The Conversation
https://theconversation.com/ why-african-farmers-should- balance-pesticides-with-other- control-methods-93289
From the Plantwise Blog
Esther Ndumi Ngumbi is a 2015 Food
Security Fellow with the New Voices, Aspen Institute
Insect
pests cause almost half of the crop losses in
Africa. If the continent is to feed its growing population, farmers must find
ways to control them. Pests account for high losses in other developing regions
too.For
smallholder farmers in particular, pest management needs to be affordable, safe
and sustainable. It should avoid the drawbacks of synthetic pesticides as far
as possible. Research is now showing that integrated approaches can achieve
these goals.The
UN Food and Agriculture Organisation, for example, recently launched a comprehensive guide that will
help millions of smallholder farmers across Africa to manage the fall armyworm.
This is a new insect pest in over 30 African countries and a serious threat to
maize crops, a staple food.The
guide suggests using biological control and local remedies rather than
insecticides that can work in an emergency but may be ineffective and harmful
in the longer run.This
is a good example of how farmers can be encouraged to balance the use of
insecticides with other forms of pest control.African
smallholder farmers produce 80% of the continent’s food. It’s imperative that
they have the tools and knowledge to sustainably control insect pests, avoiding
the almost 50% losses that arise due to them. But it’s also important that as
the pressure increases on them to produce more, they must also learn to think
of their health and our environment. Governments should make farmers aware of
the risks that come with insecticide use only.PesticidesWhen
insect pests or diseases threaten their crops, many smallholder farmers,
the majorityof whom are poor, turn to pesticides – man-made chemicals that can
prevent infestations or kill the pests.Pesticide
use is growing in many countries including Cameroon, Ethiopia, Ghana, Kenyaand Nigeria. In 2017, Nigeria alone spent
over USD$400 million on these chemicals.Pesticides
are popular because they are effective. They directly reduce the incidence of insect
pests which severely limits crop yields. This means higher yields and
surpluses, and therefore higher incomes for farmers, less malnutrition and
improved food security. Also, many of the older, more dangerous, pesticides are
cheap. The benefits are there, but they are short-term.In
the long run, their use isn’t sustainable because insects quickly become
resistant and because their use can cause significant damage to the natural
environment as well as the health of farmers and consumers. There’s also a lack
of regulation on their use. The chemicals are often sold in used bottles, with little
or no instruction on how to use them. And many farmers don’t follow appropriate safety measures.A recent study explored the relationship
between pesticide use on farmers’ fields, the value of crop output, and a suite
of human indicators in four African countries — Ethiopia, Nigeria, Tanzania,
and Uganda. It showed consistent evidence that pesticide use is correlated with
significantly greater agricultural output value. But it is also costly in terms
of human health and the loss of labour supply due to time lost to illness.In
2017, a UN report showed that about 200,000 people, mostly from developing countries, die
every year from pesticide poisoning.Agriculture
needs a way to manage harmful insects without destroying the ecological balance
of the environment.Integrated pest managementIntegrated
pest management is an approach that doesn’t rule out the use of
pesticides, but uses them as little as possible and only for strong reasons. It
promotes the use of safer alternatives, like biocontrol, which uses natural
enemies to control pests, and cultural control practices which modify the
growing environment to reduce unwanted pests.These
approaches include:- The use of resistant cultivars. These
are plant varieties that have been bred to resist insect damage
- Crop rotation which changes the crops
planted every season, or year, to break the life-cycle of insect pests and
discourage pests from staying on the farm
- Habitat manipulation techniques which
involve planting a variety of crops in and around the farm in an effort to
increase the number of natural insect enemies on the farm land
- The use of pheromone traps. These are
small glue traps that contain insect pest attractants.
Several
research centres in Africa champion this approach. The International
Centre of Insect Physiology and Ecology is one of them. It is
the only institution that specialises in insect research. Since its inception
in 1970, it has rolled out several integrated pest management programs for
major insect pests. For example, between 1993-2008, itchampioned the biological control
programme to control the stem borer pests; Busseola fusca, Chilo partellus and
Sesamia calamistis – major pests for maize in Africa. As a result, it contributed an aggregate monetary surplus
of USD$ 1.4 billion to the economies of the three countries where it was
implemented – Kenya, Mozambique and Zambia.This
is one of many success stories. First used in 1959, integrated pest management
has controlled many of Africa’s top insect pests, including aphids, Africa’s
main cassava insect pest Bemicia
tabaci), the legume pod borer a serious pest for
cowpeas, and lepidopteran stem borers which harm cereal
crops including maize, rice and sorghum.Most
importantly, it has been one of the most effective approaches in combating
the fall armyworm. Early this year development and
research agencies released a handbook on the approach which will
serve as a resource to many African countries.Despite
its success, insect pests are still a major problem. This is because they are constantly adapting to
methods used to control them and because there are
new, invasive insect species and strains emerging everyday.Moving forwardIntegrated
approaches to pest management appear to hold more promise than single
approaches.The
challenge is to ensure that Africa’s farmers adopt practices that are
sustainable and friendly to the environment and human health.Farmers
will need incentives and tools to change their practices. For example, access
to insect resistant varieties of crops.