In rice, post-harvest losses (PHL) are the quantitative and qualitative decreases in rice grain that occur in between the harvest and human consumption
(Qu et al., 2021). This encompasses any reduction in the quantity of consumable rice grain that is the result of factors that impede its utilization by humans, such as a decrease in nutritional value, a decrease in its marketability, or a decrease in its edibility
(Bendinelli et al., 2020 and
Mahendran et al., 2024). PHL should be distinguished from intentional reductions, such as the removal of bran or husk during milling, which are essential processing stages
(Muller et al., 2022). Globally, post-harvest losses in rice can range from 10% to 40% of total production, depending on the region and the techniques employed. In developing countries, losses are generally higher due to traditional methods and less advanced infrastructure. The post-harvest losses for grains, including rice, are typically estimated to be between 10% and 20% at the pre-processing stage
(Nath et al., 2024).
The quantitative harvest and post-harvest losses for cereals, which encompass paddy/rice, were estimated to be between 3.89% and 5.92% in India. According to national estimates, paddy losses total 5.53%, of which 4.67% occur during field activities and 0.86% during storage. A survey of 1,200 farmers in Punjab, Bihar and Madhya Pradesh revealed a paddy loss of 6.37% (including quantity and quality losses). The post-harvest losses are considerably higher during harvesting and threshing operations (Table 1), with traditional methods providing a significant contribution
(Gulati et al., 2022).
Post-harvest losses in rice due to insect infestation
Insect infestations are major causes of post-harvest losses of rice, which is a staple food and an important agricultural commodity in many developing countries
(Kuai et al., 2024; Sun et al., 2024a and 2024b;
Jayan et al., 2022a, 2022b). The principle insect pests of rice during post-harvest storage are rice weevil
Sitophilus oryzae, rice moth
Corcyra cephalonica, khapra beetle
Trogoderma granarium and grain borers
Prostephanus truncatus. These insects feed on the stored rice thereby causing quantitative as well as qualitative losses.
(Kumari et al., 2023). In India, it is estimated that the total post-harvest food grain loss is 12-16 million metric tonnes, which is enough to feed one-third of the country’s poor. According to
Kumari et al., 2023, insects can account for 24.2% of these loses, which totals to around ¹ 1,300 crores in each year. Weight loss, reduced market value due to damage or discoloration of grain, contamination through insect waste and the potential for diseases such as aflatoxin to spread as a result of fungal growth are among the impacts of insect infestations. Several factors such as storage conditions, period of storage, pests control methods, as well as environmental factors such as humidity and temperature, affect the amount of grain lost
(Sharma et al., 2024; Wu et al., 2022, Wu et al., 2023).
Key insect pests contributing to post-harvest losses in rice
Rice weevil (Sitophilus oryzae)
One of the most important pests of stored rice is the rice weevil. It’s a grain eater, chewing and eating the stored grains of rice to the point where up to 57% of rice weight reduction and decline in quality has been recorded for each generation in its laboratory host’s larva. Its larvae tunnel through the grain, causing the kernels to hollow out and become contaminated. Research shows that the destruction of grain by the rice weevil can be as high as 12-25% depending on storage situation.
(Yu et al., 2025).
Rice moth (Corcyra cephalonica)
Stored rice is also attacked by the rice moth. It lays its eggs on grains of rice and the larvae feed on the grain causing holes and ruining it. Rice moth infestations commonly cause damage associated with a reduction in quality of up to 18% to 22% in some regions.
Khapra beetle (Trogoderma granarium)
The khapra beetle is a serious pest of stored rice, especially in areas with bad storage conditions. Its maggots can inflict heavy damage to the grains by feeding and creating physical damage and contamination. Khapra beetle infestations cause substantial losses (20-25%) and are related to defective rice.
Grain borers (Prostephanus truncatus)
A lesser known but equally damaging pest of stored rice is the grain borer. It normally results in weight-loss and deterioration of grain quality. The losses by the grain borers are also not as high as those by the rice weevils and moths but they also give rise to the overall post-harvest loss particularly under poor storage environment.
Angoumois grain moth (Sitotroga cerealella)
Larvae of this moth at their late instar stage can infest 69% of stored rice and cause an average weight reduction of 2.11%, varying from 1.09% to 3.10%
Lesser grain borer (Rhyzopertha dominica)
It is one of the 100 insect pests that can cause economic loss to stored grains.
