Local Treatments and Vacuum Sealing as Novel Control Strategies for Stored Seed Pests in the Tropics
Agronomy for Sustainable Development
Brian Lawrence, Abram Bicksler, Kimberly Duncan
Prevention of pests while maintaining viable seed during storage is often challenging for smallholder farmers in the tropics and subtropics. Investment in costly technologies or storage equipment is often unavailable or economically unreasonable, and alternative methods of seed storage can play a role in ensuring regional and global food security. This research evaluates whether or not vacuum sealing and locally available seed storage treatments are effective techniques to control cowpea bruchid (Callosobruchus maculatus). This research also assesses the effects of such techniques on the viability of stored Lablab (Lablab purpureus L.) seed in the humid tropics. Tested treatments included vegetable oil, pulverized bamboo charcoal, galangal powder, powdered detergent, a bleach solution, and carbaryl. Infested seed samples stored in northern Thailand under local treatment options and vacuum sealing were evaluated between May 2011 and May 2012 for bruchid presence, seed viability, and seed vigor. After 1 year of vacuum storage, seed viability was 77.6% compared with 66.5% under non-vacuum conditions. Over that period, vacuum storage successfully prevented bruchid population growth (4.9 compared with 123.3 insects per 50 seeds under non-vacuum conditions; F = 22.59, P < 0.001). By contrast, the oil treatment greatly reduced seed viability (1.3%), although it restrained bruchid population growth (3.5 compared to 97.0 insects per 50 seeds). Other local treatments (galangal powder, carbaryl, and bamboo charcoal) limited bruchid population growth (F = 8.37, P < 0.05) compared with the control, while maintaining seed viability. Seed germination duration was not affected by vacuum sealing and seed treatments but was rather influenced by changing environmental conditions throughout the trial. These seasonal changes also influenced overall insect lifecycle and seed metabolism. These results demonstrate that vacuum sealing and several locally available treatments provide novel, low-cost, appropriate seed storage options for local seed banks and smallholder farmers in the developing world, thus avoiding the use of locally rare or expensive chemicals, low temperature, or low moisture conditions.