specification (if different):
 

Pest category:
 
Acari


1- Identity of the pest/Level of taxonomic listing:

Is the organism clearly a single taxonomic entity and can it be adequately distinguished from other entities of the same rank?
 
Yes

Is the pest defined at the species level or lower?:
 
Yes

Can listing of the pest at a taxonomic level higher than species be supported by scientific reasons or can species be identified within the taxonomic rank which are the (main) pests of concern?
 
  • Not relevant: Fruits (including hops) sector
If necessary, please list the species:
 
-

Is it justified that the pest is listed at a taxonomic rank below species level?
 
Not relevant

Conclusion:
 
  • Candidate: Fruits (including hops) sector
Justification (if necessary):
 
Amrine et al. (1994) concluded that all valid records of C. ribis are from buds of Ribes nigrum (blackcurrant). However also other Cecidophyopsis spp. might be involved in reports of damage (see chapter Economic impact).

2 – Status in the EU:
 
Is this pest already a quarantine pest for the whole EU?
 
No

Presence in the EU:
 
Yes

List of countries (EPPO Global Database):
 
-

Conclusion:
 
Candidate

Justification (if necessary):
 
Austria, Finland, Hungary and Sweden (Moročko-Bičevska et al., 2021).

HOST PLANT N°1: Ribes nigrum {Ribes} (RIBNI) for the Fruits (including hops) sector.


Origin of the listing:
 
Commission Implementing Directive (EU) 2014/98/EU and Commission Implementing Regulation (EU) 2019/2072

Plants for planting:
 
Plants intended for planting


3 - Is the pest already listed in a PM4 standard on the concerned host plant?
 
Yes
 
Conclusion:
 
Evaluation continues

 
Justification (if necessary):
 
Listed in Standard PM 4-9 Certification scheme for Ribes. However, in the responses to the questionnaire DE, NL and SI supported deregulation: it is considered as a vector of viruses, not causing direct damage and not mainly transmitted by plants for planting. The Fruit SEWG disagreed that the pest was not causing direct damage. Further assessment of the pathway and economic impact are provided in the corresponding sections.

4 - Are the listed plants for planting the main* pathway for the "pest/host/intended use" combination? (*: significant compared to others):
 
?
 
Conclusion:
 
Candidate by default

 
Justification:
 
Cecidophyopsis ribis, the black current big bud mite is, as the common name suggests, highly host specific and only feeds and reproduces on black current (Ribes nigrum) (Jeppson et al., 1975).

According to older literature data, the pest can only move short distances, usually within the bush.
However, dispersal over longer distances is reported to take place passively, mainly by the wind (Proeseler, 1977).
The mites disperse by walking, leaping, aerial currents, via insects and by human transportation (Amrine et. al 1994, Moročko-Bičevska et al. 2021).
Once present, mite populations increase rapidly during the following spring to attain levels of several thousands of individuals per bud in April and May. They then disperse from old to new buds (CABI, 2019).
[In responses to the questionnaire, NL considered that the vector was 'widespread in production areas'.]
The Fruit SEWG considered that there was uncertainty whether plants for planting could still be considered as a significant pathway. The pest is narrowly monophagous and living in buds, but with some uncertainty on how widespread it is in all production areas. A few individuals transported in plants for planting would develop rapidly in a large population, but infestation may also occur by wind dispersal.

5 - Economic impact:

Are there documented reports of any economic impact on the host?
 
Yes

Justification:
 
[In responses to the questionnaire, NL and SI considered that the vector was causing insignificant direct damage.]
The blackcurrant gall mite (big gall mite), C. ribis, is considered as the most important pest of blackcurrant crops worldwide.
- Direct damage: In spring the mite colonizes developing buds and causes a proliferation of cells, which results in a characteristic big-bud disorder. The buds dry up which causes yield reduction and increases frost susceptibility (Piotrowski et al., 2016). However, other authors state that most reports on damage originate from the second half of the 20th century, when identification of Cecidophyopsis species was mainly carried out by morphological means, which was hampered by similarities in morphological parameters. Later, molecular studies indicated that more than one mite species could be present on the same host species. Consequently, it seems unclear which of these other damage reports can be attributed to which Cecidophyopsis species.
- Undirect damage: In addition to direct damage, the mites also vector the Blackcurrant reversion virus (BRV, Nepovirus ribis). BRV is considered as the economically most relevant virus of Ribes, particularly on R. nigrum. Two different types of disease symptoms are described, a relatively mild so-called European and a severe so-called Russian form. Described symptoms include morphological and colour changes of leaves and flowers, sterility and decreases plant vigour. BRV is graft transmissible. In addition to C. ribis, other Cecidophyopsis species could be involved in transmission. The virus was also found in Ribes spp. free from mites, which arises the question if other vectors (such as Longidoridae nematodes) might exist. The knowledge on BRV resistant varieties is still incomplete. In any case, resistance mechanisms against mites and the virus seem unrelated (Moročko-Bičevska, et al. 2021).
In Austria, in recent years, significant mite induced damage and difficulties in pest management were reported by advisors from the province of Styria (Hutter, Landwirtschaftskammer Steiermark, personal communication). Disease management mainly relies on resistant varieties, as no other successful control methods are available (Moročko-Bičevska et al., 2021).
It is considered that direct damage of Cecidophyopsis mites and damage due to Blackcurrant reversion virus (BRV, Nepovirus ribis) vectored by these mites, severely constrain Ribes production (Moročko-Bičevska et al., 2021).

What is the likely economic impact of the pest irrespective of its infestation source in the absence of phytosanitary measures? (= official measures)
 
Medium to Major

Is the economic impact due to the presence of the pest on the named host plant for planting, acceptable to the propagation and end user sectors concerned?
 
No

Is there unacceptable economic impact caused to other hosts (or the same host with a different intended use) produced at the same place of production due to the transfer of the pest from the named host plant for planting?
 

Conclusion:
 
Candidate

Justification:
 
Economic impact was rated for R. nigrum.

6 - Are there feasible and effective measures available to prevent the presence of the pest on the plants for planting at an incidence above a certain threshold (including zero) to avoid an unacceptable economic impact as regards the relevant host plants?
 
Yes
 
Conclusion:
 
Candidate

Justification:
 
Chemical control,
Biological control,
Host-plant resistance.

[In responses to the questionnaire, DE commented that 'a generally known pest that can be easily controlled by the operator should not be regulated as RNQP. Horizontal regulation in the marketing regulations should ensure that the consignments to be marketed/moved are “practically free from pests”'.]

7- Is the quality of the data sufficient to recommend the pest to be listed as a RNQP?
 
No
 
Conclusion:
 
Candidate

Justification:
 
Uncertainty whether plants for planting should be considered as a significant pathway compared to natural spread.

CONCLUSION ON THE STATUS:
 
Recommended for listing as an RNQP, by default (uncertainty whether plants for planting should be considered as a significant pathway compared to natural spread). Conclusion was that there is insufficient evidence to recommend changes from the current regulation and measures.


8 - Tolerance level:

Is there a need to change the Tolerance level:
 
No

Proposed Tolerance levels:
 

9 - Risk management measures:

Is there a need to change the Risk management measure:
 
No

Proposed Risk management measure:
 


REFERENCES: