Development and reproduction in the East Himalaya spruce bark beetle
1989
Eidmann, H.H. (Uppsala Univ. (Sweden). Div. of Forest Entomology) | Wiersma, N.
During an outbreak of the East Himalaya spruce bark beetle, Ips schmutzenhoferi, large numbers of conifer trees have been killed, mainly Picea spinulosa. The beetle species was studied in laboratory rearing experiments at 20 degrees C in Sweden on its natural host and on P. abies. Data were obtained on the duration of development, course of emergence, production of young adults, and sex ratio. The laboratory studies were supplemented by field observations in Bhutan. The emergence of young adults culminated 68 days after colonization of the breeding substrate began and 14-29 days after the first offspring emerged. The parent beetles left the breeding substrate earlier. 1300-2500 young adults were produced per square meters breeding substrate, corresponding to 1.5-9.7 beetles per egg gallery. 43 per cent of the emerged young adults were males, whereas during colonization and breeding the male proportion was about 27 per cent. The results are compared with data on I. typographus and discussed with respect to conditions influencing the population dynamics of the species
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