Dormancy in laboratory-reared Asian longhorned beetles, Anoplophora glabripennis

An insect’s capacity to survive winter is critical for range expansion in
temperate regions. The Asian longhorned beetle (Anoplophora glabripennis)
is a polyphagous wood-boring insect native to China and the Korean
peninsula and poses a high risk of invasion in North America and Europe.
It is unclear whether A. glabripennis enters diapause, which means that
diapause cannot be included in assessments of the risk of this species
invading forests in temperate regions. Using a laboratory colony, we
examine larval developmental arrest, metabolic rates, gas exchange
patterns, thermal sensitivity, and body composition to characterize larval
dormancy. Chilled larvae entered a temperature-independent developmental
arrest which usually required more than four weeks of chilling to break,
decreased their metabolic rate by as much as 63 %, and maintained energy
stores throughout the chilling period – results consistent with an
obligate diapause. We also observed a switch to discontinuous gas exchange
at low temperatures. Thermal sensitivity of metabolic rate did not differ
between chilled and non-chilled larvae. Taken together, we conclude that
A. glabripennis enters a larval diapause during chilling and terminates
diapause after a requisite chilling period. These results will enhance our
ability to predict phenology and potential distribution of current and
future invasions of A. glabripennis. An insect’s capacity to survive
winter is critical for range expansion in temperate regions. The Asian
longhorned beetle (Anoplophora glabripennis) is a polyphagous wood-boring
insect native to China and the Korean peninsula and poses a high risk of
invasion in North America and Europe. It is unclear whether A.
glabripennis enters diapause, which means that diapause cannot be included
in assessments of the risk of this species invading forests in temperate
regions. Using a laboratory colony, we examine larval developmental
arrest, metabolic rates, gas exchange patterns, thermal sensitivity, and
body composition to characterize larval dormancy. Chilled larvae entered a
temperature-independent developmental arrest which usually required more
than four weeks of chilling to break, decreased their metabolic rate by as
much as 63 %, and maintained energy stores throughout the chilling period
– results consistent with an obligate diapause. We also observed a switch
to discontinuous gas exchange at low temperatures. Thermal sensitivity of
metabolic rate did not differ between chilled and non-chilled larvae.
Taken together, we conclude that A. glabripennis enters a larval diapause
during chilling and terminates diapause after a requisite chilling period.
These results will enhance our ability to predict phenology and potential
distribution of current and future invasions of A. glabripennis.