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The effects of different concentrations of dodine on germination and colony production by nine isolates of Metarhizium spp. were studied in liquid and solid media. It was found that all isolates were completely inhibited from germinating in liquid medium at concentrations of 50 μg/ml and over. On solid media isolates were more tolerant, requiring 500 μg/ml or over to completely inhibit colony formation. Low concentrations (10 and 50 μg/ml) added to Veen's medium were effective at isolating Metarhizium spp. from soil and reduced the number of contaminants by over 90%. Because of differences between isolates in susceptibility to dodine, the lower concentration of 10 μg/ml is recommended for selective isolation from soil. This is significantly lower than that used by other workers with similar basal media.

The effect of relative humidities (r.h.) from 90 to 100% on germination of a termite-active isolate of Metarhizium anisopliae (isolate FI25 and FI610) was studied using a liquid germinating medium to which the appropriate amount of glycerol had been added. Germination was increasingly delayed at water activities equivalent to 99, 98, and 96% r.h. and completely inhibited at 94, 92, and 90%. Twenty-one isolates were then screened for germination at 96 and 100% r.h. All isolates showed delayed germination at 96% r.h. but most isolates eventually gave a high final percentage germination at this humidity. Two isolates, FI527 and FI638, were markedly slower to germinate at both humidities. The susceptibility of two species of termites, Nasutitermes exitiosus and Coptotermes acinaciformis, to FI610 was tested at r.h. down to 86%-the lowest humidity at which the insects would survive. No consistent effect of humidity on pathogenicity was detected. Mortality occurred over the range range of humidities tested; sporulation from the disease-killed termites, however, occurred only at r.h. above 93%. It is concluded that the microclimate around living termites is usually sufficiently humid to ensure infection under most field conditions and that humidity is unlikely to limit the efficacy of the fungus in controlling termites.

Infection by Pleistophora oncoperae is widespread in populations of Oncopera alboguttata . Detailed study of insects from one site indicated that 85% of the 131 pupae and 65% of the 403 adults were infected. The infection did not adversely affect duration of larval and pupal development, adult life span, the number of eggs laid, or fecundity. Infected females were able to transmit the disease to their progeny, though the degree of transmission ranged from 0 to 92%, depending on the severity of the parental infection. Transmission of the disease by infected males could not be detected. It was estimated that 49% of the progeny from this site would have been infected by transovum transmission. Details of the incidence of P. oncoperae infection from this area during the period 1972 to 1979 are given to emphasise the possible role of this disease in O. alboguttata population dynamics.