Living With Grain Storage Pests II

Granary Weevil

Granary Weevil

The original grain elevators were focused on efficient storage and handling of grain. The elevated storage concept was adopted by grain growers throughout the US as evidenced by the grain silos that dot the rural landscape. Silos allowed grain growers to store grain harvested in fall for several months until it was used or sold.  In the global grain market, it has become economically lucrative for grain growers to store their grain for periods longer than one year. This allows grain producers to command a higher price by timing their grain sales. The longer time gives insect infestations time produce troublesome populations  Like all valuables, grain must be protected from competing species such as insects and microbes. The longer grain is stored the better the management practices need to be.

Grain is not inert like sand. It contains nutrients that are able to support competing species. Fungi such as mold can destroy stored grain. Molds are controlled by reducing the moisture level of the grain so mold cannot thrive. Insects are controlled by fumigating the grain. Unlike older grain storage, modern longer term storage for grain is engineered for efficiency and efficacy of pest management as well as storage and handling. Some modern storage units allow grain to be dried in storage, although this is typically more energy intensive that other grain drying methods. Modern storage is designed for proper aeration both to manage moisture and to allow efficient fumigation. Efficient fumigation requires that the storage be alternately sealed to keep the fumigant from leaking out and vented to release the fumigant after the process is complete.

Many older units were not designed for modern grain storage management. They do not efficiently aerate or effectively seal. Poor sealing requires more fumigant to control the insects and results in less effective control with more insect damage to the grain.  However, the increased cost of inefficient fumigation is often offset by sunk costs in the existing structure and inability to improve efficiency due to original design limitation. Grain storage structures can last decades, and prevent adoption of new technology. New designs for grain storage are being developed that have less need to fumigants to control insects. New types of containers and methods of rapidly handling those containers are potential competitors to bulk storage. New grain storage designs may eventually change the skylines of rural areas, but only after the older existing structures come to the end of their life.

About jjneal

Jonathan Neal is an Associate Professor of Entomology at Purdue University and author of the textbook, Living With Insects (2010). This blog is a forum to communicate about the intersection of insects with people and policy. This is a personal blog. The opinions and materials posted here are those of the author and are in no way connected with those of my employer.
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