Planet Earth has always been in a State of Change; the rate of change has never been constant

Global Issues in Nematode Ecology and Management

Commonalities and Differences in Nematode Issues across the Globe

Howard Ferris

Department of NematologyUniversity of California Davis

Big Issues in World Agriculture,Economy and Ecology

1. Global climate change and mitigation measures

2. Fossil fuel depletion and costs

3. Global trade agreements

4. Land ownership and land tenure

Context: the need to provide food, fiber, water, and shelter for 6.7 billion people

…………and their interlinkages

Adaptation:Shifts in land-use patterns and management practices

Climate Change

Land TenureTrade Agreements

Energy Costs

Big Issues in World Agriculture,Economy and Ecology

Mitigatio

n Mitigation

Mitigatio

n

Mitigation

Mitigation-slowing the process

Adaptation-minimizing the effect on services

How are different nematode functional groups affected by climate and land-use change?

Provide Services Provide Disservices

Mitigation tradeoffs?

A simplistic analysis of climate change effects on soil

nematodes

But.the same factors affect growth and tolerance of hosts, prey and natural enemies of the nematodes. ….And management decisions of the environmental steward.

So, the net outcome is unpredictable, at least by me.

Temperature

Higher Lower

Higher +++ -+

Rainfall

Lower +- ---

Nematode winners and losers?

Thermal amplitude of bacterivores

Ferris et al., 1995We have some of the necessary information……

Physiological Ecology

Foley et al., Science 309, 570 -574 (2005)

A conceptual framework for comparing trade-offs on ecosystem services

But we need to think at a larger scale……

Professor Shenglei Fu, Chinese Academy of Sciences:

Mitigation - reforestation – altering climateAdaptation - vegetation mixes to maximize functions and services

Services:

•pulp production

•wildlife habitat

•pollination

•refugia

•erosion control

•groundwater quality

•carbon sequestration

•decomposition

•nutrient cycling

•nutrient retention

•mineralization

•soil quality

•esthetics

•public education

Total area 50 ha.Each plot 1 ha.Treatments 14Replications 3

China, 2007

Landscape Ecology

Mitigation/Adaptation: Coffee under tree shade – Costa Rica, 2008

•Temperature effects

•Rhizosphere interactions

•Host effects

Farmscape Ecology

Winter cover crop – bell beansCalifornia, 2006

No-till soybeans, Brazil, 2006

•Soil fertility•Organic matter•Food web activity•Soil structure

•Fossil fuel reduction •Habitat conservation •Food web activity•Soil structure

Adaptations

Adapted from:Meine van NoordwijkWorld Agroforestry CentreBogor, Indonesia

Environmental and econom

ic pressures

Current crops/animals

Newcrops/animals

Newcropping system

Newfarming system

Non-farminglivelihoods

Is life still possible on this planet?

Sustainagility:Change

crops/animals

Sustainagility:Change

cropping system

Sustainagility:Change

farming system

Sustainagility:Shift to non-farming

livelihood

Sustainagility:Migration to another

region of planet

Sustainability of . . .

Soil Fauna

Sustainability is a journey, not a destination

(Howard Shapiro, Mars Inc.)

•Consistent N-yield over 75 years without input

•N-yield similar to that of high input wheat

Structure Index

Basal Index

From Glover et al., subm.

Land-use change in Kansas:Soil food web effects

Community Ecology

Soil Food Web: Functions and Services in relation to punctuated and continuous resource supply

O Pr

B

F

P

Mineralization

Reverting to prairie?

Need to understand invasion biology of omnivores and predators

O Pr

B

F

P Regulation Eas

ier

to g

o in

thi

s di

rect

ion

Some Global Issues in Nematode Management

Nematicide tradeoffs – production enhancement vs. economics, environmental hazards and food web simplification (pesticide treadmill)

Zimbabwe, 1961

California, 1999

Ten Years After Cu Application

0

10

20

30

40

50

60

0 200 400 600 800

Cu Concentration (Kg/ha)

Pre

dat

or

Nem

ato

des

Korthals et al., 1998

Impact on Higher Trophic Levels

California, 1973

An ideal:

Biodiversity-friendly nematicides that protect roots without killing non-target soil organisms:

“immunogenic nematicides”

Global Issues in Nematode Management

Management practices in industrialized agriculture result in food web simplification – cp1 and cp2 bacterivores and fungivores predominate

