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Identification & Distribution:

Adult apterae of Coloradoa bournieri (see first picture below) are pale or dirty green with dark apices to the appendages. The terminal process of the sixth antennal segment is quite short being 1.2-1.5 times the length of the base of that segment. The fused last two rostral segments (RIV+V) are 1.2 to 1.5 times longer than the second segment of the hind tarsus (HTII) (cf. Coloradoa absinthii, which has the fused last two rostral segments shorter than the second segment of the hind tarsus). Their siphunculi are clearly swollen and curved outwards towards apices, with the swelling asymmetrical and greatest on inner side (see micrograph below) (cf. most other Coloradoa species where siphunculi are cylindrical or only weakly and symmetrically swollen. The body length of Coloradoa bournieri aptera is 1.1-1.5 mm.

The alate (second picture above) has 8-14 secondary rhinaria on antennal segment three, 4-8 on segment four and 0-4 on segment 5.

The micrograph (second picture above) shows an aptera of Coloradoa bournieri in alcohol.

Coloradoa bournieri feeds on cotton lavender (Santolina chamaecyparissus) and green cotton lavender (Santolina viridis). No sexual forms are known and the species breeds parthenogenetically through the year. The cotton lavender aphid is indigenous to Mediterranean Europe and the Middle East where its host plant occurs naturally. It has now been found in Britain, and Argentina (coll. Durante, 2009).

Our observations are the third record of Coloradoa bournieri in UK to date.
First observedby: V.F. Eastop1960at: Kew Gardens, London
Secondby: E.W. Baker 2008at: Cardiff Bay, Wales
Thirdby: Influential Points12 May 2015at: Plumpton College, East Sussex

 

Biology & Ecology:

We found this species feeding on cotton lavender (Santolina chamaecyparissus) in a plant nursery in Plumpton.

Quite large numbers of ants were observed on the aphid infested plants.

The ants were feeding on the copious honeydew deposits, but did not appear to be actively tending these aphids.

The colony we found was a mixed species population with Myzus ornatus,  a highly polyphagous species (see next picture below - the aphid top right is Myzus ornatus).

 

Other aphids on same host:

Blackman & Eastop list 7 species of aphid  as feeding on Santolina species worldwide, and provide formal identification keys.

Of those aphid species, Baker (2015)  lists 6 as occurring in Britain: Aphis fabae,  Aulacorthum solani,  Brachycaudus helichrysi,  Coloradoa bournieri, Myzus persicae  and Protaphis terricola. 

 

Damage and control

Coloradoa bournieri is invasive around the world on the ornamental shrub Santolina chamaecyparissus (cotton lavender). Baker (2009)  reported finding Coloradoa bournieri in July 2008 feeding in small numbers on a Santolina chamaecyparissus, growing in a container situated in the car-park of County Hall, Cardiff Bay. Durante (2011)  reported the species from Patagonia in Argentina.

Given favourable conditions, it seems likely that this species could reach pest numbers. The populations we observed did reach large numbers, but was then rapidly eliminated by cecidomyiid larvae (see picture above).

Acknowledgements

We especially thank Plumpton College  for their kind assistance, and permission to sample.

We have made provisional identifications from high resolution photos of living specimens, along with host plant identity. In the great majority of cases, identifications have been confirmed by microscopic examination of preserved specimens. We have used the keys and species accounts of Blackman & Eastop (1994)  and Blackman & Eastop (2006)  supplemented with Blackman (1974) , Stroyan (1977) , Stroyan (1984) , Blackman & Eastop (1984) , Heie (1980-1995) , Dixon & Thieme (2007)  and Blackman (2010) . We fully acknowledge these authors as the source for the (summarized) taxonomic information we have presented. Any errors in identification or information are ours alone, and we would be very grateful for any corrections. For assistance on the terms used for aphid morphology we suggest the figure  provided by Blackman & Eastop (2006).

Useful weblinks 

References

  •  Baker, E.A. (2009). Observations of aphids (Aphidoidea) new to Wales. British Journal of Entomology and Natural History 22, 235-246. Abstract 

  •  Durante, M.P.M. et al. (2011). Three aphid species (Hemiptera: Aphididae) recorded for the first time from South America. Florida Entomologist 94(4), 839-842. Full text