Whitefly control in winterSarah Jandricic, OMAFRAGreenhouse Floriculture IPM Specialist

Whitefly Species

GWF SWFGWF eggs

GWF pupaSWF pupa

SWF GWF

1. Greenhouse whitefly Trialeurodes vaporariorum• Naturally occurring in Ontario• Wide host range• Commonly associated with

Gerbera, greenhouse vegetables

2. Silverleaf whitefly (Bemisia)Bemisia tabaci• Typically Imported on cuttings• Commonly associated with

poinsettia, mandivilla

Year-Round Control

Photo from greenhousehut.com

- WF numbers are lower in winter, but SO IS CONTROL- outbreaks in spring; WHY?

Biocontrol of whiteflies

GWF BemisiaParasitic wasps:Encarsia formosa

Eretmocerus eremicus

Eretmocerus mundus

Predators:Amblyseius swirskii

Amblydromalus limonicus

Delphastus (lady beetle)

Wasps and “Winter”ConditionsENCARSIA ERETMOCEROUS

- Lower oviposition- Reduced host feeding

- Lower oviposition- Reduced host feeding

Zilahi-balogh, Shipp, Cloutierc, and Brodeur. 2006. Env. Ent. 35: 581-589

Limonicus:

• Feeds on eggs AND nymphal stages of all WF species

• Mite least affected by environmental conditions in winter

• Perform well at low temps (13° C)

• More $$ than Swirskii, but thought to be more effective for WF

© MAP / Mise Au Point – http://www.map-photos.com

Limonicus to the Rescue?

In Winter 2015:

• Trial 1: Control of GHWF in pot gerbera

• Trial 2: Control of GHWF in cut gerbera

• Trial 3: Control of Bemisia in Mandevilla

To See How Limonicus fits in…

Trial 1: GHWF control in Potted Gerbera

• Control History: Pesticides only (Kontos, Beleaf, Intercept, etc.)

• GHWF population proving difficult to control

• Issue: needed to clean up already infested plants for sale in 4 weeks…

Treatment 1 (control) Treatment 2 Treatment 3 Treatment 4

Kontos

Trial 1: GHWF control in Potted Gerbera

010203040506070

1 2 3

% o

f Pla

nts

Infe

sted

Week After Treatment

Parasitoids Only(Control)

Kontos +Parasitoids

Limonicus +Parasitoids

Limonicus + Food +Parasitoids

• Limonicus: 150 mites/m2 – one release; Encarcia/Eretmocerus mix: high release rate• Avg. 19 °C

RESULTS: Potted Gerbera

15

25

35

45

55

65

1 2 3

% o

f Pla

nts

Infe

sted

Week After Treatment

Parasitoids Only(Control)

Kontos +Parasitoids

Limonicus +Parasitoids

Limonicus + Food +Parasitoids

• Limonicus: 150 mites/m2 – one release; Encarcia/Eretmocerus mix: high release rate• Avg. 19 °C ; 1 bench/trt

RESULTS: Potted Gerbera

• Limonicus: 150 mites/m2 – one release; Encarcia/Eretmocerus mix: High release rate; Avg. 19 °C; 1 bench/trt

0

1

2

3

4

5

6

7

8

1 2 3

Avg.

GH

WF

/ pla

nt

Week After Treament

ParasitoidsOnly (control)

Kontos +Parasitoids

Limonicus +Parasitoids

Limonicus +Food +Parasitoids

RESULTS: Potted Gerbera

Outcomes:• Kontos too slow + may have disrupted biocontrol by

wasps (foliar application)• Results suggest Limonicus has potential to help clean

up GHWF populations in winter months• Attempted to repeat trial several weeks later but not enough

WF pressure after grower added Limonicus to crop!

Trial 1: GHWF control in Potted Gerbera

Grower currently using:- Limonicus in propagation (year round)- Wasp mix out in GH (Mar – Oct)- Limonicus out in crop Oct-Mar if necessary- Relying on Swirskii for thrips control only

Trial 2: GHWF control in Cut Gerbera

• Control History: Biocontrol + Soap applications• Issue: Unhappy with level of control parasitic wasps +

Swirskii were providing over winter• Leading to high levels once temps. Warmed up

Results: GHWF control in Cut Gerbera

0

1

2

3

4

5

6

Avg.

