Small-Scale Habitat Preferences of Ground Beetles (Coleoptera: Carabidae) and Responses to Vegetative Regrowth After Kudzu Removal
Ground beetles (Coleoptera: Carabidae) are an important component of terrestrial communities; they have been useful as indicator species and they respond quickly to disturbance. We collected ground beetles by pitfall trap in a 0.5 ha field and neighboring ecotone and woodland areas to compare small-scale differences in community structure. On 21 May 2013, the field was cleared of vegetation by bush-hog and Kudzu was spot-sprayed with Clopyralid. Two transects were established in field, ecotone, and woodland areas, with 8 trapping stations along each transect. Each station consisted of 2 1L cups connected by 1m of aluminum flashing. We sampled three days/week through the summer, conducting a mark-recapture study of large beetles (Carabus, Dicaelus, and Pasimachus species), collecting other species, and measuring vegetative cover in the field. Over the entire experiment, mean carabid abundance was greatest in woodland transects, largely driven by the high woodland abundance of Cyclotrachelus sigillatus. Although there were some significant differences is species richness and Simpson’s diversity among transects, there were no significant differences in these parameters across habitat types. Community composition did vary, however, with ecotone and woods dominated by Carabus and Dicaelus species and the field dominated by Pasimachus species. Pasimachus shifted from the ecotone in the early summer to the field in late summer, correlating with increasing vegetative cover in the field. Carabid communities vary with habitat on a small scale, and respond quickly to changes in the habitat.
Interspecific Variation in Ovipositor Morphology Among Cosmetid Harvestmen (Arachnida, Laniatores, Gonyleptoidea)
Prior taxonomic studies of laniatorean harvestmen have largely ignored the external morphology of the ovipositor as a potential source for informative characters. As a result, relatively little is known about interspecific variation in female reproductive anatomy. In this study, we dissected 50 ovipositors from individuals representing 14 cosmetid species. We used scanning electron microscopy to examine the microanatomy of the distal surface, the number, texture and shape of the large peripheral macrosetae, and the general appearance of the vagina. Ovipositors were dehydrated in a graded ethanol series, dried with hexamethyldisilizane, mounted on aluminum stubs, sputter coated with 30 nm of gold, and examined with a Hitachi S-3400 SEM at an accelerating voltage of 10 kV. We observed considerable interspecific variation in the ovipositor, especially with respect to the morphology of the distal tips of the peripheral macrosetae. The functional significance, if any, of interspecific variation in setal structure is unclear. We also observed interspecific variation in vaginal shape, with most, but not all species (i.e., Erginulus clavotibialis and E. subserialis) exhibiting the typical x-shaped vagina. Additional behavioral studies of oviposition behavior are needed to determine if there is a functional relationship between reproductive morphology and oviposition behavior.
Dept of Biology, Virginia Wesleyan College, Norfolk, VA
P97 • H. Joseph Horacek, Wade B. Worthen
The Distribution of Dragonfly Larvae in a South Carolina Stream: Relationships With Sediment Type, Body Size, and the Presence of Other Larvae
We sampled dragonfly larvae by kick seine in Little Creek, Greenville, SC, during summer 2013, to describe the effects of abiotic (sediment type, water depth, distance from bank) and biotic factors (other dragonfly larvae) on larval distribution. Transects crossed the creek at ~ 5m intervals, and three or four 1m x 0.5 m plots were sampled on each transect. In each plot, sediment was characterized as sand, sand-cobble mix, cobble, coarse, or rocky, and water depth and distance from bank were measured. Larvae were identified to species, and body length, head width, and metafemur length were measured. Five common species preferred different sediment types; Progomphus obscurus preferred sandy plots, and Cordulegaster maculata preferred plots with a sand-cobble mix; Ophiogomphus mainensis avoided sandy and rocky plots while Boyeria vinosa and Stylurus albistylus preferred coarse sediments. As a consequence of using the same habitats, P. obscurus and C. maculata co-occurred more frequently than expected by chance, as did O. mainensis, B. vinosa, and S. albistylus. Although mean size varied among species, the mean size of larvae in different sediment types did not differ significantly. However, larval size was important to larval distributions. Larval size was significantly negatively correlated with distance from the bank in P. obscurus and C. maculata. In addition, larvae in small size classes (< 9mm, 9-12mm) occurred less frequently with large larvae (> 12mm) than expected by chance. This is not a function of relationships with sediment type, and may be a function of competitive displacement or intraguild predation.
Biology Dept, Furman University, Greenville, SC.
P98 • Monica Henry1, Laci Gunthorpe1, Kadie Britt1, Zachary Slifer1, Erika A. Scocco1, Wayne A. Gardner2
