Title: BiologicallyBased, Insect Pest Management in Vegetables
1Biologically-Based, Insect Pest Management in
Vegetables
University of Wisconsins Pyle Center October 21,
2008
2Vegetable Production in Wisconsin
- Important production state nationally
- Good crop climate also limits pests
- Production linked
- historically to
- canning industry
- Recent increase in
- fresh market
3Wisconsin Vegetable Production Statistics (Wis.
Ag. Stats. 2007)
4Changing Economic Ground
- Fuel prices
- Changing consumer demand
- Major market makers redefining landscape
(Wal-Mart) - Current market makers rapidly adjusting (Whole
Foods) - New institutional buyers beginning to enter the
market - Public policy national, state local
sustainability standards - Environmental costs internalized
- Food security
- TIPPING POINTS???
5Scoping Partners for Regional Food Strategy
Project
- Blue Planet Partners
- Michael Fields Agricultural Institute
- Center for Integrated Agricultural Systems
- DATCP
- REAP
- UW Center for Cooperatives
- Common Wealth Development, Inc.
- UW College of Agriculture
- Other key food systems leaders (Keystone
Leopold Groups)
6Goal of Regional Food Strategy Project
- Develop cohesive strategic framework for scaling
up this regions sustainable food system (Madison
Milwaukee Chicago) - Strategies nesting both locally and regionally.
- Goal Increase consumption of sustainable,
regionally produced and processed food from 2 to
10 in 7 to 10 years.
7Scaling Up a Sustainable Food System
- Values (Sustainable)
- Local, organic, environmentally sound, life
giving for communities, healthfulness, freshness,
taste, etc. - Economics (Profitability Sustainability)
- Financial viability
-
8Insect Management on Vegetables
- The problem
- Many Insects on Many Crops
- Some perspective on insects
- Why is it difficult to manage insects?
- Lots of insect species on the planet
- Over 1 million animal species
- ¾ are arthropods
- Remember only a few are actually pests
- Each species has lots of individuals
- Short life cycles
- High numbers of individuals
- Combination HIGH REPRODUCTIVE CAPABILITY
9Factors that regulate insect populations
- Physical Factors
- Environment
- Temperature, rainfall
- Pesticides
- Biological Factors
- ?Influence increases at higher populations?
- Competition
- Food availability
- Parasites, predators
- disease
Insect management seeks to blend various
biological and physical factors together to hold
pests at acceptable levels.
10Insect Management ? The 6-step Process
- Identify the key pests
- Look closely at
- Biology
- Ecology
- Behavior
- Impact on crop
- Identify weak links
- Develop management strategies to exploit
weaknesses - Tailor pest management to individual needs
- Fit sporadic pests into program
11IPM Integrated Pest Management
- IPM is a decision-making process considers and
utilizes ALL available pest management options or
strategies to prevent economically-damaging pest
outbreaks below an acceptable, pre-determined
injury level or action threshold while reducing
risks to human health and the environment
12What IPM is NOT!
- IPM does NOT preclude the use of pesticides!
