PARASITOIDS OF LYCAENID BUTTERFLY CATERPILLARS - DIFFERENT PATTERNS IN RESOURCE USE AND THEIR IMPACT ON THE HOSTS SYMBIOSIS WITH ANTS

Resource utilization and impact on mutualism with ants were comparativ ely studied in three parasitoids (Braconidae: Cotesia saltatoria, Alei odes bicolor; Tachinidae: Aplomya confinis) whose endophagous koinobio nt larvae develop solitarily in myrmecophilous lycaenid butterfly cate rpillars (Polyommatus coridon, P. icarus). C. saltatoria infests young host larvae, emerges when the hosts are still small (15-25 mg), pupat es in a silk cocoon near the host carcass and leaves 65% host mass (we t weight) unused. Details on the biology of this species are recorded for the first time. A. bicolor also attacks small hosts; the wasps pup ate inside the host skin when the hosts have grown to 25-35 mg. A. con finis flies lay their eggs on larger hosts, the larvae egress from mor e advanced final instar caterpillars (mean weight 73 mg) to form their puparium away from the host carcass, and leave only 43% host mass unu sed. Mutualism with ants in caterpillars parasitized by C. saltatoria is already reduced two days before parasitoid emergence, but the still living and relatively intact carcasses retain some attractiveness to ants for 1-2 days beyond parasitoid egression. A. bicolor manipulates host behaviour to resemble precocious prepupae. One day before mummy f ormation caterpillars infested by this wasp search for sites to settle down, increase delivery rate of myrmecophilous secretions, and thus i ntensify their mutualism with ants. From pupation of the wasp larva on wards, however, the mummies' attractiveness to ants is steadily declin ing. In caterpillars parasitized by A. confinis the mutualism with ant s totally breaks down on the day before maggots egress. Larvae of all three parasitoids avoid potential predation risks resulting from ant-a ttendance of their hosts when emerging.