**2. Pre- and post-harvest losses by stored grain pests**

Grains are generally attacked by several insect pests during all the stages of growth from seedlings to storage [7]. Insect pests possess a major threat to grain production and are also responsible for both direct and indirect losses of grain both in the field as well as in the storage [8]. Mihale et al. estimated that almost 15–100% pre-harvest losses and almost 10–60% post-harvest losses of stored grains are caused by stored grain pests in developing countries [9]. Two major insect groups, i.e., Coleoptera and Lepidoptera are economically important on stored grains. In the case of Lepidoptera, its larva causes the damage while in the case of Coleoptera both larva and adult causes damage.

Weevils and moths are the major stored grain pests that cause huge damage to maize and sorghum [10]. Most important stored grain pests include Angoumois grain moth (*Sitotroga cerealella* (Olivier, 1789) Lepidoptera: Gelechiidae), maize weevil (*Sitophilus zeamais* Motschulsky, 1855 Coleoptera: Curculionidae), the Indian meal moth (Plodia interpunctella (Hubner, 1813) Lepidoptera: Pyralidae), the almond moths, *Ephestia cautella* (Walker) (Pyralidae: Lepidoptera), flour beetles (*Tribolium* spp.), the flat bark beetles *Cryptolestes* spp. (Coleoptera: Laemophloeidae) and the sap beetles *Carpophilus* spp. Stephens, 1830 (Coleoptera: Nitidulidae) [11]. The maize weevil is a major pest mainly found in warm humid areas all around the world. It mainly damages a wide range of cereals and is well established in tropical countries.

Grains such as sorghum and maize are mainly attacked by pests in the field before their harvest. After one week of storage adults of *S. zeamais* were found on all maize portions of the cobs that indicating that cobs are already infested before their harvest. The level of damage to the grains in storage gives an idea about the extent of damage [12]. Maize weevil although commonly found on maize can also attack many cereal grains such as wheat, barley, sorghum, and rice. Although, maize weevil prefers whole grains it has been reported to feed on many processed grain products including pasta and pet food [13].

*Stored Grain Pests and Current Advances for Their Management DOI: http://dx.doi.org/10.5772/intechopen.101503*

Almost 10–20% losses have been reported in maize by *S. zeamais* after three months of storage [14]. Thus, millions of tons of maize are lost by stored grain pests due to inefficient storage technologies. More serious damage to maize grains is due to a larger number of adult weevils [15]. It is estimated that almost 63.85% of grain weight losses occurred due to three to six months of storage by stored grain pests.

Pulses are heavily damaged by weevils and beetles in the field and also during storage time [16]. In the case of pulses, the adzuki bean weevil *Callosobruchus chinensis* (Linnaeus, 1758) (Coleoptera: Chrysomelidae) is found to be highly damaging as a stored grain pest. It is estimated that almost 50% of losses are found in important legumes such as chickpea field pea, faba bean by stored grain pests like *C. chinensis* [17]. Bruchids are found to be serious threats to faba bean and chickpea with an extent of damage sometimes reaching 90% after three months of storage.
