Transcript 3 dis sess The effects of the biotic factors on plant

The effects of the Abiotic factors
on plant herbivory interactions
3rd Discussion session
Plant-Insect Interaction Course
• Herbivory: The consumption of
herbaceous vegetation
• Herbivores: An animal that feeds chiefly
on plants.
• Herbivorous: Feeding on plants; planteating.
• .Herbivorous - feeding only on plants
• Carnivorous - (used of plants as well as
animals) feeding on animals; "carnivorous
plants are capable of trapping and
digesting small animals especially insects“
• Insectivorous - (of animals and plants)
feeding on insects
• Omnivorous - feeding on both plants and
animals
• Plants are static organisms and cannot
escape the pressure caused by biotic and
abiotic factors. They must increase fitness
and prepare adequate responses to
external stimuli.
Plants talk, but are they deaf
Marcel Dicke et al.
Humans often consider plants to be passive
organisms, even though individual plants
display directed responses to resources
such as light and nutrients.
Plants ‘talk’
The emission of volatile chemicals has been
referred to as the ability of plants to ‘talk’, that is, to
emit information about their state of attack.
Rhoades, D.F. (1983) Responses of alder and willow to attack by tent
caterpillars and webworms: evidence for pheromonal sensitivity of
willows. In In Plant Resistance to Insects In American Chemical
Society Symposium Series 208, Washington, D.C., USA (Hedin, P.A.,
ed.), pp. 55–68
Baldwin, I.T. and Schultz, J.C. (1983) Rapid changes in tree leaf
chemistry induced by damage: evidence for communication between
plants. Science 221, 277–279
The effects of the Abiotic factors on
plant herbivory interactions
Abiotic Factors:Light
Temperature, frost/low temperature
Water- Water stress, water deficit
Nutrients
Topography – elevation
Relative humidity
Pollution
salinity,
wind
Plant Physiol. 2002 July; 129(3): 1296–1307.
The Effects of Abiotic Factors on Induced
Volatile Emissions in Corn Plants
by Sandrine
P. Gouinguené and Ted C.J.
Turlings
Institute of Zoology, Laboratory of Animal Ecology and
Entomology, University of Neuchâtel, Case Postale 2, CH–
2007 Neuchâtel, Switzerland
Sandrine et al finding
• Climatic conditions and nutrient availability
can be important factors in determining the
intensity and variability in the release of
induced plant volatiles.
Sandrine et al.
• Spodoptera littoralis Egyptian Cotton
• Leafworm
The host plant was corn
Soil Humidity
• Plants released more Volatiles when
standing in dry soil than in wet soil,
whereas for air humidity, the optimal
release was found at around 60% relative
humidity
Sandrine et al.
Soil Humidity
Caterpillar
(Spodoptera
littoralis) regurgitant
was either injected
into the stem or
applied to the
scratched leaves of
10-d-old plants
?
Sandrine et al
Air Humidity
• whereas for air humidity, the optimal
release was found at around 60% relative
humidity
Sandrine et al.
Air Humidity
Sandrine et al
Total amount (ng/3 h) of induced volatiles emitted by corn plants under
different air humidities. Circles represent the amount released by
induced corn plants and squares represent the odor released by
undamaged plants. Black curve represents the relation
Sandrine et al finding
• Temperatures between 22°C and 27°C led to a
higher emission than lower or higher
temperatures
• Light intensity had a dramatic effect. The
emission of volatiles did not occur in the dark
and increased steadily with an increase in the
light intensity.
• Fertilization also had a strong positive effect; the
emission of volatiles was minimal when plants
were grown under low nutrition
Temperature
Sandrine et al
• Total amount (mean + se) of odor emitted by corn plants under
different temperatures (°C). Black bars represent induced plants and
white bars represent undamaged plants. Stars indicate significant
differences between induced plants and undamaged plants (F =
35.148 and P < 0.001) and letters above black bars indicate
significant differences among the different temperature tested for
induced plants by Student-Newman-Keuls post hoc test (α = 0.05).
Light Intensity
Sandrine et al
• Light intensity had a dramatic effect (F =
19.174, P < 0.001, and df = 4), with an
increase in release of volatiles as light
intensity increased. Induced plants in the
dark emitted very little odor and their
releases were not different from the odor
of undamaged plants. No significant effect
of the light intensity was found for the
releases by undamaged plants (F = 0.755,
P = 0.577, and df = 4).
Light Intensity
Sandrine et al
• Total amount (mean + se) of volatiles emitted by
corn plants under different light intensities. Black
bars represent induced corn plants, and white
bars represent undamaged plants. Stars indicate
significant differences between the total amount
Light Cycle
Sandrine et al
Total amount (mean + se) of volatiles emitted by corn plants under
dark-light phases. Black bars represent induced corn plants, and
white bars represent undamaged plants. The horizontal bar
represents the respective dark and light phases.
Fertilization Rate
Sandrine et al
Sandrine et al
Fertilization Rate
Total amount (mean + se) of volatiles emitted by corn plants under
three different fertilization rates (see text for details). The graph in A
represents the amount without correction for biomass and the
graph in B represents the amount corrected for biomass.
