Insect pests population of stored maize in four regencies of South Sulawesi

Information on species, insect pest populations that attack and storage conditions determines the control strategy. This study aims to determine the various types of post-harvest pest s population in maize kernels stored in four in South Sulawesi. Identification of post-harvest insect pests at the Pest Laboratory, Department of Plant Pests and Diseases, Faculty of Agriculture, University of Hasanuddin Makassar. Sampling using the direct capture method (hand sampling) and manual instruments. Sampling was carried out by taking samples of corn kernels in sacks from five points and taking samples of the corn kernels that were scattered on the floor of the warehouse. The results showed that 10 spesies of insects were found including 9 spesies of pests namely Sitophilus sp. Cryptolestes ferrugineus, Corcyra cephalonica, Carpophilus sp, Araecerus fasciculatus, Lophocateres pusillus, Rhyzopertha dominca, Tribolium castaneum and Oryzaephilus surinamensis and one species of parasitoid :Anisopteromalus calandrae. Sitophilus sp. is the most common species found in all districts with a total population of 636 individuals then Cryptolestes ferrugineus with 53 individuals and T. castaneum with 37 individuals. Post-harvest pest populations in all districts were found more commonly around 73% in piles of sacks compared to populations found in spilage commodities, namely around 27%.


Introduction
To support the demand for maize as food, and as a staple for the animal feed industry, it is necessary to guarantee the availability of maize with good quality.One of the main factors that must be considered in order to maintain the quality and quantity of maize after harvest, by paying attention to the storage place or warehouse.
Storage is an important post-harvest handling process because during the storage process agricultural products will experience a process of damage.Forms of damage can be physical, chemical, mechanical, biological and microbiological damage [1] Weight loss in maize kernels in storage is due to post-harvest pests.Insects are one of the most common post-harvest pests found in storage.Yield losses caused by insects during the storage period, especially in Indonesia, can reach 15-20% annually [2].Another study showed that the loss caused by insect investment in stored food seeds estimated to 30% of the total material stored [3].The lack of information on the early detection of insect presence in stored maize grain products makes it difficult to 1230 (2023) 012112 IOP Publishing doi:10.1088/1755-1315/1230/1/012112 2 detect damage to stored maize products.Detection of insect pests in maize grain storage has only been done by hand sampling [4].
Insect pests can cause damage and yield loss, both in quality and quantity.Post-harvest insect pests in storage can differ in shape, size, preferred food source, and physical environment suitable for living and breeding [5].From this, early detection of insects is part of continuous monitoring and pest control activities in storage.Knowledge of the early detection of pests in storage is very important to know what to do next [6].
This study aims to determine the total population of post-harvest pests in each maize seed storage in four districts.Meanwhile, the benefits of this study are expected to provide information on the types and populations of insect pests that attack corn seeds in storage so that control strategies for these types of insect pests are known.

Materials and Methods
The tools used in this study are a plastic box measuring (17cm× 11.5cm× 4.5cm) as a place to store corn seeds taken in storage, a digital microscope with a magnification of 1000×, a Nobbe trier, a digital camera, an image brush, a collection bottle, and scissors.The materials used were corn kernels, gauze, clear duct tape, 70% alcohol, glue, and labels.
Insect sampling at four maize grain storage places namely Takalar Warehouse, Bantaeng, Maros, and Jeneponto in South Sulawesi.andthe laboratory is the identification of post-harvest pest insects in the Pest Laboratory, Plant Pests and Diseases Department, Faculty of Agriculture, Hasanuddin University Makassar which took place in from October 2022 to December 2022.Sampling was carried out in two ways, namely 1. Sampling with direct capture method (hand sampling), 2. Sampling with tools (sampling with a manual instrument).Sampling was carried out by taking samples of maize kernels in sacks from five points, namely at the corner and center diagonally in the warehouse, and taking samples of corn kernels scattered on the floor of the storage warehouse, each containing 250 grams [4].Trapped insect samples will be taken to the laboratory for population counts and species identification.For reference in identification using the key book of insect determination published [7][8] [9][10]

Observation Parameters
Observations were made by observing insect morphology including size, color, body shape, and wing shape [11].Data from insect population observations were analyzed using population average analysis.The formula used in calculating the average population:

Results
The results showed that insects that have been obtained from maize kernel storage in four districts in South Sulawesi were 10 species of insects including 9 species of insect pests Sitophilus sp.Cryptolestes ferrugineus, Corcyra cephalonica, Carpophilus sp.Araecerus fasciculatus, Lophocateres pusillus, Rhyzopertha dominca, Tribolium castaneum, Oryzaephilus surinamensis. 1 type of parasitoid insect Anisopteromalus calandrae can be seen in table 1.The insects obtained, the Coleoptera order dominates because this type of insect with the Coleoptera order attacks and enters the seeds so that it is easy to obtain at the time of sampling.
Table 1.Identification of postharvest pests caught in storage using the method hand sampling and sampling with a manual instrument  B. On the edge of the wing tips, there are yellowishbrown spots.

No Species
Table 2 shows that the highest insect population was found in Takalar warehouse (A) with a total of 315 individuals and the lowest in Jeneponto warehouse with a total of 67 individuals.While the species of insect that most found in four warehouse locations is Sitophilus sp. and the least is Rhyzopertha dominica.

