| 1. |
- Brown, Robert L., et al.
(författare)
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Attraction of the invasive social wasp, Vespula vulgaris, by volatiles from fermented brown sugar
- 2014
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Ingår i: Entomologia Experimentalis et Applicata. - : Wiley. - 0013-8703 .- 1570-7458. ; 151:2, s. 182-190
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Tidskriftsartikel (refereegranskat)abstract
- The introduction of invasive social wasp species of the genus Vespula (Hymenoptera: Vespidae) to New Zealand has caused a major ecological problem, particularly in the beech forests (Nothofagus spp.) of the South Island, where they have destabilized the native bird and invertebrate biodiversity. New attractants are under investigation as part of a search for pest management solutions. Fermenting brown sugar has been previously reported as a social wasp attractant. This work was undertaken to identify compounds from fermented brown sugar attractive to social wasps. Raw fermented brown sugar was confirmed to be attractive in a field trial and 10 chemical compounds present in the headspace were positively identified by coupled gas chromatography-mass spectrometry and synthetic references. During electroantennogram experiments, 3-methyl-1-butanol, 3-methylbutyl acetate, and ethyl hexanoate elicited high electrophysiological responses from Vespula vulgaris (L.) antennae. These compounds mediated attraction of V.vulgaris wasps in forest margins by trapping. A blend of these compounds could be used as a lure in a monitoring tool, or even a local suppression method if combined with a toxin.
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| 2. |
- Johansen, Aleksandra Irene, et al.
(författare)
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Motion level in Graphosoma lineatum coincides with ontogenetic change in defensive colouration
- 2011
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Ingår i: Entomologia Experimentalis et Applicata. - : Wiley. - 0013-8703 .- 1570-7458. ; 141:2, s. 163-167
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Tidskriftsartikel (refereegranskat)abstract
- Crypsis and aposematism are two different approaches to predation avoidance. Theoretically, the chosen strategy depends on the prevailing possibilities and constraints to the animal. Consequently, insects often change strategy between life stages, but a switch in strategy within a life stage is quite uncommon. In the Swedish shieldbug, Graphosoma lineatum L. (Heteroptera: Pentatomidae), there is a colour change from the pre-hibernating to the post-hibernating adults that alters their protective strategy from effective crypsis to aposematism, although both stages are distasteful to predators. The change in colour occurs as there is a shift of seasons, which alters the environmental background. Here, we investigate whether there is a change in behaviour in G. lineatum connected to the change in colouration and protective strategy. We therefore measured the motion levels in the two different colour forms of G. lineatum, both in the field and in a more controlled laboratory set up. Our result clearly shows that there is a change in behaviour connected to the change in colour. Thus, we found that the cryptic pre-hibernation form has a significantly lower motion level than the aposematic post-hibernation form, which is in line with the fact that motion disrupts crypsis, but not aposematism.
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| 3. |
- Lehrman, Anna, et al.
(författare)
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Estimating direct resistance in willows against a major insect pest, Phratora vulgatissima, by comparing life history traits
- 2012
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Ingår i: Entomologia Experimentalis et Applicata. - : Wiley. - 0013-8703 .- 1570-7458. ; 144, s. 93-100
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Tidskriftsartikel (refereegranskat)abstract
- Many Salix species (Salicaceae) have a high energy quotum and efficient nitrogen use, resulting in a high and stable biomass production, making these plants suitable as bioenergy crops. However, Salix coppices are sensitive to herbivory by chrysomelid beetles, such as Phratora vulgatissima L. (Coleoptera: Chrysomelidae), and to maintain high biomass yields over several years, durable plant resistance is necessary. We have developed a reliable and efficient bioassay that can be used as a tool for detection of resistance against P. vulgatissima in Salix. Screening of six clones of one susceptible (Salix viminalis L.) and one resistant (Salix dasyclados Wimm.) willow species, by the response of several life history traits of larval and adult P. vulgatissima, identified egg production as the most reliable trait for resistance. We show that a 2-week bioassay of oviposition rate is sufficient for a trustworthy estimation of both total egg production and survival of adult leaf beetles. In addition, to elucidate the variation in resistance among the studied clones, leaf concentrations of various phenolic compounds were compared with the key life history traits of the beetles. Phenolic compounds, especially salicylates, have previously been reported as the main factor controlling Salix resistance against P. vulgatissima. Indeed we found higher levels of salicylates in the resistant clones and larval performance was negatively correlated to the concentration of salicylates in the leaves. In addition, we found indications of negative effects of a luteolin derivative and quercetin-3-glucoside on leaf beetle performance, but further studies are needed to elucidate the specific roles that the different phenolic compounds play in plant resistance.
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| 4. |
- Midega, Charles A. O., et al.
