Armyworm Management in Africa:

What do we know and what can we learn?

1 Professor Ken Wilson ken.wilson@lancaster.ac.uk

FAO Expert Meeting on Fall Armyworm Accra, Ghana (18th – 20th July 2017)

Fall armyworm

(Spodoptera frugiperda)

African armyworm

(Spodoptera exempta)

Prof Ken Wilson Professor of Evolutionary Ecology

Insects & Parasites Ecology Group

Lancaster Environment Centre

Lancaster University

ken.wilson@lancaster.ac.uk

Host-pathogen

interactions

Ecology of insect

crop pests

Biocontrol of crop

pests using

baculoviruses

Nutritional ecology

of insects

1990

Unanswered questions about Fall armyworms:

FAO Harare meeting February 2017

• Where did the Fall armyworm come from?

• How does its life-cycle differ from that of the African

armyworm?

• Will it spread and will it persist long-term?

• How do we control it?

Unanswered questions about Fall armyworms

• Where did the Fall armyworm come from?

• How does its life-cycle differ from that of the African

armyworm?

• Will it spread and will it persist long-term?

• How do we control it?

Unanswered questions about Fall armyworms

• Where did the Fall armyworm come from?

• How does its life-cycle differ from that of the African

armyworm?

• Will it spread and will it persist long-term?

• How do we control it?

FAW: 2 strains, 4 haplotypes (Nagoshi et al.)

Genetic analysis of Fall armyworm from Africa

Maximum likelihood

condensed bootstrap

barcode of Zambian

larval samples using

135 bp mitochondrial

cytochrome oxidase I

(COI) sequence.

Results from Tanzania

and Rwanda being

processed.

Fall armyworm

rice strain (RS)

Fall armyworm

corn strain (CS)

Samples courtesy of ZARI

Genetic analysis of Fall armyworm from Africa:

strain ID using CO1 markers

68

32

Overall Tanzanian FAW Strains (n = 28 moths from trap in

maize field, 1 region)

% Rice % Corn

82

18

Overall Zambian FAW Strains (n = 44 larvae on maize, all

regions)

% Rice % Corn

Overall Rwandan FAW Strains (>300 larvae on

maize, all regions)

% Rice % Corn

36

64

Overall Togo FAW Strains (n = 62 larvae on maize, all regions, Nagoshi et al 2017)

% Rice % Corn

Genetic analysis of Fall armyworm from Africa:

haplotype ID using CO1 polymorphic sites

33

67

Overall Tanzanian Corn Strain Haplotypes

(n = 9 moths)

% h1 % h2 % h3 % h4

100

Overall Zambian Corn Strain Haplotypes

(n = 8 larvae)

% h1 % h2 % h3 % h4

Note relatively small

sample sizes

Unanswered questions about Fall armyworms

• Where did the Fall armyworm come from?

• How does its life-cycle differ from that of the African

armyworm?

• Will it spread and will it persist long-term?

• How do we control it?

How will Fall and African armyworms interact?

African armyworm

(Spodoptera exempta)

Fall armyworm

(Spodoptera frugiperda)

Photo: G. Goergen

Photo: Kansas State University

Photo: K. Wilson

Photo: K. Wilson

• Movement and outbreaks of both species

determined by similar environmental

factors

• Both eat maize (vegetative vs

reproductive parts)

• FAW is cannibalistic (more competitive?)

• Both susceptible to disease – do they

share pathogens (enemy release vs

spillover)?

Unanswered questions about Fall armyworms

• Where did the Fall armyworm come from?

• How does its life-cycle differ from that of the African

armyworm?

• Will it spread and will it persist long-term?

• How do we control it?