- IPM is NOT merely a biological or organic pest
control program - IPM is a decision-making process, NOT a stringent
or rigid management regime
13Components of an IPM Program
- Monitoring and Sampling (inspect)
- Pest Identification (what pest)
- Decision-making (what action(s))
- Intervention (take action (s))
- Follow-up (re-inspect)
- Record-keeping (write it down, history)
- Education (learn)
14Insect Management Trends on Vegetables
High value Low tolerance HIGH RELIANCE ON
INSECTICIDES
15Insect Management Trends on Vegetables
- Fewer insecticides
- Resistance in pests
- Label cancellations
- Reregistration
- FQPA
- Raw product residues
- Worker safety
- Environmental concerns
- Nontarget toxicity
- Groundwater
16Insect Management Trends on Vegetables
Targeted insecticide use
Integration of non-chemical alternatives
Present and Future
Reduced risk, ecologically-based IPM
17- Potato Production in Wisconsin
- 70,000 Acres, value 203 million, 3rd Nationally
- Most grown in Central Wisconsin
- Several varieties grown for seed, processing,
and tablestock
Russet Burbank
Yukon Gold
Atlantic
Dark Red Norland
18Insect Management in Potatoes - Key Pests -
Green peach aphid
Colorado potato beetle
Potato leafhopper
19Colorado potato beetle adult
20- Overwintering site
- Close to last crop
- Adults 6 to 12 deep
- Protected by mulch
21- Adults walk to crop
- Damage depends on temperature
- May - June
22- Adults lay eggs on underside of leaves
- Yellow / orange
- 20-40 eggs/mass
23- Larvae hatch 5-7 days
- 1st instar move to plant terminals
- Little damage
24- Small larvae feed in terminals
- 4 instars, 5-7 days/stage
- Large larvae (34) feed extensively
25 26- Larval feeding
- 4th instars leave plant and pupate
- in soil
27- Pupae in soil
- 2-3 weeks
- Summer adults emerge (July)
28- Summer adults emerge in July
- Very active
- Very hungry
29- Rapid defoliation
- Partial second generation
- Adults leave to overwinter or
- Can be partial 3rd gen.
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31Managing outside crop
- Rotate crop to avoid adults
- Trap adults moving into crop in spring
- - spring trap crops
- - trenching
- - border sprays
- Trap adults moving out of crop in fall
32Colorado Potato Beetle Dispersal / Crop
Colonization
33Crop Rotation avoid planting adjacent to
previous potato
Sexson and Wyman (2005)
- Rotate gt 400 m (¼mile)
- Delays infestation
- Reduces infestation size
- effect increased if small grain separates field
from source of overwintered beetles - Causes infestation to proceed from field edge
- facilitates scouting
- allows spot or perimeter applications of
insecticide
Adult CPB / 10 plants
Distance (m)
34Perimeter Insecticide / Edge Treatments
Apr 25
May 2
May 9
May 16
Larval CPB
35Trap adults moving into crop
Walking Beetles
Beetle Trench
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37Biological Controls
- Predators, parasites exist but rarely effective
38Chemical Control
- Must control overwintered generation in June
- Ignore overwintered adults unless severe feeding
- Target young larvae, 1st and 2nd instar
- Look for egg hatch
- 5 to 10 days, depending on temperature
39Chemical Control
Problem beetle has developed resistance
to many insecticides e.g.
carbamates, organophosphates,
Tools available Biological (specific)
- Bacillus thuringiensis var tenebrionis
- Target 1st, 2nd instar
- Multiple applications
- Good coverage needed
- Spinosad (Entrustorganic)
- Target 1st, 2nd generations
- 1-2 applications only
40Potato leafhopper
- Appearance
- Adults, small (1/8) wedge-shaped, bright green
- Rapid movement
- Nymphs, yellow-green, lack wings
- Occurrence
- Does not overwinter in Wisconsin
- Adults migrate from gulf states
- Arrive June, 2-3 generations/year
- Very broad host range includes potatoes, beans,
alfalfa - Can infest quickly
41Potato leafhopper damage in snap beans
- Both adults and nymphs feed
- Sucking mouthparts
- Saliva clogs plant, causes yellowing, leaf
necrosis - Can kill young plants quickly
- May only cause stunting
Untreated
Treated with insecticides
42Potato Leafhopper damage in potato
43PLH hopperburn
First signs of hopperburn
Later stages of hopperburn
44PLH Management
Cultural Biological - Plant early to avoid
- No effective biologicals
Chemical - Monitor often (June 1) - Treat only
when threshold exceeded (1/sweep) - Do not let
nymphs build up - Control is effective if
needed pyrethrins Evergreen, Pyganic
45Cole Crop Insect Control
Many crops with same insect pest complex
Head crops
Cabbage
Cauliflower
Broccoli
Also Brussels sprouts, Kale, Kohlrabi, Collards,
Mustard greens, Chinese cabbage, etc.
Root crops Turnips, Radish, Rutabaga, etc.