(författare)
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Host plant selection behaviour of Chilo partellus and its implication for effectiveness of a trap crop
- 2011
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Ingår i: Entomologia Experimentalis et Applicata. - : Wiley. - 0013-8703 .- 1570-7458. ; 138:1, s. 40-47
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Tidskriftsartikel (refereegranskat)abstract
- Female lepidopterans can display a hierarchy of preference among potential host species, a trait thought to arise from the balance between attractants and deterrents to which the insects respond. Host plant ranking by moths and larvae of Chilo partellus Swinhoe (Lepidoptera: Crambidae), an important pest of cereals in Africa, was investigated, and whether eggs deposited on specific host plants yield larvae of particular host preferences. Trap plants are used in management of this pest. However, any 'disagreement' in host ranking between moths and larvae could potentially reduce effectiveness of trap crops as larvae emigrate to the main crop from the parent's preferred trap plant. We also investigated whether host plant preference is influenced by the diet upon which larvae fed as part of an integrated assessment of the relationship between host plant selection and learning in C. partellus. Five host plants (all Poaceae) were used: maize (Zea mays L.), sorghum (Sorghum bicolor Moench), Napier grass (Pennisetum purpureum Schumach), and two varieties of signal grass [Brachiaria brizantha (A. Rich.) Stapf], viz., local (henceforth signal grass) and improved ('Mulato'). In multiple choice tests, C. partellus female moths preferentially oviposited on Napier grass, followed by sorghum, maize, and signal grass, and least preferred 'Mulato'. Larvae however equally orientated and settled on leaf cuts of maize, sorghum, signal grass, and Napier grass, but least preferred 'Mulato'. Moreover, eggs from specific host plants did not yield larvae of particular host preferences. Furthermore, oviposition preference was not altered by the larval food. These results imply only a slight 'disagreement' in host ranking behaviour between moths and larvae, which is beneficial for trap cropping as larvae would not 'reject' the trap plant and appreciably disperse to the neighboring plants. Moreover, absence of larval learning behaviour indicates that regardless of the larval food C. partellus moths would still be attracted to the selected trap plant.
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| 5. |
- Puentes, Adriana, 1982-, et al.
(författare)
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Trichome production and variation in young plant resistance to the specialist insect herbivore Plutella xylostella among natural populations of Arabidopsis lyrata
- 2013
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Ingår i: Entomologia Experimentalis et Applicata. - : Wiley. - 0013-8703 .- 1570-7458. ; 149:2, s. 166-176
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Tidskriftsartikel (refereegranskat)abstract
- The strength of plant-herbivore interactions varies spatially and through plant ontogeny, which may result in variable selection on plant defenses against herbivory both among populations and among different life-history stages. The perennial herb Arabidopsis lyrata occurs in a trichome-producing and a glabrous morph, and previous work has shown that glabrous plants tend to receive more damage than trichome-producing plants. In this study, we quantified oviposition preference and larval feeding by P. xylostella on very young A. lyrata (5-6 weeks old), originating from twelve natural populations, six from Sweden and six from Norway. Six of the populations (three from each region) were polymorphic for trichome production and allowed a comparison of resistance against P. xylostella between the glabrous and the trichome-producing morph at a stage when trichome density is low in trichome-producing plants. There was considerable variation among populations in the number of eggs received and the proportion of leaf area consumed, but not between regions (Sweden and Norway) or trichome morphs. Rosette size explained a significant portion of the variation in oviposition and larval feeding. The results demonstrate that among-population variation in resistance to insect herbivory can also be detected among very young individuals of the perennial herb A. lyrata. They further suggest that trichome densities are too low at this developmental stage to contribute to resistance, and that the observed among-population variation in resistance is related to differences in other plant traits.
