Field of Study – Zoology (N 014)

Parasitic diseases, especially those transmitted by vectors, represent a large proportion of infectious diseases worldwide. With climate change, these diseases are spreading rapidly to northern regions. Knowledge of the biology and distribution of these pathogens is essential to control the threats posed by them. Parasites of the avian family Onchocercidae (Nematoda, Filarioidea) have been studied quite intensively in the last century in southern Europe, America, Asia and Africa. These studies have found more than 160 species of filarioid nematodes parasitising birds, but data on the identification, biology, pathology and phylogeny of these parasites, and especially of the larval stages, are very scarce. The lack of molecular data (only DNA sequences of 10 species are currently available for phylogenetic studies) is a major obstacle for work on these parasites worldwide.

The study will investigate bird blood and blood-sucking insects to elucidate definitive hosts and potential vectors. Mature female onchocercidae produce microfilariae that enter the host’s bloodstream and live in the blood or skin. Microfilariae are readily detected in the blood of birds by the blood layering method. Nevertheless, the identification of parasite species using the morphological characters of microfilariae remains very difficult due to their morphological similarity, and therefore the blood of infected birds will be further investigated not only by microscopy but also by molecular genetic techniques. Adult nematodes will be studied to develop genetic markers. Molecular techniques would facilitate the diagnosis of all developmental stages of filiarioids and the identification of species in the host blood and tissues.

The study will aim to investigate the diversity and vectors of nematodes of the family Onchocercidae in the Northern Europe using molecular, morphological and experimental methods. Availability of more molecular data on parasite identification, it will be possible to link vertebrate parasite hosts and vectors, to elucidate life cycles and possible transmission routes.

Carabid beetles can effectively control the abundance of pests and weed seeds in agroecosystems. Their role as biocontrol (BC) agents is especially significant if agricultural practices aim to move towards more environmentally-friendly food production. The acceleration of the transition to a sustainable food system is emphasized in the new Farm to Fork Strategy of the EU. This EU food system strategy aims to achieve neutral or positive environmental impact, mitigate and adapt to climate change, reverse biodiversity loss, ensure food security and public health, etc. In contrast, conventional agriculture is highly susceptible to climate change (e.g., climatic extremes, such as high temperatures) and applies many synthetic agro-chemicals which both may disrupt carabid beetle efficiency while providing BC service. Furthermore, even practices allowed to apply in organic farming might potentially have negative consequences for carabid beetle functioning: for example, polyethylene coverings are used as mulch which can be source of microplastics in agricultural soils. These anthropogenic factors (pesticides, high temperatures, microplastics) may act solely as well as interactively to further deteriorate carabid BC service. Up to date, such interactive effects (but also individual effects of e.g. microplastics) were not investigated and mechanistic understanding on beneficial predatory arthropods is yet to be revealed.

The proposed project aims to evaluate individual and interactive effects of high temperature (mimicking climatic extremes), pesticides and microplastics on the functioning of carabid beetles. Here carabid beetle functioning will be expressed as locomotor activity (Sub-study 1) and selective food consumption (Sub-studies 2 – 3).

The project includes three sub-studies:

1. Interactive and individual effects of pesticides and temperature on carabid beetle locomotor activity. These lab experiments will reveal if different pesticides have negative effects on carabid movement activity and whether these negative effects increase with higher temperature. Locomotor activity will be recorded with computer-centered video-tracking system.

2. Increased temperatureand pesticide interactiveeffects on macronutrient selection (food intake and nutrient balancing) of carabid beetles. In these lab experiments pesticides which showed the effect on locomotor activity in sub-study 1 will be applied. Carabid beetles will be treated with pesticides and increased temperature and will be served with semi-artificial diets with different macronutrient content (lipid-, protein- and sugar- rich diets). Here we would also evaluate what are changes in body macronutritional content and body dry weight after treatments.

3. Microplastic effects on nutritional physiology of carabid beetles. This experiment will show the effect of microplastics that potentially present in the environment on nutrient balancing of carabid beetles. Do microplastics have any nutritional “meaning” to carabid beetles? Part of the beetles will be served with clean semi-artificial foods and another part with the same foods mixed with small known amount of microplastic powder.

Helminths parasitizing the blood circulatory organs of birds, terrestrial mammals and freshwater fish are of great economic, veterinary and medical importance. It is impossible to predict and effectively control the populations of these parasites and their spread, because the life cycles of most of them are not known. Identification of these species is based only on morphological studies of adults obtained from definitive hosts. Given the wide variety of definitive and intermediate hosts, the actual number of helminth species parasitizing the circulatory system should be higher. As a result of climate warming, reports of avian schistosomal cercarial dermatitis are increasing in association with changes in snail distribution and density. However, there are no published data on the diversity and distribution of bird schistosomes in Lithuania and other countries of the Baltic region. In Lithuania and neighboring countries, four species of Sanguinicola are known to parasitize the circulatory organs of fish, but none of the species has been confirmed by molecular tests. The nematode diversity of most vertebrate circulatory parasite species has been poorly studied by genetic methods, posing identification problems. Parasitizing helminths in the circulatory organs of fish, by damaging the capillaries of the heart, liver, kidneys, gills and lead to blood spills, open the way for secondary infections, which, in the case of more severe infections, cause mass deaths. Although pathogenic and widespread, these helminths are among the least studied fish-parasitic worms in the world. The real number of helminth species and the range of hosts, as well as their life cycles, can only be determined by molecular studies. This research is planned to collect helminths parasitizing the circulatory organs of vertebrates and gastropod molluscs in Lithuania and other countries of the Baltic Sea region. The main focus will be on assessing the genetic diversity of helminths. These studies will allow the assessment of phylogenetic and phylogeographic relationships; linking the development stages of helminths found in different hosts to reveal their life cycles and the true specificity of the parasites. Cooperation with parasitologists from Scandinavia, Poland and Ukraine is also planned. It is expected to discover and describe new species of helminths.

Parasitic diseases, especially those spread by vectors, are responsible for a large part of the world’s infectious diseases. With climate change, these diseases are spreading rapidly to northern regions. Knowledge of the biology and distribution of these pathogens is important for controlling the threats posed by them. The study will investigate bird blood and blood-sucking insects in order to identify definitive hosts and potential vectors. Mature females of Onchocercidae produce microfilariae which enter the host’s bloodstream and live in the blood or skin. Microfilariae are easily detected in the blood of birds by the buffy coat method. Nevertheless, the identification of parasite species using the morphological characters of microfilariae remains very difficult due to their morphological similarity, therefore the blood of infected birds needs to be further investigated not only by microscopy, but also by molecular genetic techniques. Adult nematodes will also be analyzed to develop genetic markers. Molecular methods would simplify the diagnosis and species identification of avian filiarioids at all stages of development, both in host blood and tissues.

World fauna of subgenus Tipula (Yamatotipula) includes 124 described valid species distributed throughout Afrotropic, Holarctic, Oriental and Neotropic regions. The subgenus, together with T. (Acutipula) ir T. (Tipula) is forming a separate phylogenetic complex in the polymorphic genus, whose status requires systematic revision. In the meantime, there are three morphological clusters recognized in subgenus T. (Yamatotipula) with systematic rank possibly equal to subgenus or higher. However, a phylogenetic analysis is required to perform a systematic revision. Some species morphologically are poorly known and features with diagnostic or phylogenetic importance are not illustrated and described. The goal of the current thesis is comparative morphology, taxonomic and phylogenetic analysis.