LIFE-HISTORY AND DESCRIPTION OF IMMATURE STAGES OF DIOXYNA-PICCIOLA (BIGOT) (DIPTERA, TEPHRITIDAE) ON COREOPSIS SPP (ASTERACEAE) IN SOUTHERN CALIFORNIA

Dioxyna picciola (Bigot) is bivoltine or trivoltine and oligophagous p rimarily on Coreopsis and Bidens spp. in southern California. It is a late-stage, aggregated attacker in flower heads at or past anthesis. M ating and oviposition by overwintered F-2 and F-3 adults occurs in spr ing on wild and cultivated Coreopsis spp. Eggs are inserted into soft achenes in which the first two instars and most early-third instars fe ed solitarily; the late-third instars also feed on sap, and at higher larval densities, score the receptacles and feed on sap accumulated in shallow depressions. Pupariation occurs in heads, with puparia restin g in the feeding depressions, or in flower heads containing only a sin gle larva, within hollowed out achenes and situated well above the rec eptacle. Adults are synovigenic, sexually immature at eclosion, but ex ceptionally long-lived as the overwintering stage. This tephritid is k nown in North America as D. picciola, but it recently was synonymized with the cosmopolitan D. sororcula, but unlike the latter species, Nea rctic flies have not been reported from Calendula officinalis L. The e gg is described and illustrated and differs from the eggs of two other species in the closely related genus Campiglossa (=Paroxyna) by the e longate, apically expanded pedicel, which bears aeropyles apically. Fi rst through third instars and the puparium also are described and illu strated. Third instars of D. picciola are similar in morphology to tho se of Campiglossa genalis (Thomson), but are more elongate and cylindr ical, have a gnathocephalon that is broader apically, with serrated ru gose pads dorsomediad of the anterior sensory lobes. The anterior sens ory lobes are larger and more prominent and the serrated rugose pads l aterad of the mouth lumen are larger and more numerous than in two Cam piglossa spp. that have been described in similar detail. Behaviors of adults of D. picciola and C. genalis in southern California were simi lar, but differed in several respects from D. picciola on C. officinal is in India. Wing lofting by D. picciola and such unique aspects of it s mating behavior in southern California as its copulatory induction b ehavior and mate guarding are described.