1:30 PREVALENCE OF LICE ON PIGS FROM SOUTHWESTERN MISSISSIPPI

Alex D.W. Acholonu and Christopher Epps*, Alcorn State University, Lorman, MS 39096

Lice are one group of the common ectoparasites of swine that are of concern to pig farmers. They are inciminated in the transmission of swine pox and Staphylococcus infection, but their main economic importance is due to their irritation to the pigs making them restive, and retarding their growth. Pigs that are infested may take a longer time to gain weight. Farmers spend a lot of money to control the infestation. U.S. Department of Agriculture farmers estimated that hog lice caused a 2-6% loss in market value of infested swine. The present study was conducted to gain an insight into the extent to which lice are a problem in the area studied. During the period Dec. 1996 to Feb. 1997, lice were collected from pigs' bodies with forceps. They were put in vials containing 70% alcohol. They were next mounted in CMC medium and identified. Of 197 pigs from 10 counties, 57 (29%) were infested with the hog louse, Haematopinus suis (Anoplura). 55 (31.4%) of 175 sows and 2 (9.1%) of 22 boars were infested. 18 farms were surveyed. Heavy infestations were observed where pigs were kept in poor husbandy conditions and left unsprayed with insecticide for a long time. To our knowledge this is the first significant report on lice infestation in pigs covering the southwestern region of Mississippi. Lice appear to be of common occurrence on pigs in Mississippi.

1:45 A SCANNING ELECTRON MICROSCOPY STUDY OF THE EPIPROCT OF THE ALLOCAPNIA RECTA SPECIES COMPLEX (PLECOPTERA: CAPNIIDAE)

Samuel G. Tucker* and Bill P. Stark, Mississippi College, Clinton, MS 39058

The Allocapnia recta complex includes six eastern North American species. The upper epiproct limb and the ninth tergal processes of male members of the complex were examined using a scanning electron microscope, in order to test the current phylogeny and to evaluate variability within the group.

2:00 NORTH AMERICAN UTACAPNIA (PLECOPTERA: CAPNIIDAE)--A SCANNING ELECTRON MICROSCOPY STUDY OF THE MALE EPIPROCTS

Amanda K. Lee* and Bill P. Stark, Mississippi College, Clinton, MS 39058

The systematics of the eleven nearctic Utacapnia species is based primarily on the morphology of the bipartite male epiproct. Epiprocts of these species were examined and measured in several orientations with scanning electron microscopy. The results support current species limits within the genus and permit the first phylogenetic analysis for the group.

2:15 ONTOGENETIC VARIATION IN THE CRANIAL OSTEOLOGICAL MORPHOLOGY OF TURTLES IN THE GENUS GRAPTEMYS: A PRELIMINARY INVESTIGATION

Patrick R. Stephens, University of South Alabama, Mobile, AL 36688

Cranial osteological morphology is important in the systematics of turtles in general, and has been of key importance in the debate as to the relationships within the genus Graptemys. Very little work has been done to illuminate the effects of ontogeny upon the cranial osteological morphology of the members of this genus. During the summer of 1997 the skull morphology of 190 Graptemys specimens from the Tulane Museum of Natural History was examined. The specimens included representatives of all currently recognized species within Graptemys save for G. caglei; data from each species were analyzed separately. The samples were grouped by age category and sex. The twenty-nine quantitative characters were converted into ratios to correct for size differences and analyzed by means of ANOVA and ANCOVA. The quantitative characters were simplified into binary codes and analyzed using the binomial probability method. The results of the study indicate that ontogenetic effects on cranial osteological morphology are much more pronounced in the females of species that exhibit rnegacephaly in adulthood. Some statistically significant ontogenetic variability was found in all species for which sufficiently large samples of adults and juveniles were available, however.

2:30 CHEMICAL PREY PREFERENCES IN NEONATE CORN SNAKES, ELAPHE GUTTATA GUTTATA

Dana S. Roberts*, Jonathan H. Cole, and Lani Lyman-Henley, Mississippi University for Women, Columbus, MS 39701

Juvenile corn snakes are known to prey on various prey species including lizards, tree frogs and young mice. As the snakes mature additional prey species become available, including adult mice, young birds and eventually rats and adult birds. Twenty-two neonate Elaphe guttata guttata from a clutch of eggs produced by a female collected in Noxubee Co., MS, were tested for chemical prey preferences prior to feeding experience. Prey cues offered included green anole (Anolis carolinensis), green tree frog (Hyla cinerea), adult rat (Rattus norvegicus), southern flying squirrel (Glaucomys volans) and bobwhite quail (Colinus virginianus),with water and pine resin (Pinus taeda) as controls. Prey chemical cues were produced by rubbing a cotton swab on live prey. Snake responsiveness was measured by counting the number of tongue flicks directed toward each stimulus swab in a 30 second period. Neonate Elaphe g. guttata showed a preference for rat and squirrel cues over the more typical juvenile prey species, anole and tree frog. A surprisingly high response to pine resin may be related to foraging behavior when searching for cavity-nesting prey species. Preferences for the larger prey species indicate innate responses which will be beneficial as the snakes mature.

