Analysis of solitariness in a parasite—host system (Muscidifurax raptor,Hymenoptera: Pteromalidae—Ceratitis capitata,Diptera: Tephritidae)*

Abstract. 1. The behaviour of the parasite Muscidifurax raptor Girault and Sanders was studied when searching for hosts, puparia of the Mediterranean fruit fly, Ceratitis capitata (Wiedemann). At low density females tend to avoid encountering parasitized hosts. This tendency decreases as density of searching females increases. 2. The proportional avoidance of superparasitism was calculated and the effect of increasing number of encounters per host on this parameter was analysed. 3. The mechanisms of solitariness were studied. These mechanisms include: outer marking of the hosts by the female parasite and deliberate physical attack of the newly hatched larvae to eliminate as yet unhatched eggs. 4. In cases of intraspecific competition between larvae, young first or second instar larvae usually have the advantage over older larvae.