Cascade effect of laurel wilt disease on the palamedes swallowtail butterfly

Laurel wilt disease (LWD) has caused widespread mortality of redbay (Persea borbonia (L.) Spreng.). Redbay is the primary larval food source for the palamedes swallowtail (Papilio palamedes Drury), a butterfly endemic to the southeastern U.S. Unfortunately, LWD-induced morality of redbay may have a direct effect on palamedes abundance and  long term effects of LWD on redbay may lead to the loss of the palamedes across much of its range. To determine if the removal of redbay has a direct effect on the abundance of the palamedes swallowtail, “Pollard transects” were walked and butterflies were tallied.  Three transects were walked per treatment (infected and uninfected stands) at least 3 times a year. Preliminary results have shown a sevenfold and fourfold reduction average numbers of butterflies in infected stands in Mississippi and North Carolina, respectively. These results indicate that LWD-induced mortality of redbay is leading to a decrease in palamedes abundance. Extinction or long term mortality of redbay may lead to the loss of the palamedes swallowtail throughout much of its range. Various other multi-trophic cascade effects may become evident as LWD increases its time in an area. Our results indicate the need for focused efforts aimed at protecting crucial palamedes habitat or refugia.