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Biological Control of Key Pests of

Greenhouse and Nursery Production

Edwin Lewis & Michael Parrella Department of Entomology & Nematology

University of California, Davis

UC ANR Pesticide Use Report Analysis Workgroup Meeting Tuesday, June 9th, 2015

PES3001, UC Davis Campus

Overview of Presentation • Value of the industry • Pesticide use in greenhouses and nurseries • Survey of biological control practices (?) • Facts about biological control in greenhouses • Case study: Entomopathogenic nematodes • Advantages as we look to the future

Pesticide Use • 2002: 22,259 lbs. a.i. applied to 27,346 acres of floriculture crops. • 2012 - 11,498 lbs. a.i. applied to 23,875 acres. • > 50% decrease in pesticide use

• Data on pesticide use in greenhouse vegetable production less

available • Fewer pesticides registered for use on greenhouse vegetables. • Tomato growers use bumblebees for pollination

• The situation for the nursery industry (outdoor plants in containers) is

not as positive. • Acreage stable from 2002 - 2012 the number of pesticide

applications actually increased • Partially due to quarantine requirements associated with invasive

species.

Greenhouse/Glasshouse Production • California is the largest producer of greenhouse vegetables

in the US – approximately 300 acres / $112 million (Hickman, 2012).

• Tomatoes are the largest greenhouse vegetable crop

– New regulation: a tomato may be labeled “greenhouse grown” when is produced in a fixed steel structure using irrigation and climate control.

– Tomatoes grown under variable conditions that do not meet the “greenhouse grown” definition may now be labeled as “hothouse”.

Greenhouse/Glasshouse Production • Sustainable production: large increases in greenhouse

vegetable crops • Major advantages over their field counterparts.

– In 25 years, US greenhouse vegetable industry has grown from about 0.5 % of retail grocery sales of tomatoes to >60 %.

– Additionally, in the ‘big box’ stores 72% of the tomatoes sold are greenhouse grown

– A large scale greenhouse can grow 30 times more pounds of tomatoes per acre using 85% less water than traditional field production due to the use of recycled water. (Bledsoe, 2014).

Greenhouse/Glasshouse Production • The conversion rate of water used to tomatoes produced is

much higher in the greenhouse than in the field. • In addition the use of IPM and biological control in

greenhouse tomatoes has a rich history and is more widely used with documented success compared to field grown tomatoes.

• Gross sales for greenhouse vegetables in California are valued at $378,00 per acre (Hickman, 2012)

Note: This is very similar to the per acre value of cut flowers

Facts About Biological Control in Greenhouses • Although crop value is high, this does not mean that

growers are more willing to use biological control – They always look at the economics and effectiveness of their choices

• There are many commercially available Arthropod natural enemies but 10 make up more than 90% of the natural enemies used – Encarsia formosa, Phytoseiulus persimilis, Eretmocerus eremicus, Amblyseius

swirksi, Aphidius colemani, Aphidoletes aphidomza, Diglyphus iseae, Stratiolaelaps scimitus, Amblyseius cucumeris, Orius insidiosus

• There will be few new commercially available natural enemies • We may be able to better utilize ‘native’ natural enemies that move

into the greenhouse

• Microbial insecticides can be effective and are increasing in number – Entomopathogenic nematodes, fungi, bacteria

Incorporating Entomopathogenic Nematodes Into Production Systems:

What Needs to Change and What Can

Stay the Same?

Using Microbials in IPM • Do not have to change everything about

crop management

• Many microbial insecticides fit into current production plans with minimal effort and change

• They require specialized information about their use

Infective Stage Juvenile Steinernema carpocapsae

Uses in Greenhouse/Nursery

• Fungus gnats • Black vine weevil • Diaprepes root weevil • Thrips • Leafminers? • Borers

Three Areas for Thought • Compatibility

• Habitat assessment and

modification

• EPN application and formulation

Three Areas for Thought • Level 1:

– What other management materials/methods

need to change so I don’t kill my biological control agents outright?

Simple Compatibility • Lots of reliable information available

– Herbicides: • Forschler et al. 1990. Steinernema feltiae activity and infectivity in response to herbicide exposure

in aqueous and soil environmentsJIP 55: 375-379

– Insecticides • Li et al. 1994. Effects of Insecticides on the Entomopathogenic Nematode Steinernema carpocapsae

Weiser. Appl. Entomol. Zool. 29: 539-547

– Fungicides • Krishnayyaand & Grewal. 2002. Effect of Neem and Selected Fungicides on Viability and

Virulence of the Entomopathogenic Nematode Steinernema feltiae. Biocontrol Sci. Technol. 12: 259-266.

