Background: Ophiocordyceps sinensis(Berk.) is a well-known entomopathogenic and medicinal fungus. It parasitizes and mummifies the underground ghost moth larvae to produce a fruiting body named Chinese cordyceps. Specific for the fungus,O. sinensisexperiences a biotrophic vegetative growth period spanning over 5 months. During this vegetative growth, it appears successively in the host hemocoel in three/four morphotypes, namely, the yeast-like blastospores (subdivided into proliferative (BP) and stationary phase (BS)), prehyphae (PreHy) and the hyphae (Hy). This peculiar morphogenesis has been elucidated through morphological and ultrastructural observations, but its molecular basis remains cryptic. In this study, transcriptome and metabolome profiling of BP, BS, PreHy and Hy stages were performed to characterize the key genes, metabolites, and signaling pathways that regulated the vegetative development ofO. sinensisinThitarodes xiaojinensislarva.Results: The molecular events and metabolic pathways that regulated different intracellular processes at various stages were examined. Cluster analyses of differentially expressed genes across the four stages revealed the stage specifically enriched pathways. Analysis of metabolome profiles showed that carbon metabolism and several amino acids biosynthesis were significantly perturbed during the tested development stages ofO. sinensisin the host hemocoel. Genes homologous toSaccharomyces cerevisiaeMAPK cascade were significantly up-regulated during the transition from blastospore to hypha. The up-regulation of Sho1, a regulator protein, suggested nutrient starvation act a role in activation of MAPK pathway and filamentous growth. In addition, up-regulation of several fatty acid synthesis genes and their corresponding products accumulation in the samples of BS might explain more lipid droplets were observed in BS than in BP. Coupled with the up-regulation of fatty acid degradation during PreHy and Hy stages, it is presumed that lipid accumulation and mobilization play important roles in filamentous development.Conclusions: This is the first report comprehensively describing developmental transcriptomics and metabolomics ofO. sinensisin vivo.Our findings provide new perspectives into the key pathways and hub genes involved in morphological changes of fungus developed in the hemocoel of its host, and are expected to guide future studies on morphogenesis and morphotype changes of entomopathogenic fungi in vivo.

Population control of small sucking insects has been challenging, and alternative control methods are constantly being sought. Visual traps have long been used to monitor and control pests. Colored sticky cards are widely used for diurnal pests, but their effects are influenced by environmental light conditions. Artificial light traps are mostly used for nocturnal pests. Here, we explored and evaluated light-emitting diode (LED) traps for the monitoring and control of small diurnal sucking insects using greenhouse tests targeting the greenhouse whitefly Trialeurodes vaporariorum. We tested the trapping efficacy of the LED water pan trap, assessed the most attractive LED light and analyzed its efficacy under different weather conditions. The results showed that the LED water pan trap was too inefficient to be useful. Green LEDs were more attractive than yellow LEDs, UV LEDs and green-UV combinations. Regardless of sunny or cloudy conditions, the green LED trap caught more than twice the number of whiteflies than the yellow sticky card alone under summer shading conditions. Our study suggests that LED traps have a significant field application value in whitefly mass trapping and may also be efficient for other diurnal insects. The design of LED traps specific for diurnal insects is discussed.

The Asian house rat (Rattus tanezumi) and the brown rat (Rattus norvegicus) are closely related species and are partially sympatric in southern China. Over the past 20 years, R. tanezumi has significantly expanded northward in China and partially replaced the native brown rat subspecies, R. n. humiliatus. Although invasive species are often more aggressive than native species, we did not observe interspecific physical aggression between R. tanezumi and R. n. humiliatus. Here, we focused on whether or not R. tanezumi was superior to R. n. humiliatus in terms of nonphysical competition, which is primarily mediated by chemical signals. We performed two laboratory experiments to test different paradigms in domesticated R. tanezumi and R. n. humiliatus. In Experiment 1, we caged adult male rats of each species for 2 months in heterospecific or conspecific pairs, partitioned by perforated galvanized iron sheets, allowing exchange of chemical stimuli and ultrasonic vocalization. The sexual attractiveness of male urine odor showed a tendency (marginal significance) to increase in R. tanezumi caged with R. n. humiliatus, compared with those in conspecific pairs. Hippocampal glucocorticoid receptor (GR) and brain-derived nutrition factor (BDNF) mRNA were upregulated in R. n. humiliatus and R. tanezumi, respectively, when the rats were caged in heterospecific pairs. In Experiment 2, we kept juvenile male rats in individual cages in rooms with either the same or the different species for 2 months, allowing chemical interaction. The sexual attractiveness of male urine was significantly enhanced in R. tanezumi, but reduced in R. n. humiliatus by heterospecific cues and mRNA expression of hippocampal GR and BDNF were upregulated by heterospecific cues in R. n. humiliatus and R. tanezumi, respectively. Although not identical, the results from Experiments 1 and 2 were generally consistent. The results of both experiments indicate that nonphysical/chronic interspecific stimuli, particularly scent signals, between R. n. humiliatus and R. tanezumi may negatively affect R. n. humiliatus and positively affect R. tanezumi. We infer that chronic interspecific interactions may have contributed to the invasion of R. tanezumi into the range of R. n. humiliatus in natural habitats.