SummaryFormulation in non‐evaporative diluents such as oils is required to exploit the advantages of controlled droplet application methods for biopesticides based on conidial suspensions of entomopathogenic fungi. In laboratory assays on desert locusts (Schistocerca gregaria), formulations of Metarhizium flauoviride conidia in cotton seed oil showed superior performance to water‐based suspensions and this was especially pronounced at low humidities (35% r.h.). The LD50s for oil and water suspensions at 5 days were 8900 and > 106 conidia/insect respectively. The dose‐mortality regression line for oil was more than four times steeper and median lethal times were typically 76% of those for aqueous suspensions. Formulation in oil improves the efficacy of this fungus and may extend the application of species with lipophilic conidia into less humid agricultural environments.

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Clinical, microbiological, and immunologic responses were evaluated in volunteers vaccinated intradermally with bacille Calmette-Guérin (BCG). Most volunteers (98%) developed ulcerative lesions that drained for a mean +/- SE of 4.3 +/- 0.29 weeks. Mycobacterial DNA was detected by a polymerase chain reaction-based amplification technique in biopsy specimens from BCG ulcers 2 weeks after vaccination and in blood specimens 3 days after vaccination. Mycobacteria were cultured from ulcer drainage 2 months after vaccination, demonstrating a prolonged potential risk of contact spread of the vaccine strain. The duration of ulcer drainage was inversely correlated with prevaccination lymphoproliferative (r = -0.515; P < .002) and interferon gamma (r = -0.841; P < .002) responses specific to mycobacteria and directly correlated with postvaccination increases in lymphoproliferative (r = 0.498; P < .002) and interferon gamma (r = 0.688; P < .02) responses specific to mycobacteria. These results demonstrate the clinical reactogenicity of BCG and the potential risk of contact spread of the vaccine strain and suggest that clinical reactogenicity is a trade-off for the induction of protective mycobacterial immunity.

An inoculation technique was developed to assay isolates of entomopathogenic fungi, mainly Metarhiziurn spp., against the desert locust Schistocerca gregaria. Both sexes can be used and neither feeding nor maintenance of a high humidity is necessary. Assays were routinely conducted at 35% relative humidity and 30°C. The technique uses a dose of 2-5 pl conidial suspension formulated in vegetable oil, which is applied with a micropipette or an automatic applicator beneath the dorsal pronotal shield of an adult locust 7-10 days post-fledging. The speed of kill i s dose dependent; at a dose of 3.75 x lo5 conidia/g body weight (7.5 x lo5 conidia/insect) chosen as a standard, locusts began dying 4 days post application. Several vegetable oils were suitable as diluents for the conidial suspensions, but neem was toxic to the insects. After inoculation, locusts had to be maintained in individual boxes. If inoculated and uninoculated insects were placed in close proximity immediately after inoculation with an oil suspension of conidia, the uninoculated insects succumbed to infection 2-3 days later than the inoculated ones, indicating transfer of inoculum.

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