46Insect Pest Complex
Key Pests - Lepidoptera
Diamond back moth
Imported cabbage worm
Cabbage looper
Sporadic Pests
Cabbage maggot
Flea beetle
Cabbage aphid
47Managing Insects on Cole Crops
- ??Excellent example of potential for biological
control ?? - (Mahr et. al. NCR Regional pub. 471)
- History of problem
- Direct damage to marketable product by key pests
- Worms on heads
- Maggots on roots
- Multiple insecticide applications used
- Resistance developed as threat to production
- Solution
- IPM implementation based on biological control of
key pests - Pesticides switched to specific, soft materials
to preserve natural control
48Key Pests of Cole Crops
- Complex of 3 lepidopteran species
- All feed on marketed crop
- Need to identify species but can treat as a
complex
Imported cabbage worm
Cabbage looper
Diamondback moth
49Diamondback moth life cycle
- Adult
- Small night flyer, short fast flights
- ½, wings have diamond pattern
- Can monitor with pheromone trap
- Eggs
- Small, hard to see
- Laid close to veins
- Larvae
- 4-5 instars up to ¾ long
- 2-3 weeks
- Cigar shaped, pointed at ends
- wiggle when touched
- Spin thread and hang
- Pupa
- Usually on underside of leaves
- Neatly spun pupal case
50Diamondback moth
- Occurrence
- Does not overwinter in Wisconsin
- Blown in on wind or imported on plants
- 4-8 generations per year
- Damage
- Window pane feeding, may also deform heads
- 1st instar mine in leaf
- Damage usually early-mid season (June/July)
- Resistance to many insecticides
- Major problem worldwide
51Imported Cabbage Worm life cycle
- Adult
- White, day flying butterfly
- Eggs
- Laid single on undersurface
- White, turning yellow at hatch
- Cigar shaped
- Larvae
- 5 instars 3-4 weeks
- Velvety green with yellow dorsal line
- Slow moving
- Up to 1 ½ inches in length
- Pupa
- Distinctive angular shape
- Usually on plant debris/old leaves
52Imported Cabbage Worm
- Occurrence
- Overwinters as pupae in Wisconsin
- 3 generations per year, 1st on weeds
- Damage
- Usually most damaging species in Wisconsin
- Large holes in leaves and heads
- Often extensive frass
- Peak damage mid-season (June/July)
53Cabbage Looper life cycle
- Adult
- Large, night flying moth
- Hour glass marks
- Eggs
- Laid singly on undersurface
- White, turning tan at hatch
- round shaped
- Larvae
- 5 instars 4-5 weeks
- Green with white stripe
- Loop when moving
- Up to 2 inches in length
- Pupa
- Roughly spun silk cocoon
- Underside of old leaves or on debris
54Cabbage Looper
- Occurrence
- Does not overwinter, adults blow in (June/July)
- 2 generations per year, persisting in late season
- Damage
- Damage usually late season
- Extensive leaf holes and head damage
55Managing the Lep. Complex
- Cultural
- Use clean transplants
- Biological
- Good complex of parasites
- Diamondback moth 70-90 parasitized
- Imported Cabbage worm 30-60
- Cabbage looper 10-30
- Multiple species
56Managing the Lep. Complex
- Chemical
- Pest Specific
- Bacillus thuringiensis (Kurstaki Btk, or Azaiwi
Bta) - Many materials registered
- e.g. Dipel, Thuricide, Biobit, Cutlass, etc.