2:45 CHEMICAL PREY PREFERENCES IN NEONATE WANDERING GARTER SNAKES, THAMNOPHIS ELEGANS VAGRANS

Rebecca L. Forrester* and Lani Lyman-Henley, Mississippi University for Women, Columbus, MS 39701

Studies with garter snakes have shown innate species-specific preferences for chemosensory prey cues, which can be modified with experience such that individuals show increased sensitivity to familiar cues. The western terrestrial garter snake, Thamnophis elegans, seem to have an unusually high incidence of feeding upon mammalian prey as compared to other garter snake species. Wandering garter snakes, T. e. vagrans, are the focus of research investigating the ontogeny of predatory responses to various chemical prey cues and the effects upon those responses of limited prey experiences. Two litters of T. e. vagrans from a Colorado population and one litter of common garter snake, T. sirtalis, from Noxubee Co. MS were offered aqueous extracts (prepared from several potential prey species) at 5 days of age, prior to feeding experience. Responsiveness was measured as the number of tongue flicks in a 30 second period directed at cotton swabs dipped in extract. Thamnophis sirtalis showed a strong preference for earthworm cues and very little response to mouse cues, while T. e. vagrans showed very high responsiveness to mouse cues. Both species showed moderate responsiveness to fish cues. These innate responses correspond with reported diets of the wild populations. Snakes were then assigned to diets balancing for initial chemical preferences such that half of the snakes recieved no experience with mouse as a food item while the other half were fed mouse pieces regularly. Chemical prey response will be measured again at 4 months of age in order to detect any effects of dietary experience upon chemical prey preferences.

3:00 Divisional Poster Session

COMPARISON OF HESTER-DENDY ARTIFICIAL SUBSTRATE SAMPLERS AND RBPMULTIHABITAT PROTOCOL: MONITORING POINT SOURCE IMPACTS AND AGRICULTURAL RUNOFF

Lisa S. Houston and Mike C. Beiser*, Alabama Department of Environmental Management (ADEM), Montgomery, AL 36109, and Mississippi Office of Pollution Control (MSOPC), Pearl, MS 39208

Since 1974, ADEM and MSOPC have conducted bioassessments at fixed sites to assess water quality trends. Until 1989, quantitative samplers (Hester-Dandy multiplates) were used to collect macroinvertebrates. Afterward, a multi-habitat protocol was adopted by these two agencies. To examine how these changes in methodology affected bioassessment results and trend analyses, both methods were used to assess water quality at 19 stations impacted by either point sources or agricultural runoff. The impacts caused by different land use affected the relationship between multi-habitat assessments and the Hester-Dendy samplers. The multi-habitat methods resulted in higher EPT indices at stations impacted by point sources, indicating that measures of taxa richness could overestimate improvements in water quality at sites monitored with the multiplate samplers and later with the multi-habitat methodology. The taxonomic and functional compositions of the macroinvertebrates collected from the multiplates were relatively to the log and leaf accumulation samples collected as part of the multi-habitat approach, which suggests that assessments based upon these habitats may be comparable to the artificial substrate data. In streams impacted by agricultural runoff, measures of EPT indices were greater on the Hester-Dendy samplers due to habitat degradation at these sites. These results suggest that, because artificial substrates samplers provide a stable habitat for colonization, that they may underestimate nonpoint source impacts which degrade habitat quality. No significant differences in biotic index values were noted between the two methods regardless of type of impact or habitat quality, suggesting that this metric may be the most useful in assessing trends regardless of the method used.
 
 

ROCKY MOUNTAIN SWELTSA (PLECOPTERA: CHLOROPERLIDAE): A SCANNING ELECTRON MICROSCOPY STUDY

Jennifer K. Delk* and Bill P. Stark, Mississippi College, Clinton, MS 39058

Epiprocts of the eight species of Sweltsa known from the Rocky Mountains were studied with scanning electron microscopy. Five species, S. albertensis (Needham & Claassen), S. coloradensis (Banks), S. gaufini Baumann, S. hondo Baumann & Jacobi and S. lamba (Needham & Claassen) share prominent apical hooks and similar setation but differ in epiproct shape. Two of the species without apical hooks, S. fidelis (Banks) and S. revelstoka (Jewett), could not be reliably identified in the male stage, but S. borealis (Banks) was distinct by virtue of the slender outline of the epiproct.

THE SWELTSA LATERALIS (PLECOPTERA: CHLOROPERLIDAE) COMPLEX: A MONOPHYLETIC GROUP

Mary Jane Kilgore and Bill P. Stark*, Mississippi College, Clinton, MS 39058

Male and female terminalia for the seven species of eastern Nearctic Sweltsa were studied with scanning electron microscopy. Epiprocts of six species, S. lateralis (Banks), S. mediana (Banks), S. onkos (Ricker), S. urticae (Ricker), S. pocahontas Kirchner & Kondratieff and S. voshelli Kondratieff & Kirchner, shared four derived characters not found among out-group Sweltsa. These species apparently form a monophyletic group apart from S. naica (Provancher), the other species known for eastern North America.

3:30 Divisional Business Meeting