**5.5 Physical methods**

Once the stored grains are infested, some physical methods used for the management of the stored grain pests are:

*Physical exclusion:* Fine perforated floors are made for the collection of dusty fines at the bottom that are susceptible to insect infestation.

*Grain distribution:* Grains inside granaries as well as inside bins and containers should be properly leveled. Improper leveling can create room for insect infestation and mold development due to the accumulation of moisture into the peakedgrained mass. To prevent the stored grains, removing grains from the old bins and redistributing them to other containers are very helpful.

*Temperature:* Based on the nature of pests, the temperature can be set either at low or high degrees. As some pests like moist and cool places and some like hot and humid regions. Most pests require temperatures above 60–70°F to reach damaging populations. Hence maintaining a cool temperature can reduce the excess loss. In certain situations, maintenance of −4°C to 0°C can kill many stored grain pests. *T. castaneum* and *Oryzaephilus mercator* are highly susceptible to cold, whereas *Trgoderma* spp., *Plodia interpunctella*, and *Ephestia* spp. are cold-tolerant species. Maintenance of very high temperatures can also be recommended but it has certain drawbacks such as it can crack, harden, and make brittle grains inside bins.

*Hermetic sealing:* To maintain a very low oxygen level inside stored grain containers this method is used. Low oxygen level causes suffocation to the pests and hence has insecticidal property.

*Aeration:* Air flown at the rate of 0.1–0.5 cubic feet per minute per bushel are used to cool stored grains. This low-volume airflow is an important component of the management of the stored grain pests. Grains remain uniform and to some extent in dry conditions as some grains are susceptible to pest attack in moist climates.

*Oxygen saturation:* Insects perform aerobic respiration for their survival. Maintenance of low O2 atmosphere is blown at the base of the containers, bins, and other stored chambers, forcing out the existing O2 rich atmosphere is a convenient method for infestation control.

*Sanitation:* All bins, containers, granaries, and other stored places should be cleaned using shovels, brooms, vacuum cleaners to clear old grains, dust, spider web, and fines from all cracks and crevices, windows, doors, vents, fans, elevators, and floor. Even a small old grain or fines left in any place where new grains are to be stored can harbor insects that can infest the whole grain. A suitable dryer should be used to remove the moisture from bins. To improve storability, especially in the case of wet, damaged, or immature grains, grain cleaners can be used frequently. Some grain cleaners are:

