Zoology and entomology.

Chair: Timothy C. Lockley, USDA APHIS PPQ IFA 

Vicechair: Alex D.W. Acholonu, Alcorn State University 

FRIDAY MORNING

Petit Bois Room

9:00 WALKING ON WATER: THE EVOLUTION OF NEUSTONIC LOCOMOTION IN SPIDERS

Gail E. [Stratton.sup.*], Patricia Miller, and Robert Suter, Mississippi University, University, MS 38677; North West Community College, Senatobia, MS; and Vassar College, Poughkeepsie, NY

The specialized rowing gait of Dolomedes (Pisauridae) on the water surface is well-studied and differs from wallking in that legs I are held parallel and anterior, legs II and III are moved in parallel, and legs IV are held parallel and posterior. In contrast, while walking, the members of each pair of legs alternate. We mapped two characters, hydrophobicity and ability to row, on cladograms of Araneae and Lycosoidea. We present a comparison of 581 individuals in 192 species with representatives from 34 families of mostly North American spiders. Six of the 34 families of spiders examined have species that adopt a Dolomedes-like gait when on the water surface. The majority of rowers were found in the Lycosoidea, from the families Ctenidae (1 of 3 species studied), Pisauridae (8 of 8 species), Trechaleidae (1 of 1 species), and Lycosidae (27 of 48 species). Other families that have species that can row include Salticidae (1 of 12 species) and Thomisidae (1 of 4 species). A quantitative means of scoring shows th at there is very little variability in the rowing of Pisauridae and Trechaleidae. In Lycosidae, variability is much higher both within and between species. Examination of the distribution of the ability to row suggests it evolved in the Lycosoidea. Differences in the variability of rowing suggests there may be selection pressures present for spiders that are more consistently near water.

9:20 METABOLIC RATES OF ADULT AND LARVA STAGES OF TENEBRIO MOLITOR

Julius O. Ikenga, Mississippi Valley State University, Itta Bena, MS 38941

This research was designed to measure the metabolic rates of adult and larva stages of Tenebrio molitor using a direct respirometric technique. T. molitor is an important pest of commercial and household stored-grains and grain products. Both the adult and larva stages are popular fish baits. They are also used as food for many small pets. The biology and characteristics of T. molitor suggest that the species holds a great promise as a cheap source of proteins for humans. Twenty-five T. molitor adults were used in this research. These beetles were randomly taken from the stock that has been raised and maintained in our laboratory. Each beetle was brushed clean with a camel hairbrush and collectively weighed before depositing them in a 250 ml respirometer that was tightly fitted with a Vernier oxygen gas sensor. The latter was interfaced to a desktop computer with a Vernier LabPro. Four samples per minute were collected over a 30-minute period at 26[degress]C. The above procedures were repeated using 25 T. mol itor larvae and with no T. molitor in the respirometer. Analysis of preliminary data showed a metabolic rate of 12.6 ppm [O.sub.2]/hr for the adult beetles and 9.6 ppm [O.sub.2]/hr for the larvae. These results parallel the level of activity exhibited by the adult and larva stages tested.

9:40 ACUTE TOXICITY AND ANTI-ESTERASE ACTIVITY OF FIVE ORGANOPHOSPHORUS INSECTCIDES AGAINST HELIO THIS VIRESCENS (F.) AND HELICOVERPA ZEA (BODDIE)

Elgenaid I. Hamadain, Jackson State University, Jackson, MS 39217

Susceptibility of laboratory strains of tobacco budworm (TBW) and corn earworm (CEW) to five organophosphorus insecticides (OP) was investigated using standard topical application procedure. The insecticides were methyl parathion, parathion, chlorpyrifos methyl, chlorpyrifos, and profenofos. In vivo inhibition of acetylcholinesterase and aliesterases by the five compounds was determined for both species. In vitro inhibition of the two enzymes by the corresponding oxons was also determined. All insecticides, except profenofos had lower LD5O values for CEW than for TBW. The tolerance ratios range from 1.3 for profenofos to 18.3 for chlorpyrifos. All oxons, but not profenofos, were more potent inhibitors of CEW acetylcholinesterase than TBW acetylcholinesterase, indicating that the target enzyme in TBW is less sensitive to inhibition by the OPs than that of CEW. Paraxon, chlorpyrifos oxon and profenofos were more effective inhibitors of aliesterases than acetylcholinesterase. Methyl paraoxon and chlorpyrifos met hyl oxon showed a reverse pattern. Although profenofos was the most toxic insecticide to both species, it had extremely high in vitro LD5O values against the target site, acetylcholinesterase for both species. Profenofos was considerably more potent against aliesterases than acetylcholinesterase in both species. Methyl paraoxon was unique in having a very poor anti-aliesterase potency. The target site, acetylcholinesterase of TBW appears to be less sensitive to inhibition by OPs than that of CEW. This may explain partially why TBWs are harder to kill by OPs than are CEWs.

10:00 A COMPARATIVE STUDY OF THE SEASONAL DISTRIBUTION OF POLLUTANTS IN EAGLE LAKE AND CHOTARD LAKE IN WARREN COUNTY, MISSISSIPPI 

Chadric O. [Neal.sup.*] and Alex D.W. Acholonu, Alcorn State University, Alcorn State, MS 39096

Contaminants alter the ecological conditions of many lakes. The present study was conducted on two lentic bodies of water, Eagle Lake and Chotard Lake in Warren County, Mississippi, to compare their habitat profiles, the seasonal distribution of pollutants in them, and to find out if they meet the Mississippi water quality standards. During the period, February 2001 to October 2001, water samples were collected in three replicates from three sites in each of the two lakes and taken to the laboratory. They were tested according to the methods indicated by the manufacturer of LaMotte pollution test kits and the results were analyzed. The parameters tested for each of the winter, spring, summer, and fall seasons were ammonia, total alkalinity, carbon dioxide, silica, phosphate, chloride, sulfide, nitrate-N, and pH. The surface and bottom water temperatures were also recorded. There were significant differences in some physical and chemical parameters tested, both between the two lakes and seasonally. However, Ea gle Lake and Chotard Lake met the Mississippi water quality standards for ephemeral water bodies.

10:20 A CHARACTERIZATION OF THE EPHEMEROPTERA, PLECOPTERA AND TRICHOPTERA FAUNA FROM HEADWATER STREAMS ON THE CAMP SHELBY TRAINING SITE IN SOUTH MISSISSIPPI

Amanda L. [Wilberding.sup.*] and Fred G. Howell, University of Southern Mississippi, Hattiesburg, MS 39406

Mayflies, stoneflies and caddisflies are pollution sensitive aquatic insects in their immature stages and make up the Ephemeroptera-Plecoptera-Trichoptera (EPT) Index, often used to characterize the "environmental health" of streams. The number of distinct taxa within these orders determines the EPT Index of a sample collection; the numerical value of this index increases as water quality increases. In our area, many of these taxa are associated with woody material. Results for quarterly collections taken from seven headwater streams at Camp Shelby's National Guard Training Site, between August 1999 and May 2001, indicated considerable seasonal and spatial variation among the EPT taxa. While some of the variation may be due to sampling error, other sources of variation might include impacts of heavy rains and their tendency to displace woody materials and associated macroinvertebrates, particularly at the "hard bottom" sites. Although the bottom substrate varies slightly from stream to stream, channels of fou r of the streams (Poplar, Pierce, Cypress, and Hickory) are made of predominately Hattiesburg clay formation and are regularly "scoured" by runoff from locally heavy rainfall. This phenomenon may be limiting the amount of suitable habitat to support many of the EPT taxa.

10:40 Divisional Business Meeting