22705
2018
eng
e4369, 1-16
6
article
1
2021-02-24
--
--
Ants contribute to pollination but not to reproduction in a rare calcareous grassland forb
The number of plants pollinated by ants is surprisingly low given the abundance of ants and the fact that they are common visitors of angiosperms. Generally ants are considered as nectar robbers that do not provide pollination service. We studied the pollination system of the endangered dry grassland forb Euphorbia seguieriana and found two ant species to be the most frequent visitors of its flowers. Workers of Formica cunicularia carried five times more pollen than smaller Tapinoma erraticum individuals, but significantly more viable pollen was recovered from the latter. Overall, the viability of pollen on ant cuticles was significantly lower (p < 0.001)-presumably an antibiotic effect of the metapleural gland secretion. A marking experiment suggested that ants were unlikely to facilitate outcrossing as workers repeatedly returned to the same individual plant. In open pollinated plants and when access was given exclusively to flying insects, fruit set was nearly 100%. In plants visited by ants only, roughly one third of flowers set fruit, and almost none set fruit when all insects were excluded. The germination rate of seeds from flowers pollinated by flying insects was 31 +/- 7% in contrast to 1 +/- 1% resulting from ant pollination. We conclude that inbreeding depression may be responsible for the very low germination rate in ant pollinated flowers and that ants, although the most frequent visitors, play a negligible or even deleterious role in the reproduction of E. seguieriana. Our study reiterates the need to investigate plant fitness effects beyond seed set in order to confirm ant-plant mutualisms.
PeerJ
10.7717/peerj.4369
urn:nbn:de:bvb:20-opus-227053
publish
PeerJ 6:e4369 (2018)
true
true
CC BY: Creative-Commons-Lizenz: Namensnennung 4.0 International
Michael Rostás
Felix Bollmann
David Saville
Michael Riedel
eng
uncontrolled
Ants
eng
uncontrolled
Breeding system
eng
uncontrolled
Geitonogamy
eng
uncontrolled
Germination
eng
uncontrolled
Inbreeding depression
eng
uncontrolled
Metapleural gland
eng
uncontrolled
Siberian spurge
eng
uncontrolled
Foraging behaviour
deu
uncontrolled
Pollen
eng
uncontrolled
Ecology
eng
uncontrolled
Entomology
Biowissenschaften; Biologie
open_access
Julius-von-Sachs-Institut für Biowissenschaften
Universität Würzburg
https://opus.bibliothek.uni-wuerzburg.de/files/22705/Ants_contribute_to_pollination.pdf
17132
2016
eng
7813–7823
12
16
article
1
2018-11-06
--
--
Role of needle surface waxes in dynamic exchange of mono- and sesquiterpenes
Biogenic volatile organic compounds (BVOCs) produced by plants have a major role in atmospheric chemistry. The different physicochemical properties of BVOCs affect their transport within and out of the plant as well as their reactions along the way. Some of these compounds may accumulate in or on the waxy surface layer of conifer needles and participate in chemical reactions on or near the foliage surface. The aim of this work was to determine whether terpenes, a key category of BVOCs produced by trees, can be found on the epicuticles of Scots pine (Pinus sylvestris L.) and, if so, how they compare with the terpenes found in shoot emissions of the same tree. We measured shoot-level emissions of pine seedlings at a remote outdoor location in central Finland and subsequently analysed the needle surface waxes for the same compounds. Both emissions and wax extracts were clearly dominated by monoterpenes, but the proportion of sesquiterpenes was higher in the wax extracts. There were also differences in the terpene spectra of the emissions and the wax extracts. The results, therefore, support the existence of BVOC associated to the epicuticular waxes. We briefly discuss the different pathways for terpenes to reach the needle surfaces and the implications for air chemistry.
Atmospheric Chemistry and Physics
10.5194/acp-2015-1024
urn:nbn:de:bvb:20-opus-171324
Atmospheric Chemistry and Physics 16:12, 7813–7823, 2016. DOI: 10.5194/acp-16-7813-2016
false
true
Johanna Joensuu
Nuria Altimir
Hannele Hakola
Michael Rostás
Maarit Raivonen
Mika Vestenius
Hermanni Aaltonen
Markus Riederer
Jaana Bäck
eng
uncontrolled
needle surface waxes
eng
uncontrolled
biogenic volatile organic compounds
eng
uncontrolled
Pinus sylvestris L.
