1 INTRODUCTION
Sex was found to be an important factor that influences gut microbiota (Costello, Stagaman, Dethlefsen, Bohannan, & Relman, 2012; Koren et al., 2012) that formed by long-term coevolution between host and microorganism (Matijasic et al., 2020). Female and male insects exhibit different ecological behaviors in terms of nutritional and dispersal capabilities (Minard, Mavingui & Moro, 2013; Rani, Sharma, Rajagopal, Adak & Bhatnagar, 2009), which lead to different gut microbiota community in host. For instance, Foster (1995) and Zouache et al. (2011) considered that male mosquitoes disperse less than female which could be a factor constraining bacterial diversity, Ng, Stat, Bunce, & Simmons (2018) proved that reduced exposure to diverse environmental microbiota could decrease in gut bacterial diversity of insect. Minard et al. (2013) found the different nutritional requirements between two sexes of mosquitos affect bacterial microbiota composition (e.g., higher relative abundance of Firmicutes and Firmicutes/Bacteroides (F/B) ratio, which contributed to nutritional efficiency (Wan et al., (2020). As a result, bacteria from generaBacillus and Staphylococcus were detected in male mosquitos, whereas Cryseobacterium , Pseudomonas andSerratia were present exclusively in female mosquitos (Rani, Sharma, Rajagopal, Adak & Bhatnagar, 2009). Moreover, Wan et al. (2020) argued that higher gut bacterial diversity in female might contribute to the vertical transmission. Although many spider species show dramatically different activity habits between the two sexes, which results in different mobility and foraging opportunities (Aisenberg & Peretti, 2011), however, the gut microbiota of spiders influenced by sex was almost ignored.
Spiders are key predators in agro-forestry ecosystem (Nyffeler & Birkhofer, 2017). However, knowledge about the gut microbial community of spiders still limited. Hu et al. (2019) and Kumar et al. (2020) studied the diversity and composition of gut microbiota from a few spider species. Kennedy et al. (2020) suggested that gut microbiota in Badumna longinqua (Desidae) is dictated by the consumed prey, and the different prey taxa may remodel the gut microbiota in drastically different ways. Hu (2019) and Sheffer et al. (2019) compared the tissue- and population-level microbiota of some spiders. It is noteworthy that only Hu (2019) who studied gut microbiota influenced by sex. However, dissimilarity to previous results found from insects, Hu (2019) showed that bacterial microbiota has no significantly different between female and male of three spider species, includingEriovixia cavaleriei (Araneidae), Larinioides cornutus(Araneidae) and Pardosa pseudoannulata (Lycosidae), which catapulted the necessity of gathering gut microbiota data between two sexes of spiders.
The wolf spiderPardosa astrigera L. Koch 1878 is a wandering spider widely distributed throughout terrestrial environments, including agricultural lands in East Asia (World Spider Catalog, 2021). It is a very active ground-dwelling predator and dominant in most part of China. As a generalist predator, it plays a very important role in pest control in farmland ecosystem (e.g., it is an important natural enemy of Plutella xylostella(Plutellidae) on both cabbage and oilseed rape) (Quan, Wu, Zhou, Yun, & Jian, 2011). Great behavioral differences between female and maleP. astrigera during the breeding period are reported, the female usually adopt a “sit and wait” strategy waiting for the male, to avoid the reduction of energy and being preyed by natural enemies, whereas the male are very active to look for female everywhere (Chen & Song, 1999). Thus, P. astrigera is a good agent while studying the effects of sex on gut microbiota. Therefore, we investigated the gut bacterial community of female and male P . astrigera by high-throughput sequencing. For this, in particular, we focused on two questions: (i) are diversity of gut bacteria in male P .astrigera higher than in the female; and (ii) are dominant gut microbiota related to their metabolic function of energy demand differences between the two sexes?