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Insect mouthparts are indispensable sensory organs that detect environmental cues over a short distance. In this study, using environmental scanning electron microscopy, we observed the types, distributions, and numbers of various sensilla occurring on the mouthparts of adult Tomicus brevipilosus, which is one of the most important coniferophagous beetles in Yunnan province. The mouthparts of adult Tomicus brevipilosus consist of one labrum, a pair of mandibles, a pair of maxillae, one labium, and a hypopharynx. There are six types of sensilla on the mouthparts; sensilla trichodea ( 2 subtypes), sensilla chaetica ( 3 subtypes), sensilla basiconica ( 2 subtypes), sensilla twig basiconica ( 3 subtypes), sensilla coeloconica, and sensilla digitiformia. Sensilla trichodea are the most abundant and generally located on the mandibles, lacinea, upper gales, and labrum. Sensilla chaetica are present on the stipes, lacinea, intersegmental joints of maxillary and labial palpus. Sensilla basiconica type I is found only on the internal view of the labium. Sensilla basiconica type II and sensilla twig basiconica are terminal pores and show an aggregated distribution on the terminal apex of the maxillary and labial palps, respectively. Sensilla coeloconica and sensilla digitiformia are located only on the lateral view of the third subsegment of the maxillary palpus. No sensilla were observed on the surface of the hypopharynx. No sexual dimorphism was observed in sensilla types, numbers, and distribution between female and male adult T. brevipilosus. However, sensilla twig basiconica type III and sensilla digitiformia showed a number variation within species. The former included 9-13 sensilla at the site of distribution, whereas the latter had 4-6. This study provides a reference for further exploration of host selection, feeding, and mate recognition of the pest Tomicus brevipilosus. [ABSTRACT FROM AUTHOR]

BACKGROUND: The Xiuwacu Mo - W deposit is a typical hydrothermal quartz vein deposit in the Yidun island arc Cu - Mo metallogenic belt, northwest Yunnan. Numerous studies have been conducted on rock and ore chronology and petrogenesis, dynamics, but its ore - forming fluid evolution has been rarely studied. OBJECTIVES: To reveal the origin and evolution of ore - forming fluids of the Xiuwacu Mo - W deposit. METHODS: Scanning electron microscope ( SEM ) cathodoluminescence method, and in situ trace element (LA - ICP - MS) and in situ Sr ( fs - LA - MC - ICP - MS) isotope analyses of scheelite. RESULTS: The occurrences of scheelite and the cathodoluminescence images indicated three generations of scheelite, I, II, and ill, with the middle stage scheelite being the most developed. The rare earth element pattern of the scheelite in the early stage was similar to that of the porphyritic granite. It showed a right - inclined pattern with light rare earth enrichment and a moderate negative Eu anomaly ( δEu = 0. 42). The average Mo content was 3. 0%, and the average 87Sr/86 Sr was 0. 7098, close to the specular feldspar granite ( 0. 7075 - 0. 7098 ) . Compared with scheelite in the early stage, the content of light rare earth elements in the scheelite from the middle stage was low, and Eu also had a medium negative anomaly ( δEu = 0. 37). Mo content was reduced to an average of 2445 µg/g, and 87Sr/86Sr increased to 0. 7113. The rare earth distribution pattern of scheelite in the later stage showed an arched pattern with relative enrichment of middle rare earth and no Eu anomaly ( δEu = 0. 93 ) . Mo content of scheelite decreased to 56µg/g, and average 87Sr/86 was 0. 7083. CONCLUSIONS: From early to late, the gradual decrease of light rare - earth elements, especially La and Ce, in scheelite indicates the crystallization of bastnaesite. The increase in δEu and the sharp decrease in Mo content indicate the transformation of ore - forming fluids from oxidation to reduction. The change of Sr isotope composition indicates the change in the source of ore - forming materials. The magmatic fluid contributed a lot in the early stage, and the large - scale interaction between the magma - hydrothermal fluids and surrounding rocks is responsible for the formation of scheelite in the middle stage. The strata provide amounts of Ca for scheelite formation, indicating that strong water - rock interaction played an important role in the formation of the deposit. [ABSTRACT FROM AUTHOR]