K. P. Pruess

Temporal constancy in grasshopper assemblies (Orthoptera: Acrididae)

ABSTRACT. 1 Temporal constancy in the structure of grasshopper assemblies (about forty‐five species each) from two types of North American grasslands was assessed; one site was followed 25 years and the other 7 years. 2 Densities and relative abundances varied but composition of assemblies based on ranks suggested significant structure when three or more species were included in the analysis. 3 Results compared favourably with other insect herbivore assemblies which have been examined; variability in population change was intermediate along the spectrum of organisms which have been studied.

Molecular phytogeny and typing of blackflies (Diptera: Simuliidae) that serve as vectors of human or bovine onchocerciasis

Abstract. A subregion of the mitochondrial large subunit (16s) rRNA gene was amplified by polymerase chain reaction (PCR) from nine species of blackflies (Diptera: Simuliidae) which serve as natural or experimental vectors of human or bovine Onchocerca parasites. PCR products from each species of blackfly were tested by directed heteroduplex analysis (DHDA), and their genotypes established according to diagnostic banding patterns of the heteroduplex products. Three alleles of mitochondrial 16s rRNA were found to exist in members of the Simulium (Ewardsellum) damnosum sensu lato complex from West Africa, and two alleles were found in the Neotropical Simulium (Psilopelmia) ochraceum Walker complex and the Simulium (Simulium) metallicum Bellardi complex. Different single alleles were detected in Austrosimulium bancrofti, in English S.(S.)noelleri and in two North American laboratory vectors: Simulium (Psilozia) vittatum Zetterstedt and S.(S.)decorum Walker. Phylogenetic analysis of 16s sequences indicated that blackflies from West Africa and the Americas formed distinct clades. Neotropical onchocerciasis vectors were found to be more closely related to Nearctic and Palaearctic non‐vector Simulium species than to the African vectors of onchocerciasis.

DNA Barcoding Distinguishes Pest Species of the Black Fly Genus Cnephia (Diptera: Simuliidae)

ABSTRACT Accurate species identification is essential for cost-effective pest control strategies. We tested the utility of COI barcodes for identifying members of the black fly genus Cnephia Enderlein (Diptera: Simuliidae). Our efforts focus on four Nearctic Cnephia species—Cnephia dacotensis (Dyar & Shannon), Cnephia eremities Shewell, Cnephia ornithophilia (Davies, Peterson & Wood), and Cnephia pecuarum (Riley)—the latter two being current or potential targets of biological control programs. We also analyzed one Palearctic species, Cnephia pallipes (Fries). Although Cnephia adults can be identified anatomically to species, control programs target the larval stage, which is difficult or impossible to distinguish morphologically. By using neighborjoining, maximum parsimony, and Bayesian methods, we found that COI barcodes successfully identified three Nearctic Cnephia species, but not C. pecuarum. The Palearctic C. pallipes was also successfully identified. Despite nonmonophyly of C. pecuarum, we show that data from COI barcoding, in combination with geographical and ecological information, can be used to distinguish all four Nearctic species. Finally, we discussed 1) possible reasons for paraphyly in C. pecuarum, 2) topological concordance to previously reported chromosomal dendrograms, and 3) evolution of diverse feeding strategies within the genus Cnephia.

GREENBUG (HOMOPTERA : APHIDIDAE) BIOTYPES CHARACTERIZED USING RANDOM AMPLIFIED POLYMORPHIC DNA

Genomic DNA was extracted from seven greenbug, Schizaphis graminum, biotypes (B, C, E, F, G, H and I) obtained from laboratory colonies maintained by USDA-ARS, Stillwater, Oklahoma. DNA was amplified using single 10-base primers. Of 100 primers tested, four were found which either alone, or in combination, distinguished all biotypes by distinct size differences in amplified fragments. Results were repeatable using aphids obtained from the same colonies 2 years later. These diagnostic primers produced unvarying banding patterns for all biotype E greenbugs collected in the field in Nebraska, Kansas, Oklahoma, and Texas.