Reduction in cp3, 4, 5 higher trophic levels

Costa Rica, 2008

Farmscape Ecology

Global Issues in Nematode Management

Nematode biomass in soil food web

Conventional

Organic

Bacterivore Biomass

Bacterivore Biomass

Herbivore Biomass

0

1

2

3

4

5

6

7

8

2 3 4 5 6 7 8 9

Ln Biomass Prey

Ln B

iom

ass

Pred

ator

s

y=-3.18+1.34x; r2=0.59, p<0.05

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 200 400 600 800

Biomass of Predators

Prop

orti

on o

f Her

bivo

res

Conventional

Organic

y=0.64-0.07(ln(x+1)); r2=0.36, p<0.01

What is the rhizosphereeffect of Theobroma on Musa?

molecular signals

border cells

protozoanematodes

arthropods

Hawes et al., 1998Farrar et al., 2003 Hirsch et al., 2003

Molecular Ecology

Other Nematode Services – enhancing soil fertility

bacteria and bacterivore nematodes

with twenty nematodes

0 nematodes with five nematodes

Fu et al. 2005

0

20

40

60

80

100

0 5 10 20 40 80 160

Nematode Abundance

Bact

eria

l Cel

lsPositive feedback Overgrazing

0

20

40

60

80

100

0 5 10 20 40 80 160

Nematode Abundance

Bact

eria

l Cel

ls

0

20

40

60

80

100

0 5 10 20 40 80 160

Nematode Abundance

Bact

eria

l Cel

lsPositive feedback Overgrazing

An example of positive and negative feedback

Behavioral Ecology

The Service - N mineralization- Functional Complementarity

0

100

200

300

400

500

600

1-A

pr

8-A

pr

15-A

pr

22-A

pr

29-A

pr

6-M

ay

13-M

ay

20-M

ay

27-M

ay

3-Ju

n

10-J

un

17-J

un

24-J

un

1-Ju

l

8-Ju

l

15-J

ul

22-J

ul

29-J

ul

Mesorhabditis

Cruznema

Rhabditis

Total N

The Importance of Biodiversity

The Service - N mineralization- Functional Continuity

0100200300400500600700800900 Mesorhabditis

Acrobeloides bod

Total N

California, 1996

Depleted Soils of AfricaCereal Yields

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

1962

1965

1968

1971

1974

1977

1980

1983

1986

1989

1992

1995

1998

2001

2004

Mt/

Ha

DevelopedCountries

AsiaDeveloping

Latin America& Carribean

Sub-SaharanAfrica

FAO - redrawn

Corn, cassava, beans - Congo

A

B

C

D

E

F

Crossover Rotations – Oostenbrink, 1959

A B C D E F

Netherlands, 1965

California, 1982

Land-use Change: The Global Spread of Nematodes

Examples:Citrus – Tylenchulus semipenetrans worldwideGrapevines and their nematode complexesSoybeans and Heterodera glycinesCereals and grass seeds – Anguina spp.Potatoes – Globodera and Meloidogyne spp.Bananas and Radopholus, Helicotylenchus, Meloidogyne, Pratylenchus.

Most major nematode pest problems in California are caused by non-native species.

Effects of global exploration, human migration, modern transportation:Despite regulatory efforts, major crops throughout the world support the same nematode complexes.

Some nematodes have attributes of invaders:

ArrivalEstablishmentIntegrationSpreadDetection Escape

Invasion Biology

sugarbeet cyst nematode

Sugarbeet Cyst Nematode - Heterodera schachtii

sugarbeet production

•Sources of resistance and other control/mitigation measures should apply in new areas of production. Caveat: consider the local acceptability of new varieties and the availability of appropriate infrastructure/technology.

But…..• Every year, we lose between 17,000 and 100,000 species as the result of human activities (The Sixth Extinction. Leakey and Lewin, 1995)• That represents an enormous loss of functions, services and genes.

•The problem is compounded by proprietary ownership of resistance genes and commercialization of seed sources, reducing local selection of desirable traits.

Adaptation to Nematode Globalization and Land-use Change

Dr. Vandana Shiva’s movement concerned with saving seeds, trading seeds, farming without corporate-derived seed.

Ghandi: “You cannot monopolize this which we need for life.”

Genetic diversity is a common legacy – it should be conserved, not owned

Svalbard Global Seed Vault will store three million different crop varieties in case of a worldwide

catastrophe.

Global Issues in Nematode Ecology and Management:Summary and Research Directions……

Organismal level:•Adapt knowledge from biological models and microcosm experiments

Farmscape and Landscape levels:•Adapt management to scale of system•Develop a biodiversity-friendly landscape

Global Issues in Nematode Ecology and Management:Summary and Research Directions……

Organismal level:•Adapt knowledge from biological models and microcosm experiments

Farmscape and Landscape levels:•Adapt management to scale of system•Develop a biodiversity-friendly landscape

Thank you