END
Sandrine et al
• The magnitude and direction of this effect
was different for each factor considered.
Higher emission of induced volatiles
occurred when the soil was relatively dry,
the relative air humidity was between 45%
and 65%, the temperature between 22°C
and 27°C, with high light intensity, and with
continuous fertilization of the soil. In many
cases
Light
• Diurnal emissions have also been reported for induced volatiles.
Loughrin et al. (1994) showed that the induced emission of volatiles
in cotton (Gossypium hirsutum) plants (Malvaceae) was higher
during the afternoon and significantly decreased at night.
• Similar results were reported by Takabayashi et al. (1994), who
found that uninfested leaves of lima bean (Phaseolus lunatus;
Fabaceae) placed under high light intensity are more attractive to
predatory mites than when they are placed under low light
conditions, which was due to different volatiles emission under the
two light regimes.
• Maeda et al. (2000) reported the importance of light on the emission
of induced volatiles in kidney beans (Phaseolus vulgaris) plants
attacked by the spider mite (Tetranychus urticae). This
corresponded nicely with the responsiveness of predatory mites;
they were more active during light periods (Maeda et al., 2000).
Effects of Light on the Tritrophic Interaction Between Kidney Bean
Plants, Two-Spotted Spider Mites and Predatory Mites, Amblyseius
Womersleyi (Acari: Phytoseiidae) byTaro Maeda et al.
• The volatiles from Tetranychus urticaeinfested kidney bean plants (Phaseolus
vulgaris) at different times for two days,
they found that they were mainly produced
in the light. Tetranychus urticae showed a
higher oviposition rate and spent more
time feeding during the day (in the light)
Effects of Light on the Tritrophic Interaction Between Kidney Bean
Plants, Two-Spotted Spider Mites and Predatory Mites, Amblyseius
Womersleyi (Acari: Phytoseiidae) byTaro Maeda et al.
• Infested leaves placed in the light attracted the
predatory mite Amblyseius womersleyi
• Amblyseius womersleyi dispersed more
frequently and consumed more T. urticae eggs
during the day (in the light)
water stress
• Takabayashi et al. (1994) reported that
lima beans under water stress were more
attractive to spider mites. With chemical
analyses, they confirmed that lima bean
plants under water stress produce more of
the attractive volatiles than non-stressed
plants. Their study was done with
undamaged plants and they did not report
on any effect of water stress on the
emission of induced volatiles
Tetranychus urticae
• An experiment conducted by Hollingsworth
and Berry (1982) revealed that densities of
twospotted spider mites, Tetranychus
urticae, increased more rapidly on
peppermint plants that were under
moisture stress than on nonstressed
plants
Tetranychus urticae
• The greatest intensities of mites were observed
on plants that had been fertilized with a high
ratio of N to P and K. The researchers also
reported that the largest populations of spider
mites were associated with plants grown at
higher air temperatures. This observation
supports the earlier hypothesis of Simpson
and Connell (1973) that high temperatures may
be important for mite population expansion.
Tetranychus urticae
• moisture stress reduced both soybean
plant and total spider mite population
growth and apparently also reduced
intensity." This pattern is similar to the
trend observed with twospotted spider
mites on radish plants (Mellors and Propts
1983),
J. A. G OOLSBY et al
• CONTINENTAL COMPARISONS OF THE
INTERACTION BETWEEN CLIMATE AND THE
HERBIVOROUS MITE, FLORACARUS
PERREPAE (ACARI: ERIOPHYIDAE)
• J. A. G OOLSBY et al
leaf roll galling mite, Floracarus perrepae (ACARI:
ERIOPHYIDAE)
The Old World climbing fern, Lygodium microphyllum
Florida
J. A. G OOLSBY et al
J. A. G OOLSBY et al
• Within sites the mean maximum
temperature was the only significant
weather variable, showing a decrease in
the incidence of leaf rolls above 27°C, and
it was predicted that no leaf rolls would
form above 35°C.
J. A. G OOLSBY et al
• Mattson and Haack (1987) discuss several
hypotheses that may explain why drought
stress tends to promote outbreak of planteating arthropods. They listed the possible
outcomes of a drought that could influence
insect and plant interactions.
M. Gray et al
Although mites are not insects, we assume that phytophagous
mites respond to drought conditions similarly to plant-eating
insects, particularly those that have piercing and sucking
mouthparts.
1. Drought provides a more favorable thermal environment for growth
of phytophageous insects.
2. Drought-stressed plants are behaviorally more attractive or
acceptable for insects.
3. Drought-stressed plants are physiologically more suitable for
insects.
4. Drought enhances insect detoxification systems to some plant
allelochemicals.
5. Drought may not favor natural enemies of phytophagous insects.
6. Drought may induce genetic changes in insects.
Plant Stress Hypothesis (PSH)
• The plant stress hypothesis predicts that
environmental stresses on plants decrease plant
resistance to insect herbivory by altering
biochemical source–sink relationships and
foliar chemistry, leading to more palatable food.
Such changes in the nutritional landscape for
insects may facilitate insect population
outbreaks during periods of moderate stress on
host plants.
