Methods of controlling stored-grain pests:
Spinosad is effective at controlling lesser grain borer after short exposure, but was less effective at controlling
rice weevil, red flour beetle, and the psocids (Athanassiou 2010, J. Econ. Ent). Another study showed that the lesser grain
borer and larger grain borer were very susceptible to spinosad, followed by rice weevil. The confused flour beetle was least
susceptible (Athanassiou et al, 2008, J. Insect Sci.).
Actellic Super, Stocal Super, Shumba Super (all pyrethroids),
Protect-It, and Dryacide (diatomaceous earths) each provided protection of uninfested grain for 40 weeks. If grain is infested
prior to treatment, the Actellic Super dust was most effective. Actellic must be obtained from an approved source and applied
correctly to be effective. Traditional treatments such as cow dung ash, sunflower head ash, mkalya, rice husk ash, wood ash,
marimba, or giri giri mo showed little or no improvement over untreated controls (Stathers et al 2008, Crop Protection).
earth formulations Protect-It, PyriSec, and DEA-P were evaluated for controlling the larger grain borer. DEA-P was the only
formulation that was effective (Athanassiou et al, 2007, J. Econ Ent.)
Hermetic (oxygen free) storage can be an effective means of
controlling insects. The container must be air-tight, and grain must be dry before storing. We have shown that metal containers,
rigid plastic containers, glass jars, and hermetic plastic bags (such as those marketed by GrainPro, www.grainpro.com) can
control lesser grain borer in stored grain (Dowell, C.N. and Dowell, F.E. , 2009, unpublished). One key to this method is
preventing any source of air leaks, such as damage to bags by rodents. Quezada et al (2006, Postharvest Biology and Technology)
showed 100% control of larger grain borer by hermetic storage. Murdock et al. (2003) has shown that triple bagging is effective
at controlling insects in some grain. This cheap and effective technique is used in some West Africa countries.
treated with permethrins such as deltamethrine can provide effective control of lesser grain borers (Dowell, C.N., and Dowell,
F.E., 2010, unpublished).
Thus, there are many different ways of controlling pests in stored grain. Local availability and
economics will influence the selection of proper insect control methods.
stored grain pests:
· Lesser grain borer, Rhyzopertha
dominica (F.) (Coleoptera: Bostrychidae)
weevil, Sitophilus oryzae (L.) (Coleoptera: Curculionidae)
· Confused flour beetle, Tribolium confusum Jacquelin du Val (Coleoptera:
· Larger grain borer, Prostephanus
truncatus (Horn) (Coleoptera: Bostrychidae)
· Psocid, Lepinotus reticulates (Enderlien) (Psocoptera: Trogiidae).
Types of products used to control
· Spinosad (Dow AgroSciences)
is a pyrethroid, labeled for use at 1 ppm in the US.
· Actellic Super (Syngenta), Stocal Super (same product from different vendors, containing 1.6%
pirimiphos-methyl and 0.3% permetrin, and Shumba Super (1% fenitrothion and 0.13% deltametrin) are other pyrethroids.
· Diatomacieous earths (DE’s)
are naturally occurring insecticides that are non-toxic to mammals. Often applied at 1000 ppm. Commercial
products include Protect-It, PyriSec, DEA-P, and Dryacide.
It is essential
to store grain at the proper moisture content! This is about 12-15% for maize. The longer the intended
storage time and the warmer the temperature, the lower the moisture content must be.