2.1 Sample collection
S. chinensis samples were
collected from fresh mature galls on R. chinensis , in Wufeng
county (30°10′ N, 110°52′ E, 960 m above sea level), Hubei Province
China, on October, 2019. A colony was established through artificial
cultivation for further genetic studies. Briefly, autumn migrants ofS. chinensis from mature galls, transferred to a nursery of the
moss Plagiomnium maximoviczii , and maintained in a greenhouse. In
the following year, nymphs and spring migrants (sexuparae) were
harvested from mosses and cultivated in laboratory.
Male and female produced by spring
migrants were collected in laboratory. After fundatrix emergence, aphids
were transferred to host trees for gall induction. Aphid samples were
collected separately at different stages, including fundatrix,
fundatrigeniae, autumn migrants, overwinter nymphs, spring migrants,
male and female sexuales.
Fundatrigeniae (females) contained
in a gall were transferred to a petri dish after dissecting the gall.
Impurities like waxes were removed manually. All aphids within a gall
were presumed to be the clonal offspring of a single fundatrix, since
all the S. chinensis galls contained only one single fundatrix
that produced offspring in the gall via parthenogenesis. All aphid
samples were immediately frozen in liquid nitrogen for two hours and
subsequently stored at -80°C until further analysis.