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Transcript
Herbivores offense
Vasakorn Bullangpoti, Ph.D.
Email: [email protected]
Contents
 BEHAVIORAL MECHANISM – LEAST AGGRESSIVE
 Feeding choice
 Oviposition choice
 PHYSIOLOGICAL AND MORPHOLOGICAL TRAITS –
sometime aggressive
 Enzymes
 Sequestering Host Chemicals
 Morphological Adaptations
 Symbionts
 Herbivores Manipulate their host- Aggressive
 Gall and Induced Plant susceptibility
 Trenching, Mowing, Haying and Gardening
 Gregarious Feeding
BEHAVIORAL MECHANISM –
LEAST AGGRESSIVE
Feeding choice
 Self-selection of food is likely to be more
important for herbivores that are more mobile
and can gain access to varied diets.
 When herbivores fail to make appropriate
decision, these “mistake” tend to
conservative. Such that herbivores reject food
that are actually nutritious to them
http://www.treesaregood.org/treecare/insect_disease.aspx
BEHAVIORAL MECHANISM –
LEAST AGGRESSIVE
 Cannibalism and predation on other herbivores is
associated with nutritional benefits and is more
likely when plant foods are scarce or less
nutritious.
Three Mormon crickets eating a fourth Mormon cricket
Behavioral adaptations
Selectively in space and time or season
 winter moth, feeding on oak leaves early in the season maximized the
amount of protein and nutrients available to the moth, while minimizing the
amount of tannins produced by the tree
Herbivores can also spatially avoid plant defenses.
 The piercing mouthparts of species in Hemiptera allow them to feed around
areas of high toxin concentration.
 Several species of caterpillar feed on maple leaves by "window feeding" on
pieces of leaf and avoiding the tough areas, or those with a high lignin
concentration.
 Similarly, the cotton leaf perforator selectively avoids eating the epidermis
and pigment glands of their hosts, which contain defensive terpenoid
aldehydes.
http://www.infonet-biovision.org/res/res/files/970.400x400.jpeg
Trichoplusia caterpillars
http://www.flickr.com/photos/[email protected]/2148457971/
Behavioral adaptations
Some animals ingest large amounts of poisons in their food, but
then eat clay or other minerals, which neutralize the poisons. This
behavior is known as geophagy.
Behavioral adaptations
Plant defense may explain, in part, why herbivores employ
different life history strategies.
 Monophagous species (animals that eat plants from a single genus)
must produce specialized enzymes to detoxify their food, or
develop specialized structures to deal with sequestered chemicals.
 Polyphagous species (animals that eat plants from many different
families), on the other hand, produce more detoxifying enzymes
(specifically MFO) to deal with a range of plant chemical defenses.
BEHAVIORAL MECHANISM –
LEAST AGGRESSIVE
Oviposition choice
 Many herbivorous insects cannot move much
during the course of their development.
According to the prevailing paradigm, mobile
ovipositing female assess different host plant
species and place their eggs or offspring on
those host that result in the highest
performance.
 More than half of the recent literatures
supported this positive correlation between
adult oviposition and offspring performance
BEHAVIORAL MECHANISM –
LEAST AGGRESSIVE
Oviposition choice
 The correlation between mean oviposition
preference and survival and growth of larvae
averaged across many females in an
herbivore population.
 Herbivores may select host plants that
provide poor growth but good protection from
their own natural enemies
BEHAVIORAL MECHANISM –
LEAST AGGRESSIVE
Oviposition choice
 One recent study, the correlation between
adult choice and performance of offspring.
 The future field studies of the preferenceperformance correlation should consider adult
performance as distinct from offspring
performance.
 EX: Dr.Kainoh’s lab
WIND TUNNEL
PHYSIOLOGICAL AND
MORPHOLOGICAL TRAITS
– sometime aggressive-
Teeth Structures
Insect mouthparts
The development of
insect mouthparts
from the primitive
chewing mouthparts
of a grasshopper in
the centre (A), to the
lapping type (B) and
the siphoning type
(C). Legend: a,
antennae; c,
compound eye; lb,
labium; lr, labrum;
md, mandibles; mx,
maxillae.
