The yellow mealworm, T. molitor, is a freeze-susceptible, stored product pest. When provided with sufficient food supply, T. molitor Maraviroc larvae have low humidity tolerance and can survive under relatively xeric conditions because of their ability to metabolize water from ingested food [12]. Clopton et al. [13] sterilized adult and larval T. molitor by incubation at 36°C to 37°C for 5 d to

eliminate the effect of existing gregarine infections on the tests. In the present study, the host insects were cultured and sterilized by generational dilution in sterile wheat bran substrates, and the insects were almost fully sterilized when given enough generation culture. This new method may provide host insects for strict experimental infections. The efficacy of M. anisopliae under desiccation stress was tested in dry wheat bran substrate with initial moisture content of 8%. At this low moisture level, M. anisopliae was difficult

to grow, but the isolate MAX-2 was still active, whereas the other isolates showed very low efficacy. This result suggests that the infection of sterile T. molitor larvae in wheat bran substrates with low moisture content could constitute a valid laboratory bioassay system to study M. anisopliae efficacy under desiccation stress. Efficacy of M. anisopliae isolate MAX-2 This study demonstrated that M. anisopliae isolate MAX-2 had pathogenicity PD-0332991 price against T. molitor larvae in all the tested moisture levels, particularly

lower moisture levels, and showed relatively high tolerance to desiccation stress. Daoust et al. [14] indicated that the efficacy of M. anisopliae against insects depends on conidial germination. Conidial germination of all tested isolates in the present study showed a tendency to decrease with the decrease in substrate moisture content within the tested scope (8% to 35%). The mortality of larvae for the isolates in different moisture levels also showed the same tendency, which indicates the correlation between conidial germination and efficacy of M. anisopliae. However, the mortality for MAX-2 decreased much more slowly than those of the other isolates. At the substrate with 8% moisture, which was too low for M. anisopliae to facilitate germination, MAX-2 still Rucaparib purchase showed medium mortality of 41% versus low mortality < 5% for the other isolates against T. molitor larvae. Howard et al.[15] observed that high virulence of M. anisopliae against mosquitoes is not significantly affected by low viability, and they deduced that the difference is possibly due to the different abilities of the fungal conidia to germinate on mosquito cuticles and the agar. Leger [16] also reported the existence of two diverse sets of selection pressures on Metarhizium spp., one for optimum characteristics for soil survival and another for virulence to insects.