- Short persistence ? timing critical
- Stomach poison ? coverage important
- Weak on looper
- Spinosad Entrust
- Broad Spectrum
- Pyrethroids
- Multiple applications
- Resistance can be a problem
- Eliminate biological controls
57Key Pest of Root Crops
Cabbage Maggot Life Cycle
- Adult
- Small grey/black fly
- Similar to housefly
- Eggs
- Small, white
- Laid in soil at base of plants
- Larvae
- White, legless maggots
- 4 instars up to 1/4
- 3-4 weeks per generation
- 3 generations per year
- Pupa
- Brown, oval shaped
- In or close to the roots
58Cabbage Maggot Life Cycle
- Occurrence
- Overwinters in soil as pupa
- Adults emerge in spring
- 3 flight peaks
- First peak is most serious and occurs at 300 heat
units or when lilacs bloom (May) - Damage
- Larvae tunnel on root surface
- May be secondary rot
- Major importance on root crops
- Causes wilting, death on head crops
300 DD
59Cabbage Maggot Management
- Cultural
- Rotate crop away from overwintering site (1/4-1/2
mile) - Prevent egg laying with barrier, row cover
- Predict egg laying with heat units (300 HU with
43F base) - Plant early or late to avoid eggs fly free
periods - Biological
- Some egg predation by beetles
- Chemical
- None currently available
- Experimental seed treatments in review (spinosad)
60Sporadic Pests of Cole Crops
Flea beetle (several species)
- Appearance
- Small, shiny black beetles
- Hind legs enlarged for jumping
- Overwinter as adults
- 2 generations per year
- Damage
- Adults chew small circular holes
- Can kill small plants
- Larvae in soil are not damaging
61Flea Beetle Management
- Cultural
- Exclude adults with row cover
- Attract adults to alternate trap crop (Indian
mustard) - Avoid early planting
- Biological
- No effective controls
- Chemical
- Repeat applications of natural pyrethrums
- DO NOT disrupt biological controls for lepidoptera
62Vine Crops Calendar of Insect Pests
April May June July
Aug Sept Oct
Cucumber Beetles
Aphids
April May June July
Aug Sept Oct
63Striped and Spotted Cucumber Beetles
- Lifecycle
- Adult beetles 8-10 mm length
- and 3-4 mm wide
- Striped cucumber beetle
- Acalymma vittatum
- Spotted cucumber beetle
- Diabrotica undecimpunctata
- Striped cucumber beetles overwinter in protected
areas as adults and become active in mid-spring. - Appear early, lay eggs at the base of cucurbits,
and have 2 generations / year - Striped is most severe
Striped cucumber beetle
Spotted cucumber beetle
64Striped cucumber beetle(Acalymma vittatum)
65Cucumber Beetles Damage
Pollination interference
Defoliation
Feeding scars
Rindworms
66Cucumber Beetles Bacterial Wilt
- Most damage is from bacterial wilt, Erwinia
tracheiphila - Closely associated with beetle, vectored via
posterior-station - No cure for bacteria, control through vector
- Susceptibility
- Melons (not watermelon) gt cucumbers gt
butternut and Hubbard squash
- Causal agent Erwinia tracheiphila, transmitted
by the cucumber beetle
67Management Bacterial Wilt
- Avoidance of bacterial wilt is accomplished
through effective cucumber beetle control. - Cucumber beetles are not always present
- Cucumber beetles are not efficient vectors of the
bacterium - Sampling can be accomplished with yellow sticky
traps - Established Thresholds (direct counts)
- 1 beetle / plant for melons, cucumbers, and
- young pumpkins
- 5 beetles / plant for watermelon, squash,
- and older pumpkins
68Cucumber beetles Management
- Cultural
- Later planting
- Eliminate weeds, weedy edges
- (sanitation)
- Row cover early
- Crop rotation
- Transplants
- Trap crops on plastic mulches
- Biological
- None effective
- Chemical
- Avoid flowering to protect bees (late afternoon
sprays) - At-plant systemic (nicotinyls) and foliar
insecticides (pyrethroids, carbaryl) - Attract-and-Kill, (Adios) discontinued
69Alternative Chemical Control
- Insecticide seed treatments (2008-09)
- Cucumber and squash seeds treated with spinosad
Entrust - Cucurbit seeds treated with thiamethoxam or
clothianidin reduced cucumber beetle densities
and damage in Ohio similar control as Admire and
Platinum (Welty 2006, unpublished)
70Insects Impact Cucurbit Production
Pollinators
and Devastators
European honey bee
Striped cucumber beetle
71European honey bee (Apis mellifera)
72Can we rely on honey bees to pollinate cucurbit
crops?