Labrum
Mandible
Siphoning Insects
Stylet
Proboscis
Figure female soapberry bugs from Florida in a 100 year period
http://www.fiu.edu/~biology/class_sites/pcb4674/CH2-EVIDENCE-SPRING-2008/CHAPTER2_SPR_2008.HTML
Morphological adaptation
Many other herbivores traits besides
mouthparts can be important and
offensive.
Bruchid seed beetles, female adjust
egg size and probably other traits in
response to particular host plant.
 On host with hard seeds, fitness is maximized
by laying large eggs whereas on hosts with
softer seeds, fitness is higher when females
lays more, but smaller, eggs (Fox et al, 1997)
PHYSIOLOGICAL AND
MORPHOLOGICAL TRAITS
– sometime aggressive-
ENZYME
Enzymes
 Detoxification
enzyme system
 Proteinase
Inhibitors
 Salivary
enzymes
Detoxification Enzyme system
XENOBIOTICS
Highly Lipophilic
Lipophilic
Polar
Accumulation
in fat body
Polar
Phase II
Conjugation
Phase I
Oxidation, reduction, Hydrolysis)
Hydrophilic
Excretion
Hydrophilic
Phase I reaction
 Includes oxidative, reductive and hydrolytic
reactions.
 In these type of reactions, a polar group is
either introduced or unmasked, so the drug
molecule becomes more water-soluble and
can be excreted.
Esterase
 A type: arylesterase
 that are not inhibited by
organophosphate.
 B type: alliesterase,
carboxylesterase
and cholinesterase
 There are inhibited by
organophosphate due to
irreversible phosphorylation
of the active serine site
Carboxylesterase
mechanism
Paranitrophenylacetate (pNPA) -------> paranitrophenol
O
O
NH - C
C2H5
0=C
NH - C
C2H5
0=C
NH - C
NH - C
O
O
Phenobarbitone
p- hydroxyphenobarbitone
NO2
NO2
OP (OC2H5)2
OP (OC2H5)2
S
O
Parathion
OH
Paraoxon
P450 enzymes
Cytochrome P450 (abbreviated CYP, P450,
infrequently CYP450) is a very large and
diverse superfamily of hemoproteins found
in all domains of life.
Usually they form part of multicomponent
electron transfer chains, called P450containing systems.
P450 enzymes
One of very important enzyme
http://www.uky.edu/Pharmacy/ps/porter/CPR_partners.gif
P450 enzymes
The most common reaction catalysed
by cytochrome P450 is a
monooxygenase reaction
Phase II reaction
 These reactions involve covalent attachment of small
polar endogenous molecule such as glucuronic acid,
sulfate, or glycine to form water-soluble compounds.
 This is also known as a conjugation reaction.
 The final compounds have a larger molecular weight.
Process
in vivo reactant
Product
UDP-alpha-D-glucuronate
Glucuronide (X = O, N,
or S)
Glucuronide
formation
Glutathione
conjugation
Mercapturic acid
glutathione (Glu, Cys, Gly)
Sulfate conjugation
PAPS = Adenosine-3'-P-5'Phosphosulfate
Aryl or alkyl sulfates
and sulfamates
Glutathione-s-transferase
 Enzymes of the glutathione Stransferase (GST) family are
composed of many cytosolic,
mitochondrial, and microsomal
proteins.
 GSTs catalyse a variety of reactions
and accept endogenous and
xenobiotic substrates.
 They are members of Membrane
Associated Proteins in Eicosanoid
and Glutathione metabolism family
of transmembrane proteins.
