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| 2. |
- Björkman, Christer, et al.
(författare)
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A rare event – an isolated outbreak of the pine-tree lappet moth (Dendrolimus pini) in the Stockholm archipelago
- 2013
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Ingår i: Entomologisk tidskrift. - 0013-886X. ; 134, s. 1-9
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Tidskriftsartikel (refereegranskat)abstract
- The pine-tree lappet moth, Dendrolimus pini (L.), belonging to the family Lasiocampidae has a wide distribution in Eurasia. In Sweden it is normally found up to 61°N and normally occurs at low densities. In central Europe there have been several reports of outbreaks in historical time. In Sweden the last known outbreak before the one reported here was in 1938-40 in Värmland. In this paper we report a recent severe D. pini outbreak that was discovered in 2012 on the small island Furuskär in the Stockholm archipelago. The distribution of the damage on the island as well as a detailed inventory of larvae and pupae on individual trees is presented. Several photographs are presented to illustrate the damage. In the paper we formulate and try to answer several questions that arose as a natural consequence of this rare event: Why was this particular island hit? What are the causes behind the outbreak? What will happen to the trees and the vegetation on the island? Will the outbreak continue? Will the outbreak spread?
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| 3. |
- Chen, Yayuan, et al.
(författare)
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Seasonal timing and recurrence of methyl jasmonate treatment influence pine weevil damage to Norway spruce seedlings
- 2021
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Ingår i: New Forests. - : Springer Science and Business Media LLC. - 0169-4286 .- 1573-5095. ; 52, s. 431-448
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Tidskriftsartikel (refereegranskat)abstract
- Defense can be induced in conifer seedlings to reduce pine weevil (Hylobius abietis) damage, by treatment with the plant hormone methyl jasmonate (MJ). Few studies have addressed important practical issues regarding the use of MJ such as treatment incidence and timing, seedling age and its compatibility with plant nursery practices. We examined if levels of pine weevil damage depend on seasonal timing and recurrence of MJ treatment, and if the observed effects depend on plant age. Norway spruce (Picea abies) seedlings from two age cohorts (1 year and 1.5 years old) received four MJ treatments: MJ application before winter storage in the previous year, after winter storage but before spring/summer planting, repeated MJ application (both before winter storage, and before planting) or no MJ application at all. Pine weevil damage was evaluated in a lab and field experiment. We found that the timing and recurrence of MJ treatment affected the amount of damage inflicted by pine weevils in different ways, but these effects were consistent among age cohorts. MJ application before winter storage provided the most effective protection, and this reduction in damage was comparable to that provided by a currently used physical protection method against pine weevil feeding. Our results indicated that MJ can be applied in line with nursery practices (before winter storage) and provides adequate protection for two growing seasons.
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| 5. |
- Fedderwitz, Frauke, et al.
(författare)
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Diel behaviour and time budget of the adult pine weevil Hylobius abietis
- 2014
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Ingår i: Physiological Entomology. - : Wiley. - 0307-6962 .- 1365-3032. ; 39, s. 103-110
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Tidskriftsartikel (refereegranskat)abstract
- The pine weevil [Hylobius abietis (L.); Coleoptera: Curculionidae] has a high economic impact on forest regeneration in Europe. The general biology of the pine weevil has received considerable attention, although there is insufficient knowledge about its diel behaviour and time budget. Therefore, in the present study, the feeding and locomotion behaviour of individual adult weevils on Norway spruce seedlings [Picea abies (L.) Karst.] is observed for 24-h periods in the laboratory. Both girdled and nongirdled seedlings are used to assess how the behaviour of weevils is influenced by the physiological response of plants to the girdling. The locomotion pattern shows a distinct maximum during the beginning of the dark phase, whereas most feeding occurs during the second half of the dark phase and the firsthours of the subsequent light phase. The girdling treatment increases the time that weevils spend on the seedlings during the first part of an observation session, although it has no effect on their feeding pattern. The time budgets of weevils on girdled and nongirdled seedlings are similar. On average, weevils spend 34% of their time in locomotion and 6% on feeding. Females spend more time feeding than males (7.1% versus 4.2%), possibly because they have higher food requirements (e.g. for egg production). Females also spend more time in total on the seedlings than males (26.3% versus 7.0%). The present study reveals, in high temporal resolution, the diel feeding and locomotion behaviour and time budget of male and female pine weevils.
