Lifetime ovipositional patterns of mated and virgin onion flies, Delia antiqua (Diptera: Anthomyiidae)

Over their 47.2±1.9 (mean±SEM) day lifespan, mated onion flies, Delia antiqua, oviposited more uniformly than did virgins. Mated females began ovipositing at 6.4±0.2 days old and regularly deposited 14.2±0.6 eggs/day for 3–4 weeks. Thereafter, oviposition slowed and stopped at about 1 week before death. Virgin flies began ovipositing 24.7±1.5 days into their 59.0±3.8 day lifespan, and deposited eggs at an increasing rate for 3–4 weeks, generating a mean overall ovipositional rate of 5.8±0.5 eggs/day. The later onset of virgin oviposition (ovipositional activation) and not a shorter ovipositional period largely accounted for the disparity between virgin and mated female lifespans. Mean lifetime egg production of mated females was 475±27 eggs versus 179±30 eggs for virgins. Ovipositional and post-ovipositional periods (34.4±1.8 and 7.2±1.0 days) for mated females were not significantly different from those of virgin females (30.9±3.6 and 6.7±1.2 days). Over 90% of virgin females laid eggs. The distinction between mated and virgin ovipositional patterns may be specifically attributed to differences in: (1) egg maturation, (2) age at ovipositional activation, and (3) egg-laying rate.