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Cotton lavender aphidIdentification & Distribution Biology & Ecology Damage & Control
Identification & Distribution:Adult apterae of Coloradoa bournieri are pale or dirty green with dark apices to the appendages. Their siphunculi are clearly swollen (see pictures below). The body length of Coloradoa bournieri aptera is 1.1-1.5 mm.
The terminal process of the sixth antennal segment is quite short (see first picture below) 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). This last character distinguishes Coloradoa bournieri from Coloradoa absinthii, which has the fused last two rostral segments shorter than the second segment of the hind tarsus. The first micrograph below shows an aptera in alcohol.
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.
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, having been recorded from Kew Gardens (coll. Eastop, 1960), Cardiff Bay (coll. Baker, 2008) and Brighton (coll. Brightwell & Dransfield, 2015). Coloradoa bournieri has also been recorded from Argentina (coll. Durante, 2009).
Biology & Ecology:
We found this species feeding on cotton lavender (Santolina chamaecyparissus) in a plant nursery in Brighton.
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).
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).