eng
uncontrolled
atmospheric chemistry
Biowissenschaften; Biologie
open_access
Julius-von-Sachs-Institut für Biowissenschaften
Universität Würzburg
https://opus.bibliothek.uni-wuerzburg.de/files/17132/Joensuu_Atmospheric_Chemistry_and_Physics.pdf
3748
2009
eng
article
Deutsche Forschungsgemeinschaft, SFB 567 TP B9
1
2010-03-05
--
--
Insects had it first: surfactants as a defence against predators
Insects have evolved an astonishing array of defences to ward off enemies. Well-known and widespread is the regurgitation of oral secretions (OS), fluids that repel attacking predators. In herbivores, the effectiveness of OS has been ascribed so far to the presence of deterrent secondary metabolites sequestered from the host plant. This notion implies, however, that generalists experience less protection on plants with low amounts of secondary metabolites or with compounds ineffective against potential enemies. Resolving the dilemma, we describe a novel defence mechanism that is independent of deterrents as it relies on the OS’ intrinsic detergent properties. The OS of Spodoptera exigua (and other species) was found to be highly amphiphilic and well capable of wetting the hydrophobic cuticle of predatory ants. As a result, affected ants stopped attacking and engaged in extensive cleansing. The presence of surfactants was sufficient to explain the defensive character of herbivore OS. We hypothesize that detergency is a common but unrecognised mode of defence which provides a base level of protection that may or may not be further enhanced by plant-derived deterrents. Our study also proves that insects ‘invented’ the use of defensive surfactants long before modern agriculture had started applying them as insecticides.
urn:nbn:de:bvb:20-opus-35031
3503
In: Proceedings of the Royal Society B, 276, 633-638. - DOI: 10.1098/rspb.2008.1281
Michael Rostás
Katrin Blassmann
deu
swd
Pflanzenfressende Insekten
deu
swd
Grenzflächenaktiver Stoff
deu
swd
Ameisen
deu
swd
Zuckerrübeneule
deu
uncontrolled
Abwehr
deu
uncontrolled
Oralsekret
eng
uncontrolled
anti-predator defence
eng
uncontrolled
caterpillars
eng
uncontrolled
regurgitation
eng
uncontrolled
secondary metabolites
eng
uncontrolled
biosurfactants
Tiere (Zoologie)
open_access
Julius-von-Sachs-Institut für Biowissenschaften
Universität Würzburg
https://opus.bibliothek.uni-wuerzburg.de/files/3748/Rostas_Insects_had_it_first_OPUS3503.pdf
12868
2013
eng
193
13
article
1
2016-03-04
--
--
Gall volatiles defend aphids against a browsing mammal
Background: Plants have evolved an astonishing array of survival strategies. To defend against insects, for example, damaged plants emit volatile organic compounds that attract the herbivore’s natural enemies. So far, plant volatile responses have been studied extensively in conjunction with leaf chewing and sap sucking insects, yet little is known about the relationship between plant volatiles and gall-inducers, the most sophisticated herbivores. Here we describe a new role for volatiles as gall-insects were found to benefit from this plant defence.
Results: Chemical analyses of galls triggered by the gregarious aphid Slavum wertheimae on wild pistachio trees showed that these structures contained and emitted considerably higher quantities of plant terpenes than neighbouring leaves and fruits. Behavioural assays using goats as a generalist herbivore confirmed that the accumulated terpenes acted as olfactory signals and feeding deterrents, thus enabling the gall-inducers to escape from inadvertent predation by mammals.
Conclusions: Increased emission of plant volatiles in response to insect activity is commonly looked upon as a “cry for help” by the plant to attract the insect’s natural enemies. In contrast, we show that such volatiles can serve as a first line of insect defences that extends the ‘extended phenotype’ represented by galls, beyond physical boundaries. Our data support the Enemy hypothesis insofar that high levels of gall secondary metabolites confer protection against natural enemies.
