Estimating rodent losses to stored rice as a means to assess efficacy of rodent management

Abstract

Context. Post-harvest losses by rodents have traditionally been calculated by estimates of consumption determined in the laboratory. Methods for assessing storage losses by rodents under small-holder conditions will help farmers and policy makers understand the impact rodents may have on food security, nutrition and health. Stored product loss assessment methods could also be used to monitor the effects of rodent control in villages.Aims. The present study examined a method to measure the amount of rice eaten by rodents in household granaries. The effects of trapping and better hygiene around granaries to reduce rodent populations were investigated using the post-harvest monitoring method to determine whether the programme was successful in lowering rodent numbers sufficiently to reduce post-harvest losses.Methods. Baskets with known quantities of rice were placed within household granaries and periodically monitored for moisture content, weight loss, faecal contamination and percentage of rodent-damaged grains. Using an empirical treatment-control study, rodent management was carried out at the community level through daily trapping in two Bangladesh villages and in Myanmar at the granary storehouse level. Post-harvest losses were monitored in villages/granaries with rodent management and in similar villages/granaries where there was no management. Key results.Estimates of household losses in the absence of rodent control were 2.5% in Bangladesh and 17% in Myanmar. These losses were reduced when rodent control was implemented, down to 0.5% in Bangladesh and 5% in Myanmar.Conclusions. The impact of rodents on small-holder storage can be accurately assessed in the field under realistic conditions. Intensive daily trapping at the community level together with improved hygiene practices can successfully reduce rodent numbers and this can significantly reduce stored grain losses and rodent contamination and damage levels.Implications. In addition to the threat of rodent pests during crop production, rodents are a major threat to food security after harvest and have, as of yet, unquantified impacts on household nutrition and health through potential transmission of gastro-enteric diseases and zoonoses to householders 2 and domestic livestock. Trapping and environmental management are affordable and effective tools to reduce rodent impacts on stored grain within communities and are viable alternatives to rodenticides.

Post-harvest impacts of rodents in Myanmar; how much rice do they eat and damage?

“…The study was conducted in both Maubin Township (Ayeyarwady Region) and Daik U Township (Bago Region) in 2013 and 2014. The loss data from both townships in 2013 was published in Belmain et al However, this earlier study did not estimate the amount of stored grain that was lost from the farmer granary . We monitored ten stores in each township.…”

“…The surface area changes inside the granary, and the level of cleanliness inside and around the granary were recorded at each sampling time. The surface area loss was calculated using the equation in Belmain et al The losses in 2013 and 2014 were compared using a general linear model.…”

“…Parshad stated that post‐harvest losses by rodents are higher than preharvest losses in India and Bangladesh. However, there have been only a few studies in the past 25 years that have quantified these losses in rice‐based agricultural systems …”

Food Sustainability Challenges in the Developing World

“…mice, rats and voles) is substantial and can greatly risk food security in a region. Moreover, on a global scale, it has been stated that damages incurred during pre-h arvest (on structural damage to plants) and post-harvest stages (during storage) can contribute significantly to malnourishment and reduced food security (Belmain et al 2015;Brown et al 2008Brown et al , 2013Meerburg et al 2009;Oerke 2006). Besides, individuals working in the farming sector can also get infected, as rodents in the fields can be carriers of human pathogens and this can lead to various disease transmissions (such as arena viruses, murine typhus, leptospirosis, etc.)…”

A meeting of mice and men: rodent impacts on food security, human diseases and wildlife conservation; ecosystem benefits; fascinating biological models

“…Both studies highlighted the importance of understanding the timing and length of the breeding season, and the extent of nesting habitat of the principal pest species when developing management approaches. The third study focused on postharvest losses to smallholder rice farmers in lowland habitats in Bangladesh and Myanmar (Belmain et al 2015). This study is of particular note because there have been precious few studies of the impacts of rodents on grain stores in developing countries (John 2014).…”