How fire and other habitat characteristics affect the habitat selection of Exyra ridingsii, the Riding’s pitcherplant looper moth

Background/Question/Methods

Exyra ridingsii is a host specific moth that spends its entire immature life cycle in the Sarracenia flava pitcher plant.  Sarracenia flava requires acidic, moist soil that undergoes frequent burns.  Habitat selection and the effects of fire as well as other habitat characteristics were examined for E. ridingsii during this study.  From summer 2012 to fall 2013, five sites in the Croatan National Forest, North Carolina were surveyed four times each year.  One site had no burn disturbances; the remaining four sites were evenly split with two having had burns occur in them and two having burns occur nearby in 2012.  At each site seven to twenty quadrats were selected randomly for sampling. In each quadrat, trumpets were counted and measured for height.  Also recorded was whether the trumpets were healthy or affected by herbivory, and the fraction affected was calculated (herbivory per clump). Also measured were soil saturation levels (SSI) at each site every sampling date; soil saturation levels were assigned from 0-6 with 0 being a complete dry site and 6 being a site that had water depth of 44 cm or above.

Results/Conclusions

 Highest median herbivory per clump values were found at the burned sites.  Millis 2 had 100% herbivory for the late summer 2013 sampling date, and Millis 1 had an herbivory per clump value of 0.86; 86% of clumps at this site exhibited herbivory.  All other values were above 50% with the exception of Catfish Lake Road which was 32%. Herbivory per clump was not found to be statistically correlated to site and therefore burn status. The sites that had the mid total soil saturation levels, Millis 1(SSI = 25) and Millis 2 (SSI = 13), had the highest herbivory per clump and also shared Mandarin sand as their soil type. Burn status, soil saturation, and woody understory growth all seem to play a role in the habitat selection of E. ridingsii but there is much research still to be done.