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Dissertation

Pine Weevil Feeding Behaviour in Relation to Conifer Plant Properties

01 Jan 2014-
TL;DR: 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.
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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References
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Journal ArticleDOI
TL;DR: Experimental induction of plant chemical defences with methyl jasmonate (MeJa) was effective against the pine weevil, as induced seedlings were 21% less damaged than control plants and resin concentration after weevil wounding was greater.
Abstract: Experimental induction of plant chemical defences with methyl jasmonate (MeJa) is a valuable tool for understanding the ecology of plant defensive responses. However, few studies have examined whether MeJa-induced defences in conifers are effective against insect herbivores. We studied, in 17 half-sib Pinus pinaster families, (i) the effect of MeJa application on plant growth and on the induction of diterpenoid resin in different sections of the stem; (ii) whether MeJa-induced defences increase the resistance of living pine juveniles against the large pine weevil Hylobius abietis in an in vivo bioassay and (iii) the induction of resin content after weevil wounding. Resin concentration was greater in the upper section of the stem compared with basal sections in both MeJa-induced and non-induced seedlings. Sixty days after MeJa application, treated plants showed 40% greater resin content all along the stem, but reduced height growth compared to control plants. MeJa-induction was effective against the pine weevil, as induced seedlings were 21% less damaged than control plants. Wounding activity by H. abietis produced a strong local defensive response after 48 h, where resin concentration was double that observed in the basal and apical sections not exposed to the insects.

53 citations


"Pine Weevil Feeding Behaviour in Re..." refers background in this paper

  • ..., 1991), although conifers can respond to damages within a few hours (Ralph et al., 2006; Sampedro et al., 2011)....

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  • ...In general, the application of MeJA reduced the feeding on the bark of conifer plants, but the efficiency of the treatment is plant species and concentration dependent (Moreira et al., 2009; Sampedro et al., 2011; Zas et al., 2014)....

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  • ...Additionally, the efficiency of treatments for plant protection has been tested (Heijari et al., 2005; Moreira et al., 2009; Sampedro et al., 2011; Paper III)....

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  • ...The effects of MeJA-induced defence in conifers on the damages caused by the pine weevil have been studied in several publications during the past years (e.g. Heijari et al., 2005; Sampedro et al., 2011; Zas et al., 2014)....

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Journal ArticleDOI
TL;DR: The types of naturally occurring antifeedant compounds identified in this study may become useful for the protection of planted conifer seedlings against damage by H. abietis.
Abstract: Egg-laying females of the pine weevil, Hylobius abietis (L.), regularly deposit feces adjacent to each egg. Egg cavities are gnawed in the bark of roots of recently dead conifer trees. After egg deposition, the cavity is sealed by feces and a plug of bark fragments. Root bark containing egg cavities with feces is avoided as food by pine weevils, which indicates the presence of natural antifeedants. Here we present the first results of the isolation and chemical analyses of antifeedant compounds in the feces of H. abietis. In feeding bioassays, methanol extracts of the feces revealed strong antifeedant properties. Methanol extracts were fractionated by medium-pressure liquid chromatography and the antifeedant effects were mainly found in the fractions of highest polarity. Volatile compounds in the active fractions were identified by gas chromatography-mass spectrometry (GC-MS) and the nonvolatile compounds were characterized by pyrolysis-GC-MS. Based on mass spectra, a number of compounds with various chemical structures were selected to be tested for their antifeedant properties. Antifeedant effects were found among compounds apparently originating from lignin: e.g., a methylanisol, guaiacol, veratrol, dihydroxybenzenes, and dihydroconiferyl alcohol. A weak effect by fatty acid derivatives was found. The types of naturally occurring antifeedant compounds identified in this study may become useful for the protection of planted conifer seedlings against damage by H. abietis.

53 citations

Journal ArticleDOI
TL;DR: Flies were usually relatively inactive following a meal, with the extent of this post‐prandial quiescence being a function both of meal size and concentration of sugar.
Abstract: . The pattern of feeding is described for males of the Australian sheep blowfly, Lucilia cuprina, with ad libitum access to either 0.1 M or 1.0 M glucose solution. Flies given the 0.1 M solution ingested nearly 3 times the volume taken by flies given the 1.0 M solution by eating meals of, on average, twice the size about 1.5 times as frequently. Flies were usually relatively inactive following a meal, with the extent of this post-prandial quiescence being a function both of meal size and concentration of sugar. Quiescence lasted only about 20% of the average intermeal interval, however, and there was no correlation between meal size and time to the next meal. The crop emptied more slowly when it contained 1.0 M rather than 0.1 M glucose solution and the crop was, on average, fuller at the beginning of a meal on the higher concentration. The volume of solution imbibed during a meal was positively correlated with time since the end of the preceding meal. The average crop volume at the end of a meal was similar in flies feeding on 0.1 M and 1.0 M solutions. The results are considered in relation to published information on control of feeding and compensation in the blowfly Phormia regina.

