FruitDisease - Entomology, Ribes pests

Ribes pests


Introduction

Blackcurrant sawfly larva

The currants or Ribes contains some of the most important bush fruits in Europe. Although most of the research at SCRI is related to the breeding of blackcurrants entomological research has concentrated on understanding phenology of the mites of the family Cecidophyopsis in collaboration with researchers elsewhere in the World  and the damage they do.

Image above is a larva of blackcurrant sawfly

 Blackcurrant gall mite

The most important mite species is the blackcurrant gall mite (Cecidophyopsis ribis), the vector of Blackcurrant Reversion Virus. C. ribis feed within the bud causing the characteristic galled buds that fail to open in the spring. Fortunately, commercially blackcurrant gall mite resistant blackcurrants cultivars are now becoming available. Cultivar Ben Hope and several advanced genotypes now show high levels of resistance. The release of gall mite resistant cultivars is timely as the number of suitable acaricides approved for their control declining rapidly.

 
Blackcurrant gall mite damaged shoot Blackcurrant TS Gall
Blackcurant shoot with galled buds

Transverse section of blackcurrant bud infested with blackcurrant gall mites (small white specks)

SEM Blackcurrant gall mite colony Blackcurrant gall mite _ SEM

Scanning electronic image of part of blackcurrant gall mite colony in a galled blackcurrant bud. The elongated, cigar-shaped objects are mites and the round objects eggs

Closeup of an individual black currant gall mite feeding on individual cells within a blackcurrant galled bud

Gooseberry and other Ribes mites

Gooseberry mite (C. grossulariae) damages both gooseberry and blackcurrant. However, the damage to blackcurrants is often associated with crops grown in warm moist climates. They also colonise the buds which do not swell and become galled, but the flower initials are killed, and in severe attack yields are reduced. Other, as yet unidendified, mites have been associated with redcurrant in Central Europe. These mites cause bud to swell slightly and internal necrosis is associated with feeding.

 In northern Europe, several very closely related Cecidophyopsis species are associated with several wild and cultivated Ribes. The virus vector capability of these mites is unknown. 

 Gooseberry mite damage Ribes bud  Eriophyid mite feeding in Ribes alpinum bud

Gooseberry mite damage to white currant bud showing extensive necrosis of floral parts

Eriophyid mites feeding in a bud of Ribes alpinum from Sweden 

Eriophyid mite gall on redcurrant from Hungary Transverse section of galled redcurrant

Eriophyid mite induced galls on redcurrant Hungary

Transverse section of redcurrant gall showing necrotic patch (left of centre) associated with mite feeding

 

Other important Ribes pests

 

Blackcurrant leaf curling midge

Blackcurrant leaf curling midge (Dasineura tetensi) is becoming more problematic in Northern Britain, particularly in blackcurrant nurseries. Different levels of susceptibility have been observed in blackcurrant cultivars. Cultivar 'Ben Connan' appears to have some resistance.

Clearwing moth

Although Synanthedon tipuliformis are frequently found in Europe and elsewhere in the world, they have been relatively uncommon in Scotland. However, in recent years they have been frequently observed in breeding plots at SCRI. These small day-flying moths are brown in colour have three narrow yellow stripes running across the body. The wings are mostly clear, but have orange edges and tips. There occurrence in the north may result from the climate becoming more favourable to the insect. Pheromones are commercially available to attract and trap the males by mating disruption. There is no strong source of resistance available so development of the pest status of this insect will continue to be monitored.

Ribes Aphids

Several aphid species colonise currants in northern Britain. Most damage leaves but are not known to transmit any viruses. When extensive leaf feeding occurs, there is an increased risk of contamination of the fruit by honeydew. Should this become colonised with moulds, such as sooty mould, then the quality is further decreased.  At SCRI, susceptible genotypes and selections are actively screened out of the breeding lines.  

Scale insects

Several scale insects are associated with Ribes. In northern Britain few cause any economic loss, but one in particular, the woolly vine scale (Pulvinaria vitis syn. P. ribesiae) is now found occasionally in Scotland. Apart from weakening the plant, the honeydew produced can be contaminated by sooty mould. Any susceptible plants are screened out as part of the selection process.

Woolly vine scale on blackcurrant Closeup of Woolly Vine Scale egg mass

Blackcurrant stem infested by the woolly vine scale

Close up of part of colony of woolly vine scales showing the 'woolly' egg masses

Ribes sawflies

In Scotland, there are two important sawflies that are sporadic pests of Ribes, the Gooseberry Sawfly (Nematus ribesii) and the Blackcurrant Sawfly (Nematus olfaciens). Apart from gooseberry, the gooseberry sawfly can cause sever defoliation of Jostaberry whereas the blackcurrant sawfly is found mainly on blackcurrant. As far as we are aware there is no sources of resistance. We continue to monitor the levels of infestation.

 
Blackcurrant sawfly damage to blackcurrant leaves Closeup of blackcurrant sawfly feeding

Blackcurrant sawfly feeding damage to blackcurrant

Close up of blackcurrant sawfly feeding on blackcurrant (click on image to enlarge)

References

Fenton B, Malloch G, Jones AT, Amrine JW, Gordon SC, A'Hara S, McGavin WJ & Birch ANE (1995) Species identification of Cecidophyopsis mites (Acari: Eriophyidae) from different Ribes species and countries using molecular genetics, Molecular Ecology. 4 383-387. 
Hummer KE, Carter J, Postman JD & Gordon SC (1999) Survey of Gooseberry Mite Infestation in Ribes L. HortScience. 34, 678-680.