BMC Evolutionary Biology
10.1186/1471-2148-13-193
urn:nbn:de:bvb:20-opus-128687
BMC Evolutionary Biology 2013, 13:193. doi:10.1186/1471-2148-13-193
Michael Rostás
Daniel Maag
Makihiko Ikegami
Moshe Inbar
eng
uncontrolled
capra hircus
eng
uncontrolled
enemy hypothesis
eng
uncontrolled
extended phenotype
eng
uncontrolled
herbivory
eng
uncontrolled
intraguild predation
eng
uncontrolled
plant defence
eng
uncontrolled
tannins
eng
uncontrolled
terpenes
eng
uncontrolled
volatile organic compounds
Genetik und Evolution
open_access
Julius-von-Sachs-Institut für Biowissenschaften
Universität Würzburg
https://opus.bibliothek.uni-wuerzburg.de/files/12868/012_Rostas_Gall_volatiles.pdf
2320
2008
eng
article
1
2008-04-17
--
--
Ontogenetic and spatio-temporal patterns of induced volatiles in Glycine max in the light of the optimal defence hypothesis
Plants attacked by herbivorous insects emit a blend of volatile compounds that serve as important host location cues for parasitoid wasps. Variability in the released blend may exist on the whole-plant and within-plant level and can affect the foraging efficiency of parasitoids. We comprehensively assessed the kinetics of herbivore-induced volatiles in soybean in the context of growth stage, plant organ, leaf age, and direction of signal transport. The observed patterns were used to test the predictions of the optimal defence hypothesis (OD). We found that plants in the vegetative stage emitted 10-fold more volatiles per biomass than reproductive plants and young leaves emitted >2.6 times more volatiles than old leaves. Systemic induction in single leaves was stronger and faster by one day in acropetal than in basipetal direction while no systemic induction was found in pods. Herbivore-damaged leaves had a 200-fold higher release rate than pods. To some extent these findings support the OD: i) indirect defence levels were increased in response to herbivory and ii) young leaves, which are more valuable, emitted more volatiles. However, the fact that reproductive structures emitted no constitutive or very few inducible volatiles is in seeming contrast to the OD predictions. We argue that in case of volatile emission the OD can only partially explain the patterns of defence allocation due to the peculiarity that volatiles act as signals not as toxins or repellents.
urn:nbn:de:bvb:20-opus-26991
2699
Chemoecology (2008) 18:29-38
Michael Rostás
Katharina Eggert
deu
swd
Chemische Ökologie
deu
swd
Pflanzeninhaltsstoff
deu
swd
Verteidigung
deu
swd
Pflanzenfressende Insekten
deu
uncontrolled
Indirekte Abwehr
deu
uncontrolled
Sojabohne
deu
uncontrolled
Spodoptera frugiperda
deu
uncontrolled
Tritrophische Interaktionen
eng
uncontrolled
indirect plant defence
eng
uncontrolled
soybean
eng
uncontrolled
Spodoptera frugiperda
eng
uncontrolled
tritrophic interactions
Biowissenschaften; Biologie
open_access
Julius-von-Sachs-Institut für Biowissenschaften
Universität Würzburg
https://opus.bibliothek.uni-wuerzburg.de/files/2320/Rostas_Chemoek08r.pdf
2829
2007
eng
article
Deutsche Forschungsgemeinschaft, SFB 567 TP B9
1
2009-03-31
--
--
The effects of 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one on two species of Spodoptera and the growth of Setosphaeria turcica in vitro
Maize seedlings contain high amounts of glucosidically bound 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA). The effects of DIMBOA on the feeding behaviour and performance of two noctuids, Spodoptera exigua Hübner and S. frugiperda Smith, were compared. The question was raised whether S. frugiperda, preferring maize and other Poaceae, is better adapted to DIMBOA than S. exigua. In addition, the effects of DIMBOA on the mycelial growth of the plant pathogen Setosphaeria turcica Leonard et Suggs (causal agent of northern corn leaf blight) was assessed in vitro. DIMBOA had an antifeedant effect on S. exigua but stimulated feeding in S. frugiperda in dual-choice experiments. In a no-choice setup, larvae of S. exigua gained less biomass and had a prolonged development when feeding on an artificial diet containing DIMBOA. However, pupal weight was not significantly different between treatments. In contrast, larvae of S. frugiperda were not affected by DIMBOA. Strong detrimental effects of DIMBOA were found on the mycelial growth of the pathogen S. turcica.
