SEASONAL CYCLE AND BIOLOGY OF WINTHEMIA RUFOPICTA (DIPTERA: TACHINIDAE) AS A PARASITE OF HELIOTHIS SPP. (LEPIDOPTERA: NOCTUIDAE) ON TOBACCO IN NORTH CAROLINA

Publisher Website
Google Scholar
Abstract
The first adult generation of Winthemia rufopicta (Big.) emerged during April in North Carolina, males preceding the females by about a week. This was several weeks prior to the occurrence of large larvae of Heliothis zea (Boddie) and H. virescens (Fab.), two commonly recorded hosts of W. rufopicta. The average female, after a pre-ovipositional period of several days, deposited about 60 eggs over a further several days. The sex ratio was normally unity, with the exception that flies overwintered in the field showed a predominance of males.Populations of W. rufopicta declined in spring, apparently from a shortage of hosts, then slowly built up through several overlapping generations: developmental rates at different temperatures are indicated. In the fall, local host concentrations were more frequent, and parasitism of Heliothis hosts on tobacco occurred consistently and sometimes reached high levels. Parasites overwintered as fully grown diapausing maggots in shallow cells in the soil.Experimental populations of Heliothis spp. (mainly H. virescens) maintained on tobacco were not parasitized by W. rufopicta until late in the season. Temporal and spatial interactions between host and parasite populations at that time are discussed.