Japanese encephalitis virus (JEV) is a significant vector-borne zoonotic pathogen, causing devastating encephalitis in humans. Its geographical range includes a majority of Asian countries and has also been recognized in some western Pacific areas. The main vectors of JEV are mosquitoes belonging to the genus Culex. Birds and pigs function as hosts and virus amplifiers, whereas humans are accidental hosts. Japanese encephalitis is commonly regarded as a rural disease.

Francisella tularensis, the causative agent of the zoonotic disease tularaemia, is highly contagious and potentially fatal for a wide range of wildlife species of the northern hemisphere, also humans. Although recognized as a pathogen for over 100 years, much still remains to be elucidated concerning the ecology and transmission of the bacterium, hence this literature overview aims at compiling data regarding the aquatic association and the role of mosquitoes in transmission of Francisella tularensis subspecies holartica, the sole subspecies in Sweden. While a linkage between the bacterium and natural waters stands beyond dispute, there is no consensus in the literature concerning its potential as a reservoir. However, two prevailing theories can be distinguished; one proposes the water association being mammaldependent and thus merely the result of contamination from semi-aquatic mammals living in close vicinity to the water source. The other, quite contrary, suggests mammal-independence and hence that water, possibly in association with protozoa, serves as an environmental reservoir for the bacterium.

Mosquitoes are found in extremely large numbers in the lower parts of the River Dalälven. In the year 2000 the mosquito nuisance was especially high, resulting in foundation of the Biological mosquito control project. Since 2001 Mosquito larvae are controlled by using a biological pesticide BTI (Bacillus thuringiensis ssp israelensis). The mosquito fauna in the area is dominated by flood water mosquitoes, a group of mosquitoes that are very aggressive and form new generations of mosquitoes during every single flooding event during the summer. To be able to efficiently control the mosquitoes it is essential to know the extension and locality of the flooding.

Dragonflies are fascinating. The larvae stays larvae from a couple of weeks up to 5 years, it depends on the species (Hansen, 1981). The temperature, nourishment and time of the year also play a role for the growing factor for the larvae. Both Sahlén (1985) and Begon a.o (1990) say so. My report contains information about the branched setae on the front legs from the family damselflies (Zygoptera) and the species Coenagrion.

Larvae of Lepidopteran Manduca sexta and Spodoptera littoralis are pests of economical importance in several horticultural and agricultural crops. Knowledge of insect feeding preferences and behavior is crucial in order to find economically and ecologically sustainable solutions to the problems caused by these herbivores. The aim of this thesis was to study the behavior and the induced feeding preferences in larvae of M. sexta and S. littoralis when reared on certain host plants. The hypothesis was that larvae of M. sexta would have an innate preference for plants of the Solanaceae family and therefore discriminate the previously experienced nonhost when faced with the choice between a true host and the previous food source.

Infection with intestinal parasites can in many cases be the reason for decreased performance or production. The gastro-intestinal nematode, Ostertagia ostertagi, and the lungworm, Dictyocaulus viviparus, are the most pathogenic nematodes of cattle and severe infection can lead to death. They have both a direct lifecycle and on the pasture the parasites spread as freeliving worms. The parasites are mainly a problem for the first season grazers. They have not developed immunity against the parasites and are therefor more sensitive to parasite infections.

A plant's defensive ability against herbivore attack can be influenced by many different factors, one of them being domestication. During human selection to improve the yield of plants, the resistance against herbivore attack can have been lowered, due to a trade-off for use of resources between these traits in the plants. In this thesis I investigated the effect of domestication on resistance against herbivorous insects in cotton plants. I used different varieties and species of wild and domesticated cotton in three different experiments. A feeding assay was conducted, the mortality, development time and pupal weight of larvae of the Egyptian cotton leaf worm Spodoptera littoralis was studied. In a second experiment the preference of the root-feeding beetle Agriotes spp.