Indianmeal moth (Plodia interpunctella)
This moth’s caterpillars are known as waxworms in their caterpillar stage. They are a prevalent kind of grain-feeding pest that can be found in the whole world and that feed on cereals, fruit and related commodities. The larvae can chew through plastic or cardboard packaging, allowing infestations of even stored food.
Rust red flour beetle (Tribolium castaneum)
A common pest of stored grains, causing contamination and weight loss.
Saw toothed grain beetle (Oryzaephilus surinamensis)
Infests stored grains, leading to quality degradation and weight loss.
Almond moth (Cadra cautella)
Infests stored grains, leading to contamination and quality degradation.
Pulse beetles (Callosobruchus species)
While primarily pests of pulses, they can infest stored rice, causing damage and contamination.
A majority of small scale farmers depend on conventional rice storage and processing methods which are rudimentary and are not efficient in preventing losses. Antiquated machinery and methods of pest control have led to high wastage
(Ponsiva et al., 2025). Lack of post-harvest storage facilities, especially in rural regions, also contributes to post-harvest losses. Rice is more easily damaged by pests and spoilage if it does not have adequate temperature and humidity control. Warmer temperatures and altering weather patterns can exacerbate existing post-harvest storage conditions and make crops more susceptible to pests and diseases. A lot of the farmers and actors are not adequately trained and/or knowledgeable on best practices for PHH, pest control and storage capacity which results in avoidable loss
(Gulati et al., 2024).
Insects infestations are responsible for large amount of postharvest losses particularly in countries such as India which has a significant focus on food security and their main crop rice
FAO (2022). Among the most important implications are Economic Loses, Food Scarcity and Quality deterioration. The farmer and market handlers suffers the losses due to damage of rice caused by insects during storage. As a result, less rice is left for sale and hence lower income for farmers. In areas where rice is the staple diet, any decrease in yield caused by insect attack can result in serious food shortages, particularly if it occurs during the lean season. The post-harvest rice that are infested with insects have a lower market value that is not worth for farmers and retailers to keep as stock or sale it. In addition, low-quality rice can lead to health problems for consumers through insect eggs, excrements, or it is toxicologicaly undevaluable for moulds (Table 2). Better Storage, Insecticides and Fumigation, Farmers Training, Improved Milling Procedures, Research into Pest Resistant Varieties, Research and Innovation and Government Policies and Support are the Mitigation Strategies for Insect-Related Post-Harvest Losses (
Pradhan Mantri Fasal Bima Yojana, 2025).
Post-harvest losses in rice due to disease and microbial discoloration
Although infections caused by bacteria or viruses may result in discoloration in rice kernels, fungi are more frequently related to this particular condition.
Sarocladium oryzae,
Fusarium spp. and
Pyricularia oryzae are the fungi causing grain discoloration in the field. During storage,
Aspergillus and
Penicillium are frequently related to discolouration. The moisture content, temperature, length of storage, insect activity and condition of the grain at the time of storage significantly affect the development of fungus in stored grains (Table 3).
Symptoms of seed discoloration
The microorganism and infection severity may cause different symptoms. Rice seed discoloration can cause brown to black stripes or patches on the grains and hollowed-out panicles with empty grains, depending on the fungus. Grain discoloration affects size, color and shape. Wind pressure during pollination, a lack of food, a low plant population, improper fertilization or pollination, immature grain filling and maturity-stage rainfall can cause black blotches
(Hariharan et al., 2025c). Discoloration was greatest during flowering, milking and soft dough.
Diseases that cause discoloration in seeds. 99 different species and 59 different genera of fungi were found to infect rice seeds. There are two categories for these fungi: Field fungi are parasitic fungi that contaminate grains before harvest, whereas storage fungi are saprophytes that grow after harvest.
Pyricularia oryzae,
Drechslera oryzae,
Sarocladium oryzae,
Ustilaginoidea virens,
Curvularia spp.,
Fusarium spp.,
Phoma spp.,
Alternaria spp.,
Aspergillus spp.
and Xanthomonas oryzae pv.
oryzae are some of the primary pathogens that lead to color changes in seeds. Additionally, there are several minor pathogens, including
Penicillium spp.,
Pseudomonas spp.,
Burkholderia glumae,
Tilletia spp.
and Cladosporium spp.