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| 6. |
- Fedderwitz, Frauke, et al.
(författare)
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Does the pine weevil (Hylobius abietis) prefer conifer seedlings over other main food sources?
- 2018
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Ingår i: Silva Fennica. - : Finnish Society of Forest Science. - 0037-5330 .- 2242-4075. ; 52
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Tidskriftsartikel (refereegranskat)abstract
- Adult pine weevils (Hylobius abietis (L.)) feed on the tender bark of branches and roots of mature conifer trees and on the stem bark of conifer seedlings. Their feeding on mature trees does not cause any economic damage, but their feeding on planted seedlings is so devastating that the pine weevil is considered one of the most important forest pest insects in Europe. We asked whether the pine weevil prefers seedlings over other regularly utilized food sources. This question is of particular interest because new approaches to seedling protection are based on decreasing any preference for seedlings by using less palatable plants or by enhancing their defence (by genetic selection or by methyl jasmonate treatment). In a laboratory choice experiment we tested pine weevil feeding preferences for seedlings compared with branches and roots from mature trees (separately for Norway spruce and Scots pine). Pine weevils preferred roots, but not branches, of Norway spruce over seedlings of the same species. With Scots pine there were no clear preferences, but the weevils showed a tendency to prefer roots over seedlings. These results provide support for seedling protection approaches that attempt to redirect pine feeding from planted seedlings to other food sources.
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| 7. |
- Fedderwitz, Frauke, et al.
(författare)
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Effects of jasmonate-induced resistance in conifer plants on the feeding behaviour of a bark-chewing insect, Hylobius abietis
- 2016
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Ingår i: Journal of Pest Science. - : Springer Science and Business Media LLC. - 1612-4758 .- 1612-4766. ; 89, s. 97-105
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Tidskriftsartikel (refereegranskat)abstract
- Conifer defences can be induced by exogenous chemical elicitors, thereby reducing damage caused by bark-feeding insects. However, the insect behavioural mechanisms involved are poorly understood. Thus, effects of artificially induced plant defences on feeding behaviour of the pine weevil (Hylobius abietis), a serious forest pest, were examined to explore mechanisms involved in decision- making processes connected to feeding. To induce plant defences, we applied methyl jasmonate (MeJA), a naturally occurring plant hormone, to young Norway spruce (Picea abies) plants. The weevils’ feeding behaviour on plants with and without MeJA treatment was studied in both a no-choice and a choice laboratory experiment. MeJA treatment did not affect the initiation of feeding, but it affected the weevils’ subsequent feeding patterns. In the no-choice experiment, the only observed effect of its treatment was that it reduced the size of the initial feeding scars. In the choice experiment, it reduced both the numbers and sizes of the feeding scars and hence the total debarked area. Thus, the MeJA-induced resistance did not deter the pine weevils from attacking the spruce plants, but reduced the amounts they consumed at one place, which would reduce risks of girdling and plant death. This may be the behavioural mechanism behind the previously recorded increases in survival rates of MeJAtreated plants in the field.
