Toxicity, sublethal effects, and performance of sulfluramid against the German cockroach (Dictyoptera: Blattellidae)

Topical and oral toxicity of sulfluramid (N-ethyl perfluorooctane sulfonamide) were determined for the German cockroach, Blattella germanica (L.). The topical LD50 of sulfluramid was 175.6 micrograms/g for adult males, 117.8 micrograms/g for adult females, and 122.3 micrograms/g for gravid adult females. Ingestion increased toxicity approximately 1.4 times for adult male B. germanica. Twenty-four hours after topical treatment with 20 micrograms/insect sulfluramid, the percentage of female cockroaches that dropped their oothecae increased approximately 50% compared with controls treated with acetone. Sulfluramid also decreased oothecal hatch of both dropped and retained oothecae. Approximately 90% of oothecae from untreated females hatches, whereas less than 20% hatched from females treated with 20 micrograms/insect. Mean time for oothecal hatch increased linearly with increasing sulfluramid concentration. In arena studies in Ebeling choice boxes, LT50's ranged between approximately 2.3 and 3.9 d for a 0.331 mg/cm2 deposit and a 1.5% bait, respectively. Higher concentrations of sulfluramid were more repellent in both bait and residual formulations. Performance index values indicated excellent potential field efficacy. Field trials with 1.0 and 1.5% (AI) baits showed up to a 71.3% reduction in cockroach numbers. Baits controlled cockroaches throughout the 12-wk test.     

Pichia sorbitophila sp nov.

A new species of the genus Pichia has been described. The species was isolated from a 70 percent solution of d-sorbitol and is distinctly osmotophilic.     

In vivo and in vitro studies of hafnium-binding to rat serum transferrin

The binding of hafnium to rat serum transferrin was studied using the time differential perturbed angular correlation (TDPAC) technique. Hafnium is interesting as a toxic metal binding to transferrin because it behaves metabolically similarly to plutonium. The isotope 181Hf offers favorable access to the TDPAC-method. Samples were prepared in vivo by intravenous injection of Hf-NTA, Hf-citrate, and Hf-oxalate solutions, respectively, into Sprague-Dawley rats and in vitro by adding Hf-NTA solution to fresh rat serum. In both cases two specific electric quadrupole interactions were observed, which correspond to two well-defined binding configurations. They may be attributed to the N-terminal and the C-terminal binding site in the transferrin molecule. The 181Hf-distribution between these two binding states depends on pH, salt and hafnium concentrations, temperature, and incubation time. With a fast TDPAC-setup of four BaF2-detectors a time resolution of about 600 ps could be achieved. The specific binding configurations of 181Hf and the comparatively slow relaxation times lead to spectra of considerable accuracy.