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Cotton lavender aphidOn this page: Identification & Distribution Biology & Ecology Other aphids on the same host Damage & Control
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 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).
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.
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).