73Factors Harming Honey Bee Populations
- Diseases (e.g., American foul brood)
- Parasitic mites (NRC 2006)
Tracheal mite (Acarapis woodi)
Varroa mite (Varroa destructor)
74Factors Harming Honey Bee Populations
- Insecticides (Kevan et al. 1997)
- - Do not apply to crops in bloom
- - Application timing apply in the late
- afternoon or early evening
- - Choose short residual products
- - Adjust spray to weather conditions
- low temps extend residual
- protract foraging times
- - Application formulation (s)
- EC gt WP, WSP, D
75Factors Harming Honey Bee Populations
- Colony Collapse Disorder (CCD)
- caused by the Israeli Acute Paralysis Virus
(IAPV) that weakens bees immune system (Stokstad
2007) - honey bee colonies lose all of their worker bees
- responsible for a loss of 50-90 of colonies in
beekeeping operations across the U.S.
76Understanding Colony Collapse Disorder (CCD)
- Israeli Acute Paralysis Virus (IAPV)
- - May not be the sole cause (ESA 2007)
- Bee colony attrition may be linked to a
combination of factors - - Mites associated acaricides
- - Stress associated with production
- - Pesticides
- - IAPV
77Squash bug, Anasa tristis
- Occurrence
- Adults are large black bugs which aggregate on
plants - Round eggs are laid in neat rows
- Nymphs are white/grey
- Damage
- Phytotoxic saliva causes wilting
- Cucurbit yellow vine decline
- - Hubbard and winter squash more severely
affected
78Squash bug - Management Thresholds
- Seedling Stage
- Treat if wilting and squash bugs are observed
- Flowering Stage
- Treat if gt 1 egg mass is
- found per plant
- Control
- pyrethrums
- Cultural
- - sanitation remove overwintering sites
- - destroy crop residue
79Two-spotted spider mites, Tetranychus urticae
- Occurrence
- Usually occur in hot dry conditions
- More severe in dusty, road side locations
- Multiple generations on undersurface of
- leaf
- Damage
- Adults feed in large numbers on leaf surface
causing silvering - Lower surface often covered with webbing
- Late season pest
- Can be flared by pyrethroids
80Spider mite, Management
Leptothrips
- Cultural
- Maintain good plant growth, irrigate
- Avoid dusty roads
- Biological
- Several effective predators
- Avoid broad-spectrum insecticides
- Chemical
- Unless necessary, do not use
- Hormoligosis boosts egg production
- Insecticidal soap, M-pede
Minute pirate bug
81Squash Vine Borer
- Occurrence
- Adults are diurnal, wasp-like moths
- Lay eggs singly on vines
- Larvae bore into plants and destroy
- vascular tissues wilting and death.
- Not a pest of watermelon,
- muskmelon, or cucumbers
- Emerging issue on winter
- squash (Hubbard) and pumpkin
- Occasional second generation
Adult moth
Larvae
82Squash Vine Borer Control
- Sampling
- Field history past problems future problems
- Often more serious in smaller plantings
- Pheromone traps
- Direct observation entrance holes frass
- Cultural
- Practice good field sanitation
- destroy residue
- Chemical (re-application)
- Natural pyrethins
- Bacillus thuringiensis var. kurstaki
83Cucurbit Virus Complex
Major Viruses Cucumber mosaic virus
(CMV) Watermelon mosaic virus-2 (WMV-2) Papaya
ringspot virus (PRV) (synonymous WMV-1) Squash
mosaic virus (SqMV)-cucumber beetle /
seed Zucchini Yellow Mosaic Virus (ZYMV) Minor
Viruses Tobacco ringspot virus
(TRV)-nematode Tomato ringspot (TmRSV)-nematode Cl
over yellow vein virus (ClYVV) Beet curly top
virus (BCTV) Beet pseudo-yellows virus (BpYV)
Papaya ringspot virus
84Cucumber mosaic virus
- Widely distributed
- Non-crop inoculum sources
- Stunting, leaf curl
- Elongate, shoestring leaf
- Color breaking
- Regularly encountered
- Leguminous plant hosts (e.g. clover)
- Mild mosaic
- Rugose leaf, cupping
- Fruit distortion and color breaking
Watermelon mosaic virus - 2
85New Pest
2005 Distribution
86AMV
CMV
Emerging bean viruses the problem
German et al. (2004)
87Non-Persistent Virus Transmission
- Non-circulative (CMV, WMV-2, PRV, ZYMV)
- often referred to as stylet-borne
- Non-propagative
88Non-Persistent Transmission Movement in Insects
- Food Ingestion
- Pathogen particles attach
- to maxillary lumen
- Egestion
- Pathogen particles released
- with saliva
Ingestion
Salivation
89Nonpersistent Transmission
- Acquisition time - time required to acquire
pathogen - Seconds
- Inoculation time - time required by infectious
insect to inoculate a susceptible host - Seconds
- Latent period - (minimum time between acquisition
of a pathogen and ability to transmit) - Zero
- Retention time - time after acquisition
- that a vector remains capable of
- transmitting the virus
- - Minutes to hours
Chemical controls no option!!
