A SEX-SPECIFIC TRI-TROPHIC-LEVEL EFFECT IN A PHORETIC ASSOCIATION

Hemisarcoptes coccophagus (Acari: Astigmata: Hemisarcoptidae) is an ob ligate parasite of armored-scale insects (Homoptera: Diaspididae). Hyp opodes (non-feeding heteromorphic deutonymphs) of this mite cannot com plete their development without a phoretic sojourn on the coccinellid beetle Chilocorus bipustulatus. We tested whether the feeding history of the beetles affects the probability of the hypopodes completing the ir development. Two diets were offered: armored-scale insects (Homopte ra: Diaspididae) (suitable for both beetles and mites) and soft-scale insects (Homoptera: Coccidae) (suitable for the beetles but not for th e mites). The hypopodial survival was similar for mites which had been on beetles reared on the different scales. However, female hypopodes which had stayed on beetles reared on soft scales suffered higher mort ality than those from Chilocorus reared on armored scales. Male surviv al was not affected. A tri-trophic-level effect on sex-specific surviv al in a phoretic association was thus demonstrated.