Predation is a strong dective force on invertebrate prey. Asellus aquaticus differs in pigmentation reed and submerged vegetation habitats in lakes. Light pigmented individuals al vegetation dominated by Chara sp. while dark pigmented individuals dominate in the reeds. These differences have been hypothesized to result from background matching.

Warmer climate is a driving factor to species expansion northwards. Expansion to new areas can result in escape from natural enemies, resulting in reduced levels of mortality and thereby potentially increasing the rate of expansion. The most important parasitoid species attacking butterfly larvae belong to the families Tachinidae, Ichneumonidae and Braconidae. The aim of this thesis was to investigate parasitism and difference between populations in established area and newly colonized area for the European map butterfly, Araschnia levana, in order to examine if the butterfly has escaped from some natural enemies. In 1982 the first European map butterfly was observed in Sweden and has now established up to middle Småland.

Modern methods for managing pine (Pinus sylvestris) create homogenized forests. This decreases nature?s potential for biodiversity and might threaten species in need of different types of milieu. The main purpose of this study was to investigate how important older pine trees are for biodiversity. In the Hall-Hangvar Reserve in the north-west part of Gotland, insects collected from traps showed that more species were found in old or dead trees compared to younger pine trees.

Plagionotus detritus is a threatend longhorn beetle that only exists at one site in Sweden. It is saproxylic and depending on recently dead coarse oak wood for its larval development. Trees at Djurgården, Stockholm that have been colonized by Plagionotus detritus has been studied to find out the habitat preferences of the species and to see what affects the density of beetles in a tree. The bark of some trees and wood from the breeding project at Nordens Ark has also been studied to find out what affects the species reproductive success. The reproductive success was measured in two ways, the larval mortality and the size of the hatching holes.

The natterjack toad (Bufo calamita) is one of three species of toads living in Sweden. During the last decades declines in population numbers have been detected and are thought to be primarily due to loss of habitat, overgrown breeding ponds and competition from common toad (Bufo bufo) and common frog (Rana temporaria). In 2012 20 ponds in the location of Glommeskallen in Smögen were restored by clearing the ponds from overgrowth. The aim of this study was to investigate if natterjack toads used the restored ponds and if the restoration had made an impact on the natterjack population on the location. Presence of common toad and common frog was recorded, as was the presence of eggs and larvae of any of the three species.

This thesis deal with tick burden on roe deer (Capreolus capreolus) fawns, in relation to age, weight, hind foot length, and as well as to vegetation and habitat on bed sites. Roe deer fawns (N = 25) were captured from May 27 to June 27. Samples of ticks were collected and tick burden were estimated. Of all sampled ticks the nymphs and adults were Ixodes ricinus, while the larvae were not identified. 4.4 % of the sampled ticks were larvae, 55.0 % nymphs, 26.8 % adult females, and 13.8 % adult males.

Many wood living insects are considered threatened by modern forestry due to the reduction in amount of dead wood. During the last decade various methods have been used to enhance the quantity of dead wood in managed forests. However little is known how and if these methods are aiding saproxylic insects. The threatened tenebrionid beetle, Upis ceramboides, is already extinct in southern Sweden. It develops in white rotted dead birch (Betula spp) and requires sun-exposed sites.

The purpose of this paper is to examine what problems cabbage growers have with the Swede Midge. The last few years the Swede Midge, Contarinia nasturtii, has become a larger problem for cabbage growers in several countries in Europe as well as in Sweden. In Canada the problems are so severe that the midge is classified as a quarantine pest and therefore certain rules have to be followed. I have collected facts of the biology, host plants and reproduction of the Swede Midge, as well as the growers experiences and the occurrence of the midge in Canada, Europe and Sweden. The Swede Midge is hard to control because of its short life cycle and the larvae are protected between the heartleaves of the plant. When the larva feeds on the growth point the plant becomes distorted, in some cases several heads develop or none at all. When the midge infests spring rape its flower buds become undeveloped and rosette like.