Lecture16

Slide1: 

Caterpillar Pests- Decision Factors The threat Plant health Site conditions Abundance of pest Client Concerns Regulatory Concerns

Caterpillar Pests- Decision Factors: 

Types- Exposed, Concealed Abundance – Solitary, or Gregarious? Host Range – What do they eat? Number of Generations /Year Abundance of Natural Enemies Caterpillar Pests- Decision Factors

Pesticides for Controlling Caterpillars: 

Pesticides for Controlling Caterpillars Biologicals Bacillus thuringiensis (BT) Spinosad (Conserve, Fertilome etc) Insect Growth Regulators Diflubenzuron = Dimilin Fenoxycarb = Precision Tebufenozide = Confirm Pyriproxifen = Distance Neem, Azadirachtin

Pyrethroids- Rescue Treatments: 

Pyrethroids- Rescue Treatments Bifenthrin (Talstar) *M Cyfluthrin (Decathalon) *HO Deltamethrin (Deltagard) Fluvalinate (Mavrik) *HO Lamda -Cyhalothrin (Scimitar, Battle) *M Permethrin (Astro, Spectracide) *B, *HO *M = miticide ; *B = borers; *HO= Products available for home owners

Slide5: 

The Attack of the Amazing Gypsy Moth: Living with an Invasive Exotic Pest History of Gypsy Moth The Threat Biology Biological Control Gypsy Moth Management Population/Panic Cycle Slow the Spread Suppression Education

Map of the Gypsy Moth Regulated Area: 

Map of the Gypsy Moth Regulated (Quarantined) Area Map of the Gypsy Moth Regulated Area Introduced into western Massachusetts in 1869 • Now established in Northeastern states, Michigan, parts of Ohio, Wisconsin and 5 counties in Indiana

Slide8: 

Why Gypsy Moth Is A Problem • Caterpillars eat leaves of 500 species of trees and plants • 8 million acres of forested lands defoliated in 1990 • Preferred trees - oaks • Repeated annual defoliation may kill trees in 2-4 years

How Gypsy Moth Defoliate: 

How Gypsy Moths Defoliate Leaves: • Caterpillars eat everything but the leaf midrib • 11 sq. ft. of foliage consumed by each caterpillar Trees: • Eggs laid in groups of 50-1500 • Caterpillars hatching from 100 egg masses will consume over 3 acres of foliage • During pest outbreaks each tree can have more than 200 egg masses How Gypsy Moth Defoliate

Slide10: 

When are forests defoliated? • Defoliation starts in May and continues into early June • A second set of new leaves come out in July

Slide11: 

Adult Egg Laying • White female moths emerge from brown pupae and lay large hidden egg masses • Often found on trees, house siding, firewood and under car bumpers • Sheer number insects can be nuisance during outbreak

Gypsy Moth Oubreaks Cause Household Nuisance: 

Gypsy Moth Outbreaks Cause Household Nuisance • After defoliation, caterpillars wander long distances searching for food and places to make pupae • Caterpillars crawl across lawns, and can cover the sides of houses. Note caterpillars on walls of this house Gypsy Moth Oubreaks Cause Household Nuisance

Slide13: 

Gypsy Moth Outbreaks Cause Household Nuisance (contd.) • Dead caterpillars and their feces accumulate under defoliated trees Picnic tables and other outdoor items can be pelted with a constant rain of caterpillar excrement

Slide14: 

Gypsy Moth Outbreaks Cause Household Nuisance (contd.) • In later stages of defoliation cycle, gypsy moths often struck by disease, fall from trees and rot • Odor of rotting insects adds to unpleasantness of outbreak

Trees Most at Risk to Gypsy Moth: 

Trees Most at Risk to Gypsy Moth Aspen Sweet gum Apples and crabapples Serviceberry Birches Mountain ash Blue spruce Witch hazel American beech White pine Basswood Hawthorn Hazelnut Linden Oaks Poplar

Slide17: 

Gypsy Moth Females Lay Eggs in July and August • Females are unable to fly because they produce too many eggs • Egg masses contain 50-1500 eggs

Slide18: 

