Thesis (licentiate)--Swedish University of Agricultural Sciences, 2005. / Appendix reprints three papers and manuscripts co-authored with others. Also partially issued electronically via World Wide Web in PDF format; online version lacks appendix.

The distribution, population ecology, behavior and host interactions of the root weevil, Hylobius warreni Wood were investigated in lodgepole pine forests in Alberta. Highest incidence of the weevil occurs in the Lower Foothills Section of the Boreal Forest Region, between 2,500 and 4,000 feet in elevation. In even-aged forests weevil numbers are distributed according to stand maturity, stand density, tree size and duff depth. Interactions between these variables modify the patterns of abundance in different stands. Attack incidence upon the host varies, being highest in the collar zone and least on lateral roots. As tree size increases the ratio of weevils on roots/weevils on collar tends to increase. During normal stand development initial invasion of weevils occurs at age 6-10 years, and persists with successive attacks throughout the life of the stand. Weevil populations are highly aggregated in mature stands; "k" values of the negative binomial varied from 0.09 to 0.68, while Taylor's power law gave an aggregation index "b" value of 1.92. Estimates of weevil populations indicated that low levels are characteristic of this species and are maintained, mostly within the range 200-1200 weevils per acre. Estimates of absolute numbers indicate similar levels of abundance occur in young and old stands alike, while population intensity values increase with stand maturity. The highest rate of increase of attack density per tree appears to occur during the ages of 30-45 years. The structure of weevil populations was described and mortality factors were identified and measured for larval, pupal and teneral stages. The main mortality factor of these stages appeared to be from excess moisture in the larval gallery and pupal cell. Only the first 3 larval instars are definable by head capsule width measurement. The feeding behavior of larvae varies with its maturity. In the early instars the feeding pattern relates to bark thickness, but damage is insignificant. Damage of late instars may consist of decorticated gallery lengths up to 24 cm. Larval and pupal habitats are described to indicate the special adaptations for survival. Adults live at least 3 years but lay their eggs during the second and third summers of adulthood. Their seasonal peak of activity occurs in June and early July. Dispersion in the forest tends to be random, commencing about 2 hours after sunset and when temperatures exceed 36-40 °F. Host trees are located partly by vision, the pattern of selection being related to host size. Maximum fecundity per female per season may be 36 or more eggs, but in the field the actual number may not exceed 12.0. Most eggs are deposited singly in niches excavated by the female in the root-collar bark, and are subsequently covered over with excreta. The egg requires a moist environment maintained for up to 42 days for successful hatch. During stand development up to 100 percent of trees may sustain larval feeding damage accumulated to various degrees of intensity. Young trees up to 30 years of age show less resistance to girdling damage than older trees, and reasons are given for this. Estimates of mean height losses of 20-25-year old tree stems sustaining 50 percent girdling were 11.5 and 10.9 percent over 2- and 3-year periods respectively. The total impact of the weevil in the stand as a whole appears to hasten successional changes during stand development. A method of regulation of weevil abundance is postulated and takes into account the behavior of the female during oviposition, host selection, larval feeding habits, cumulative damage and host interactions. Overall numerical restraint and stability of numbers are considered to be effected largely through the inherent behavior of adults. Several weevil control measures are suggested through forest management. Clearcutting of mature timber in alternate strips reduced a weevil population by an estimated 67 percent, but some larvae developed to adults in the cut stumps one and two years after tree removal. The effect of cutting resulted in a concentration of weevils on adjacent trees along stand peripheries, 3-5 years after cutting. / Forestry, Faculty of / Graduate

Thesis (doctoral)--Swedish University of Agricultural Sciences, 2004. / Appendix reprints four papers and manuscripts co-authored with others. Includes bibliographical references. Also partially issued electronically via World Wide Web in PDF format; online version lacks appendix.

The pine weevil (Hylobius abietis L.) is one of the two topmost economically important insect pests in Swedish conifer forests. The damage increase in areas were the silvicultural practice is to use clear cuttings were the insects gather and breed. During egglaying the female protects her offspring by creating a cave in roots and stumps were she puts her egg and covers it with frass, a mixture of weevil feces and chewed bark. Adult pine weevils have been observed to feed on the other side of the egg laying site and antifeedant substance has been discovered in the feces of the pine weevil. We think it is possible that microorganisms present in the frass contribute with antifeedant/repellent substances. Little is known about the pine weevils associated bacteria community and their symbiotic functions. In this thesis the bacterial community is characterized in gut and frass both from pine weevils in different populations across Europe as well as after a 28 day long diet regime on Scots pine, silver birch or bilberry. Volatile substances produced by isolated bacteria as well as from a consortium of microorganisms were collected with solid phase micro extraction (SPME) and analyzed with GC-MS. The main volatiles were tested against pine weevils using a two-choice test. Wolbachia, Rahnella aquatilis, Serratia and Pseudomonas syringae was commonly associated with the pine weevil. 2-Methoxyphenol, 2-phenylethanol, 3-methyl-1-butanol were found in the headspace from Rahnella aquatilis when grown in substrate containing pine bark. 2-Methoxyphenol and 3-methyl-1-butanol, phenol and methyl salicylate were found in pine feces. Birch and bilberry feces emitted mainly linalool oxides and bilberry emitted also small amounts of 2-phenylethanol. A second part of the thesis discusses the role of fungi in forest insect interactions and the production of oxygenated monoterpenes as possible antifeedants. Spruce bark beetles (Ips typhographus L.) aggregate with the help of pheromones and with collected forces they kill weakened adult trees as a result of associated fungi growth and larval development. A fungi associated with the bark beetle, Grosmannia europhoides, was shown to produce de novo 2-methyl-3-buten-2-ol, the major component of the spruce bark beetle aggregation pheromone. Chemical defense responses against Endoconidiophora polonica and Heterobasidion parviporum were investigated using four clones of Norway spruce with different susceptibility to Heterobasidion sp. Clone specific differences were found in induced mono-, sesqui and diterpenes. A number of oxygenated monoterpenes which are known antifeedants for the pine weevil were produced in the infested areas. / <p>QC 20160601</p>

