ECOLOGICAL ANALYSES OF NITIDULIDAE - SEASONAL OCCURRENCE, HOST CHOICEAND HABITAT PREFERENCE

Temporal, chemical and spatial separation of nitidulid beetles (Coleop tera) were examined with baited traps over two seasons (1989 and 1990) in temperate North America. In both years, Stelidtoa geminata (Say), Carpophilus lugubris Murray, Glischrochilus fasciatus (Olivier) and Gl ischrochilus quadrisignatus (Say) comprised 95-99% of all nitidulid be etles collected. These species were collected in greatest numbers in J uly, except for C. lugubris, which was collected in high numbers in Ju ly and late September in 1990. Peaks in trap catch were preceded, in m ost cases, by high percentages of gravid females. Carpopophilus hemipt erus us (L.) was the only nitidulid species that showed a significant preference for Candida krusei-inoculated fruit and vegetable baits ove r aseptic baits in 1989. For three of the four dominant species, the r esponse to baits was broad: C. lugubris is was the only species that e xhibited a specialized response to one substrate over the entire trapp ing period in both years. G. quadrisignatus showed a seasonal or local specialization to maize baits in the spring of 1989 and at two of the three locations in the spring of 1990. There was a clear division in habitat preference for the dominant species: C. lugubris and G. quadri signatus occurred almost exclusively in agricultural settings, whereas G. fasciatus occurred predominantly in woodlots. Numbers of S. gemina ta fluctuated seasonally, showing a preference for woodlots early and late in the season and a preference for agricultural settings througho ut most of the summer. Less common nitidulid species also displayed ha bitat preferences. Although the Nitidulidae have had a longer associat ion with climax communities than with ruderal communities, the diversi ty of nitidulid beetles was similar in the two habitat types. This may be because many of the resources these beetles use for food and ovipo sition sites in climax communities are ephemeral and closely related t o the resources that they use in ruderal communities (i.e. wild versus domesticated strawberries, wild versus domesticated cherries and hawt horn fruit versus apple).