52 citations


"Pine Weevil Feeding Behaviour in Re..." refers background in this paper

  • ...Feeding rates are also variable for migratory locust, the first instar of the American bird grasshopper and the Australian sheep blowfly while their meal durations are constant; unless meals are very large (Simpson et al., 1988; Simpson et al., 1989; Chapman & Beerling, 1990)....

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  • ...There are relatively few previous studies on insects’ short-term feeding behaviour that use a meal criterion (Bowdan, 1988b; Simpson et al., 1988; 11 Simpson et al., 1989; Raubenheimer & Bernays, 1993; Bright et al., 1994; Mitchell & Low, 1994; Wright et al., 1999; Jones & Raubenheimer, 2002;…...

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  • ...In addition, females had a lower feeding rate on MeJA-induced plants (Paper III), which is either due to a slower food intake or an increase in the time spent in intrameal intervals (Simpson et al., 1989; Colasurdo et al., 2007)....

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  • ...Other insects have been shown to have either both a significant pre- and post-prandial correlation (Colorado potato beetle and migratory locust), a significant pre- but no post-prandial correlation (Australian sheep blowfly, tobacco hornworm caterpillar, American bird grasshopper) or a significant post- but no pre-prandial correlation (Costa Rican weevil) (Simpson, 1982; Reynolds et al., 1986; Simpson & Ludlow, 1986; Bowdan, 1988b; Bowdan, 1988a; Simpson et al., 1989; Chapman & Beerling, 1990; Mitchell & Low, 1994; Wright et al., 1999)....

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Journal ArticleDOI
TL;DR: Visual stimuli appear to be at least as important as odour for the pine weevil in finding an undamaged conifer seedling in the field.
Abstract: The influence of noncontact plant cues is investigated on the likelihood that individual conifer seedlings will be found by walking adults of the pine weevil, Hylobius abietis, in the field. Traps with solely odour or solely visual stimuli catch significantly more weevils than stimulus-free traps, and traps with the combination of odour and visual stimuli catch more weevils than traps with odour or visual stimuli alone. There is essentially an additive effect between odour and visual stimuli. The reactions to odour and visual stimuli are similar for three phases of the pine weevil's life cycle associated with three ages of clear-cuttings (i.e. sites where all trees have been harvested). Visual stimuli appear to be at least as important as odour for the pine weevil in finding an undamaged conifer seedling.

51 citations


"Pine Weevil Feeding Behaviour in Re..." refers background in this paper

  • ...On the other hand, the short time between girdling and weevil exposer chosen in the current study also represents the naturally occurring situation for plants established on clear cuts (Nordlander, 1991; Björklund et al., 2005)....

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  • ...Walking weevils take advantage of both visual and olfactory cues to locate conifer plants (Björklund et al., 2005)....

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Journal ArticleDOI
TL;DR: The novel methodology proposed here will avoid biased conclusions from analyses of feeding behavior associated with previous methods and can be applied across a range of species to address questions relevant to the control of food intake.
Abstract: Meals have long been considered relevant units of feeding behavior. Large data sets of feeding behavior of cattle, pigs, chickens, ducks, turkeys, dolphins, and rats were analyzed with the aims of ...

49 citations


"Pine Weevil Feeding Behaviour in Re..." refers background or methods in this paper

  • ...The shortest non-feeding interval considered to be between two meals is called meal criterion (Tolkamp et al., 2011)....

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  • ...This statistical approach has been developed in recent years and takes into consideration that feeding is not started at random (Tolkamp et al., 1998; Tolkamp et al., 2011)....

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  • ...Insect meal criteria have so far been determined based on log-survivorship or log-frequency analysis (e.g. Sibly et al., 1990; Mitchell & Low, 1994; Tolkamp et al., 1998; Tolkamp et al., 2011)....

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