Jan Havelka

Jan Havelka


Research Focus & Metrics

Academic Career Length

20Years (2007-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

View All Publications
3 January 2007 in European Journal of Entomology
Verified
Journal Article
Open access
PDF file
JHJan Havelka
Jan Havelka
VLVladimír Landa
Vladimír Landa
Determination of embryonic stages is an important prerequisite for the long-term cryopreservation of eggs and embryos of the predatory gall midge Aphidoletes aphidimyza. This paper describes the embryonic development of this insect based on light microscopy. Gall midge embryogenesis lasts, on average, 102 h at 17?C and 144 h at 15?C. Living embryos can be quickly separated into ten stages that are clearly defined by specific morphological markers. The necessity for selecting definite embryonic stages for cryobiological storage is discussed.

22 June 2013 in Journal of Applied Entomology
Verified
Journal Article
Closed access
PDF file
JHJan Havelka
Jan Havelka
MŽM. Žurovcová
M. Žurovcová
SRS. Rychlý
S. Rychlý
PSP. Starý
P. Starý


20 August 2020 in Forests
Verified
Journal Article
Open access
PDF file
JHJan Havelka
Jan Havelka
JHJekaterina Havelka
Jekaterina Havelka
PSPetr Starý
Petr Starý
Nearctic aphid Cinara splendens (Gillette and Palmer, 1924) was collected on ornamental Douglas fir (Pseudotsuga menziesii (Mirb.) Franco) in South Bohemia in 2009. It was the first record of this species in the Palaearctic region. The aim of this research was to study the bionomy of this species in Central Europe and to make descriptions of all available morphs, as previous morphological descriptions of C. splendens appeared to be incomplete. Six monitoring sites of this species were established in South Bohemia and were then regularly attended in the period of 2009–2019. The colonies of C. splendens were observed; its natural enemies and honeydew users were also registered. Aphids were collected for the microscope slide preparation, followed by the evaluation of thirty of the basic quantitative and seven qualitative morphological characteristics. Partial sequences of mitochondrial COI and nuclear EF-1α were used to confirm morphology-based identification and to compare samples from the Czech Republic with those of North American origin. Cinarasplendens survived successfully under new ecological conditions, but its population density remained quite low, except for 2009 and 2019, due to a synergistic effect of the dry weather and very high population density of the adelgid Gilletteella coweni (Gillette, 1907), which is a key pest of Douglas fir in the Czech Republic. The principle predators were coccinellid beetles, while the aphidophagous hover flies were less abundant. Together with a weak ability to migrate due to a low number of alate viviparous females in population, C. splendens cannot be a potential pest of P. menziesii in Central Europe.