Journal of Applied Entomology (2017) 141, 768-779

J. Holusa and K. Lukásová (2017)
Pathogen's level and parasitism rate in Ips typographus at high population densities: importance of time
Journal of Applied Entomology 141 (9), 768-779
Abstract: We compared the levels of pathogen infection in parental beetles, parasitism of the offspring, abundance of predators and breeding performance success of univoltine populations of Ips typographus in plots characterized by short-term (2–3 years) outbreaks vs. those with long-term (>10 years) outbreaks on two localities at ca. 1100 m altitude in the Sumava Mts. The numbers of I. typographus were high in all plots, whether the plots were characterized by long-term outbreaks or short-term outbreaks. The numbers of maternal galleries in the sample areas ranged from 300 to 400 per m². The density of parental beetle galleries, abundance of surviving specimens of I. typographus, and length of maternal galleries did not differ between plots. The short-term outbreaks had only fewer ectoparasitoids of I. typographus and a lower percentage of parasitism and infection level of Mattesia schwenkei than the long-term outbreaks even though the maternal gallery densities and beetle production were the same. The most mortality appeared to be caused by intraspecific larval competition, and the identical reproductive success in plots with short-term and long-term outbreaks indicates that the negative feedback resulting from parasitoids and entomopathogens does not substantially reduce beetle numbers. Although entomopathogenic fungi as Beauveria bassiana occur naturally in the galleries of spruce bark beetles, there was no evidence of its presence in the studied population. The low levels of predation and/or parasitism in both kinds of plots indicate that natural enemies did not play a significant role in reducing outbreak numbers of I. typographus.
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Link to article at publishers website
Database assignments for author(s): Karolina Lukasova, Jaroslav Holusa

Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
Research topic(s) for beneficials or antagonists:
surveys/distribution/isolation

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Ips typographus		Czech Republic
Beauveria bassiana (entomopathogen)	Ips typographus		Czech Republic