Farmers in Nepal lose up to one-third of stored grain to pests and diseases. This results in food insecurity and loss of income. To mitigate these losses, farmers use several approaches including pesticide applications on stored grains. We interviewed 241 farmers in Bagmati Province, Nepal, to assess the current on-farm grain storage practices and challenges to improve postharvest management. The results show that rice was the most stored crop (median 1150 kg). About half of farmers stored for at least nine months and grain was mainly used for home consumption. Grain was stored by 66.5 and 69.8% of farmers in granaries (rice) and plastic drums (legumes), respectively. Insects were the most important challenge during storage, and farmers used pesticides to control them. Farmers were more likely to use insecticide on grain (p = 0.000) if they stored rice, used traditional granaries, and had insect damage during storage. The use of improved storage methods (e.g., hermetic bags) was very low for rice (3.5%). There is a need to improve on-farm grain storage by disseminating storage innovations to address postharvest challenges in important crops such as rice.
Elevation gradients are used as a proxy to simulate climate change effects. A field study was conducted along an elevational gradient in Nepal to understand the effects of abiotic conditions on agriculturally important insect herbivore populations (tobacco caterpillar: Spodoptera litura, tomato fruit worm: Helicoverpa armigera, and South American leaf miner, Tuta absoluta) and herbivory damage on tomatoes. Elevation ranged from 100 m to 1400 m above sea level, representing different climatic zones where tomatoes are grown. Contrary to our hypothesis, natural herbivore populations and herbivory damage significantly increased at higher elevations. Individual insect species responses were variable. Populations of S. litura and T. absoluta increased at higher elevations, whereas the H. armigera population was highest at the mid-elevational range. Temperature variations with elevation also affected insect catch numbers and the level of plant damage from herbivory. In the context of climate warming, our results demonstrate that the interactive effects of elevation and climatic factors (e.g., temperature) will play an important role in determining the changes in insect pest populations and the extent of crop losses.
Sitophilus oryzae is one of the most destructive pests of stored grains. It leads to significant quantitative and qualitative losses, resulting in food and income insecurity among farmers. Chemical pesticides are the most common methods used by farmers and other grain value chain actors to manage this pest. However, pesticides are increasingly becoming unattractive for pest control due to health hazards posed to applicators, consumers, the environment, and insect resistance. Modified atmospheres have the potential to manage stored insect pests as an alternative to pesticides. There is limited understanding of when insect pests die when grain is stored in airtight containers. This experiment was conducted to assess the time required to reach mortality of adult S. oryzae when exposed to 1, 3, and 5% oxygen levels. Results revealed that the LT50 for 1, 3, and 5% of oxygen were reached after 69.7 h, 187.8 h, and 386.6 h of exposure, respectively. No adult emergence was observed on infested grains following exposure to 1 and 3% oxygen levels. This result provides vital rationale for storing grain in hermetic storage conditions for at least 39 days to achieve adult S. oryzae mortality and minimize grain reinfestation.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.