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This article is from ECHO Asia Note # 37.

Seed saving in sub-tropical and tropical climates is challenging. Without equipment designed to maintain dry and cool environments, the quality of seeds may quickly deteriorate. High temperature and humidity during storage increase seed metabolism and encourage the proliferation of seed-eating insects (Lale and Vidal, 2003; Upadhyay and Ahmad, 2011). Technologies such as refrigerators, dehumidifiers, and pesticides can help prevent these seed-damaging conditions, but may not be available to smallholder farmers in the tropics. Traditionally, many locally available treatments have been used to prevent insect pests. These treatments, typically added to seeds prior to storage, are meant to poison, damage, or discourage movement of insects around the seeds. Some treatments may effectively reduce insect growth, but they may also damage seed viability; it is important to identify which treatments are effective and appropriate for use by farmers. ECHO Asia research staff analyzed five low-cost treatments to determine their effectiveness in preventing the growth of a common seed storage pest called cowpea bruchids (Callosobruchus maculatus) in stored Lablab bean seeds (Lablab purpureus L.). In keeping with previous ECHO research by Croft et al. 2012, each treatment was also analyzed with and without vacuum sealing. 


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Preventing Insect Damage of Stored Seed Using Low-Cost Control Options

Brian Lawrence, Abram Bicksler and Kimberly Duncan

This article is from ECHO Asia Note # 37.

Introduction
Seed saving in sub-tropical and tropical climates is challenging. Without equipment designed to maintain dry and cool environments, the quality of seeds may quickly deteriorate. High temperature and humidity during storage increase seed metabolism and encourage the proliferation of seed-eating insects (Lale and Vidal, 2003; Upadhyay and Ahmad, 2011). Technologies such as refrigerators, dehumidifiers, and pesticides can help prevent these seed-damaging conditions, but may not be available to smallholder farmers in the tropics. Traditionally, many locally available treatments have been used to prevent insect pests. These treatments, typically added to seeds prior to storage, are meant to poison, damage, or discourage movement of insects around the seeds. Some treatments may effectively reduce insect growth, but they may also damage seed viability; it is important to identify which treatments are effective and appropriate for use by farmers. ECHO Asia research staff analyzed five low-cost treatments to determine their effectiveness in preventing the growth of a common seed storage pest called cowpea bruchids (Callosobruchus maculatus) in stored Lablab bean seeds (Lablab purpureus L.). In keeping with previous ECHO research by Croft et al. 2012, each treatment was also analyzed with and without vacuum sealing. 
Seed pests like cowpea bruchids are difficult to detect, since they lay eggs on developing seeds in the field (Figure 1A) and hatch during storage to consume the mature seeds (Chauhan and Ghaffar 2002). The bruchids rapidly multiply under warm and humid conditions. Within a short period of time, they can consume large amounts of stored seeds, which otherwise would have been used for food or for planting the following year (Figure 1B). However, like all insects, bruchids cannot complete their life-cycles without oxygen (Ahn et al. 2013). Vacuum sealing can be used to reduce available oxygen to insects during storage (Van Huis 1991; see Figure 1C). The goal of this experiment was to explore low-cost seed treatment options along with vacuum sealing, to determine how they affect the growth of bruchid insects and whether or not they maintain seed viability. 


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