XENOBIOTICS
Highly Lipophilic
Lipophilic
Polar
Accumulation
in fat body
Polar
Phase II
Conjugation
Phase I
Oxidation, reduction, Hydrolysis)
Hydrophilic
Excretion
Hydrophilic
Excretion of Toxins
Toxins leave the body
through:
Kidney (Urine)
Feces
Lungs (e.g., mucus,
breathing out)
Proteinase inhibitor
 Plant also contain antinutritive compounds that
make essential constituents unavailable for
digestion by herbivores.
 Inhibit the action of digestive protease enzymes
in herbivores and thus make protein unavailable
 However, careful work have reveled that although
proteinase inhibitors effectively reduced the
function of particular protease in the gut of six
lepidopteran species, corresponding reduction in
catepillar growth were minimal (Broadway,
1995,1997)
http://www.ysbl.york.ac.uk/~proteinase/
Salivary enzymes
Herbivores also produce salivary enzymes
constitutively, prior to ingestion, that
minimize the effectiveness of plant
defenses.
Such enzymes are applied to leaf wounds
as the herbivores chew and these may
reduce the activation of induced defense
in plants.
Salivary enzmes
 Glucose oxidase is a major constituent of
caterpillar saliva that appears to suppress early
signaling events in plant defense (Felton and
Eichenseer, 1999)
 Glucose oxidase inhibits lipooxygenase activity, a
critical step in the biosynthesis of the induction
signal and thereby reduces induced resistance in
plants
 Caterpillars that were inhibited from producing
glucose oxidase fed less and grew les, indicated
that offense had been block (Musser et al, 2002)
Salivary enzymes
Other herbivores may also secrete saliva
that interferes with plant defense.
Salivary constituent from grasshoppers
have been implicated in enhanced growth
of plant
In this case, the offensive strategy may be
to stimulate plant growth. However, to the
individual herbivores has not been
demonstrated in this sample.
PHYSIOLOGICAL AND
MORPHOLOGICAL TRAITS
– sometime aggressive-
Herbivores that specialize on particular
host plant often have very specific
enzymatic systems that allow them
metabolize the secondary chemicals of
those hosts.
PHYSIOLOGICAL AND
MORPHOLOGICAL TRAITS
– sometime aggressiveSequestering host chemicals
 Many herbivored incorpate or sequester the
biologically active chemicals of their host
plants into their own tissues or glands, and
thereby gain protection from their predators
and parasites (Duffey, 1980)
Sequestering host chemicals
(Kargan & Agrawal, 2002)
The herbivore must willing to ingest the host’s
secondary chemicals
The herbivores must be relatively tolerant of
the chemicals
The herbivores must ingest the chemicals
without metabolizing them into biologically
inactive products
The herbivores must deposit the secondary
chemicals in particular tissues, or otherwise
store them.
Interactions between plant, herbivorous
insects and carnivores
http://www.biozentrum.uni-wuerzburg.de/fileadmin/REPORT/BOT2/bot2004.htm
Sequestering host chemicals
 Decorator crabs sequester protective chemicals behaviorally
by attaching noxious plants to the outsides of their bodies
and thereby reduce their risk of predation (Stachowicz and
Hay, 1999)
http://www-eve.ucdavis.edu/stachowicz/decorator.shtml
Sequestering host chemicals
(Kargan & Agrawal, 2002)
 Sequestration may be relatively expensive as an offense
strategy.
 Although the strategy allows herbivores to save costs
associated with synthesis of defensive chemicals, it often
requires specialized structures to separate, selectively
uptake, and/or modify plant compounds Bower,1992)
 Common sense suggest that sequestration may require a
very specialized diet.
Microbial symbionts
 Herbivores are unable to digest complex cellulose and rely
on mutualistic, internal symbiotic bacteria, fungi, or
protozoa to break down cellulose so it can be used by the
herbivore. Microbial symbionts also allow herbivores to eat
plants that would otherwise be inedible by detoxifying plant
secondary metabolites.
