Fall armyworm, major threat, CABI

February 2017. After the posting of an item from PhysOrg (below) entitled: Crop destroying armyworm ‘major threat’ to world farming: NGO there were a number of comments from members.

One member wrote: After all the ‘false news’ (at least it is about something important!) I am still confused – this report says:

‘A crop-destroying caterpillar native to the Americas is “spreading rapidly’ in Africa…
‘Two species of the fall armyworm, which can devastate maize production, have been found in Ghana…’
‘This is the first time it has been shown that both species or strains?are established on mainland Africa’

The member had assumed that S. frugiperdahad arrived in Africa in a big way and was causing havoc alongside S. littoralis.

In response, Matthew Cock from CABI wrote:

Spodoptera frugiperdahas been thought to occur as two strains since the 1980s: a rice strain and a corn (maize) strain. Recent DNA studies indicate that there are two barcode species variously referred to as S. frugiperdasp. 1 and S. frugiperdasp. 2. , S. frugiperdaDHJ01 and S. frugiperdaDJH02, corn strain and rice strain, C strain and R strain, with a mean sequence divergence of 2.1% and different Barcode Index Numbers: ACE4783 and AAA4532. They are morphologically indistinguishable but align with the maize and rice strains recognised earlier – although in fact both feed readily on maize. Whether they represent two species, two strains or two haplotypes is not entirely clear yet, but a 2.1% divergence is comparable with known Lepidoptera sibling species and there is some evidence of barriers to hybridization, so opinion is shifting towards two species. The two species / strains / haplotypes are sympatric from Argentina to southern USA and both disperse into temperate regions. Georgen et al 2016 report one species / strain / haplotype in São Tomé , and the other from Nigeria. The work of the Plant Protection and Regulatory Services Directorate of Ghana and CABI’s Plantwise team found that they are both present in Ghana attacking maize, having spread from further east, and the indications are that both are spreading together through Africa.

So for the moment, we can refer to them as ‘species / strains / haplotypes’, but you will appreciate that most journalists will find this confusing, and opt for something simpler.

For more detail:

Goergen, G., Kumar, P.L., Sankung, S.B., Togola, A. & Tamò, M. First report of outbreaks of the fall armyworm Spodoptera frugiperda(J E Smith) (Lepidoptera, Noctuidae), a new alien invasive pest in West and Central Africa.PLoS ONE11(10),e0165632, doi:10.1371/journal.pone.0165632 (2016).
Pashley, D.P., Johnson, S.J. & Sparks, A.N. Genetic population structure of migratory moths: the fall armyworm(Lepidoptera: Noctuidae). Ann. Entomol. Soc. Am.78,756–762 (1985).
Juárez, M.L. et al. Host association of Spodoptera frugiperda(Lepidoptera: Noctuidae) corn and rice strains in Argentina, Brazil, and Paraguay. J. Econ. Entomol.105,573–582 (2012).
Kergoat, G.J. et al. Disentangling dispersal, vicariance and adaptive radiation patterns: A case study using armyworms in the pest genus Spodoptera(Lepidoptera: Noctuidae). Molec. Phylogenetics Evol. 65,855–870 (2012).
Dumas, P. et al. Phylogenetic molecular species delimitations unravel potential new species in the pest genus SpodopteraGuenée, 1852 (Lepidoptera, Noctuidae). PLoS ONE10(4),e0122407, doi:10.1371/journal.pone.0122407 (2015).
Dumas, P. et al. Spodoptera frugiperda(Lepidoptera: Noctuidae) host-plant variants: two host strains or two distinct species? Genetica143,305–316 (2015).

See also, CABI Invasive blog: CABI Invasive Blog:
https://mail.google.com/mail/u/0/#inbox/15a28827e4c1649a?compose=15a29ae65648c04b

PhysOrg

https://phys.org/news/2017-02-crop-destroying-armyworm-major-threat-world.html

Crop-destroying armyworm ‘major threat’ to world farming: NGO

February 6, 2017

Essential for food security in large parts of Africa, maize is particularly vulnerable to the fall armyworm larvae, which burrow into the cobs

A crop-destroying caterpillar native to the Americas is “spreading rapidly” in Africa and threatens farming worldwide, the Centre for Agriculture and Bioscience International (CABI) warned on Monday.

Two species of the fall armyworm, which can devastate maize production, have been found in Ghana, and could spread to Asia and the Mediterranean, according to the Britain-based not-for-profit group.

“This is the first time it has been shown that both species or strains are established on mainland Africa” CABI chief scientist Matthew Cock said after analysis was conducted in the group’s labs.

“Urgent action will be needed to prevent devastating losses to crops and farmers’ livelihoods,” he said.

Essential for food security in large parts of Africa, maize is particularly vulnerable to the larvae, which attack the crop’s growing points and burrow into the cobs.

Maize or corn accounts for almost 70 percent of total cereal production in southern Africa according to the Famine Early Warning Systems Network, with a large percentage grown directly for home consumption.

The pest is also known to have caused major damage to other economically important crops including rice, soybean and cotton.

The United Nations Food and Agricultural Organization (FAO) has announced an emergency regional meeting to be held on February 14-16 in Harare, Zimbabwe after the pest was also identified in southern Africa.

“Preliminary reports indicate possible presence (of the pest) in Malawi, Mozambique, Namibia, South Africa, Zambia and Zimbabwe” FAO subregional coordinator for southern Africa, David Phiri, said in astatement last week.

Zambia has already spent $3 million (2.8 million euros) in an attempt to control the pestthat has affected approximately 130,000 hectares (320,000 acres) of crops.

But the FAO emphasised that the full extent of the damage there and in other affected countries is yet to be established.

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