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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.
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The rate of development and body size of carrion beetles (Coleoptera: Silphidae).
Štrait, František ; Jakubec, Pavel (advisor) ; Qubaiová, Jarin (referee)
The goal of this review is to introduce the Silphidae family to the reader and summarize the ecological and geographical aspects of this family, their morphological features, and their dietary requirements.
Additionally, I analyze the evolution of insects when exposed to abiotic factors and their adaptation to them. I also described the issue of forensic entomology depending on the evolution of insects, the complete developmental stages of insects including the time of feeding, and the competitive fight for carrion.
I also described the application of insects in forensic entomology and the identification of insect larvae.
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The rate of development variability of carrion beetles (Coleoptera: Silphidae).
Ejemová, Magda ; Jakubec, Pavel (advisor) ; Novák, Martin (referee)
This Bachelors thesis is focused on ecology and rate of development of insects, with special focus on carrion beetles (Coleoptera: Silphidae), of the genus Thanatophilus. The process of the development is affected by both biotic and abiotic surroundings. My thesis is focused on the abiotic aspect.
Main influences on the rate of development in the abiotic surroundings have the temperature, moisture, photoperiod and the quality and amount of sustenance. Temperature is the most important of them all, as it influences the physiological processes inside of the insect's body. The relation between the temperature and rate of development can be described by temperature characteristics. Amongst the most important features are the lowest developmental threshold (T0) at which the development begins and the sum of effective temperatures (SET), which is stated in diurnal mean temperatures that are needed for reaching certain stage of development.
The relationship between rate of the development and temperature can be described by linear or nonlinear models. The easiest and most commonly used model for figuring out the lower developmental threshold is the linear one. The linear model is convenient for its mathematical simplicity, but only the nonlinear models can show us the of development temperatures beyond the linearity.
These models are used in many different fields, but mostly in forensic entomology or the agriculture.
This thesis also suggests the methodology for future study of the rate of development variability for necrophagous beetle. Thanatophilus rugosus between geographically separated populations and for calculation of its developmental constants (T0 and SET).
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