Plant Parasitic Nematodes
Nematodes are one of the world's major
agricultural pests, causing an estimated $80 billion in worldwide crop damage
annually. These parasitic worms attack crop root systems siphoning crucial nutrients,
diminishing yields, and making the plant more vulnerable to secondary infections,
drought, and other stresses. Traditional nematicides are environmentally dangerous,
expensive, and difficult to apply. Nematode-infested crops with major economic losses
include soybeans, potatoes, bananas, cotton, corn, citrus, strawberries, tomatoes,
coffee, carrots, peppers, turf, and greenhouse ornamentals.
Divergence's innovations in this area include novel mode-of-action nematicides and crops
with resistance to nematode infection. Divergence is achieving gains in both parasite
control efficacy and environmental safety over current grower options.
Nematicides
Nematode control has traditionally depended on highly toxic contact and fumigant
pesticides which have now been restricted or eliminated in the United States by
the Environmental Protection Agency (EPA). Similar restrictions have occurred in
other countries. Organophosphate and carbamate contact nematicides are non-specific
neurotoxins and are among the most dangerous pesticides for humans, birds,
fish, bees, and other non-target organisms. Fenamiphos was removed from the U.S.
market in 2007 due to its toxicity, carbofuran is also slated for removal, and
use of aldicarb has been further restricted. Methyl bromide (MeBr) was the predominant
fumigant used for nematode, disease and weed control in crops like tomatoes and
strawberries. An ozone-depleting compound as well as a broadly toxic molecule, MeBr
production and import ended in the U.S. in 2005 under the Montreal Protocol. Use
of remaining stockpiles requires annual critical use exemptions from the
international protocol. Other fumigants like Metam-Sodium and 1,3 dichloropropene
are also highly toxic and are restricted in their use. It is estimated that the
current market for nematicides is between $700 million and $1 billion each year
worldwide. However, an analysis of the economic impact of nematodes and growers'
decision-making indicates that, given effective and safe control methods, the
nematicide market could grow to several billion dollars annually. Damage caused by
nematodes is comparable to that caused by insects and worldwide insecticide sales are
typically $8 billion annually. Divergence is discovering and developing nematicides with novel
modes of action and superior safety profiles to current products. The EPA Reduced
Risk Initiative allows for accelerated timelines for regulatory review for safer
pesticidal products.
Nematode Resistant Crops
An alternative means of nematode control is the generation of plants with internal
nematode resistance. While some crops have genetic sources of resistance, many
lack identified resistant germplasm. Furthermore, selection for parasites that
can overcome genetic resistance in crops like soy and potato has rendered some
traits ineffective. Providing nematode resistance as a biotechnology trait offers
the possibility of providing highly-specific season-long protection from nematode
damage without requiring chemical treatment. This biotech approach is particularly
attractive in high-acreage row crops such as soybeans, corn, and cotton where
costs of in-furrow nematicide treatment are often prohibitive. The adoption of
biotechnology traits in these markets is already very high. In the United States,
greater than 90 percent of soybeans, 85 percent of cotton, and 50 percent of corn
acreage contain one or more biotechnology traits. Divergence is developing safe
and effective biotechnology traits for nematode control based around the discovery
of nematicidal metabolites, proteins, and nucleic acids.
Broader Context
Achieving safe and effective nematode control is a key part of a crucial movement
toward environmentally sustainable agriculture. An estimated one-third of all
agricultural output is lost to plant diseases including nematodes, fungi, insects,
and weeds. Increases in world population (now 6.6 billion) and changes in diet are
on a trend that will double global demand for crops used in food and other
agricultural outputs (feed, fuel, etc.) between 2000 and 2050. Unless improvements
in yield far outstrip historical trends, vast stretches of land will need to be
converted from natural ecosystems to agriculture (much of it requiring irrigation
with water beyond current supplies); a devastating and unsustainable proposition.
In addition to environmental benefits, significant yield improvements would also
have positive consequences for food security and poverty alleviation.
Simply put: safer, more efficient agriculture is critical to our future, and
control of pests including nematodes is an important part of the equation.
Related Links
Introduction to Plant Nematology
Plant Biotechnology
What is a Nematode?
Divergence Publications on Nematode Resistant Crops
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