2.1 Spider and sample collection
Adult specimens of P . astrigera (n = 80; female, n = 40; male, n = 40) were randomly collected by pipe buckle method on 10 April, 2021 from corn field (41°56′N, 123°22′E) aside by Puhe River, Northern Shenyang city, China. All spiders were transported to laboratory (Insect Ecology Laboratory, College of Life Science) and kept singly in plastic tubes (each 30 mm in diameter and 110 mm long) with moistened cotton at the bottom to maintain air humidity.
Spiders were starved for 10 days before dissection to remove the non-native microorganisms in the gut (Hu et al., 2019). To ensure the sterile condition during dissection, the aseptic table was wiped with 75% ethanol for 3 times and irradiated with ultraviolet lamp for 60 min. Before dissection, each spider was sterilized by 75% ethanol for 5 min while rinsing 3 times by sterile water before and after sterilization to remove contaminants on its body surface. Then the residual water on surface of spider was sucked dry by sterilized filter paper. The gut was dissected in sterile phosphate-buffered saline (PBS) solution with a sterilized scissor under a microscope and washed with sterile water, placed into 1.5 ml microcentrifuge tube and temporarily stored in refrigerator (Haier BCD-252WBCS, Qingdao, China) at -20℃. The dissection was done on ice. Ten guts were added in a tube as 1 sample and instantly quick- freezed in liquid nitrogen, finally stored in a -80°C freezer (AUCMA DW-86L500, Qingdao, China) until DNA extraction. Each female and male has four biological replicates.