Transcript 1999 Rangeland Grasshopper Outbreak Forecast

GRASSHOPPER MANAGEMENT
IN NEW MEXICO
Train-the-Trainers Workshop presented by
Alexandre Latchininsky and Scott Schell,
UW Extension Entomologists
Sponsored by: USDA-APHIS-PPQ
Disclaimer
• Trade or brand names used in this
presentation are used only for
the purpose of educational
information.
• No product endorsement is
implied.
Workshop Principle:
Everybody is ignorant,
only on different subjects
-- Will Rogers
Or
I don’t know everything and neither do
you, so let’s learn from each other
(a.k.a. – when I’m wrong, let me know)
Workshop “Rules”
It’s called a workshop on purpose
Ask any question, at any time
Be a constructive skeptic
What animal is the primary
above-ground herbivore
in a grassland biome
in North America?
Role of Grasshoppers
in a Prairie Ecosystem
•Natural “mowers” stimulate plant growth
•Nutrient cycling
•Food for many prairie animals
Biology of the Species of Concern
Grasshoppers may be an important component in
the diet of Sage Grouse chicks
Weed Biocontrol Agents?
Some Grasshoppers ARE Beneficial!
Snakeweed grasshopper
Cudweed grasshopper
Plains Lubber
Ebony
Diversity
≈170 species in NM
>450 species in N.A.
Twostriped
Rainbow
PESTS!
BIOLOGY & ECOLOGY
Taxonomy
Class:
Order:
Insecta
Orthoptera (22,500 species;
1,015 – in N. America)
Close relatives:
Blattodea (Cockroaches)
Mantodea (Praying Mantises)
Dermaptera (Earwigs)
Taxonomy
Order Orthoptera
Suborder Caelifera
(short-horned)
Grasshoppers
Suborder Ensifera
(long-horned)
Katydids
NOT Grasshoppers
katydids
crickets
Curved ovipositor
Straight ovipositor
Is Mormon Cricket
a grasshopper?
Mormon cricket
is neither a grasshopper
nor a cricket…
…it’s a A KATYDID!
Anabrus simplex
Grasshopper Taxonomy
Family:
Acrididae
Subfamilies: - Melanoplinae (spurthroated),
- Gomphocerinae (slantfaced),
- Oedipodinae (bandwinged),
- Romaleinae (lubbers),
- Cyrtacanthacridinae (bird
grasshoppers)
Genera:
Species:
≈70 in New Mexico
≈170 in New Mexico,
>450 in Western US
GRASSHOPPER
PESTS IN THE WEST
- economically important in 17 western states
- 20-25 pest species (out of >450)
- annually remove 20-22% of rangeland vegetation
- estimated average loss $400 million per year
- forage losses in 2000 in Texas: $190 million
- require vast areas to be chemically treated
(up to 20 million acres per year during
outbreaks)
What to Expect in 2006?
Rangeland Grasshopper Hazard Map
2005
2006
Grasshopper Biology
All you need to know in order to get rid
of unwanted dinner guests
flights
final molt
mating
Life
cycle
nymphal
instars
1 to 5
~ 30-40 d
egg-laying
egg-pod
1st instar critical stage
for GH
survival
(up to >90%
mortality)
Development
• One generation per year
= univoltine
• Oviposition mostly in soil
• 1-4 egg-pods per female
• 5-40 eggs per egg-pod
Grasshopper Egg-pods
Twostriped grasshopper
Biology & Ecology
Seasonal Development
Typical:
- hatching in spring
- nymphal and adult development
in summer
- overwinter as eggs
Some species: - overwinter as late-instar nymphs
- adults in early summer (usually,
band-winged species)
Development: Gradual Metamorphosis
1
2
3
4
5
Adult
Nymphal instars: 5 (rarely 4)
Developmental stages
1
2
3
4
Nymphal development: 26-40 days (~1 wk/instar)
Clearwinged grasshopper
5
Adult
Nymph or Adult?
N
A
A
N
Wing Venation
NYMPH
No cross veins
ADULT
A lot of cross veins
Biology & Ecology
Physiology and Behavior
Feeding:
Herbivores (necrophily & scavenging)
50% of total consumed by adulthood
Adults: feeding on flowers and seeds
Feeding is “constant” in assemblage
Movement:
Primarily walking (1-3 m/day upwind)
Flight for escape and dispersal
Migration due to crowding and genetics
Biology & Ecology
Food Preferences & Feeding Habits
Grass feeders: Slantfaced and many Bandwinged
species (Aulocara, Ageneotettix, Camnula, Arphia)
Forb feeders: many Spurthroated species (Melanoplus
foedus, M. angustipennis, Hesperotettix viridis)
Mixed feeders: many Spurthroated species (Melanoplus
sanguinipes, M. bivittatus, M. differentialis).
