SPECIFICITY OF ACCESSORY-GLAND EXTRACTS IN 3 DELIA FLY SPECIES (DIPTERA, ANTHOMYIIDAE)

Extracts of testes and male accessory (paragonial) glands made from th ree species of Delia (onion fly (D.antiqua), seedcorn fly (D.platura), and cabbage fly (D.radicum)) were injected into conspecific virgin fe males. Extracts of paragonial glands, but not testes, from onion, seed corn and cabbage fly males stimulated oviposition and suppressed matin g when injected into conspecific virgin females. When extracts of para gonial glands from males of these species were injected into heterospe cific virgin females, the extracts of D.antiqua and D.platura were ful ly cross-reactive with respect to oviposition; interspecific injection stimulated oviposition at the level of the conspecific mated controls . Injection of D.radicum extract fully activated the D.antiqua and D.p latura ovipositional response. D.antiqua extract caused mating inhibit ion and partial oviposition in D.radicum; that of D.platura had no eff ect on either oviposition or mating inhibition in D.radicum. These res ults suggest that D.antiqua and D.platura are more closely related to one another than either is to D.radicum, and agree with published anat omically-based phylogenies and a genetic distance calculation based on eight enzyme loci. The occurrence of sex peptide cross-reactivity, th ough asymmetrical, between D.radicum versus D.antiqua and D.platura in dicates that, functionally, sex peptides have changed little during th e evolution of this genus. An emerging pattern of broad cross-reactivi ty within genera suggests that sex peptides are not an initiator of re productive isolation.