Post-harvest damage to stored grain by rodents in village environments in Laos

Rodents can cause significant damage to grain stores in developing countries, affecting food security and income of small-holder farmers. This study assessed a method to measure the losses caused by rodents to grain stores in rural upland areas of Laos, where black rats, Rattus rattus, are the main rodent pest species. Known amounts of grain were put into metal bowls, placed inside farmer grain stores, and monitored every 2 wk after harvest for a dry and wet season rice crop. There were 2.5–3.0 droppings and 1.4–2.2 hairs per 100-g sample. There was a positive relationship between the number of fecal droppings and hairs from within the bowls and from samples from the grain stores. Weight loss was 10.3% in the dry season and 7.4% in the wet season. There was a weak but positive relationship between fecal droppings and weight loss. It was not possible to ascribe rodent damage to environmental or hygiene conditions. Loss by rodents was calculated at 117 kg, which could feed a Lao household for 1.5 months. Improvements in the methodology are needed to control for interference with the bowls. An experimental approach is suggested to examine potential factors that might influence rodent damage.

► We assessed a method to measure and quantify losses to stored rice by rats in Laos.
► Known amounts of grain were monitored inside bowls every 2 weeks for 2 seasons.
► There were 2.5–3.0 faecal droppings and 1.4–2.2 hairs per 100 g sample.
► Percent weight loss was 10.3% in the dry season and 7.4% in the wet season.
► It was not possible to ascribe rodent damage to environmental conditions.