RETENTION OF EXTERNAL AND INTERNAL MARKERS BY SOUTHERN PINE BEETLES (COLEOPTERA, SCOLYTIDAE) DURING GALLERY CONSTRUCTION

If retained, markers used in mark-release-recapture studies of bark be etle dispersal could provide valuable tools in the determination of po st-dispersal fate. Retention of the internal marker rubidium (Rb) and of the external marker fluorescent powder during egg gallery construct ion, oviposition, and feeding were quantified at intervals from 0 to 9 6 h by allowing marked Southern pine beetles, Dendroctonus frontalis Z immermann, to carry out these activities in untreated host material. S ignificant differences in Rb concentrations were found between fed and unfed Rb-marked beetles at all intervals after 12 h. Unfed Rb-marked beetles were detectable at all intervals, whereas reliable detection o f fed Rb-marked beetles declined with time. Over 90% of fed southern p ine beetle marked with fluorescent powder were detectably marked after 96 h, while less than 50% of the Rb-marked beetles were detectable af ter 72 h. Neither marking technique adversely affected the gallery len gth or number of eggs produced by marked beetles compared to unmarked beetles allowed to excavate for 96 h. Practical aspects of both techni ques are considered.