A 'new' aphid is causing severe damage to lupins in East Anglia

A 'NEW' APHID IS CAUSING SEVERE DAMAGE TO LUPINS IN EAST ANGLIA G. D. HEATHCOTE

Essig's lupin aphid, Macrosiphum albifrons Essig, is a most unwelcom recent newcomer to East Anglia and other parts of England. This very large, blue-green aphid originated in North America and wasfirstfound in Britain in 1981 at the Royal Botanic Gardens, Kew (Stroyan, 1981). It was on lupins (Lupinus spp.) on which it completes its life cycle. It is not known to attack any other genera of Leguminosae or other plants.

The lupins at Kew had all been grown from seed and the origin of the infestation is not known. It is at least possible that the infestation was started by a winged aphid which came as a stowaway on an aircraft landing at Heathrow. The chance of an aphid crossing the Atlantic in this way and of thenfindinga suitable host plant is, of course, extremely remote. However, even those aphids which attack only a limited number of plant species can sometimes be abundant locally and a few may then be carried by the wind or transported accidentally by man long distances from these sites. As most aphids are female, capable of producing twenty or more young without mating, and these young will in turn reproduce asexually, producing a similar number of young within about two weeks, it does not take long for a Single aphid to Start an infestation if conditions are favourable.

The lupin aphid was caught for thefirsttime in the suction trap at Broom's Barn, Higham, Bury St Edmunds (run as part of Rothamsted's Insect Survey) in late June and early July 1983. In the same period Utamphoro phora humboldti (Essig), which is another aphid which is thought to hav come to England originally as a passenger on an aircraft, was trapped at Broom's Barn. They might conceivably have reached Europe overland from America by a series of long hops via Siberia and Central Europe, or by way of a very high air-mass (Dr C. S. Wood-Baker,pers. comm.).

Whenfirstfound in Britain the lupin aphid was not thought to pose a serious threat, although it was considered prudent to keep a watch on gardens and nurseries for this pest, but in 1982 it had spread to many parts of London, and it had been found in Hertfordshire, Bedfordshire, Leicestershire and more generally in the South-east. In 1983 it was reported from Somerset, Dorset, the Isle of Wight, Anglesea, Yorkshire, many parts of Norfolk and Suffolk and in other counties.

Several species of lupins are attacked, including the garden Russell lupin, L. polyphyllus Lindl., and the tree lupin, L. arboreus Sims. The aphi first discovered on L. albifrons Benth. in California in 1911. In Suffolk it ha been found on L. polyphyllus at Lowestoft, Southwold, Wenhaston, Bun gay, Haiesworth and Bury St Edmunds, and on L. arboreus at Lowesto Corton, Kessingland, Haiesworth, and from Southwold to Thorpness. In Norfolk it was reported on L. polyphyllus at Norwich, Felthorpe, Brundal Taverham, Stoke Holy Cross, Long Stratton, Pulham Market, Harleston, Bungay, Thetford, Downham Market, Fakenham, Lyng, Thursford, Trans. Suffolk Nat. Soc. 21

A ' N E W ' A P H I D IS CAUSING SEVERE DAMAGE TO LUPINS

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Blakeney, East Hunton, Hemsby and Gorleston, and on L. arboreus at Blakeney, Happisburgh, Sea Palling, Eccles, Broome nr. Bungay and Gorleston (Gt. Yarmouth). It doubtless occurred at other sites as well.

M. albifrons is related to the well-known rose aphid, M. rosae (L.), and the potato aphid, M. euphorbiae (Thos.), which can cause 'top roll' in potato crops when present in large numbers. Lupin aphids may be winged or wingless, and up to 5mm long, which is large for an aphid. This perhaps inspired a Journalist of The Sun newspaper to write a paragraph on 10 August 1983 under the headline ' G O L L Y ! G R E E N GIANTS' which began: 'Giant greenflies have invaded Britain from America - and are threatening to ravage farmers' crops. Leading northern botanist Don Williams said "These things are huge - you could almost throw a saddle over them." The Essig's lupin aphid is sweeping the north of England like a plague Apart from their size and colour, lupin aphids can be recognised by their covering of a waxy powder, which helps to protect them against insecticide sprays. An entomologist identifies M. albifrons by examining its cornicles, a pair of tubes projecting backwards from the abdomen. Popularly known as 'honey-tubes', the cornicles do not give out the sweet, sticky 'honey-dew' as was once thought (which is excreted through the anus). Their real function is to secrete a waxy fluid which rapidly hardens and gives some protection from predators. It also contains a highly volatile chemical (a pheromone) the scent of which w a m s other aphids of danger. The cornicles of an adult M. albifrons are long and straight with a dusky, reticulated tip, but those of the immature forms are uniformly dark like those of M. rosae.

