RESUMEN
Arundo donax (giant reed) is invasive in Mediterranean, sub-, and tropical riparian systems worldwide. The armored scale Rhizaspidiotus donacis is approved for biocontrol in North America, but an adventive population was recently discovered in southern California. We documented this population's distribution, phylogeny, phenology, potential host spillover to Phragmites spp., and potential for parasitism by a common biocontrol parasitoid of citrus scale. The adventive scale was found within a single watershed and is genetically closest to Iberian scale genotypes. Rhizaspidiotus donacis developed on Phragmites haplotypes but at much lower densities than Arundo. The adventive population is univoltine, producing crawlers from March-June. Aphytis melinus parasitoids exhibited sustained interest in R. donacis during choice and no-choice trials and oviposition resulted in a small second generation. Rhizaspidiotus donacis appears limited in distribution by its univoltinism and sessile adult females. This presents challenges for broad biocontrol implementation but allows for targeted application. The genetic differentiation between imported biocontrol samples and adventive populations presents an opportunity for exploring benefits of hybrids and/or alternative genotypes where establishment has been difficult. While unlikely to occur in situ, spillover to vulnerable endemic Phragmites or deleterious parasitoid effects on scale biocontrol agents warrants consideration when planning use of R. donacis.
RESUMEN
Ants have been suggested as one of many population pressures sea turtles face potentially affecting nesting-beach survival of eggs and hatchlings. However, little is known about the extent to which ants act as incidental or primary mortality factors. Most research has focused on New World fire ants (genus Solenopsis), with confirmed records of other ant species interactions with sea turtle nests in situ being rare. Our study documented the ant species associated with loggerhead sea turtle Caretta caretta (Linnaeus) (Testudines: Cheloniidae) nests in Georgia and determined if ant presence was linked to lower hatching or emergence success. Samples (n = 116) collected from sea turtle nests on eight islands contained 14 ant species including Solenopsis invicta Buren (Hymenoptera: Formicidae), the red imported fire ant, which was the most common ant species encountered. Ant presence was not correlated with lower hatching success, but when other known disturbances were removed, correlated with significantly lower nest emergence success (P < 0.0001). Logistic modeling suggests that proximity of sea turtle nests to the primary dune significantly increases risk of ant predation on hatchling sea turtles. Population managers can reduce this risk by maintaining a 1-m buffer shoreward between dune vegetation and relocated sea turtle nests. Our results suggest that ants may exert a density-dependent pressure on nesting sea turtle populations and call for additional investigations to determine if managing native and invasive ants augments other efforts to improve hatchling survival.
