SSR data of Plutella xylostella samples collected from Southern China and Southeast Asia

Genetic makeup of insect pest is informative for source-sink
dynamics, spreading of resistant genes, and effective management. However,
collecting samples from geographical populations without
considering temporal resolution and calculating parameters
related to historical gene flow may not
capture contemporary genetic pattern
and metapopulation dynamics of highly dispersive pests.
Plutella xylostella (L.), the most widely distributed
Lepidopteran pest that developed resistance to almost all current
insecticides, migrates heterogeneously across space and time. To
investigate its real-time genetic pattern and dynamics,
we executed four samplings over two
consecutive years across Southern China and Southeast Asia, and
constructed population network based on contemporary gene flow. Across
48 populations, genetic structure analysis identified
two differentiated insect swarms, of which the one with higher genetic
variation was replaced by the other over time. We further inferred gene
flow by estimation of kinship relationship and constructed
migration network in each sampling time. Interestingly,
we found mean migration distance at around 1000 km. Such
distance might have contributed to the formation of
step-stone migration and migration circuit over large geographical
scale. Probing network clustering across sampling times,
we found a dynamic metapopulation of P. xylostella with
more active migration in spring than in winter,
and identified some regions are
consistent sources (e.g., Yunnan in China, Myanmar and
Vietnam) while several others are persistent sinks (e.g.,
Guangdong and Fujian in China) in its
overwintering regions. Rapid turnover of insect swarms and highly
dynamic metapopulation highlight the importance of temporal sampling and
network analysis in investigation of
source-sink relationships and thus effective pest management.