Fungi are highly dependent on the ambient microclimate. The performance of M. anisopliae products is affected by various environmental
factors, such as soil moisture, air and soil temperatures, air relative humidity, and solar UV radiation. The conidia of M. anisopliae attach to the cuticle of the host via germ tubes. The conidia germinate and directly penetrate the hyphae into the body integuments, and grow into the haemocoel, where they produce a blend of organic compounds that cause internal mechanical damage, nutrient depletion, and death. For successful infection, GSK872 manufacturer optimum moisture is needed for spores to germinate after attachment to the hosts. Germination, germ tube extension, and infection of M. anisopliae are optimized at Relative Humidity (RH) > 95%
and temperatures between 20°C and 30°C . Neutral trehalase has an important function in environmental stress response in many organisms, including Metarhizium spp. . The successful development of entomopathogenic fungi as biological control agents significantly depends on the selection of highly efficient isolates, and the fungi must be adapted find more to the environmental conditions of the area where they are to be employed . A successful microbial insecticide should possess desirable characteristics, such as high spore germination, high production, and high virulence . The virulence of M. anisopliae against pests significantly varies among isolates . The next low virulence and low tolerance to adverse conditions in the field limit their applications . More efforts should be made in obtaining Metarhizium isolates
with high virulence and antistress capacity to overcome environmental stress. In our pre-experiment, Metarhizium isolates were obtained from arid regions of Yunnan Province in China during the dry season and identified (data not shown). One M. anisopliae isolate, MAX-2, which was obtained from Shangri-la (3200 m to 4100 m above sea level), showed high activities under desiccation stress. This study aimed to evaluate the capacity of M. anisopliae isolate MAX-2 for infection under desiccation stress, and develop a valid laboratory bioassay system in testing the efficacy of M. anisopliae under desiccation stress with sterile Tenebrio molitor L. (yellow mealworm) larvae in a substrate with low moisture content. The efficacy of M. anisopliae isolate MAX-2 and its Mizoribine purchase potential for controlling pests in desiccation environment were discussed. Results Sterile culture of host insects T. molitor larvae were successfully reared in sterile wheat bran substrates with 15% moisture content at 25°C under natural day light, and cultured for more than five generations before use for the tests (Figure 1e). The microbes on the larval surface were diluted from generation to generation, and the larvae were relatively sterile. The larvae used for tests were cultured on sterile wheat bran with 50% moisture content to investigate their sterility. T.