Collection and inventory of pests on several sorghum varieties

The research with aim of collecting and inventorying several pests of sorghum (Sorghum bicolor L. Moech) crops was carried out in Bajeng Agricultural Technology Research and Development Installation, Gowa District, South Sulawesi, and Entomology Laboratory of Indonesian Cereals Research Institute from March until October 2021 and from March until July 2022. Observations on 11 sorghum varieties (Mandau, UPCA-S1, Numbu, Kawali, Super 1, Super 2, Suri 3, Suri 4, Soper 6, Soper 7, and Soper 9) and several types of pests attacked were carried out at vegetative and generative stages by determined 25 plant samples at random. The results in 2021 showed that at vegetative stages, pests were Ostrinia furnacalis Gueene, Sesamia inferens Walker, Spodoptera frugiferda JE Smith, and Aphis sp. each with a population of 1-3 larvae/plant, 5-13 larvae/plant, and 1-2 larvae/plant respectively, while the scoring of Aphis sp. between 5-7 for all varieties of sorghum. At the generative stage of O. furnacalis and Nola sorghiella Riley was found with a population between 3-5 larvae/panicle, 9-13 larvae/panicle, and a score of Aphis sp. between 5–9. In 2022 at the vegetative and generative stage, the same pests’ species were found with O. furnacalis were 1-2 larvae/plant, S. inferens 3-5 larvae/plant, and S. frugiferda 1-2 larvae/plant. The score of Aphis sp. was between 5-7 for all varieties. At the generative stage, O. furnacalis, N. sorghiella, Heliothis sp., and Aphis sp. were found. Each pest species was 3-5 larvae/panicle, 9-13 larvae/panicle, and 1-2 larvae/panicle while scoring for Aphis sp. between 5-9.


Introduction
Sorghum (Sorghum bicolor L. Moench) is a cereal crop that has the potential to be cultivated and developed, especially in marginal and dry areas in Indonesia.Sorghum plants have long been and are widely known by Indonesian farmers, especially in Java, West Nusa Tenggara, and East Nusa Tenggara.Nowadays, sorghum attracts the Indonesian government's attention to developing wheat substitute crops to maintain national food security.In more detail regarding the roadmap for sorghum development until 2024, the target area for planting in 2023 is 30,000 ha spread over 17 provinces with a production of 115,848 tons (assuming 4 tons/ha).Meanwhile, the target area for planting in 2024 is 40,000 ha spread over 17 provinces with a production of 154,464 tons (assuming the province is 4 tons/ha).Therefore, facilities and infrastructure to support the achievement of government programs have been prepared including plant cultivation, varieties, and plant protection [1].
From the aspect of cultivation, one of the biotic constraints is the disturbance caused by plant pest organisms in the form of insect pests.More than 150 species of insect pest cause damage to sorghum 1253 (2023) 012004 IOP Publishing doi:10.1088/1755-1315/1253/1/012004 2 crops worldwide [2].This abundance of pests affected different problems in the plant-body part in one growing season.This damage will significantly relate to the loss-production of the sorghum.Several strategies have been developed such as genetic studies to develop the resistant sorghum and insecttolerant varieties of sorghum [3].biotechnology has been recognized as an important tool for controlling insect pests and increasing sorghum production.Some of the main pests that attack sorghum plants include seed flies (Atherigona soccata), stem borers, armyworm, fruit borers, aphids, ladybugs, mites, grasshoppers, birds, urets, and several species of warehouse pests.Promising sources of resistance to these key pests were identified both under natural and artificial infestation conditions, and efforts were made to utilize these resistant sources in breeding programs to develop genotypes with resistance to major pests in sorghum [4].Despite a large number of pest attacks on sorghum, there are differences in pest infestation in the different planting areas.Because of that, it is necessary to observe the main types of pests that attack an area to control the control measures that must be carried out.
Sorghum can produce high yields even under adverse environmental conditions, however, the impact of various types of pests at each stage of plant development can reduce its productivity.Important pests of sorghum are leaf suckers, leaf-eating species, stem borers, panicle pests, and stored grain [5].Several research about pest inventory in a specific area on certain plant species has been published to give information about the condition of pest attack.In North Sumatera, information about specific insects has been published.That research focused on four insects Orders (Coleoptera, Diptera, Hemiptera, and Lepidoptera) with 9 families (Chrysomelidae, Scarabaeidae, Cecidomyiidae, Muscidae, Aphidae, Dephiciodae, Pentatomidae, Noctuidae, Pyraliidae) and 16 species [6].In Mexico and USA, the sugarcane aphid, Melanaphis sacchari (Zehntner), become a major insect pest of sorghum [7].In West Africa, yield losses due to stem borer attacks ranged from 11-49%, while in East Africa it ranged from 15-88%, and in Southern Africa 50-60% [8].
This research was conducted to get information about the abundance of Ostrinia furnacalis Gueene, Sesamia inferens Walker, Spodoptera frugiferda JE Smith, and Aphis sp. that become the main problem insect pest found in Bajeng Agricultural Technology Research and Development Installation, Gowa District, South Sulawesi.
FAW's preference for sorghum depends on the variety grown.It was reported that among 7 sorghum varieties evaluated, the Agromen 50A40 variety showed a lower attractiveness rating for the S. frugiperda [9].