urn:nbn:de:bvb:20-opus-35079
3507
Journal of Pest Science (2007) 80, 35-41
Michael Rostás
deu
swd
Eulen <Schmetterlinge>
deu
swd
Pilzbefall
deu
swd
Mais
deu
uncontrolled
DIMBOA
deu
uncontrolled
Abwehr
eng
uncontrolled
DIMBOA
eng
uncontrolled
Performance
eng
uncontrolled
Spodoptera
eng
uncontrolled
Fungus
eng
uncontrolled
Zea mays
Biowissenschaften; Biologie
open_access
Julius-von-Sachs-Institut für Biowissenschaften
Universität Würzburg
https://opus.bibliothek.uni-wuerzburg.de/files/2829/Rostas_J_Pest_Sci_Open_Access.pdf
2501
2008
eng
other
Michael Rostás
1
2008-10-17
--
--
Plant surface wax affects parasitoid's response to host footprints
The plant surface is the substrate upon which herbivorous insects and natural enemies meet and thus represents the stage for interactions between the three trophic levels. Plant surfaces are covered by an epicuticular wax layer which is highly variable depending on species, cultivar or plant part. Differences in wax chemistry may modulate ecological interactions. We explored whether caterpillars of Spodoptera frugiperda, when walking over a plant surface, leave a chemical trail (kairomones) that can be detected by the parasitoid Cotesia marginiventris. Chemistry and micromorphology of cuticular waxes of two barley eceriferum wax mutants (cer-za.126, cer-yp.949) and wild type cv. Bonus (wt) were assessed. The plants were then used to investigate potential surface effects on the detectability of caterpillar kairomones. Here we provide evidence that C. marginiventris responds to chemical footprints of its host. Parasitoids were able to detect the kairomone on wild type plants and on both cer mutants but the response to cer-yp.949 (reduced wax, high aldehyde fraction) was less pronounced. Experiments with caterpillar-treated wt and mutant leaves offered simultaneously, confirmed this observation: no difference in wasp response was found when wt was tested against cer-za.126 (reduced wax, wt-like chemical composition) but wt was significantly more attractive than cer-yp.949. This demonstrates for the first time that the wax layer can modulate the detectability of host kairomones.
urn:nbn:de:bvb:20-opus-29201
2920
Naturwissenschaften
Michael Rostás
Daniel Ruf
Vanessa Zabka
Ulrich Hildebrandt
deu
swd
Brackwespen
deu
swd
Wirtsfindung
deu
swd
Gerste
deu
swd
Mutante
deu
swd
Pflanzenwachs
Biowissenschaften; Biologie
open_access
Julius-von-Sachs-Institut für Biowissenschaften
Universität Würzburg
https://opus.bibliothek.uni-wuerzburg.de/files/2501/Rostas_et_al._2008_Naturwissenschaften_Postprint.pdf
19854
2016
2016
eng
7813-7823
16
article
1
--
--
--
Role of needle surface waxes in dynamic exchange of mono- and sesquiterpenes
Biogenic volatile organic compounds (BVOCs) produced by plants have a major role in atmospheric chemistry. The different physicochemical properties of BVOCs affect their transport within and out of the plant as well as their reactions along the way. Some of these compounds may accumulate in or on the waxy surface layer of conifer needles and participate in chemical reactions on or near the foliage surface. The aim of this work was to determine whether terpenes, a key category of BVOCs produced by trees, can be found on the epicuticles of Scots pine (Pinus sylvestris L.) and, if so, how they compare with the terpenes found in shoot emissions of the same tree. We measured shoot-level emissions of pine seedlings at a remote outdoor location in central Finland and subsequently analysed the needle surface waxes for the same compounds. Both emissions and wax extracts were clearly dominated by monoterpenes, but the proportion of sesquiterpenes was higher in the wax extracts. There were also differences in the terpene spectra of the emissions and the wax extracts. The results, therefore, support the existence of BVOC associated to the epicuticular waxes. We briefly discuss the different pathways for terpenes to reach the needle surfaces and the implications for air chemistry.
Atmospheric Chemistry and Physics
10.5194/acp-16-7813-2016
urn:nbn:de:bvb:20-opus-198547
Atmos. Chem. Phys., 16, 7813–7823, 2016
CC BY: Creative-Commons-Lizenz: Namensnennung 4.0 International
Johanna Joensuu
Nuria Altimir
Hannele Hakola
Michael Rostás
Maarit Raivonen
Mika Vestenius
Hermanni Aaltonen
Markus Riederer
Jaana Bäck
eng
uncontrolled
Biogenic
eng
uncontrolled
volatile
eng
uncontrolled
organic
eng
uncontrolled
compounds
Biowissenschaften; Biologie
open_access
Julius-von-Sachs-Institut für Biowissenschaften
https://opus.bibliothek.uni-wuerzburg.de/files/19854/009_Joensuu_ATMOSPHERIC-CHEMISTRY-AND-PHYSICS.pdf