GH

WF

/leaf

Mites + Wasps Mites+ Wasps + Pollen

0

0.5

1

1.5

2

2-Dec 22-Dec 11-Jan 31-Jan 20-Feb

Avg.

imm

atur

e W

F/le

af

Outcomes:• Suggests Limonicus can help keep WF populations

stable in winter in cut gerbera; pollen feeding may help

• Grower happier with GHWF numbers this year than previous years

Trial 1: GHWF control in Potted Gerbera

Grower currently using:- Wasp mix (Mar – Nov)- Wasps + Limonicus (Nov-Mar)- Spot treatments with Delphastus, Soap

Trial 3: Bemisia control in Mandevilla• History: Grower already using Eretmocerus eremicus

and Swirskii at high rates; pesticides didn’t work in past (Kontos, Beleaf, others).

• Issue: not happy with results using current bios

Treatment 1 (control) Treatment 2 Treatment 3

- 2 blocks/trt; 20 plants/trt sampled biweekly

Trial 3: Bemisia control in Mandevilla

Results: Bemisia control in Mandevilla

0

5

10

15

20

25

30

12-Nov 2-Dec 22-Dec 11-Jan 31-Jan 20-Feb 11-Mar 31-Mar 20-Apr

AVG

. WH

ITEF

LY P

ER P

OT

Wasps Only + Limonicus + Limonicus with Food

• Eretmocerus, High Rate: 75 wasps/m2/week; Limonicus, High Rate: 150 mites/m2

every 3 weeks ;16-18 °C

Koppert “heavy curative rate” = 9/m2/week for 3 weeks= 28 wasps/m2 total

Us: 75 wasps/m2/week= banana pants (1000 waps/m2 total)

Results: Bemisia control in Mandevilla

0

5

10

15

20

25

30

12-Nov 2-Dec 22-Dec 11-Jan 31-Jan 20-Feb 11-Mar 31-Mar 20-Apr

AVG

. WH

ITEF

LY P

ER P

OT

Wasps Only + Limonicus + Limonicus with Food

• Eretmocerus, High Rate: 75 wasps/m2/week; Limonicus, High Rate: 150 mites/m2

every 3 weeks ;16-18 °C

Koppert “heavy curative rate” = 250 mites/m2 for 3 weeks = 750 mites/m2 total

Us: 150 mites/m2 every 3 weeks = 750 mites over 14 weeks

Koppert “heavy curative rate” = 9/m2/week for 3 weeks= 28 wasps/m2 total

Us: 75 wasps/m2/week= banana pants (1000 waps/m2 total)

Results: Bemisia control in Mandevilla

0

5

10

15

20

25

30

12-Nov 2-Dec 22-Dec 11-Jan 31-Jan 20-Feb 11-Mar 31-Mar 20-Apr

AVG

. WH

ITEF

LY P

ER P

OT

Wasps Only + Limonicus + Limonicus with Food

First Release

• Eremicus, High Rate: 75 wasps/m2/week; Limonicus, High Rate: 150 mites/m2

every 3 weeks ;16-18 °C

Results: Bemisia control in Mandevilla

0

5

10

15

20

25

30

12-Nov 2-Dec 22-Dec 11-Jan 31-Jan 20-Feb 11-Mar 31-Mar 20-Apr

AVG

. WH

ITEF

LY P

ER P

OT

Wasps Only + Limonicus + Limonicus with Food

First Release

• Eremicus, High Rate: 75 wasps/m2/week; Limonicus, High Rate: 150 mites/m2

every 3 weeks ;16-18 °C

Results: Bemisia control in Mandevilla

0

5

10

15

20

25

30

12-Nov 2-Dec 22-Dec 11-Jan 31-Jan 20-Feb 11-Mar 31-Mar 20-Apr

AVG

. WH

ITEF

LY P

ER P

OT

Wasps Only + Limonicus + Limonicus with Food

First Release

• Eremicus, High Rate: 75 wasps/m2/week; Limonicus, High Rate: 150 mites/m2

every 3 weeks ;16-18 °C

• Outcomes• Even exorbitantly high rates of wasps did not provide

control in winter (more ≠ better)

• Limonicus $$$ but MUCH better than industry standard in winter

• Parasitoids get themselves together in early March

Trial 2: Limonicus for Bemisia control

Grower current using:- Dips at receipt- Eretmocerous only March – Oct- Limonicus only Oct-March- Relying on Swirskii for thrips control only

Where does Limonicus fit in?

• Though Swirskii is sold for WF control, not a key player

• Limonicus more effective than WF parasitoids for both GHWF and Bemisa control in winter

• Just adding more parasitoids doesn’t work

• Limoncus probably only makes sense in from Oct-Mar max. due to $$$• Qs: Can you skip Swirskii for thrips

control when using Limonicus? Use lower rate?

Summary

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