Frog Fungus Infects Coqui: In 2004, the state Department of Agriculture began to consider whether a fungus that was devastating frog populations across the globe might be useful as a biocontrol agent for the Puerto Rican tree frog, or coqui, which has become an unwelcome noisy presence in parts of Maui and the Big Island.
As it turns out, the fungus is already here. University of Utah scientists Karen Beard and Eric O’Neill took tissue samples of 382 coqui taken from 10 different sites on Maui and the Big Island. Using DNA analysis to detect the fungus, they found the fungus had infected 2.4 percent of the study animals, at four study sites. Most of the infected frogs were subadult, leading Beard and O’Neill to speculate that “(1) infected subadults have a lower survival rate than uninfected subadults, (2) we sampled a greater proportion of each subadult than of each adult, or (3) subadults are more vulnerable to infection than adults.” Boosting option 3 is the fact that the juveniles, with a greater need for moisture than adults have, tend to roost closer to the forest floor. The fungus, Batrachochytrium dendrobatidis, is water-borne, so, they write, “the high moisture environment found closer to the forest floor could contribute to greater infection in subadult frogs.”
While advocating further research on the susceptibility of coqui to the chytrid fungus, the authors recommend against considering it as a biocontrol agent, “because it is not a species-specific pathogen, many amphibians are highly susceptible, alternative hosts have not yet been identified, and it has been shown to be readily dispersed by human activities.”
As if to underscore that conclusion, Beard and O’Neill point out that coqui from Hawai`i have already reached Guam. “The potential for E. coqui to transmit B. dendrobatidiswith future introductions adds to its capacity to threaten native communities,” they write. (Their work appears in the journal Biological Conservation 126 , 591-595.)
In Line for Listing:The Fish and Wildlife Service has released its annual “Candidate Notice of Review,” which looks at the species that may qualify for inclusion on the federal list of endangered or threatened species. Of the 279 candidate species, the Pacific Islands account for 115; of those, Hawai`i accounts for 103.
As noted elsewhere in this issue, many of the species put in perennial appearances on the candidate list, including the Kaua`i creeper and six species of damselflies.
In addition to two bird species, Hawaiian flora and fauna is represented on the list by four snails, nine insects, four crustaceans, four ferns, and 81 flowering plants. “Hawai`i leads the nation with the greatest number of candidates on the list,” the Fish and Wildlife Service press release stated.
Three Hawaiian species were eliminated from consideration this year: two species of anchialine pond shrimp and the po`olanui gall fly. The shrimp were removed because of insufficient information on their range-wide status; the gall fly because it “does not have a valid taxonomic description or name, thus it does not meet the definition of a species.”
Volume 17, Number 4 October 2006