• Source-sink dynamics is a theoretical
model used by ecologists to describe how
variation in habitat quality may affect the
population growth or decline of organisms
Plant Stress Hypothesis (PSH)
• Traditionally, herbivorous insects are
thought to exhibit enhanced performance
and outbreak dynamics on water-stressed
host plants due to induced changes in
plant physiology. Recent experimental
studies, however, provide mixed support
for this historical view
Stress Hypotheses
• Three hypotheses predict how insect herbivores perform
on stressed host plants.
• The plant stress hypothesis (PSH) predicts improved
insect performance on stressed hosts.
• The plant vigour hypothesis (PVH) predicts that
insects closely associated with their host, such as gallformers, will perform better on vigorously growing nonstressed hosts.
• The Insect Performance Hypothesis (IPH) predicts
that wood-feeders, sap-feeders and miners will perform
better on stressed hosts, while leaf-feeders and gallformers will perform better on non-stressed hosts.
• Archer et al. (1995) reported that the
number of The Russian wheat aphid
(RWA's) on wheat plants that are not
irrigated was significantly higher than well
watered wheat plants.
Water stress
Water stress alters the plant and its thermal
environment so that plants become more
susceptible and suitable for insect growth, survival
and reproduction in many insect species, mainly
because: (1) plant nutrients are either more
concentrated or better balanced; (2) the plant
becomes more favorable thermal environment;
and (3) the plant has lower defenses (Mattson
and Haack, 1987b).
Pollution
The effects of environmental change on the
insect-plant interaction are currently the
subject of much investigation. Increasing
atmospheric carbon dioxide concentration,
and increasing availability of nitrogen due to
depositing of nitrogenous pollutants and
increased mineralization rates in warmer
climate, both have a potential to alert plant
nutritional quality and insect performance
EFFECTS OF HEAVY METAL POLLUTION
AND HOST PLANT LEAF CHEMISTRY
ON THE IMMUNE DEFENSE AND
LIFE HISTORY TRAITS OF
AN INSECT HERBIVORE
by
Tapio van Ooik
Turku 2008
Pollution Tapio van Ooik
Mountain birch (Betula pubescens.
czerepanovii) was the host tree
Autumnal moth, Epirrita autumnata
family Geometridae
Phenoloxidase (PO) activity to gain more
information about immune defense in E.
autumnata.
Pollution Tapio van Ooik
Even the pollution arising from the
factory complex at Harjavalta does not seem
to affect the moth very much. Pollution
decreases the growth of the larvae on Betula
pubescens leaves, but the moth seems to be able
to offset this by extending the time spent
consuming leaves before pupating.
Pollution Tapio van Ooik
The moderate amount of pollution at Harjavalta
enhances the moth’s immune defense, which
may actually benefit the moth: enhanced
immune defense helps it to defend itself
against parasites and diseases Thus, when
pollution increases the immune response in
insects, the parasitism rates of insects may
decrease in metal-polluted areas. This could
lead to another outbreak of the moth
Pollution Tapio van Ooik
• It is noteworthy that he found sex
differences in the immune function of the
autumnal moth. Heavy metal pollution
decreased PO activity in female moths,
but in males the activity increased.
Pollution Tapio van Ooik
Additionally, we found clear differences
between the sexes in their encapsulation
rate. The encapsulation rate of females was
higher in the heavy-metal treatment than in
the controls, while male immunity showed
no effect of treatment
Pollution Tapio van Ooik
This supports previous findings showing sex
differences in the effect of environmental and
genetic factors on immunity in E. autumnata
(Rantala and Roff, 2007). We suggest that this
is probably a result of sex differences in the
genetic architecture of the immune system
Pollution Tapio van Ooik
Pollution had also a large effect on the
chemistry of mountain birch leaves. E.g.,
heavy metals had among other things an
effect on the amount of phenolic
compounds. However, accumulation of
phenolics does not necessarily have an
adverse effect on the performance of
herbivores
Nature 05( 53 - 52 ,307 January 1984 ;)
Air pollution increases Aphis fabae pest
potential
G. P. Dohmen, S. McNeill & J. N. B. Bell
G. P. Dohmen
• We show here stimulatory effects of
SO2 and NO2 and ambient London air
on the growth of the black bean aphid,
Aphis fabae, and demonstrate that
these have been mediated entirely via
the host plant.
Effect of air pollution at a motorway on the
infestation of Viburnum opulus by Aphis fabae.
Bolsinger, M., Flückiger, W.
• The influence of air pollutants from cars on a motorway
on the population development of the aphid Aphis fabae
on potted Viburnum opulus was investigated in field
experiments in Switzerland.
• After 3 weeks, artificially infested shrubs at the
verge of the motorway were 5 times as infested
with aphids as those 300 m away from the road.
• Chambers receiving ambient air had 8 times as
many apterous aphids as those receiving filtered
air after 4 weeks.
Bolsinger, M., Flückiger, W.
• Chamber experiments at the verge with
filtered and unfiltered ambient air showed
similar results,
• Many observations have been made of
increased population densities of
herbivorous insects in areas subject to
air pollution