Trends in host plant resistance
for the control of insect croppests
D
uring April this year, the Interna-
tional Plant Resistance to Insects
Workshop, also known as IPRI,
was held inMarrakech,Morocco.
It was the 21st biennial workshop, which
is a specialised forum for agricultural re-
searcherswho use host plant resistance for
thecontrolof insectpests.The2014meeting
was organised by the Institut National de
la Recherche Agronomique (INRA), the
Association Marocaine de la Protection
des Plantes (AMPP), the International Plant
Resistance to Insects Working Group (IPRI)
and the International Centre for Agricultural
Research in the Dry Areas (ICARDA). This
workshop is seen as the most important
forum for the exchange of information on
host plant resistance to insects in theworld.
Approximately 100 participants from 36
countries (from the continents of Asia,
Africa, Europe, America and Australia)
attended the three day long workshop.
A special emphasis was placed on host
plant resistance to hessian fly, with several
awards being given to researchers working
on the control of this pest. Hessian fly is a
very severe pest of wheat, which occurs
in many wheat producing regions of the
world,but is luckilynot found inSouthAfrica.
Russian wheat aphid was also one of the
prominent pests that were discussed.
This aphid occurs in all wheat producing
regions of the world, except Australasia.
In South Africa, new biotypes of Russian
wheat aphid have overcome all but three
of the commercial cultivars, and breeders
are nowmaking use of novel and effective
resistancegenes foundwithin collectionsof
breadwheat lineskept inspecial germplasm
banks throughout theworld.
SevenpresentationsweremadeonRussian
wheat aphid research conducted in South
Africa. Five studies were conducted by
students and staff at Stellenbosch Uni-
versity while the other two presentations
highlighted research from the ARC-Small
Grain Institute andRhodesUniversity.
The use of natural resistance from the host
plant species to control insect pests is a
safe and very environmentally responsible
method of pest control. The most obvious
benefit is that producers save millions
because they do not need to use pesticides
to protect their crops. Additionally, in
regions where cropping is influenced by
climate change and shrinking profit mar-
gins, these resistant cropsareveryvaluable.
Crops relating to food security, like wheat,
maize, rice and grain legumes featured
prominently in the discussions. No less
than fourmajor pestsofwheat are currently
controlled using host plant resistance,
namely Russian wheat aphid, hessian fly,
greenbug and sunnpest.
Information was however not limited to
these crops,withpresentationsbeingmade
on insect resistance invegetablecropssuch
as tomato, paprika and cabbage, fruit crops
such as citrus and even thrips resistance in
chrysanthemum flowers.
Most research currently being done can be
categorised into the following four research
areas:
Biotechnology:Molecular
markers
A lot of research funding is currently being
directed towards the use of biotechnology
and particularly the use of molecular
markers to follow resistancewhilst speeding
up thebreedingprocess.
Biotechnology:
Metabolomics
Many efforts are being focused on un-
derstanding the exact processes within
the plant that cause it to be resistant. The
chemical processes involving metabolites
within the plant cells are studied using
advanced technologies in order to under-
stand which genes are being activated to
protect theplant from insect attacks.
Biotechnology: Biotype
characterisation
Modern DNA-technology is being utilised
to tell the difference between biotypes of
the same species of pest insect. A biotype
is a strainof the original species that differs
in its ability to injure resistant plants. The
formationof resistancebreakingbiotypes is
the biggest challenge facing the use of host
plant resistance for pest control.
Focused exploitation of
germplasm collections
Germplasm collections around the world
contain thousands of wild relatives of crop
species and it can be quite problematic for
researchers to identify the lines that have
natural resistance to the pests, in among
all theothers. The latest wayof overcoming
this problem is to focus attention on only
the lines that come from regions where the
pest insect endemically occurs, as lines
from theseareashave thehighest chanceof
being resistant.
The next IPRI Workshop
will beheld in2016 inCape
Town.
51
September 2014
VICKI TOLMAY,
ARC-Small Grain Institute
Hessian flyandRussianwheat aphid featured
on theworkshopbanner.
FOCUS
Integratedpest control
Special
