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Vol. 44 No. 4, 2005
Variations in the Embryonic Stages of Overwintering Eggs of
Eight Grasshopper Species (Orthoptera: Acrididae) in Inner Mongolian
Grasslands
Yun-Xian
Zhao, Shu-Guang Hao, and Le Kang*
State
Key Laboratory of Integrated Management of Pest Insects and Rodents,
Institute of Zoology, Chinese Academy of Sciences, Beijing 100080, China
Yun-Xian
Zhao, Shu-Guang Hao, and Le Kang (2005) The embryologic
developmental stages at which the eggs overwinter were investigated in
8 dominant grasshopper species in Inner Mongolian grasslands in 2000
and 2001. Eggs deposited by adult grasshoppers in different seasons
enter the winter at different embryological developmental stages. The
mean development stages of the early-period species, Dasyhippus barbipes, Myrmeleotettix palpalis, and Omocestus haemorrhoidalis, were at
about embryonic stage 19. Among mid-period species, Calliptamus
abbreviatus, Oedaleus decorus asiaticus, and Angaracris barabensis,
embryonic development reached stages 17, 13, and 10, respectively;
developmental stages of late-period species, Chorthippus dubius and Ch. fallax, were respectively at
about the stages 11 and 3. Embryonic stage 19 is regarded as the
diapause stage of these grasshoppers for 2 reasons: no embryos
developed beyond stage 19 without hibernating before the onset of
winter, and for 2 late-period species, Ch. dubius and Ch. fallax, most of the eggs
remained at stage 19 when incubated at 25°C for 100 d. No significant
difference was found between the supercooling points (SCPs) of eggs in
a diapause or pre-diapause status, except for Om. haemorrhoidalis, Ch. dubius and Ch. fallax, for which the SCPs were
higher in diapause eggs (stage 19) than in pre-diapause eggs.
Relationships between embryological developmental stages of
overwintering eggs and the grasshoppers, hatching sequences are
discussed.
Key words: Grasshoppers,
Embryological development, Overwintering eggs, Supercooling point,
Hatching sequence.
*Correspondence: Tel: 86-10-62558304. Fax: 86-10-62565689.
E-mail: lkang@ioz.ac.cn
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