Our studies about host specificity of pre-dispersal predators and herbivory start with our project, where we work with a set of species belonging to the subfamily Carduoideae (Asteraceae family). In this project we suggest an alternative approach using data on large number of traits of the plant and the insect and using this knowledge to predict potential hosts of the herbivores. Specifically we plan to combine field observations of plant herbivore associations with feeding experiment and plant and insect trait measurements including composition of secondary metabolites in the plant. We will use the species traits to predict the results of the field observations and feeding experiment. In this way we will identify traits that can be used to predict host specificity of insect herbivores and thus develop a predictive tool that will allows to identify possible host of the insects without time consuming field observations and experiments. We will validate the model created using data from Europe by similar data obtained from USA.
The subfamily Carduoideae in the Czech Republic includes 16 genera with 43 species and numerous hybrids. Recently, we have studied 32 of them. Many members of this tribe are well known as important and dangerous invasive plants. Many European species from this subfamily are invasive in North America (e.g. Cirsium arvense, Carduus nutans, Carduus acanthoides, Centaurea maculosa).
Species of the Carduoideae subfamily are known to have many natural enemies, especially insect. They include many different herbivores; leaf feeders (e.g. Cassida rubiginosa, Lema cyanella, both Coleoptera: Chrysomelidae), stem feeders (e.g. Hadroplontus litura, Coleoptera: Curculionidae); root feeders (e.g. Cyphocleonus achates, Mogulones cruciger, Coleoptera: Curculionidae) and also seed predators (e.g. Rhinocyllus conicus, Larinus carlinae, both Coleoptera: Curculionidae; Terellia ruficauda, Diptera: Tephritidae). Pre-dispersal predators (seed preadators) are often considered as the first potential enemies in the generative reproduction of plant. The most known pre-dispersal predators used as biological control agents are classified into the weevils (Coleoptera: Curculionidae, especially Lixinae and Ceutorhynchinae) and tehpritids (Diptera: Tephritidae).
The profile of secondary metabolites (SM) is often characteristic for the particular plant taxa and can serve also as a phylogenetic marker (Emerenciano et al. 2001, Zenk & Juenger 2007). There are several typical groups of SM occurring in family Asteraceae, which show biological activity towards insects and therefore they can modulate insect preferences of the host plant. They involve the following groups: monoterpenes, aldehydes, esters, flavonoids, triterpenes and sterols, polyacetylenes and other hydrocarbons, alkaloids, sesquiterpene lactones, phenolic acids and lignans (Jordon-Thaden & Louda 2003, El-Sayed et al. 2008).
Insect-plant associations are presented here:
a, List of studied plants included all known pre-dispersal preadtors for each plant species
b, List of known pre-dispersal predators included all theirs host plants for each insect species