Truly polyphagous; high economic importance
Mormon cricket: may feed on >400 plants but prefers forbs
Comparative size
Twostriped
female
1.1 g
1 ¾ in
1 in
Clearwinged
female
0.6 g
Biology & Ecology
Assemblages
In a habitat, grasshopper population
consists of several (usually 5-20) species
Often, 1-4 species occupy a predominant
position accounting for >50% of total
grasshopper population
Clearwinged grasshopper
Biology & Ecology
Population Dynamics
Normally:
…Outbreaks!:
Grasshopper dynamics are
regulated by abiotic (weather) and
biotic (natural enemies) factors, but
if they fail…
Last for 1-4 yrs, occur at irregular
intervals - every 4-10 yrs
Warm/dry conditions in the
summer are particularly
favorable for outbreaks
Anthropogenic effects (overgrazing
and insecticides)
Weather: Direct and Indirect Effects
•Slower development
•More susceptible to
diseases and
natural enemies
•Higher mortality
•Less eggs produced
Less damaging
Weather: Direct and Indirect Effects
•Faster development
•Less susceptible to diseases and
natural enemies
•Lower mortality
•More eggs produced
More damaging
Biology & Ecology
Population Dynamics
Spatial:
- Outbreaks clumped in space
- Association with static features
(e.g., soil type)
- May spread from localized “hot spots”
Biology & Ecology
Natural Enemies
Predators
Natural Enemies
• Egg predators
Diptera Bombyliidae
Bombyliidae larvae
Blister
beetles
Natural Enemies
• Internal parasites (nematodes)
Grasshopper parasitized
with a mermithid nematode
Nematode egg
and larva
Natural Enemies
• Parasitoids
Wasp Scelio sp.,
Egg parasitoid
Flies (Muscidae, Tachinidae)
Parasitoids of nymphs and adults
Predator “saturation”
Biology & Ecology
Bionomics
Damage:
Primary concern is rangeland
Movement into cropland is relevant
Control:
Economic Injury Level =
= Damage > Treatment cost
Economic Threshold =
= 20, 3rd-4th instars per sq. yd
Variation with timing, species, efficacy, cost, etc.
Biology & Ecology
Bionomics
Other:
Cultural (grazing, plowing, planting)
Mechanical (crushing)
Integrated Pest Management
Future:
Fewer external resources with more
environmental concern, economic demands,
people, need for control, and change
Purpose of Management
Emerging Philosophy:
The purpose of grasshopper management is
to keep good stewards on the land –
to keep those people who live with the
Land, on the Land.
National Grasshopper Management Board
Integrated Pest
Management
IPM is an approach that substitutes
knowledge and information for materials
and external inputs:
Essential components:
Monitoring
Decision-making
Methods & Materials
The 3-Phase
Approach to
Grasshopper
IPM
Endorsed by the National Grasshopper Management Board
Prevention:
Range management practices
(“twice over” livestock grazing)
have been shown to yield
habitat conditions that both:
produce more forage
and
yield fewer grasshoppers
Twice-over vs. 5-month season-long grazing:
~300 lbs/acre more herbage biomass
66 to 75% reduction in grasshopper populations
BUT,
If
Prevention
fails …
Intervention:
Efficient survey combined with
treatment of incipient infestations
or “hot-spots” has been shown to
prevent the expansion of
grasshopper infestations into
large-scale outbreaks
BUT,
If
Intervention
fails …
Suppression:
The use of Reduced Agent-Area Treatments
after analysis with CARMA allows
rangeland grasshopper control to yield:
significant economic profits
with
minimal environmental harm
Putting the “I” in IPM
Prevention
survey/sampling + cultural control
Intervention
survey/sampling + decision support (forecasting) +
hot-spot chemical control
Suppression
survey/sampling + decision support (economic model)
+ chemical control + conservation biological control
Accurate and Timely Survey is
Critical for Efficient Control
• Grasshopper density
assessment
• Species composition
• Developmental stages
(age structure of
population)
• Acreage infested
• Egg-bed location