HOST-PARASITE RELATIONSHIPS IN 6 SPECIES OF SPHECODES BEES AND THEIR HALICTID HOSTS - NEST INTRUSION, INTRANIDAL BEHAVIOR, AND DUFOURS GLAND VOLATILES (HYMENOPTERA, HALICTIDAE)

Nest invasion behavior was studied in six kleptoparasitic Sphecodes sp ecies at four nesting sites of their respective social and solitary ho sts. Sphecodes females preferred to enter unguarded nests. Nest intrud ing strategies observed in the different Sphecodes species did not dep end on whether host species were solitary or social, as long as the ne sting cycle of a social host was in the solitary stage (i.e., a single host female). Observation of intranidal behavior revealed that Spheco des monilicornis females kill all host individuals within art usurped nest. They stay in the nest for several hours, laying eggs in adequate ly provisioned brood cells. Gas chromatography-mass spectrometry analy ses of Dufour's gland secretions revealed species-specific composition s. Qualitative comparisons of whole patterns and quantitative comparis ons considering the predominant hydrocarbons common to both host and p arasite contradict the hypothesis of chemical mimetism, a mechanism su pposed to permit parasite intrusion by qualitatively similar odor bouq uets in host and parasite females.