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| 8. |
- Fedderwitz, Frauke
(författare)
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Pine weevil feeding behaviour in relation to conifer plant properties
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The pine weevil (Hylobius abietis (L.)) is a forest insect distributed over the Palearctic region. The adults feed on the phloem of young conifer plants causing high economic losses for the European forest industry. Still, there is very little knowledge about the structure of its feeding behaviour. Feeding behaviour can be studied in several different temporal resolutions, from differences in feeding after several weeks to diel patterns and short-term feeding, i.e. feeding patterns at the level of feeding events and meals. The aim of this thesis was to increase the knowledge about the pine weevils’ feeding patterns and the underlying behavioural mechanisms. I studied the pine weevils’ time budget and diel behaviour as well as its short-term feeding behaviour based on video recordings. In addition, I assessed how changes in plant properties due to girdling or induction of plant defences with a chemical elicitor, methyl jasmonate (MeJA), affect the feeding pattern and preferences of the pine weevil. Pine weevils allocated only 6 % of the time to feeding. Most of the time was spent away from the plant (70 – 80 %). Damaged plants appeared to attract the weevils because they spent more time while not feeding on damaged plants than on undamaged plants. Feeding behaviour was mostly concentrated to the second half of the dark phase, after a peak of locomotion behaviour during the first part of the dark phase. During the light phase, pine weevils mostly rested. Analysis of the short-term feeding behaviour showed that pine weevils made 4-5 meals per day, removing about 13 mm2 during about 24 minutes in each meal. Some of the feeding properties, such as how much time was spent not feeding during a meal, differed between male and female weevils. Girdling did not affect the time budget or feeding properties. The induced plant defences with MeJA caused a reduction in meal duration. When meals consisting of only phloem, only needles or both were compared, the meal duration and the time until the initiation of a meal were more similar between the different meal contents on induced plants. In addition, the results from a no-choice and a choice experiment indicate that the protective effect of MeJA-induced defences is, besides an overall reduction of feeding, mainly due to the reduced amount that a pine weevil can feed at one place. Thus the risk of girdling and death of the plant is reduced.
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| 9. |
- Fedderwitz, Frauke, et al.
(författare)
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Pine weevil (Hylobius abietis) feeding pattern on conifer seedlings.
- 2012
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Konferensbidrag (refereegranskat)abstract
- The pine weevil (Hylobius abietis) is one of the most important forest pests in Europe, yet there is very littleknown about its detailed feeding behaviour. We study the temporal feeding pattern of individual pine weevils ofboth sexes for 24 hours with two treatments, intact and girdled seedlings. Properties of a meal, such as feedingduration, size and ingestion rate are of particular interest. The shortest interval considered to separate onefeeding bout from another, the meal criterion, has never been published and it is only available for a few otherinsect species. Video recordings are analysed for feeding behaviour (e.g. duration of feeding activity, intervallength between feeding activities, movements between and within feeding scars). We measured general activitypatterns as there is insufficient knowledge on the daily behavioural patterns. We thereby got an in-depth view ofthe pine weevil feeding activity that would otherwise be difficult to assess.
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| 10. |
- Fedderwitz, Frauke, et al.
(författare)
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The structure of feeding behavior in a phytophagous insect (Hylobius abietis)
- 2015
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Ingår i: Entomologia Experimentalis et Applicata. - 0013-8703 .- 1570-7458. ; 155, s. 229-239
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Tidskriftsartikel (refereegranskat)abstract
- Analysis of the feeding behavior of animals using such a high temporal resolution that meals can be defined may improve our understanding of the mechanisms regulating feeding. Meals can be distinguished in an ethologically meaningful manner by using the ‘meal criterion’, the shortest non-feeding interval between feeding bouts recognized as meals. However, such a criterion has only been determined for a few insect species. Applying a recent method developed for assessing meal criteria for vertebrates, we determined the meal criterion for Hylobius abietis (L.) (Coleoptera: Curculionidae) based on data from video recordings of single individuals feeding on seedlings of Norway spruce, Picea abies (L.) Karst. (Pinaceae). The pine weevil is an economically important pest insect because it feeds on the stem bark of planted conifer seedlings. Weevils had 4-5 meals per day. Each meal lasted about 24 min during which about 13 mm2 of bark per meal were removed. Females had longer total meal durations and longer non-feeding intervals within meals than males. Girdling seedlings did not affect the weevils’ feeding properties. The size of meals was significantly correlated to the duration of non-feeding intervals before and after them. This study is one of few describing the feeding behavior of an insect at a temporal resolution that allows individual meals to be distinguished. With more meal-related data from insects available, differences in meal properties may be interpreted based on phylogeny, ecology, and physiology. Our results may also assist in the setup and interpretation of studies of plant-insect interactions, and facilitate the evaluation and development of methods to protect plants against herbivores.
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