Coloradoa bournieri

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.

Micrographs of clarified mounts by permission of Roger Blackman, copyright AWP all rights reserved.

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 observed	by: V.F. Eastop	1960	at: Kew Gardens, London
Second	by: E.W. Baker	2008	at: Cardiff Bay, Wales
Third	by: Influential Points	12 May 2015	at: 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 (Show World list). Of those aphid species, Baker (2015) lists 6 as occurring in Britain (Show British list).

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. Our particular thanks to Roger Blackman for images of his clarified slide mounts. Whilst we make every effort to ensure that identifications are correct, we cannot absolutely warranty their accuracy. We have mostly made 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