CROPS PestControlin Maize
C
ertain varieties of maize
are genetically engineered
to express proteins
from the soil bacterium Bacillus
thuringiensis (Bt). These are toxic
to a number of important maize
pests, enabling farmers to reduce
the use of chemical pesticides.
However, a potential concern
forSouthAfrica’sfarmers
ofBtmaizehybridsis the
resistanceofmaizestalkborer
(Busseolafusca) totheproteins
expressedbya particular
Bttechnologyincorporated
intothesemaizehybrids.
Theownerofthistechnology,
BayerCropScience(Bayer),has
admittedthatalthougha small
degreeoffeedingontheleaves
ofMON89034Btmaizehybrids
wasexpectedunderhighinsect
pressure,thelevelofdamageseen
recentlyinsouthernKwaZulu-
Natal’sHimevilleandKokstad
areascameasa surprise.
AccordingtoMagdaduToit,
spokespersonforBayer
SouthernAfrica,mitigating
actionwastakenassoonas
themaizestalkborerdamage
wasdiscovered.Effortswere
alsomadetounderstandthe
causesoftheproblem.
“Larvaefromtheaffectedarea
werecollectedandsenttothe
AgriculturalResearchCouncil
inPotchefstroomforevaluation.
Theresultsfromthefeeding
studiesindicateda potential
localisedpopulationofB.fusca
showingresistancetotheproteins
expressedbyMON89034.
“Bayerconsultedwith
customersintheimpactedareas
todiscussa mitigationplan
andmothtrapswereinstalled
inthelandstomonitormoth
flightpatterns.Bayeris also
monitoringallmaizelandsin
thearea,aswellastheplanting
ofrefugeareasintheregion.”Bt-resistantstalk
Borerlimitedinsa
Du Toit points out that, since
2011, thousands of hectares have
been planted with MON89034
technology in South Africa,
and the area of Bt-resistantWhileBt technologyin geneticallymodifiedmaizehelpsfarmers
to controlcertaincrop pestsmoreeffectively,measuresshouldbe
takento preventthedevelopmentof resistanceto thetechnology.
SeedindustryrepresentativesGrantPringleandMagdaduToit
sharedtheiropinionsonthisimportantissuewithLloydPhillips.
Tools to prevent
build-up of pest
tolerance in Bt maize
36 farmer’sweekly 23 August 2019