ABSTRACT
Whole-crystal preparations from strains HD-1 and HD-133, activated Cry1Ab and Cry1C toxins as well as Cry1Aa, Cry1Ac, Cry1D, and Cry2Aa protoxins were tested for toxicity to 2nd-instar larvae of the diamondback moth, Plutella xylostella. Mortality data recorded after 2 and 5 days provided different results that were related to differential rates of solubilization, activation, and degradation of insecticidal crystal proteins. The two most active proteins are Cry1Ab and Cry1C, which are both present in HD-133. The Cry1Ab protoxin is activated within 2 days, whereas activation of the Cry1C protoxin occurs between 2 and 5 days. HD-133 is more active than HD-1 immediately after infection and remains toxic over 5 days owing to the sequential activation of its crystal components. Solubility properties of crystals and rates of activation of protoxins influence the overall toxicity of HD-1 and HD-133 to the diamondback moth.
Subject(s)
Bacillus thuringiensis/chemistry , Bacterial Proteins/metabolism , Bacterial Toxins , Endotoxins/metabolism , Moths/metabolism , Pest Control, Biological , Animals , Bacillus thuringiensis Toxins , Crystallization , Hemolysin Proteins , Inclusion Bodies/chemistry , Larva/metabolism , Lethal Dose 50 , Moths/growth & development , Time FactorsABSTRACT
STUDY OBJECTIVE: To describe the incidence of injuries associated with motorbike use in Bermuda and discuss prevention strategies. METHODS: We conducted a population-based study of all incident of traffic accidents involving motorbikes. Demographic characteristics and mechanisms, rates, and outcomes of injury for tourists and residents were compared. RESULTS: We identified 657 cases of road trauma that occurred between July and September 1993. Of these cases, 538 (81.9%) involved motorbikes. The tourist rate of motorbike-related injury was 94.1/1,000 person-years at risk, whereas that of the local population was 16.6/1,000. The injury rate among residents was highest for young males, whereas among tourists it was highest among older persons. The relative risk (RR) of injury for tourists was 5.6 (95% confidence interval [CI], 4.8 to 6.7). Tourists also had an increased risk of fracture (RR, 1.43; 95% CI, 1.22 to 1.67). CONCLUSION: Tourists visiting Bermuda are at high risk of injury from motorbike use, with rates of injury much higher than the local population. Prevention strategies, particularly for older tourists, should be developed and implemented.