Geographic variation in cold hardiness of eggs and neonate larvae of the yellow‐spotted longicorn beetle Psacothea hilaris

Abstract

Cold hardiness of eggs and neonate larvae of the yellow-spotted longicorn beetle, Psacothea hilaris (Pascoe) was examined using six geographical populations in Japan. Particular attention was paid to cold hardiness of eggs and neonate larvae of the subtropical population (Ishigaki), because the east Japan populations are considered to have been introduced from a subtropical area, and the overwintering stage in the east Japan populations is incidentally shifted from the original mature larval stage to the egg or neonate larval stages. When the eggs were exposed to low temperatures for 1 h, the decrease in hatchability became signi®cant at ±12°C in the southernmost two populations (Ishigaki and Naze), and at ±16°C in the northern populations. After 1 h exposure to ±20°C, few eggs could hatch in the Ishigaki population, whereas 27±55% of the eggs survived in the northern populations. Pre-chilling of the eggs at 10°C for 10 days enhanced the cold hardiness in all populations. This effect was particularly distinct in the subtropical population; the eggs of the Ishigaki population became as cold hardy as those of the northern populations after acclimation. These results suggest that the subtropical population is capable of establishing itself in east Japan, where the winter is cold.

Geographical variation in egg cold hardiness: a study on the adaptation strategies of the migratory locust Locusta migratoria L.

“…There are also some genetic differences among locust populations from south to north in China (Zhang & Kang, 2000), but it is unknown whether such differences affect their cold hardiness. The geographic variations in cold hardiness of a single species or inter-population have also been supported strongly in previous studies (Turnock et al, 1990(Turnock et al, , 1998Shintani & Ishikawa, 1999;Kallushkov & Nedved, 2000), however a comprehensive study of locust cold hardiness and its relationship with geographical distribution has not been conducted.…”

“…Leather et al (1993) also outlined the great influence on the population dynamics of some insect species of temporal and spatial variation in winter temperatures. Similarly, Shintani and Ishikawa (1999) considered cold hardiness of the yellow-spotted longicorn beetle Psacothea hilaris to be essential in assessing its potential to establish a population in east Japan.…”

Cold hardiness as a factor for assessing the potential distribution of the Japanese pine sawyerMonochamus alternatus(Coleoptera: Cerambycidae) in China

“…In most parts of China, apart from the western high-plateaux, the sum of effective temperatures is high enough for the beetle development during the summer. Several researchers have reported that winter cold is one of the most important factors that limit the distribution of insects in the high-latitude zones [4,12,20,23]. We suggest that low temperatures in winter also play an important role in limiting the distribution and dispersal range of the beetle in China.…”

“…Within the family of long-horned beetles, only the cold hardiness of eggs and neonatal larvae of the yellow-spotted longicorn beetle Psacothea hilaris have been studied in Japan [20]. Although several studies have been conducted on the biology of the Japanese pine sawyer and its vectoring nematode B. xylophilus [11,13,14], research on its cold tolerance is still lacking.…”

Supercooling capacity and cold hardiness of the eggs of the grasshopper Chorthippus fallax (Orthoptera: Acrididae)

“…The egg stage is the principal overwintering stage in many insects and other terrestrial arthropods, and considerable interest has been shown by entomologists in the cold resistance of eggs (SØmme, 1982(SØmme, , 2000Gehrken, 1989;Hanson & Craig, 1994;Block et al, 1995;Strathdee et al, 1995;Shintani & Ishikawa, 1999;Jing & Kang, 2003). Cold hardiness is defined as the capacity of a species to survive long or short term exposure to low temperature (Lee, 1991).…”