forest insects and pathogens: ecology and management
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Forest insects and pathogens: ecology and management. by Kristen Baker. Insect Feeding categories. Foliage: defoliators, reduce capacity for photosynthesis. Stems: bark beetles may kill whole tree or individual branches Cone and seed feeders - PowerPoint PPT PresentationTRANSCRIPT
Forest insects and pathogens:
ecology and management
byKristen Baker
Insect Feeding categories Foliage: defoliators, reduce capacity
for photosynthesis. Stems: bark beetles may kill whole
tree or individual branches Cone and seed feeders Twig and shoot insects: damage new
buds and growth Root insects
Biotic causes of plant disease Fungi - most common Nematodes Bacteria Viruses Protozoa Parasitic plants
The Disease Triangle
Amount of Disease
Pathogen
Host
Environment
Management and control options Chemical
– DDT, copper sulfates, botanicals Biological
– use of one organism to control adverse effects of another (natural enemies such as insect predators, viruses, pathogens)
Cultural– active management of vegetation to prevent
or reduce damage or decrease pest population
Integrated pest management Use of a combination of control
techniques that are ecologically, economically, and socially acceptable
Does not mean eradication necessarily, but reduction of pest to tolerable level
Native insects and pathogens Regulators of forest ecosystems
– cause mortality of weakest trees– create gaps within forest, increase
nutrient cycling, available light, insects may increase nutrient availability
– provide wildlife habitat (snags and downed woody debris)
Example: bark beetles Many species, some cause
widespread mortality of trees, others create small pockets of dead trees
Kill trees by mass attacking: many beetles attack the same tree and breed within the tree
Example: root diseases Fungi that cause tree decline and
death by attacking root system (disrupts water uptake by tree)
Often creates distinctive circular patches of mortality
Creates conditions for non-susceptible species to establish in forest
Exotic insects and pathogens Non-native to an area: abnormally
large amounts of mortality common Insects: natural enemies not present
in new location to control population Pathogens: no co-evolution for
genetic resistance to pathogen; long life span of trees a problem
Example: balsam woolly adelgid Native to central Europe; introduced
to North America ~1900 Adelges piceae Infests true fir (balsam fir, Frasier fir,
subalpine fir, grand fir) Feeding causes host to produce
“early heartwood”, reducing water transport.
Management and control Biological control
– insect predators, pathogens– limited success to date
Environment– cold winter temperatures– early or late frost
Example: white pine blister rust Introduced from Europe ~1900 Infects all 5-needled pines: sugar
pine, eastern and western white pine, whitebark pine
White pine blister rust
Whitebark pine (Pinus albicaulis) High elevations in the western US
and Canada Keystone species Mutualistic relationship
with nutcracker Wildlife dependence Restoration treatments
Example: sudden oak death
First reported in 1995, Marin County Widespread mortality of coast live
oak and tanoak Numerous other hosts: California
bay, buckeye, rhododenron Phytophthora ramorum: a fungus-
like organism (Oomycete).