External Feeders of Stored Grains and their Management

External Feeders of Stored Grains and their Management

Hi, welcome to agrifunda today post  on ‘External Feeders in Stored Grain Pests and their Management’. As you
have understood that the storage pests are normally classified as internal
feeders and external feeders. Now in this post, let us look at the important external feeders,

Internal Feeders of Stored Grains and their Management

Internal Feeders of Stored Grains and their Management

 which are causing main damage to the storage grains. And how they cause the damage and how you are going
to manage them.
So among the external feeders, the most important pest that comes to the picture is the red flour
beetle. So there are two species of the red flour beetle. Tribolium castaneum and Tribolium confusum,
which belongs to the family Tenebrionidae of Coleoptera. As the name indicates, they are dark reddish
or the reddish brown in color. The adult and as well as the grubs are the damaging stage here. And
basically they prefer the broken grains and the flour material, and some condiments or spices, then
almonds and all these storage materials, and on which they actually multiply. The adults lay the eggs in
the storage grains; on the storage grains in fact. And these grubs will actually feed externally, by
scraping the surface of the storage product. And also they construct the webbing and as a result we see
the webbed material on the storage grains in the stored condition.

Like the rava or sooji, is commonly we see the webbed condition. And so also the broken grains like rice
or jowar or whatever it might be. And so during the process of multiplication, they are also known to
produce a quinone gas, and which emits an acidic odor. And this is also quite unhealthy for the people
who come in contact with. And because due to this their acidic nature, and as well as the moist
condition they are going to create, while feeding.

So this leads to the secondary infection on the grains
and development of the fungal infection. And basically they feed like the flour material; peanuts, cocoa
beans etc. And in my estimation it is known that the majority of the storage products are destroyed or
damaged, especially by the red flour beetle.
And the another important beetle, that is external feeder is Trogoderma granarium, which belongs to
the family Dermistidae. The beetle is quite small and the elytra is quite hairy. And whereas the larva is
also creamish colored. And it has got a long hairs. And basically the khapra beetle feeds on the seed
coat in a very irregular manner of all cereals as well as wheat, and the dried fruits, oil cakes and animal
products also.

As the name indicates, they actually prefer to feed on the animal products, especially the
skin materials, the thin skin scales, hairs, the wool materials. So in sericulture industry, they are a big
In case of museums, especially in the museums of large animals. So these are the major problems which
are actually causing. Then the next external feeder is the saw toothed beetle, that is Oryzaephilus
surinamensis. It belongs to the family Silvanidae. This is again a very small beetle and the saw toothed
name basically comes from the tooth like structures or the serrations which are present on the
prothoracic edge. And both the grubs and as well as the adults. So they feed on the grains and other
condiments and the spices. And they actually contaminate the food by feeding externally on them.
Then there is a long headed flour beetle. Ananother beetle Coleopteran external feeder. That is the
Lathyticus oryzae. Which is also a Tenebrionid. And as the name indicates, so the head is quite long and
that is an identifying character from the red flour beetle. And it is also a secondary feeder, and feeds on
rice, sorghum, wheat etc.

Now coming to the Lepidopteran groups which mainly feeds externally. The most important is the rice
moth. So the rice moth or the Corcyra cephalonica or of late is known as Aphomia cephalonica is one which belongs to the Pyralidae. And here, so the larvae they are creamish white in color. And they are
known to construct galleries extensively, and feed on these broken grains. And in fact, so this if the
grains are kept for a long time without caring, then these rice moths are bound to occur. Then similarly
we have another Lepidopteran moth called as the Plodia interpunctella, which also belongs to the
Pyralidae. And as well as the fig moth or the almond moth, Cadra cautella; which also belongs to the
Pyralidae. And these are known to attack the broken grains or the milled products and even the dried
fruits and sweets. And whereas the almond moth, as the name itself indicates is a serious storage pest
on the pulses, spices and then coffee beans and almonds etc.
Then the Mediterranean flour moth. The Mediterranean flour moth is Ephestia kuehinella. So this also
attacks the flour and broken grains. And as well as Cocoa moth, that is Ephestia elutella is also attacks
the cocoa, chocolates and as well as the tobacco leaves. So the pest which basically belongs to the
Coleoptera and Lepidoptera, so they cause lot of damage, just by feeding externally. Not only feeding on
them but also contaminating with their excreta, catskins, dead bodies etc.

How to manage them? So it is always advisable especially in the storage grains. That so we need to look
for preventing these storage pests from getting into these stored grains system rather than controlling
them after they enter into it. Because it becomes very difficult to manage it. As a preventive measure
we always advise, that so it is always better to see that grains are to be properly dried and keep the
moisture below 10%. So this will actually make these pests in what is called as unfavorable for their
multiplication as they don’t get sufficient moisture. Then maintain the hygienity in the storage. So by
plugging the cracks and crevices of holes in the warehouse, as these storage pests will always hide in
these places; when the grains are not there. That is how they become a good source of inoculum for the
next grains. And remove all debris and clean the storehouse before the storage.

Or we can also go for spraying of certain chemicals like Malathion 50 EC @ 10ml per liter or DDVP @ 7ml
per liter. So for 3 liters of solution for 100 cubic meter area. So which is going to disinfect the area. And
then you can actually store the grains. And also good to give a what is called as providing a dunnage or
the leave gangways, for the proper aeration and as well as the proper sunlight. Because these stored
grain pests, they always avoid the aeration and as well as the light conditions. So then by providing
these kinds of alleyways or gangways, then we can actually prevent the cross infestation to a little
And what happens if the pests have already attacked the stored grains. So if the grains are actually
stored for seed purposes.

 Then there is a provision for treating the seeds, either with the edible or the
non-edible oil. Such as you treat the seeds with castor oil or you can treat the seeds with the edible oil
or the neem oil @ of 5ml per kg. Or you can also mix the seeds with mixed neem leaves. Or you can
make use of, there is an Acorus calamus powder, which is also known to deter the stored pest @ 10g
per kg of seeds. Or you can actually treat the storage bags @ 250g per quintal of seeds.
But however for the edible purposes if you are storing the grains. It is always better to use insect proof
bins, such as the Pusa bin or the metal bin or the aluminium bin, a plastic bin etc. And also it is better to
store the grains in the insect proof bags. So there are different quality bags that are available, where
after cleaning the grains and seeing there is no infestation or the initial inoculum. If you store them in
these insect free bags, then you can store the grains for a longer period of time.
Thank You.

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