Eggs hatch in late April and caterpillars climb to treetops • Caterpillars dangle from tree tops to be blown to new trees • Wind can blow caterpillars long distances • Movement by wind - “natural spread”

Slide19: 

Second Instar Gypsy Moth Caterpillars • After landing on new trees they feed and go through several molts

Slide20: 

Empty Gypsy Moth Caterpillar Skin • Skins are found during heavy infestations • First 3 instars feed day and night in tree canopy

Gypsy Moth Caterpillars: 

Gypsy Moth Caterpillars • Older caterpillars have distinct color markings on their backs • Five pairs of blue dots are followed by 6 pairs of red dots Gypsy Moth Caterpillars

Slide22: 

• Later stage caterpillars feed on leaves only at night • Caterpillars crawl to the base of trees before daybreak to hide from birds

Slide23: 

Gypsy Moth Pupa And Larval Skin • In June caterpillars stop feeding and wander to protected place to change into pupae • Brown pupae can be found anywhere

Slide24: 

Adult Female (White) and Male (Brown) Moth • Emergence from pupae about 4 weeks (~July) • Males able to fly to find mates • Males fly upwind to find scent of mates • Scent called “sex pheromone”

Slide25: 

Sex Pheromone Trap • Traps are deployed throughout the state each spring to monitor gypsy moth populations • These traps lure male moths with the scent of gypsy moth females. This scent is called a sex pheromone. • Traps have been used since 1973 in Indiana • Spot infestations outside the infested area have been found and eradicated several times since trapping began • Trapping is used in infested areas to track intensity of populations

Map of 2002 Trap Catch: 

Map of 2002 Trap Catch • Trap catches are reported to monitor the spread • Areas with greatest trap catch are probably infested • Trap counts higher in Michigan than Indiana • View link to trace changes in trap catch over the years Map of 2002 Trap Catch http://www.gypsymoth.ento.vt.edu/%7Esharov/stsdec/results2.html

Slide27: 

How The Gypsy Moth Population Spreads • Population moves from a generally infested area through a transition zone to the un-infested areas • Hot spots or locally infested areas decrease in size when moving away from generally infested areas Infested Transition Un-infested

Slide29: 

How Is Gypsy Moth Controlled In Nature? Factors Related To Weather: - Fungal disease - Entomophaga maimaiga - spreads through population during wet springs - Spores blown in wind will germinate on caterpillars exposed to soaking rains and kill them - Dead caterpillars covered with spores will infect nearby caterpillars

Slide30: 

Gypsy Moth Caterpillar Covered By Fungal Spores • Spores easily seen on caterpillars

How is Gypsy Moth Controlled in Nature?: 

How Is Gypsy Moth Controlled In Nature? Factors related to gypsy moth abundance: LOW ABUNDANCE - mice and other rodents eat them MEDIUM ABUNDANCE - predatory insects (ground beetles) - parasitic wasps (Cotesia melanoscelus) HIGH ABUNDANCE - Nuclear polyhedrosis virus (NPV) How is Gypsy Moth Controlled in Nature?

Slide32: 

Why doesn’t NPV work in low level gypsy moth infestations? - Like people and the common cold, healthy caterpillars can defend themselves against some viral diseases - In heavy infestations caterpillars don’t get enough high quality food to eat - Starved caterpillars get can’t defend themselves from NPV - Sick caterpillars turn into leaking sacks of virus particles that spread disease to nearby caterpillars that are plentiful in heavy infestations

V-shaped Gypsy Moth Caterpillar: 

V-shaped Gypsy Moth Caterpillar • NPV has killed caterpillar and is handing in V-shaped position • V-shaped position caused from virus changing tissues and muscles into a soup filled with infectious virus spores V-shaped Gypsy Moth Caterpillar

NPV Infected Caterpillar: 

• NPV infected caterpillars rupture and splash soupy virus-filled contents on neighboring leaves • Caterpillars eating the soup will die • Virus spreads rapidly to new caterpillars leaving few, if any, to develop into moths NPV Infected Caterpillar

Gypsy Moth Pathogens: 

