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Insect Pests of GreenhousesIdentification & Management

by Jamee HubbardWI Aquaculture/Aquaponic Boot Camp-2

Session 8 - Plant and Fish Health

University of Wisconsin-Stevens Point

Aquaponics Innovation Center

Nelson and Pade, Inc.®

September 15th, 2018

Overview• What is an insect?

• What are the main insect pests & how do we identify them?

• How do they get in and what does that mean for your operation?

• How do I find them?

• What do I do once I find them?

What Is an Insect?• 3 body regions

• Head – eyes, antennae

• Thorax – 6 legs, wings

• Abdomen - cornicles, cerci, filaments

• Damage plants by chewing, sucking, scraping

• Some are nuisances

Insect Pests of Plants & Identification• Aphids

• Identification:

• Small, soft-bodied, longish antennae

• Cornicles

• Piercing-sucking mouthparts

• Most unwinged, dispersal stage winged

Insect Pests of Plants & Identification• Aphids

• Identification:

• Damage:

• Sucks plant sap

• Honeydew –

• watch for ants

• Leaf curling

• Chlorosis

Insect Pests of Plants & Identification• Thrips

• Identification:

• Very small, elongated, soft-bodied, short antennae

• Feathery wings in adults

Ercinothrips femoralisPhoto credit: Manfred R. Ulitzka

Insect Pests of Plants & Identification• Thrips

• Identification:

• Damage:

• Punches, scrapes, sucks plant surface of leaves, fruits

• White, yellow, otherwise discolored splotches or lines on surface

• Vector plant viruses – e.g., tomato spotted wilt virus

Photo credit: Manfred R. Ulitzka

Insect Pests of Plants & Identification• Fungus gnats

• Identification

• Small black fly

• Tiny head

• Long legs

• Long antennae

• Larvae: clear w/black heads

Insect Pests of Plants & Identification• Fungus gnats

• Identification

• Damage

• Feed on root hairs, crown, stem

• Drought symptoms

• Nutrient deficiencies

• Introduces pathogens

Insect Pests of Plants & Identification• Whiteflies

• Identification

• Small, powdery white

• Wings held roof-like over back

• Jump from plants when disturbed

• Larva & pupa flat, waxy filaments

Insect Pests of Plants & Identification• Whiteflies

• Identification

• Damage

• Found on underside of leaf

• Suck plant sap

• Cause chlorosis, some leaf curling

Other Greenhouse Pests & Identification• Drain flies

• Adult small, fuzzy, looks like moth

• Larva clear, black head & tail

• Larvae breed in organic matter in drains

• Manage by exclusion

Other Greenhouse Pests & Identification• Blood worms

• Adult has long legs, fuzzy antennae, do not bite

• Larva is red in color, has hemoglobin

• Larvae found in stagnant, low oxygen water

How to Know What You Have• Monitoring

• Sticky traps – yellow, some insects (e.g., thrips) like blue better

• Count, keep records

Photo credit: Alan T. Eaton.

How to Know What You Have• Monitoring

• Scouting

• Get out and look

• Establish regular routine

• Count, keep records

• Tools:

• Hand lens

• Hand-held counter

What to Know Before You Treat• Biology of the Pest & Plant

• May determine when to apply biological control agents or pesticides

• Usually with insects that do not have overlapping generations

• If using pesticides, leaf development may prevent access to insects

• One reason biocontrol best

What to Know Before You Treat• Biology of the Pest & Plant

• What are the economic thresholds (ET) for control?

• Develop economic injury level (EIL) – pest population density that causes losses equal to cost of control measures

• Then determine economic threshold –population below the EIL

What to Know Before You Treat• Biology of the Pest & Plant

• What are the economic thresholds(ET) for control? Examples:

• Whiteflies:

• Trap threshold = ½ per card per day when crop is young, 2 per card per day when crop approaches maturity

• Leaf threshold = 10 nymphs per leaf

• Thrips: 5-20 per trap per week

• Aphids: If winged aphids found, populations already high –wings are dispersal stage

What to Know Before You Treat• Biology of the Pest & Plant

• What are the economic thresholds for control?

• Are there effective cultural management practices

• Inspect new plants before transplant

• Repair screens, doors, ventilators

• Cover drains, open pumps to exclude

• Keep floors clean and dry

• Avoid wearing yellow clothing – reduce hitchhikers

• Remove heavily infested plants

• Are there resistant cultivars available?

What to Know Before You Treat• Biology of the Pest & Plant

• What are the economic thresholds for control?

• Are there effective cultural management practices

• Effectiveness & hazards of pesticides

What to Know Before You Treat• Biology of the Pest & Plant

• What are the thresholds for control?

• Are there effective cultural management practices

• Effectiveness & hazards of pesticides

• Benefits of Biological Controls• no re-entry intervals (REI) to

follow• less worker exposure to toxic

pesticide residues,• less chance of spray damage,• improved plant quality,• minimum equipment needed

for application

• part of “green” marketing• preserving the effective life of

pesticides used by the greenhouse industry by removing the selection pressure for development of resistance

What to Know Before You Treat• Biology of the Pest & Plant

• What are the thresholds for control?

• Are there effective cultural management practices

• Effectiveness & hazards of pesticides

• Benefits of Biological Controls

• Biology of the biological control agent

• Does it attack adults, larvae, both, other?

Treating for Insect Pests• Example Biological Control Agents

• Parasitic/parasitoid wasps against aphids – aphid mummies

• Predatory beetles – generalist against soft-bodied insects, insect eggs

• predatory mites against thrips – they harass them, reduce foraging time

• beneficial nematode Steinernema feltiaeagainst fungus gnat larvae and thripspupae

• Beauveria spp. fungus against whiteflies, aphids, thrips – dissolves insect cuticle

• Bacillus ( Bt) bacteria against fungus gnat larvae – damages insect stomach

A really good site: http://msue.anr.msu.edu/uploads/resources/pdfs/FINALtoBOOKSTORE_BCAFactSheets.pdf

In Conclusion• There are several types of insects you will see in

aquaponics, but aphids, thrips, and fungus gnats top 3

• Use cultural controls to reduce insect infestations

• Monitoring & scouting is key to management

• Use EIL to determine when to treat

• Select appropriate treatment and time properly by knowing biology of pest, plant, biocontrol agent

Resources• General Greenhouse Pests & Management:

• https://entomology.ca.uky.edu/ent60

• http://msue.anr.msu.edu/uploads/resources/pdfs/Pest_Scouting_in_Greenhouses.pdf

• https://learningstore.uwex.edu/Assets/pdfs/NCR581.pdf

• https://www.hort.vt.edu/ghbusiness/documents/GreenhouseInsectAndMitePests_EricDay.pdf

• Aquaponics Specific:

• https://aquaponics.com/ufaqs/how-do-i-control-pests-in-aquaponics/

• https://www.friendlyaquaponics.com/2017/04/06/3555-1/

• https://www.ctahr.hawaii.edu/SustainAg/workshop/downloads/Aquaponics-May2013/KHWang.pdf

• Thresholds:

• https://articles.extension.org/pages/18538/integrated-pest-management-concepts-for-weeds-in-organic-farming-systems

• https://gpnmag.com/article/grower-101-pest-counts-and-action-thresholds/

• http://www.greenhouse-management.com/greenhouse_management/integrated_pest_management_greenhouse_crops/integrated_pest_management_ecomomic_thresholds.htm

• Biological Control:

• http://msue.anr.msu.edu/uploads/resources/pdfs/FINALtoBOOKSTORE_BCAFactSheets.pdf

• http://ipm.uconn.edu/documents/raw2/html/608.php?aid=608