Low-temperature derived temporal change in the vertical distribution of Sesamia inferens larvae in winter, with links to its latitudinal distribution

Abstract

To escape or alleviate low temperatures in winter, insects have evolved many behavioral and physiological strategies. The purple stem borer, Sesamia inferens (Walker) is currently reported to be expanding their northern distributions and causing damage to summer maize in Xinxiang, China. However, their method of coping with the lower temperature in the new northern breeding area in winter is largely unknown. This paper investigates the overwinter site of S. inferens, and identifies the cold hardiness of larvae collected from a new breeding area in winter and explores a potential distribution based on low temperature threshold and on species distribution model MaxEnt. The results show that the overwintering location of the S. inferens population is more likely to be underground with increasing latitude and the population gradually moved down the corn stalk and drilled completely underground in later winter (February) in the north. The cold hardiness test shows the species is a moderate freeze-tolerant one, and Supercooling Points (SCP), Freezing Points (FP) and the incidence of mortality during the middle of winter (January, SCP:-7.653, FP:-6.596) were significantly lower than early winter (October) or late winter (March). Distribution in the new expansion area was predicted and the survival probability area was below N 35˚for the Air Lower Lethal Temperature (ALLT 50) and below N 40˚for the Underground Lower Lethal Temperature (ULLT 50). The suitable habitat areas for S. inferens with MaxEnt were also below N 40˚. This study suggests the overwinter strategies of S. inferens have led to the colonization of up to a five degree more northerly overwintering latitude.

Pre- and post-oviposition behavioural strategies to protect eggs against extreme winter cold in an insect with maternal care

“…This finding highlights the fact that some ectotherms, such as earwigs, cannot only develop physiological mechanisms to withstand their own freezing during wintering (Toxopeus and Sinclair 2018), but may also prefer to find places exhibiting a large thermal difference from the ground temperature to establish nests and deposit their eggs (Leather et al 1993). Multiple strategies have been reported in insects to achieve this goal, among which digging nests or burrows to obtain efficient isolation from above-ground temperatures (Davis et al 2015;Huang et al 2020), hiding under rocks and nesting into trunks to use the thermal inertia of the substrate as a shelter (Brower et al 2009;Trájer et al 2014), and nesting close to human constructions (e.g. underground pipeline, houses, building walls, etc) to benefit from their constant source of heat during winter (Labrie et al 2008;Trájer et al 2014).…”

Pre- and post-oviposition behavioural strategies to protect eggs against extreme winter cold in an insect with maternal care

“…This finding highlights the fact that some ectotherms, such as earwigs, cannot only develop physiological mechanisms to withstand their own freezing during wintering (Toxopeus and Sinclair 2018), but may also prefer to find places exhibiting a large thermal difference from the ground temperature to establish nests and deposit their eggs (Leather et al 1993). Multiple strategies have been reported in insects to achieve this goal, among which digging nests or burrows to obtain efficient isolation from above-ground temperatures (Davis et al 2015; Huang et al 2020), hiding under rocks and nesting into trunks to use the thermal inertia of the substrate as a shelter (Brower et al 2009; Trájer et al 2014), and nesting close to human constructions (e.g. underground pipeline, houses, building walls, etc) to benefit from their constant source of heat during winter (Labrie et al 2008; Trájer et al 2014).…”

A chromosome-level genome assembly of Sesamia inferens

“…and pesticides resistance assessment 7,8,10,[17][18][19][20] . Indeed, the knowledge of the population structure and genetic bases of the rapid adaptation of S. inferens in its expanded habitat are limited.…”