90Traps for Winged Aphids
water pan trap
sticky traps, green yellow
91Landing of Migrating Aphids
- Alighting aphids orient preferentially to plants
showing a contrast against a bare soil background - concentrates landing
- around field margins if field has a bare soil
border - on young plants before canopy closure
- Eliminating contrasting background reduces
landing rates - border planting inter-planting
- reflective mulches
92Reflective Mulch for Aphid/Virus Management
- Theory
- Repels winged aphids (reflected UV)
- Delays aphid colonization
- Delays virus infection
- Reduces virus symptoms
93Aphid Management
- Cultural
- Trap cropping
- Weed control
- Rouging
- Light mineral oils
- Resistant varieties
- Biological
- Effective predators
- Chemical
- Ineffective
94Resistance
- A genetically controlled decrease in
susceptibility of a population to a control
measure - resistance to insecticides (IRAC 2006)
- 500 insect species resistant to 1 or more
insecticides - 1800 species/insecticide resistance combinations
- adaptation to pest resistant crop varieties
- adaptation to crop rotation
95Chronology of Insecticide Resistance in Colorado
Potato Beetle Long Island, NY
96Resistance Development
- Resistance genes occur naturally at low
frequencies - 10 -8 to 10 -12
- Proportionately more insects with R-genes survive
and leave offspring when exposed to toxin than
insects with only S-genes
SS
RR
RS
97Measuring Resistance
- LD50 (or LC50) dose (or concentration) that is
lethal to 50 of the test population under
defined conditions - LD90 dose that is lethal to 90 of the test
population
90
Percent mortality
50
LD50
LD90
Dose
98Resistance Ratio
- Ratio of LC50 of test population to LC50 of
reference population - LC50(test) / LC50(reference)
- Resistance ratios of susceptible (controllable)
populations can vary as much as 20-fold
99Wisconsin, 2007 Imidacloprid Bioassays
- Survey Sites
- Adams County (8)
- Langlade County (7)
- Oconto County (1)
- Portage County (8)
- Waushara County (11)
- Total (35)
- CPB Populations
- Over-wintered adult
- 2nd generation adult
- Adult Topical Bioassays
100Wisconsin, 2007 Imidacloprid Bioassays
Preliminary Assays(2007) 35 populations, LC50
range (0.021 1.355)
LD50 (µg/beetle)
30X
20X
10X Susceptible LD50
Location
101Insecticide Mixtures Strategy
- Apply tank mixture of insecticides A B
- individuals resistant to one compound in the
mixture will be killed by the other - Basic principle
- if resistance to each compound is independent (no
cross resistance) and initially rare, individuals
resistant to both compounds will be extremely
rare - Equal persistence of both compounds
- If A loses activity before B, all individuals
resistant to B will not be killed by A - a 5 difference in persistence of A B can
completely negate advantages of mixture
102Rule Out Common Causes of Control Failures Other
Than Resistance
- Calibration error
- Mixing error
- Use of inappropriate product
- Use of out-dated product
- Re-infestation following application
103Impediments to Resistance Management
- Must be implemented before resistance problem
exists - Involves added costs and/or complexity
- Pesticide dealers may not always stock inventory
for required rotations - Sales incentives favor maximizing pesticide sales
in short-term - No positive feedback
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