Forest Health

Forest Entomology
the study of the interrelationships of insects and trees; includes damaging and beneficial species; does not include those that do not affect forest health
J.C. Schaffer
(German) 1752 article on the Gypsy Moth
J.T.C.

Ratzeburg

(German) father of forest entomology; published “Die Forstinsekten” (1837-1844)-defined forest entomology as the study of forest insects which have an influence on the thriving and the utility of those wood plants with which the forester is concerned
A.D. Hopkins
(U.

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S.) first professional forest entomologist in the US, “the American Ratzeburg”; head of the Division of Forest Insect Investigation of the USDA; Bark Beetle specialist

Development of Forest Entomology
Taxonomic/Natural History Phase
tried to indentify all they could and made associations between insects and trees and identified the damage that was caused
Divegent Phase
theories of population changes; density dependent or independent
Ecosystem Analysis Phase (1950-80)
interrelationships of all environmental factors; ecological webs, food chains, weather, etc.; looks at the host, stand, temp, season, enemies of the insects; end of the use of DDT
Predictive Modeling Phase
models developed from the data collected in the divergent and ecosystem phases; tries to predict and shoe economic impacts
insect importance
trees
mortality, reduce overall value (bark beetles)
seeds and cones
mortality, unsuccessful regen (Southern pine coneworm)
seedlings
reduces stand survival, unsuccessful planting (white grub larva)
wood products
damage structure (termites, carpenter bees)
spread disease
S. pine beetle spreads blue stain and bark beetles spread dutch elm disease
benefits
plant pollinators, natural enemies of pests
Lepidoptera “scale wing”
butterflies and moths; defoliators, majority of damage is done by larvae (eastern tent caterpillar)
Coleoptera “sheath wing”
beetles; damage caused by larva and adult; there are many beneficial Coleoptera
Hymenoptera “membrane wing”
bees, wasps, ants, and sawflies; damage caused by larvae and adults; only adult ants cause damage; many beneficials
Homoptera-Hemiptera “half wing”
aphids, agelids, leafhoppers, and true bugs; damage caused by nymphs
Orthoptera “straight wing”
grasshoppers, katydids, and walking sticks; defoliators
Diptera “two wing”
flies and mosquitoes; damage done by all life cycles (cone gall midge)
Isoptera “net wing”
termites; damage done by adults
three ways insects cause damage
feeding, nesting, oviposition
Odonata “tooth”
dragonflies, damselflies
Ephemeroptera “short-lived wing”
mayflies
Thysanoptera “fringe wings”
thrips
chelicerata
mouthparts outside of head; 2 body regions, no antennae, 4 pair of walking legs; arachnida
mandibulata
mouthparts inside head
exoskeleton
support, muscle attatchment, body covering/protection, water conservation, growth restriction, good mechanical advantage
tagma
(head, thorax, abdomen) group of segments that function together to do a task
head
perception, food intake
thorax
locomotion, food processing
abdomen
reproduction, excretion
compound eyes
eyes composed of many individual units called ommatidia
simple eyes
(ocelli) one unit, often arranged in the shape of a triangle on adults
prothorax
legs
mesothorax
legs, wings
metathorax
legs, wings
coxa
attatches leg to body
femur
largest leg segment
tibia
lower leg, stability
tarsus (tarsal segments)
foot
tarsal claws
claws you idiot
wing vein function
carry blood, add strength, alter shape
cerci
non-reproductive appendage that can be used for defense or balance
hemocoel
blood filled cavity
ostia
one way valves that allow blood to enter the heart, blood is then forced out via aorta
functions of the circulatory system
transport of food and hormones, protection via immune system antibodies and clotting agents, hydraulic inflation of wings, minor respiration, and thermoregulation
foregut
located in exoskeleton; esophogus-conducts stores and guides food
midgut
located is mesodermal; small intestine-major site of food absorption, enzyme production
hindgut
exoskeleton; large intestine-transports waste from body, reabsorbs water, and eliminates uric acid
salivary glands
function as a food solvent, digestive enzymes, produce glue, silk, plant hormones
tracheal system (respiration)
a system of air tubes that carry gasses to and from body tissues
spiracles
external openings of tubes that open and close
trachea
transports air through body
taenidia
spiral bands of the exoskeleton in the walls of the trachea; adds strength and pumps creating diffusion
ecdysis
the act of molting-losing the exoskeleton which contains the foregut, hindgut, and tracheal system
generations
egg to adult; more than 2/year is considered a pest
no metamorphosis (simple)
each instar looks exactly like previous except larger, adults look like nymphs except larger and sexually mature (silverfish)
incomplete metamorphosis
eggs-nymph-naiads-adult (mayflies)
gradual metamorphosis
eggs-nymphs- adult (hemiptera-true bugs)
complete metamorphosis
egg-larvae-pupa-adult (hymenoptera, diptera, coleoptera)
what is a pest?
pest status depends on population levels, economic factors, and stand objectives
equilibrium position (EP)
avg pop level of an insect species
economic threshold (ET)
the pop level at which management action should be taken to prevent the pest from reaching the economic injury level
economic injury level (EIL)
lowest # of insects that will cause economic damage
botanicals
derived from plants; quick knock down, short residual, expensive (nicotine)
organochlorines (chlorinated hydrocarbons)
generally have long residue, toxicity varies greatly (DDT)
organophosphates
cholinesterase inhibitors (nerve impulses) generally very effective, varied toxicity, short residual (malathion)
carbamates
cholinesterase inhibitor, lower toxicity levels than OC, limited residual but larger than OC (Sevin dust)
Synthetic Pyrethroids
much more affective than natural P, used at low rates, relatively safe, resistance has become a serious problem (Ambush, Warrior T)
Integrated Pest Management
the combination of all suitable techniques to reduce or manipulate a pest population so that they remain below economically important levels