Table 2. Insects populations found in maize grain storage warehouses in four districts
The figure shows the most common insects found in maize grain storage in four regions in South Sulawesi.Sitophilus sp. was found in most of the maize grain storage warehouses.The abundance of the pest population obtained based on the collection point showed significant results, where the sampling of maize kernels in the overall sack pile was 73% and the collection of maize kernels scattered on the floor obtained 27% of the insect pest population.Can be seen in table 3 The percentage of seed damage in the four storage warehouses can be seen in Table 4. found in Bantaeng 37.16%, and the least is found in Jeneponto which is 11.74%.Table 4. Average percentage of seed damage in 4 warehouses in 4 districts.

Discussion
The presence and population of each insect species in storage are influenced by the abundant availability of food for these insects and several other factors [12].In the results of the identification of insects that have been obtained (Table 1), species from the beetles (order Coleoptera) are most commonly found compared to other insect groups in storage.Sitophilus sp.Cryptolestes ferrugineus, Carpophilus sp.

Warehouse
Seed Damage (%) Araecerus fasciculats, Lophocateres pusillus, Rhyzopertha dominca, Tribolium castaneum, Oryzaephilus surinamensis.Coleoptera order is a type of post-harvest pest that does a lot of damage to stored materials such as seeds.Coleoptera insect species are most commonly found at the sampling site compared to the order Lepidopetra, and Pscopetra [13].Table 2 shows the species of post-harvest pests on maize grains for the four storage warehouses in different locations.The difference in the number of post-harvest pest species be caused by many factors including differences in storage of length, and moisture content of the stored-products [14].The most common types of pests found in the four warehouses are Sitophilus sp. and Cryptolestes ferrugineus, because these two pests are primary and secondary.The spread of other post-harvest pests such as Cryptolestes ferrugineus.appears after the S. zeamais pest attack on corn grains [13].Figure 1 shows that S. zeamais is the most prevalent pest in each storage warehouse because it is the main warehouse pest that attacks maize crops before harvest and in storage [15] [16].
The pest population that has been obtained based on the two collection points, (Table 3) shows a considerable difference in results, although the difference in the difference in results is far sampling on scattered seeds showed a result of 27%, with this result it must be considered the level of cleanliness in the storage warehouse because pests in storage warehouses can hide in scattered seeds and will multiply so that they can attack corn kernels that have just entered the warehouse.The presence of insect pests at the beginning of storage was not found, the presence of insects after some time of storage is likely due to the migration of insects found in scattered piles of seeds that are not in sacks and stored in the same room [17].The percentage of damaged kernels in the four warehouses where corn kernels are stored (Table 4) is different, which is due to the factor of the length of storage of corn kernels in different warehouses, the longer the storage process, the greater the amount of damage experienced by the stored corn kernels.The availability of food and environmental conditions such as the physical condition of the warehouse, moisture content, temperature, humidity, strongly support the development of pests, thus causing an increase in seed damage.The existence of a species population in a place is strongly influenced by the ability of the species to adapt to environmental factors that are limiting factors for the growth of the species population [18].

Conclusion
There were 10 species of insects found in four different storage warehouses, namely Sitophilus sp.Cryptolestes ferrugineus, Corcyra cephalonica, Carpophilus sp.Araecerus fasciculatus, Lophocateres pusillus, Rhyzopertha dominca, Tribolium castaneum, Oryzaephilus surinamensis, and Anisopteromalus calandrae.Sitophilus sp. was the most common species found in all storage warehouses with a total population of 636 individuals, followed by Cryptolestes ferrugeneus with 53 individuals and T. castaneum with 37 individuals.The population of post-harvest pests in all storage warehouses was found more around the pile of sacks, which was around 73% compared to the population found in spilled commodities, which was around 27%. Storage conditions, sanitation, and storage time play a role in the high and low population of post-harvest pests found.

3
The percentage of maize kernel damage can be calculated using the formula: of maize kernel damage a = Weight of damaged maize (g) b = total of weight sample The head is elongated to form a snout.B. The adult is brownish black and reddish brown, on the two forewings there are two slightly reddish yellow spots.C. The body length of the adult is between 3.5˗5 mm.The antennae are long filiform type.B. Adult is golden brown on the thorax and head.C. The wings are transparent with a clear venation system.D. The labial palpi is curved upwards and tapered at the tip.Adult is oval-shaped with a length of about 2-4 mm and is black, brown, or yellow with spots.The body has fine hair.B. The elytra is short and the abdomen looks out.C. The antenna consists of 11 segments.Three segments are oval or, like rounded mace.Adult is brownish black, body length 3˗5 mm.Body cylindrical, elytra pattern with irregular light and dark spots.adult black-brown is flat and its body length is 2.3-4.4 mm.B. Viewed from the bottom and sides, the eyes appear round and large.The Adult is dark brown, body length of 2.5˗3.5 mm.B. the side of the prothorax has six pairs of sawtooth-like serrations.C. On the pronotum there is a clear longitudinal line.D. the shape of the head resembles Adult is reddish brown and oval/flat, body length of 1˗1.5 mm.B. The antennae filiform type.Thread-like antennae are longer than half the length of the body.The adult is light brown and dark brown, the body length is 2.5˗5 mm, and flattened.B. lateral part of the body widens to form a flange.C. elytra cover the entire dorsal segment of the abdomen.
The adult is dark brown/black, and the body length is 2˗4 mm.B. pronotum is like a helmet covering the head and the mouth is facing down.C. The antennae are of the capitate type with the last three segments enlarge Adult is black and yellow.

Table 3 .
Pest population based on sampling points of maize kernels