Density and Spatial Relationships Between a Wasp Parasite and Its Housefly Host

Abstract

The density and spatial relationship between the wasp parasite, Nasonia vitripennis, and the housefly host, Musca domestica, were investigated. As parasite dispersion decreased in a defined space, parasitism increased from 30 to 76% and host survival decreased from an average of 65.0 to 18.9%. The number of host pupae producing parasite progeny and the survival of host pupae decreased as the proportion of small host pupae increased. With host numbers increasing and parasite numbers constant, the mean number of eggs deposited per host increased significantly from 31.25 to 87.25 and the number of stings increased from 2.25 to 8.00. As parasite density increased and host number remained constant, the number of hosts which were nor attacked declined from a mean of 2.2 with 1 parasite to none with 32 parasites. Host survival declined from about 50% at the 1:8 ratio of female parasites to hosts to no survival at the 2:1 ratio.