BR. J. ENT. NAT. HIST., 6: IW1 



ANT DEFENCE OF COLONIES OF APHIS /ABA/; 



SCOPOLI (HEMIPTERA: APHIDIDAE), AGAINSI 



PREDATION BY LADYBIRDS 



Christopher Jiggins, Michael Majerus* and Ursula Gough 



Department of Genetics, University of Cambridge, Downing Street, Cambridge CB2 3 EH. 



INTRODUCTION 



The symbiosis of ants and honeydew-producing aphids is well studied (Way, 1963). 

 Most myrmecophilous Homoptera show behavioural and structural modifications 

 for life with ants. The ants eat honeydew, a waste product of the aphids. Honeydew 

 is rich in carbohydrate and also contains free amino acids and amides (Ewart & 

 Metcalf, 1956; Gray, 1952; Maltais & Auclair, 1952; Mittler, 1958), proteins (Maltais 

 & Auclair, 1952), minerals and B-vitamins (Hagen, 1962). The ants may also obtain 

 protein by preying on excess aphids in and around the colony (Nixon, 1951; Pontin, 

 1958). The assumed benefits to the aphids are primarily protection from natural 

 enemies and improved hygiene through removal of honeydew and dead aphids. There 

 is conflicting evidence concerning direct action by ants to defend aphids. El-Ziady & 

 Kennedy (1956) showed that Lasius niger L. workers attacked and drove away larvae of 

 Adalia bipunctata L., and adults of A. bipunctata, Coccinella 7-punctata L. and Propylea 

 14-punctata L. Banks (1962) observed that ants of this species remove coccinellid 

 eggs from the vicinity of attended aphids. However, other workers have recorded 

 that L. niger rarely interferes with adult coccinellids feeding on its attended aphids, 

 Herzig (1938) and Wichmann (1955) both concluding that coccinellids preying on L. 

 niger-tended aphid colonies are little affected by ants. A similar set of contradictory 

 observations may be found in the literature on Formica rufa L. Wellenstein (1952) 

 and Kloft (1953) report that only newly emerged or very old adult coccinellids were 

 attacked, while Majerus (1989) reports adults of nine out of ten species of coccinellid. 

 and larvae of two out of three species, were attacked and driven away by F. rufa. 

 The one exception was that both larvae and adults of Coccinella magnifica 

 Redtenbacher, a known myrmecophile (Donisthorpe, 1920, 1927, 1939), were ignored 

 by the ants. Majerus (1989) suggests that this species uses pheromonal manipulation 

 of the ants to allow it access to a large food source in the form of ant tended 

 aphids. 



Nixon (1951) concludes that any protection afforded aphids by their association 

 with ants is only incidental, ants either accidentally disturbing some aphid 

 predators or being naturally hostile to rapidly moving organisms including a 

 number of aphid predators. More recently other authors (Way, 1963; Rotheray, 

 1989) have suggested that this is an over-simplification, and that the relationships 

 between ants, aphids and aphid predators are more complicated and still little 

 understood. 



The aim of this project was to look at the behavioural interaction between ants 

 and ladybirds. 



Methods 



Fieldwork was carried out at Juniper Hall Field Studies Centre, Mickleham, Surrey. 

 from 27 June to 3 July, 1991. A natural colony of Aphis fabae (black bean aphid) 



*Addressee for correspondence. 



