130 BR. J. ENT. NAT. HIST., 6: 1993 



on Cirsium arvense L. (creeping thistle) tended by Myrmica ruginodis Nylander was 

 studied. There were approximately 40 ants on the aphid colony at any one time. A 

 similar colony tended by L. niger — about six ants on the colony at any one time — 

 was used for some preliminary tests and observations. 



Ladybirds were collected from nettle beds in the vicinity of the Field Centre. They were 

 kept in petri dishes for 1-2 days before the experiment. Ladybirds were starved prior to 

 the experiment to ensure that they would be hungry and take an interest in the aphids. 

 This standardized, at least to some extent, the nutritional status of the ladybirds. 



A single ladybird was placed on the stem of the thistle 5 cm below the colony. 

 Ladybirds are positively phototactic and negatively geotropic (Majerus & Kearns, 

 1989) so they tended to walk up the stem towards the colony. A variety of species 

 of ladybird were used (see Table 1). 



The results were recorded as a series of timed observations, noting, for example, 

 each encounter between a ladybird and an ant, its position relative to the aphid colony, 

 and the result of the encounter. 



The experiment ended when the ladybird walked or flew off the plant, or went 

 into a prolonged state of inactivity away from the colony. If it cleaned itself after 

 an encounter with an ant, this was recorded. Sometimes the ladybird would start food- 

 searching behaviour away from the colony without encountering an ant or aphid. 

 This was recorded and the experiment ended by removing the ladybird. Another 

 individual was then placed on the stem. Virtually all aphid colonies in the vicinity 

 were tended by ants; however, one similar but untended aphid colony was found and 

 this was used to carry out a small run of experiments as controls. 



Table 1 . Number of experiments with each species of coccinellid used. The 

 finding of only one untended aphid colony meant that few control tests 

 could be conducted. 



Experiments Controls 



Carnivorous species 







Adults 







Adalia bipunctata 

 Coccinella 7-punctata 

 Calvia 14-guttata 

 Propylea 14-punctata 

 Myrrha 18-guttata 

 Anatis ocellata 

 Exochomus 4-pustulatus 

 Myzia oblongoguttata 



(2-spot ladybird) 

 (7-spot ladybird) 

 (cream-spot ladybii 

 (14-spot ladybird) 

 (18-spot ladybird) 

 (eyed ladybird) 

 (pine ladybird) 

 (striped ladybird) 



21 5 

 13 4 

 ■d) 5 

 5 

 3 

 1 

 2 

 2 



Non-carnivorous species 



Halyzia 16-guttata 

 Micraspis 16-punctata 

 Psyllobora 22-punctata 



(orange ladybird) 

 (16-spot ladybird) 

 (22-spot ladybird) 



5 

 2 

 8 



Larvae 







Adalia bipunctata 

 Coccinella 7-punctata 

 Anatis ocellata 



(2-spot ladybird) 

 (7-spot ladybird) 

 (eyed ladybird) 



5 

 4 

 3 