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| 6. |
- Schroeder, Martin
(författare)
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2-(Undecyloxy)-ethanol is a major component of the male-produced aggregation pheromone of Monochamus sutor
- 2013
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Ingår i: Entomologia Experimentalis et Applicata. - : Wiley. - 0013-8703 .- 1570-7458. ; 149, s. 118-127
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Tidskriftsartikel (refereegranskat)abstract
- The small white-marmorated longicorn beetle, Monochamus sutor (L.) (Coleoptera: Cerambycidae), is widely distributed throughout Europe and Asia. It is a potential vector of the pine wood nematode, Bursaphelenchus xylophilus (Steiner et Buhrer) Nickle, the causal agent of the devastating pine wilt disease. Volatiles were collected from both male and female beetles after maturation feeding. In analyses of these collections using gas chromatography (GC) coupled to mass spectrometry, a single male-specific compound was detected and identified as 2-(undecyloxy)-ethanol. In analyses by GC coupled to electroantennography the only consistent responses from both female and male antennae were to this compound. Trapping tests were carried out in Spain, Sweden, and China. 2-(Undecyloxy)-ethanol was attractive to both male and female M.sutor beetles. A blend of the bark beetle pheromones ipsenol, ipsdienol, and 2-methyl-3-buten-2-ol was also attractive to both sexes in Spain and Sweden, and further increased the attractiveness of the 2-(undecyloxy)-ethanol. The host plant volatiles -pinene, 3-carene, and ethanol were weakly attractive, if at all, in all three countries and did not significantly increase the attractiveness of the blend of 2-(undecyloxy)-ethanol and bark beetle pheromones. 2-(Undecyloxy)-ethanol is thus proposed to be the major, if not only, component of the male-produced aggregation pheromone of M.sutor, and its role is discussed. This compound has been reported as a pheromone of several other Monochamus species and is another example of the parsimony that seems to exist among the pheromones of many of the Cerambycidae. Traps baited with 2-(undecyloxy)-ethanol and bark beetle pheromones should be useful for monitoring and control of pine wilt disease, should M.sutor be proven to be a vector of the nematode.
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| 7. |
- Yahya, Asha
(författare)
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Cordeauxia edulis and Rhododendron tomentosum extracts disturb orientation and feeding behavior of Hylobius abietis and Phyllodecta laticollis
- 2011
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Ingår i: Entomologia Experimentalis et Applicata. - : Wiley. - 0013-8703 .- 1570-7458. ; 138, s. 162-174
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Tidskriftsartikel (refereegranskat)abstract
- The use of plant-based compounds to control insect pests is an alternative to the use of synthetic pesticides. We evaluated the repellent and antifeedant effects of Cordeauxia edulis Hemsley (Fabaceae) and Rhododendron tomentosum Harmaja (Ericaceae) extracts against Hylobius abietis L. (Coleoptera: Curculionidae) and Phyllodecta laticollis Suffrian (Coleoptera: Chrysomelidae). Repellent properties were evaluated by monitoring responses of adult insects toward the odor from extracts or extraction solvents (controls) in a Y-tube olfactometer, and choice or no-choice feeding tests were conducted by applying extracts or extraction solvents on stems of Scots pine [Pinus sylvestris L. (Pinaceae)] and European aspen [Populus tremula L. (Salicaceae)], host plants of H. abietis and P. laticollis, respectively. Extracts of R. tomentosum repelled adults of both insect species effectively. However, extracts of C. edulis did not repel H. abietis although its ethyl acetate extract showed repellence against the adults of P. laticollis. Feeding by H. abietis was significantly reduced by a methanol extract of C. edulis, and methanol and hexane extracts of R. tomentosum. Feeding by the adults and larvae of P. laticollis was significantly reduced by extracts from both plant species. Concomitant with less feeding, larval growth was retarded by ethyl acetate extracts of both plant species. Gas chromatography-mass spectrometry analyses of the volatile components of the extracts showed that extracts from both plant species were mixtures of various terpene and non-terpene compounds, which showed quantitative and/or qualitative variations between plant species and extraction solvents. This experiment showed that extracts from both plant species effectively manipulated the orientation and/or feeding behavior of the two beetle species. Hence, they may be considered as potential alternatives to synthetic chemical pesticides.
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| 8. |
- Öberg, Sandra, et al.
(författare)
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Pollen beetles are consumed by ground- and foliage-dwelling spiders in winter oilseed rape
- 2011
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Ingår i: Entomologia Experimentalis et Applicata. - : Wiley. - 0013-8703 .- 1570-7458. ; 138, s. 256-262
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Tidskriftsartikel (refereegranskat)abstract
- Pollen beetles, Meligethes aeneus (Fabricius) (Coleoptera: Nitidulidae), are major pests in oilseed rape (OSR), Brassica napus L. (Brassicaceae). Among the predator species in the generalist predator complex present in OSR fields, wolf spiders (Araneae: Lycosidae) are found on the ground and cobweb spiders (Araneae: Theridiidae) build webs in the foliage. Here we study the incidence of predation of pollen beetles by these two spider groups using DNA-based molecular analysis. Wolf spiders of the genus Pardosa and the cobweb spider, Theridion impressum L. Koch, were each collected in three winter OSR fields over a period of about 3 weeks. Pollen beetle densities as well as the occurrence of predators and alternative prey were monitored. In total, 13.8% of the collected Pardosa spp. tested positive for pollen beetle DNA in the PCR analyses, whereas 51.7% T. impressum were positive. The likelihood of detecting pollen beetle DNA in the gut contents of both spider groups was positively related to pollen beetle larval density. The implications of these results for conservation biological control and future studies of food webs in OSR are discussed.
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