INTRODUCTION Maize (Zea mays L.) is an important cereal crop, ranking third in India (APEDA, 2020). Maize is native to Central America and Mexico and has adapted to a wide range of agro climatic situations. It serves three functions in the Indian subcontinent: as a staple food, feed, and fodder, particularly for farmers with limited land holdings, promoting food security and income generation (Lakshmi Soujanya et al., 2017). It has numerous applications in corn-based industrial products, and the demand for maize export has been increasing year after year due to its higher nutritional value. It is mostly grown in the Indian states of Gujarat, Madhya Pradesh, Rajasthan, Bihar, Uttar Pradesh, Tamil Nadu, and Telangana. In Tamil Nadu, the area under maize cultivation is 3.33 lakh ha with a production of 24.76 lakh tonnes and productivity of 7424 kg/ha (INDIASTAT, 2020). Maize is stored after harvesting, either for use as seed or for human consumption or to obtain a favourable market price at times (Reddy and Pushpamma 1980). One of the greatest barriers to achieving food security in emerging and underdeveloped nations is post-harvest loss during storage (Rounet, 1992). More than 37 species of arthropod pests have been linked to maize grains in storage (Abraham, 1996). Insect pests and diseases have a significant influence in diminishing production and productivity, as well as germination potential during the storage period (Mollah et al., 2016). Majority of the maize growers lack knowledge on the storage pests occurring in maize and subject their produce to improper storage conditions which results in both qualitative and quantitative losses. The present study was conducted to assess the major arthropod pests of stored maize and the extent of damage caused by them under storage conditions. MATERIALS AND METHODS Survey area and sampling of maize grains. A laboratory study was conducted from December to May (2021-2022) in the Department of Agricultural Entomology, Tamil Nadu Agricultural University, Coimbatore with grain samples obtained from major maize growing districts of Tamil Nadu to find out the status of arthropod pests infesting stored maize, their damage and losses. Approximately, 1 kg of sample was collected from major maize growing districts of Tamil Nadu viz. Coimbatore, Salem, Namakkal, Dharmapuri, Trichy, Perambalur and Virudhunagar. Preferably, the maize grains were obtained from farmer’s stored produce besides collecting from Departmental stores, bulk storage godowns and feed industries. Each sample was tightly packed in a paper bag after tagging with information on the location, date of collection, etc. and brought to the laboratory for further scrutiny (Firidissa, 1999). Collection and identification of insects. Laboratory observations were made at the Department of Agricultural Entomology, Tamil Nadu Agricultural University, Coimbatore, at weekly intervals for 6 months at a room temperature of 28±3ºC and relative humidity of 65±10%. Samples were sieved at every inspection over a 2 mm mesh sieve (Abraham, 1996) and all the fractions were examined. Later, the insects were removed, counted and catalogued and were preserved as dry specimens or preserved in 70% ethyl alcohol for identification at a later stage. The detailed analysis of specimens was done with a Leica SA8PO and photographed with a Leica M205C microscope (with LAS X Application Suite montage software). Identification was done by using taxonomic keys provided by Akter et al. (2013); Koehler et al. (2006); Rita Devi et al. (2016); Sowmya et al. (2020), besides referring to books, journals, pictures and comparison with already identified specimens. Analysis of diversity indices. Margalef Index (α) (Margalef, 1958), Shannon Weiner (H΄) index (Shanon and Weiner, 1949), Pielou's evenness index (J) (Peilou, 1966) and Berger-Parker Dominance index (May, 1975) were performed in R Studio version 4.0.4 using vegan package to reveal the diversity, species richness, evenness and dominance of arthropod pests associated with stored maize grains. Data collection Grain weight loss: After storing for a period of 6 months, 100 grains were randomly removed from each samples and separated into infested and uninfested seeds. The weight of infested and uninfested seeds was separately recorded and the per cent weight loss was calculated