DIFFERENTIAL USE OF PITCHER PLANT SPECIES AS NESTING SITES BY ISODONTIA WASPS

Philip Sheridan1, Brian Hawley1, and David Karowe2

      1.  Meadowview Biological Research Station and
       2.  Dept. Of Biology, Western Michigan University.
Isodontia are grass-carying wasps which use hollow cavities to make straw nests to rear their young.  We had observed that this wasp seemed to preferentially use slender-leaved pitcher plant species, such as Sarracenia rubra, as nesting sites over other pitcher plant species.  We wanted to determine which species this wasp would choose if given a choice between S. alata, S. flava, S. leucophylla, S. minor, and S. rubra.  Wasps strongly prefer S. minor and avoid S. alata.  Overall wasps prefer smaller pitchers.  However the fact that wasps prefer S. minor over S. rubra, despite similar pitcher sizes, suggests that factors other than pitcher size also play a role in nest selection.