Differential interactions between an aphid endohyperparasitoid and three honeydew-collecting ant species: A field study of Alloxysta brevis (Thomson)(Hymenoptera : Alloxystidae)

The behavioral interactions between the chemically protected aphid hyperpar asitoid Alloxysta brevis and three trophobiotic ant species were examined i n the field on thistles. The patterns were not essentially influenced by hy perparasitoid sex. Ants differed in their guarding behavior of aphids and t heir response toward A. brevis. Lasius niger attacked the hyperparasitoid m ore readily than Myrmica laevinodis, while aggression by Formica rufa was i ntermediate. Apart from applying chemical defense A. brevis responded to an ts by flying away (mainly at L. niger) or with avoidance behavior (mainly a t M. laevinodis). Additionally, females might switch their tactics from fli ght to defense with increasing age. Females left the plant more often after encounters with L. niger or F. rufa than with M. laevinodis. Disturbance b y any ant species affected the foraging activities, reducing oviposition su ccess to nearly zero.