based on the count and weight method (Adams, 1976). Weight loss (%)= ((Wu×Nd)-(Wd×Nu))/(Wu×(Nu+Nd) )×100 Where, Wu = Weight of undamaged seed, Nu = Number of undamaged seed, Wd = Weight of damaged seed, Nd = Number of damaged seed Per cent grain damage: The count approach was used to assess insect damage after 6 months storage period. From each collected samples, 100 grains were chosen at random, and they were divided into categories of damaged and undamaged grains. Following that, the percent grain damage (Lemessa et al., 2000; Wambugu et al., 2009) was determined using the following formula. Per cent grain damage (%)= (Number of insect damaged grains)/(Total number of grains)×100 RESULTS AND DISCUSSION Maize grain samples collected from different locations were found to be infested with different insect pests. The major pests observed from samples, their abundance and status are furnished in Table 1 and 2. A total of five arthropod pests were collected from the samples representing Coleoptera and Lepidoptera, besides a mite from Acarina. The rice weevil, Sitophilus oryzae (Linnaeus) was the predominant pest followed by Angoumois grain moth, Sitotroga cerealella (Olivier) and red flour beetle Tribolium castaneum (Herbst). In a similar study conducted in 3 states of USA, Eden (1967) listed out 17 species of insects from farm stored maize, of which S. oryzae was found to be the predominant one. Also, in a South Ethiopian sample, Getu (1993) identified S. cerealella and S. zeamais as the two most important stored maize pests. Maize weevil, grain moth and flour beetle were the most abundant insect pests in stored maize samples of western Ethiopia (Abraham, 1997) and Bangladesh (Alam et al., 2019), confirming our investigations. The grain weevil, S. oryzae has been recorded as a polyphagous pest causing significant yield loss in stored maize grains in India and South East Asian countries (Hossain et al., 2007). Being an internal feeder, S. oryzae is capable of causing severe losses to the stored maize grains, both qualitatively and quantitatively. S. oryzae was observed in all the seven locations followed by S. cerealella, T. castaneum and Acarus siro in six locations each. According to Margalef richness index (α), Perambalur (1.03) had the maximum number of insect pests (6 insect pests) followed by Trichy (0.84), Namakkal (0.80) (5 insect pests in each), Salem (0.68), Coimbatore (0.63) (4 insect pests in each) and Virudhunagar (0.43) (3 species). In Dharmapuri, only two insect pests were recorded (Table 3). Higher the value of Shannon-weiner index indicates higher the diversity of insect pests in stored maize grains. Shannon index indicated higher insect pest diversity was found in Perambalur (1.51) and Trichy (1.50) which were collected from feed industries and bulk storage godowns and the lowest diversity was noticed from farm samples collected from Dharmapuri (0.69). Peilou’s evenness index showed that higher species evenness in Dharmapuri (0.72) and lower in Perambalur (0.42) (Table 3). According to Berger-Parker index of dominance, S. oryzae was dominant in all sampling districts except in Coimbatore (Table 4). In the present investigation, samples collected from various sampling sites revealed 24.4 percent grain damage resulting in 53.9 percent yield loss within a storage period of six months (Table 5). The variations in per cent grain damage and weight loss in different locations were due to diverse sampling sites. Samples collected from feed industries, bulk storage godowns were prone to severe infestations than famer’s store point because of large scale holding of maize grain samples in the former. The per cent grain damage and yield loss is attributed to the combined impact of different stored insect pests, though S. oryzae was the major contributor. It was also noticed that the extent of damage increased as the storage time extended. Our literature survey revealed grain losses ranging from a minimum of 10-20 per cent (Hell et al., 2010, Golob, 1984; Giga et al., 1991, Abebe and Bekele 2006,) to as high as 80 percent under unprotected conditions (Schmutterer, 1971; Mutiro et al., 1992; Pingali and Pandey 2001). Within a period of five to six months, upto 80 percent grain loss was realized in grain samples stored at Cameroon (Nukenine et al., 2002) and at Bangladesh (Alam et al., 2019).