Microbial symbionts
 For example, fungal symbionts of cigarette beetles
(Lasioderma serricorne) use certain plant allelochemicals as
their source of carbon, in addition to producing
detoxification enzymes (esterases) to get rid of other
toxins.
 Thus, Symbionts may increase feeding and exploitation of
plants by herbivores by providing nutrients, digestion and
detoxification.
Microbial symbionts
 More aggressive strategies involve inoculating hosts with
microbes that mobilized nutrients or diminish plant
defenses.
 Herbivores that vector plant diseases (Thrips, beetle, mite,
Homopterans) may manipulate plants to their won benefits
through infection.
Microbial symbionts
 bark beetle introduce blue stain fungi of the genera and
into trees before feeding. The blue stain fungi cause lesions
that reduce the trees’ defensive mechanisms and allow the
bark beetles to feed
Herbivores manipulates their host
–aggressive-
Gall and induced plant susceptibility
 Gall are plant structures that are inhabited
and fed upon by small herbivores (or by fungi
or microorganisms)
 These structures are made of plant tissue
although gall morphology is controlled by the
herbivores
 Variation in the morphology of the gall
depends upon the phylogeny of the gallmaking insect and is independent of the host
phylogeny.
Herbivores manipulates their host
–aggressive-
 Gall and induced plant susceptibility
 Gall form is determined by substances secreted by
the oviposition female or by the spatial pattern of
larval or adult feeding
 Aphids that feed in galls are more efficient than free
feeding aphids (Llewellyn, 1982)
 This evidence implicates the induction of galls as
probable offensive traits.
 Galls provide the gall maker with a specific
microhabitat that may include relative safety from
pathogens, predators, and parasites as well as
source of high quality nutrition
(Weis&Kapelinski,1994)
Herbivores manipulates their host
–aggressive-
Gall and induced plant susceptibility
 These tactics can greatly reduce the
effectiveness of photoactive plant defense.
 Leaf rolling reduces light inside the roll and
this behavior was associated with reduction in
leaf toughness and tannin concentration.
 This tactic increase rates of development and
decrease mortality of larvae and qualifies as
offensive.
Herbivores manipulates their host
–aggressive-
Trenching, mowing, haying and
gardening
 Plant can immobilized herbivore mouthparts
and reduce feeding by releasing secretions
from pressurized canals such as lacifers when
herbivores bite.
 In response, many insects cut vein across the
leaf blade prior to feeding.
 The herbivores then feed beyond the cuts,
free from the plant exudates that would
normally deter herbivores.
Herbivores manipulates their host
–aggressive-
Trenching, mowing, haying and
gardening
 Many insect herbivores reduce harmful effects of trichomes by
mowing them before feed.
 Some catepillars avoid trichromes by laying down a silk covering
or scaffolding over them
Herbivores manipulates their host
–aggressive-
Trenching, mowing, haying and
gardening
 Certain mammalian herbivores clips vegetation and cache it
before consuming it, a behavior know as ‘haying’ (Vander
wall,1990)
 Plants cached in ‘hay piles’ facilitated food storage and also
allowed toxin degrade so that cached food become much more
palatable after storage (probable offense)
Herbivores manipulates their host
–aggressive-
Trenching, mowing, haying and
gardening
 Leaf-cutting ants gather pieces of fresh leaves and flowers which
they use to culture fungi, their ultimate sources of nutrition
VIDEO LINK
Herbivores manipulates their host
–aggressive-
Gregarious feeding
 To enhance the ability of herbivores to exploit
their host plants.
 Enhanced host finding and reduce predation
risk
 Gregarious caterpillars grew twice as fast as
in large groups compare with a small groups
of herbivores
Richard Karban and Aunrag A. Agrawal. 2002.
Herbivore offense. Annu. Rev.Ecol.Syst.33:641-64
Richard Karban and Aunrag A. Agrawal. 2002.
Herbivore offense. Annu. Rev.Ecol.Syst.33:641-64