Presumed distribution of FAW: Feb 2017

Data from Rose et al. (2000)

https://youtu.be/A8VTL1sP0KE

Presumed distribution of FAW: Jun 2017

Data from Rose et al. (2000)

https://youtu.be/CWhk1u2DBjU

Historical analysis of armyworm

Patterns of African armyworm outbreaks

16

Providing free accessible information on

Fall and African armyworm The Armyworm Network http://www.lancaster.ac.uk/armyworm @spodoptera007

Fall armyworm spread movie: https://youtu.be/CWhk1u2DBjU (updates available on the Armyworm Network)

50 years of African armyworm outbreaks: https://youtu.be/A8VTL1sP0KE

Early-warning system needed – the power of pheromones!

Courtesy of Prof Nkunika, UNZA

Early-warning system needed – the power of pheromones!

Rain gauge

Community forecaster with

pheromone traps

Community-based armyworm forecasting:

- Pheromone trap

- Rain gauge

- Local operators chosen by the village

- Simple rules for assessing risk of attack

Mushobozi, Grzywacz, Musebe, Kimani & Wilson (2005) Aspects of Applied Biology 75: 37-45.

How do we control it?

• Chemicals?

- Which chemicals are effective and safe? Resistance?

• GM crops?

- Is Africa ready? Costs? Resistance?

• Biological pesticides?

Biological control

• Bt pesticide spray can be effective (resistance?)

• Botanicals (e.g. neem) can also be effective, especially

for smallholder farmers who lack access to chemicals

• Biopesticides – natural diseases of insects (viruses,

fungi, bacteria, etc.) …

Botanicals

• Botanicals (e.g. neem, Tephrosia vogelii, pawpaw, etc.)

can also be effective, especially for resource-poor

smallholder farmers who lack access to chemicals.

Biopesticides

Ken Wilson (Lancaster University,

U.K.)

David Grzywacz (Natural Resources

Institute, U.K.)

Wilfred Mushobozi (EcoAgriConsult Ltd,

Tanzania)

A virus-processing plant built in Tanzania

ready to produce tonnes of SpexNPV biopesticide locally

Funding for registration and commercialisation to end product is still needed

There is a similar biopesticide (SfMNPV) that is being produced commercially against Fall armyworm in the Americas!

Does SpexNPV also kill African FAW?

Probably not … but

Very preliminary results at this stage (just one replicate of each, single isolates)

Resistance management

• Baculoviruses compatible with other IPM approaches due to

low impact on non-target organisms

• Baculoviruses tend to be genetically diverse (more targets

for selection) - >100 genotypes of SpexNPV in Tanzania alone

• Resistance very unlikely (only one known case, swiftly

resolved)

• Governments panic buy pesticides, so let’s make sure there

are safe pesticides for purchase (registration).

What about microbes in the wild - NPV?

Preliminary analyses of Tanzanian moths suggest the presence of

SfMNPV virus – possibly 2 strains (but needs sequencing); lower

prevalence in Zambian larvae – plus other viruses may be present.

What about microbes in the wild - fungus?

What about other natural enemies?

Earwig (Dermaptera)

Parasitoids (incl. Campoletis sp.)

Other natural enemies of AAW well described

Summary • Fall armyworm has spread across Africa at an alarming rate,

though the true impact on maize production has yet to be

established

• We know lots more than we did even just a few months ago –

but there still remain many unanswered questions

• We can learn a lot from African armyworm experiences, as

well as experiences in the native range of the FAW

• We now need a regional strategy for the monitoring and

management of this new invasive pest.

The End

LANCASTER UNIVERSITY

S. frugiperda host strain: Corn Strain (CS) EcoRV negative (GATACC), Rice Strain (RS) = EcoRV positive (GATATC)

S. frugiperda host strain: Nucleotides 1178-1183: Corn Strain (CS) EcoRV negative (GATACC), Rice Strain (RS) = EcoRV

positive (GATATC)

Nucleotides 1164/1287 Corn Strain Haplotype 1 = A/A Corn Strain Haplotype 2 = A/G Corn Strain Haplotype 3 = G/A Corn

Strain Haplotype 4 = G/G