Gypsy Moth Pathogens Both NPV and Entomophaga maimaiga are considered pathogens because they infect gypsy moths with disease. Other kinds of disease causing organisms including microsporidia, are being explored for potential use in management programs. Gypsy Moth Pathogens

Natural Enemies of Gypsy Moths: 

Natural Enemies Of Gypsy Moths • Natural enemies play major role in controlling gypsy moth • Natural enemies reduces damage levels • Three types; pathogens, parasitoids, and predators attack gypsy moth at different stages of its life cycle Parasitoids Predators Pathogens Eggs x x Larvae x x x Pupae x x x Adults x Natural Enemies of Gypsy Moths

Gypsy Moth Population Cycle: 

Gypsy Moth Population Cycle Density Dependent Low Density Rodents, Mammal Medium Density Insect Predators Insect Parasitoids High Density Nuclear Polyhedrosis Virus Delayed drought trigger Density Independent Fungus Entomphaga maimaiga Spring drought trigger

Gypsy Moth Panic Cycle: 

Gypsy Moth Panic Cycle Density Dependent – First Wave Low Density - No defoliation Nobody cares, until spray is imminent People afraid of sprays High Density – Defoliation imminent People worried about trees, Afraid of new pest Most want trees sprays, Many trees will die Density Dependent – 2nd or 3rd wave(>20yrs) Less intense defoliation Accepted like other more established pests, e.g. Japanese beetle Not such a big deal

Slide40: 

Slow the Spread Program (STS) Objective: Slow the rate of GM movement to UN-INFESTED areas Mechanism: Local estimates of gypsy moth abundance and canopy cover guide the program Possible Outcomes in Targeted Areas: Coordinated aerial spray of Bacillus thuringiensis or pheromone flakes delays quarantine Failure to take action results in quarantine of entire county

Slide41: 

Benefits of Slow The Spread (STS)

Slide42: 

Don’t Give Gypsy Moths A Free - Ride When visiting or moving from locations where gypsy moths reside you may accidentally bring this pest to new locations. Prevent this type of accidental spread by inspecting items that have been stored outside Inspection is most critical near areas where defoliation has occurred

Rule of Thumb: 

The key to a good inspection is to remember that gypsy moths like to hide their egg masses. Rule of Thumb

Aerial Application of Bt: 

Aerial Application of Bacillus Thuringiensis • Gypsy moth can be controlled with 2 aerial applications of BTk • BTk kills only caterpillars and is not dangerous to mammals • Residue not visible from applications • Aerial applications are preferred over ground applications - especially for getting the material to treetops Aerial Application of Bt

Pheromone Flakes: 

At 3 flakes per square foot these flakes are hard to see Pheromone flakes Pheromone Flakes

Questions about Pheromone Flakes and Gypsy Moth: 

Questions about Pheromone Flakes and Gypsy Moth • What is gypsy moth pheromone? • How is aren’t they always used to control gypsy moth? the pheromone used to control gypsy moth? • What are pheromone flakes? Will pheromone flakes be noticeable in the treatment area? Are pheromone flakes dangerous to people and wildlife? If pheromone flakes are so safe, why Questions about Pheromone Flakes and Gypsy Moth

Suppression Program: 

Suppression Program- Objective: Minimize tree damage in WILLING* communities AFTER gypsy moth is established Mechanism: Local estimates of gypsy moth abundance and canopy cover guide the program Communities / forests that meet the threshold are eligible for Federal matching $$ Potential Outcomes in Eligible Communities: Coordinated Aerial Spray of Bacillus thuringiensis No spray-Trees are defoliated * voluntary program Suppression Program

Gypsy Moths Around the Home: 

Gypsy Moths Around the Home Realistic Goal: Help trees survive gypsy moth infestation It takes 2-3 years of consecutive defoliation >50% to kill a healthy tree Unrealistic Goal: Prevent all gypsy moth defoliation

Factors Contributing to Gypsy Moth Risk: 

Factors Contributing to Gypsy Moth Risk Tree Preference Young caterpillars survive best on preferred trees Tree Health Healthy trees are more able to survive defoliation Site characteristics Paved, and unsuitable sites reduce health of trees.