Robert J. Argauer

Relative Effectiveness of Selected Stilbene Optical Brighteners as Enhancers of the Beet Armyworm (Lepidoptera: Noctuidae) Nuclear Polyhedrosis Virus

Abstract The addition of a stilbene optical brightener, Tinopal LPW, at 1% concentration (wt:wt) significantly reduced the LC50 of the beet armyworm nuclear polyhedrosis virus (SeMNPV) from 2.9 PIB/mm2 to 0.02 PIB/mm2. Moreover, the LT50 of SeMNPV was reduced by 34% by the addition of Tinopal LPW. Seven other structurally related stilbene brighteners were also tested as viral enhancers. Five of these brighteners (Tinopal LPW, Blankophor BBH, Blankophor HRS, Blankophor P167, and Blankophor RKH) reduced LD50s, whereas three brighteners (Blankophor BSU, Blankophor DML, and Blankophor LPG) had little effect. Among the active brighteners, LC50s were reduced by 10.5-fold (Blankophor P167), 52.4-fold (Blankophor RKH), 87.3-fold Tinopal LPW), 131-fold (Blankophor BBH), and >400-fold (Blankophor HRS). LT50s were also decreased by the addition of Blankophor BBH, Blankophor P167, and Blankophor RKH, but were increased by the addition of Blankophor BSU, Blankophor DMLO, and Blankophor LPG to SeMNPV suspensions.

Evidence for a Novel Insecticidally Active Exotoxin Produced By the HD 116 Strain of Bacillus thuringiensis var. morrisoni

Liquid chromatographic and bioassay data provide evidence for a novel exotoxin produced by the HD 116 strain of Bacillus thuringiensis var. morrisoni. The exotoxin from HD 116 differs from the well known beta-exotoxin produced by the HD 59 strain of Bacillus thuringiensis var. thuringiensis. Chromatograms of aliquots of filtered fermentation broth taken before and after inoculation with the organisms HD 116 and HD 59 were compared. Based on retention times of the obtained peaks, chromatographic fractions were obtained and activity against first instar larvae of the Colorado potato beetle (Coleoptera: Chrysomelidae) was determined. Fractions based upon similar retention times that were active from var. morrisoni were not active from var. thuringiensis and vice versa. Our conclusion that the new exotoxin may be a diphosphate analog of thuringiensin is based on a comparison of relative retention times among several adenine nucleotides. We have tentatively named this new extracellular exotoxin sigma-exotoxin.

Stability of oxytetracycline in diets fed to honeybee colonies for disease control

Abstract Antibiotic extender patties, pollen patties, and sugar solutions containing oxytetracycline hydrochloride (OTC) were incubated at freezer (−9°C), refrigerator (4°C), room (25°C), and brood nest temperature (34°C) for 1, 2, 3, 7, and 11 weeks to determine the stability of the antibiotic. The OTC in antibiotic extender patties and pollen patties was stable at brood nest temperature for at least 11 weeks. The OTC in sugar solutions degraded within 1 week at brood nest temperature.

A fluorometric method for determining oxytetracycline in treated colonies of the honey bee, Apis mellifera

Abstract A chemical method based on a fluorescent complex of oxytetracycline (OTC) was developed and used to analyze for the antibacterial agent in pollen patties, and larvae and adults of the honey bee, Apis mellifera . An average of 0.34 μg OTC per adult bee was recovered from hives fed pollen patties that contained 60 ppm OTC.

Degradation of Oxytetracycline in Sugar Syrup and Honey Stored by Honeybee Colonies

SummaryDegradation of two concentrations of Oxytetracycline hydrochloride (OTC) in medicated syrup and honey in store in colonies of honeybees (Apis mellifera) was followed using a spectrofluorometric technique. The rate of degradation was similar in syrup and honey, and most of the OTC had gone 6–9 weeks after the end of feeding medicated solutions. However, a small residual fluorescence appeared to persist indefinitely; it was presumed to be due to a product of the degradation and might be useful as an indicator of previous medication with OTC.