This thesis is based on three inter-related studies: the first part deals with the microbial consortium, the identification of microbes and their volatiles, the second part deals with the study of bio-chemical control methods of two conifer pests; the pine weevil Hylobius abietis (L.) and the root rot fungi Heterobasidion spp., and the third part describes the production of styrene by a fungus using forest waste.The large pine weevil (Hylobius abietis L.) is an economically important pest insect of conifers in reforestation areas of Europe and Asia. The female weevils protect their eggs from feeding conspecifics by adding frass (mixture of weevil feces and chewed bark) along with the eggs. In order to understand the mechanism behind frass deposition at the egg laying site and to find repellents/antifeedants for pine weevils, microbes were isolated from the aseptically collected pine weevil frass. Microbial produced volatile organic compounds (VOCs) were collected by solid phase micro extraction and analyzed by GC-MS after cultivating them on weevil frass broth. The major VOCs were tested against pine weevils using a multi-choice olfactometer. Ewingella sp., Mucor racemosus, Penicillium solitum, P. expansum, Ophiostoma piceae, O. pluriannulatum, Debaryomyces hansenii and Candida sequanensis were identified as abundant microbes. Styrene, 6-protoilludene, 1-octene-3-ol, 3-methylanisole, methyl salicylate, 2-methoxyphenol and 2-methoxy-4-vinylphenol were the VOCs of persistently isolated microbes. In behavioral bioassay, methyl salicylate, 3-methylanisole and styrene significantly reduced the attraction of pine weevils to their host plant volatiles. Heterobasidion spp. are severe pathogenic fungi of conifers that cause root and butt rot in plants. Bacterial isolates were tested for the antagonistic activity against fungi on potato dextrose agar. Bacillus subtilis strains significantly inhibited the growth of H. annosum and H. parviporum. Styrene is an industrial chemical used for making polymeric products, currently produced from fossil fuel. A strain of Penicillium expansum isolated from pine weevil frass was investigated for the production of styrene using forest waste. Grated pine stem bark and mature oak bark supplemented with yeast extract produced greater amounts of styrene compared to potato dextrose broth. / <p>QC 20130507</p>

Diss. (sammanfattning) Alnarp : Sveriges lantbruksuniversitet, 2009. / Härtill 5 uppsatser.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv., 2004. / Härtill 4 uppsatser.

Diss. (sammanfattning). Uppsala : Sveriges lantbruksuniversitet, 2004. / Härtill 4 uppsatser.

Diss. (sammanfattning). Uppsala : Sveriges lantbruksuniversitet, 2005. / Härtill 4 uppsatser.

Vid föryngring ger markberedning en bra förutsättning för plantan att överleva och växa, och med mindre risk för snytbaggeangrepp. Syftet med denna studie var att undersöka hur snytbaggeskydd och olika markberedningsmetoder långsiktigt påverkar stamantal, medelhöjd och volymproduktion hos gran (Picea abies). Markberedningsmetoderna som jämfördes var högläggning, fläckmarkberedning och inversmarkberedning. De jämfördes med att inte markbereda alls. Hälften av plantorna var behandlade mot snytbagge med permetrin, dessa var jämt fördelade i försöket. Studien genomfördes i en försöksyta 9284, vid SLU:s försökspark i Siljansfors, Mora kommun. Beståndet var 17 år när det mättes (16 år efter plantering) hösten 2018. Då mättes trädens höjd, diameter samt grönkronans höjd. Volym beräknades med volymfunktioner. Högläggning, inversmarkberedning, och fläckmarkberedning (i nu nämnd ordning) och snytbaggeskydd gynnade granplantornas volymtillväxt, gav flest stammar samt högst höjd. Att högläggning och inversmarkberedning var så framgångsrika i detta försök beror troligen på att marken i Siljansfors är näringsfattig och fuktig. Hög planteringspunkt ökar risken för en planta att torka. Permetrinbehandling hade en positiv effekt på volymen och stamantalet, dock var det ingen signifikant skillnad vad gäller höjden. Markberedning samt permetrinbehandling ger bestående långsiktiga resultat för produktionen. / In regenerations, soil preparation provides good conditions for plants to survive and grow, and reduces the risk of damage by pine weevil (Hylobius abietis). The aim of this study was to investigate the long-term effect of protection against pine weevil damage and the long-term effect of different soil scarification methods on the number of trees, tree height and the volume production of spruce (Picea abies). The soil preparation methods that were compared were mounding, patch scarification and the inverse method. These were compared as well as to, no soil preparation at all. Half of the plants were treated against pine weevil with permethrin. These were evenly distributed in the experiment. The study was conducted in the trial area 9284, at SLU's experimental park in Siljansfors, Mora municipality. The trees were 17 years old when measured (16 years after planting) in the autumn 2018. Then tree height, diameter and the height of the green crown was measured. Volume was calculated with volume functions. Mounding, the inverse method and patch scarification (in the order mentioned) and pine weevil protection benefited the volume production of the spruce trees, the numbers of trees and tree height. The fact that mounding and the inverse method was so successful in this experiment is probably due to that the soil in Siljansfors is nutrient-poor and moist. High planting points increases the risk of drought. Permethrin treatment had a positive effect on volume production and the number of plants, however, there was no significant difference regarding tree height. Soil preparation and permethrin treatment provide lasting long-term effects on production.