|
|
Ecological and evolution strategies of necrophagous beetles (Coleoptera)
Jakubec, Pavel ; Růžička, Jan (advisor) ; Petr, Petr (referee)
Necrophagous beetles (Coleoptera) are very interesting and diverse ecological group of species with an immense impact on a natural nutrient cycle. Their main food source and breeding ground are carrions of vertebrates, human remains included. This relationship is often used in various ways by forensic entomology, but its potential was not jet fully reached, because our knowledge of biology and ecology of these beetles is very much incomplete. In this thesis I would like to explore geographic distribution, ecological requirements and developmental biology of several Central European necrophagous beetles as an outcome of their ecological and evolution strategies. For that I raised three broad research questions. Which factors are determining the local abundance of carrion beetles (Coleoptera: Silphidae)? How the current geographical distribution of open-landscape carrion beetles looks like in the Czech Republic? How the temperature affects the development of Sciodrepoides watsoni (Spence, 1813)? We found out that soil type can have significant effect on abundance of carrion beetles. They showed preference for chernozem -- Nicrophorus antennatus (Reitter), N. germanicus (Linnaeus), N. interruptus (Stephens), N. sepultor (Charpentier), Silpha obscura obscura (Herbst), T. sinuatus (Fabricius) or for fluvisol as did N. humator (Gleditsch). These findings support our hypothesis that soil type could be an important factor determining the occurrence of necrophagous European carrion beetles. To collect novel data of the current geographical distribution of carrion beetles we used 420 baited pitfall traps at 84 localities, and we collected 71 234 specimens of 15 silphid species. Among them, three endangered carrion beetle species listed on the Czech Red List of Invertebrates, were found. Two are vulnerable thermophilic species of open landscapes, Nicrophorus antennatus (Reitter, 1884) (collected around Louny and Židlochovice) and Nicrophorus germanicus (Linnaeus, 1758) (Louny, Zábřeh and Židlochovice). The third is the near threatened species, Nicrophorus sepultor Charpentier, 1825 (collected around Louny, Kutná Hora, Zábřeh and Židlochovice), which also prefers open landscapes. We studied development of common Holarctic beetle Sciodrepoides watsoni under five constant temperature regimes in laboratory (15, 18, 21, 25 and 28°C). Parameters of thermal summation models and their standard errors were calculated for each developmental stage (egg, three larval instars and pupae). We also find a new character for larval instar determination (head width) and proposed novel approach for future studies of size-based characters in instar determination.
|
guest ::