– Fertilizer

• Shapiro et al. 1999. Effects of Fertilizers on Suppression of Black Cutworm (Agrotis ipsilon) Damage with Steinernema carpocapsae. J Nematol. 31: 690–693.

…..But, is Compatibility Enough?

• When can EPNs do something that conventional approaches can’t do? – Seeking fungus gnats beneath soil surface – Dispersing via flying adults

Navel Orangeworm Pest of many nut crops in CA Multivoltine Overwinters as larvae in dropped nuts Larvae in nuts susceptible to EPN infection The only material useful to attack overwintering generation

Three Areas for Thought • Level 2:

– What conditions in the crop

environment can be changed to optimize field viability and efficacy?

Habitat Assessment • Improved tools for assessment of

soil for suitability for EPNs

Diaprepes abbreviatus Life Cycle

Adults

Eggs

Neonates

Larvae Pupae

Perc

ent m

orta

lity

Sand Sandy Clay Loam 0

20

40

60

80

100

+ S. riobrave Untreated

Field Experiment

Nematodes Most Effective in Coarse Sandy Soils

(Duncan et al., unpublish

What to do in California?

• Soil type has major impact on efficacy

• Soils in California much more diverse than in Florida

Objective • Develop methods to determine whether

or not entomopathogenic nematodes will be effective biological control agents of citrus root weevils in CA citrus

Column Assay Units

Num

ber o

f S. r

iobr

avae

(±S

E)

Soils

0

200

400

600

800

1000

1 2 3 4 5 6 7 8 9 10

11 12 13 14 15

16 17 18 19

20 21 22 23 24

25 26 27 28 29 30 31 32 33

S. riobrave – Efficacy Bioassay

8

9

11 10 12 13

7

4

24

25

26

6 5

3

1

2

23

22

21

14

15 16

17 18

19 20

28

27

31 30

32

34

35

33

36

29

S1

S2

S3

S4

S5

Silt

Cla

y

pH

EC

MR

A

B

C

D O

M

Cluster analysis: grouped similar soils based on physical and chemical characteristics

Med

ian

Num

ber o

f Nem

atod

es (±

25t

h per

cent

ile )

Efficacy of EPNs

in different clusters

600

0

100

200

300

400

500 (a)

0

20

40

60

80

100

120

25cm

0

10

20

30

40

50

60

A B C D

Cluster

(b)

(c)

10cm

50cm

a a

b c

a b

c

d

a

b b

c

Kaspi et al., 2008

8

9

11 10 12 13

7

4

24

25

26

6 5

3

1

2

23

22

21

14

15 16

17 18

19 20

28

27

31 30

32

34

35

33

36

29

S1

S2

S3

S4

S5

Silt

Cla

y

pH

EC

MR

A

B

C

D O

M

Cluster analysis: grouped similar soils based on physical and chemical characteristics

Using This Information

Can soilless media be constructed to enhance persistence and efficacy of microbial insecticides?

Foraging of S. riobrave in Soilless Media Components

0

2

4

6

8

10

Sand Peat Moss Cedar/PineBark

RecycledPlant

Material

Redw oodSaw dust

(w /o bark)

Redw oodSaw dust(w /bark)

Perlite Vermiculite

Dis

tanc

e tr

avel

led

(cm

)

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ab

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Foraging of S. riobrave in Soilless Media Components

0

2

4

6

8

10

Sand Peat Moss Cedar/PineBark

RecycledPlant

Material

Redw oodSaw dust

(w /o bark)

Redw oodSaw dust(w /bark)

Perlite Vermiculite

Dis

tanc

e tr

avel

led

(cm

)

02550

a

ab

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Movement and Infection of S. riobrave

Three Areas for Thought

• Level 3: – What can be altered in the nematode and/or

formulation to optimize field viability and efficacy?

• Application of EPNs via infected cadavers

• Use of adjuvants (Barricade) to prolong field lifespan

Advantages As We Look to the Future

• Increased costs of some new pesticides make biological control economically competitive

• Increasing state and federal regulation of pesticide use • Increasing problems with pesticide resistance • Negative impact on overall plant quality with repeated

applications of insecticides • Potential for integration of some of the newer, more specific

pesticides (i.e., insect growth regulators; entomopathogens) with natural enemies

Advantages As We Look to the Future • General move toward sustainability and 3rd party

certification of sustainable practices lead by the California Cut Flower Commission

• A new generation of growers more concerned about pesticide use and their potential non-target effects

• The field expertise offered by the international and local commercial insectaries

• The ability of growers to screen a greenhouse (physical barriers)

• The potential to completely clean a greenhouse between crops

Advantages As We Look to the Future

• Year-round production systems allow natural enemies to establish and move from crop to crop

• Advances in the use of banker plants and new mechanical applicators for natural enemy release

• The greater and more effective use of entomopathogens for control of all agricultural pests