The damage caused by lupin aphids can be very severe. Even if lupins are not killed, the aphids will cause abortion of the flower buds and general debilitation of the plants. Control of the damage is difficult. The structure of the plants makes them difficult to spray with an insecticide and damage is caused before the natural enemies of the aphid reduce their number . . . Dr J. Waage of Imperial College, Silwood Park, is beginning a research project to study the establishment of natural predators of this foreign pest and some natural control has already been seen to occur. Mr J. Sillet reported finding up to a dozen small yellow-and-black ladybirds associated with the aphid on tree lupins at Corton. These will have been the 14-spot ladybird, Propylea 14-punctata (L.). E A E has reared a few hover-flies (Episyrphus balteatus (Degeer) from aphid colonies in Suffolk, and late in the season some lupin aphids were killed by parasitic fungi. The most common fungus appears to have been Erynia neoaphidis Rem. & Henn. ( = Entomophthora aphidis H o f f m a n ) but Entomophthora planchoniana Cornu was also found. Birds may also help to control this aphid. In two instances lupin aphids were seen to be eaten avidly by house sparrows.

The future for lupins in East Anglia looked very bleak. However, unfavourable weather and natural enemies can greatly reduce the threat of damage by the lupin aphid in many seasons, even though it seems unlikely that the pest will ever be eradicated in England now. Lupin aphids were not caught in the Broom's Barn suction trap during 1984 (pers. comm. Dr Alan Dewar) and they do not appear to have been common throughout the county in 1984.

Trans. Suffolk Nat. Soc. 21

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Suffolk Natural History, Vol. 21

Acknowledgements I am most grateful to our President, Dr E. A. Ellis, for sending me details of the localities in Suffolk (and in other counties) where the lupin aphid has been found, and for his observations on predators attacking the pest. Dr M. B. Ellis determined the identity of the fungi.

Reference Stroyan, H. L. G. (1981). A North American lupin aphid found in Britain.

PI. Path., 30, 253.

DrG. D. Heathcote, 2, St Mary's Square, Bury St Edmunds, IP33 2AJ

Plants Growing on Old Walls Mr J. Last, a botanist of Stowmarket, showed me Sedum dasyphyllum Thick-leaved Stonecrop, growing on the top of an old brick andflintwall at Rickinghall Inferior on 8 July, 1984. This is an uncommon plant. It is very likely the site seen by Hind and recorded for this parish in his Flora of 1889.

The wall probably dates from the late 18th Century or early 19th and is now partly crumbling.

Mrs A. G. Morgan informs me that Sempervivum tectorum L., Hous grows on the old wall of Cliff House, Shottisham. This is another member of the Crassulaceae. The previous owner of Cliff House informs Mrs Morgan that it was there 63 years ago when she married and came to live there.

Church walls, in particular, are important habitats for some of our rare Suffolk ferns. Unfortunately many are being ruthlessly cleaned and sprayed with herbicides. Ferns do not damage to any extent the fabric of buildings.

Their conservation is one important point to remember in the management of churchyards as nature reserves.

In 1888, the Rev. Francis Galpin recorded Ceterach officinarum D Rusty-back fern, on the church wall at Mendham in his 'Account of the Flowering Plants of Harleston,' but the fern was reported to have been destroyed during restoration work in 1970/71. I visited Mendham on 30 August 1984, accompanied by the Misses B. and R. Copinger Hill, and was dismayed tofindthat workmen were repairing the north side and had removed a healthy specimen of the Rusty-back fern. The Rector, who had not noticed any ferns in the previous seven years, climbed a ladder and had the fern replanted. I do not know if it survived. However, I did see one other specimen above the porch, but it was small and dried-up. Arriving on the very afternoon when the fern was being removed was an almost uncanny coincidence.

F. W. Simpson.

Trans. Suffolk Nat. Soc. 21