Materials and method
The research was carried out at the Bajeng Agricultural Technology Research and Development Installation, Gowa Regency, and in the Entomology and Plant Pathology Laboratory of ICERI at Maros.The research activities took place from March to October 2021 and March to July 2022.The varieties planted in 2021, were: Suri 4, Super 2, Mandau, UPCA -S1, Numbu, Soper 6, and Suri 3. The varieties planted in 2022 were: Suri 4, Super 2, Kawali, Numbu, Suri 3, Soper 6, Soper 7, Soper 9, and Super 1.Each sorghum variety was planted with a plot area of 30 X 10 m, spacing of 70 X 20 cm, and 5 seeds per hole.Fertilization was done by applying 300 kg/ha of Phonska, 250 kg/ha of Urea 2500, and 100 kg of KCl.Half the dose of Urea, the whole dose of Phonska and KCl were applied 10 days after planting (DAP), and half the dose of urea was applied at 30 DAP.
Observations were made once in the vegetative phase and once in the generative phase of plants by randomly determining 25 plant samples, 5 plants each at four corners, and 5 plants in the center.Observations of the pests were carried out directly, by noting the number and types of larvae found.For more details, the larvae were brought to the laboratory in Maros to observe the characteristics of adult insects.The attack intensity of Aphis sp. was calculated by conducting an assessment/scoring of the total population/plants using the scoring system as in Table 1.

Result and discussion
The results showed that the pests of sorghum found in the 2021 crops at the vegetative phase were: Ostrinia furnacalis, Sesamia inferens, and Sodoptera frugiferda.These three species of pests belong to the order Lepidoptera.The moths of the three species of pests have laid eggs on young plants, namely 21 DAP so symptoms of an attack can be seen at the age of about 30 DAP.These three types of pests are found in plants in the flowering, fruit formation, seedling, and vegetative phases [11][12][13].
The young larvae of O. furnacalis damage the young sorghum leaves that are still rolling, after becoming 3rd instar larvae, they burrow the plant stems (Figure 1).Similarly, the young larvae of S. inference damage young plants, where the young leaves are still curled.If S. inference destroys it early in growth, the plant will die.This was due to the fact that in one plant S. inference larvae were found between 2-15 larvae.This is because the larvae of S. inference live in groups on one plant [13].If the damage is rather slow, the plant growth will be stunted (Figure 2).Young S. frugiferda larvae also damage the young leaves that are still curling [11].The difference in attack for the 3species of the pests is that when S. frugiferda is destructive, it attacks almost all plants and the symptoms of an attack are evenly distributed on each plant (Figure 3).Attack of Aphis sp. was also found at the beginning of plant growth but still uninfected plants were found, and in some plants, aphis was found to start forming several colonies with an average score of 4 (Figures 4 and 5).In Figure 4, we can also see the sooty mold on the surface of the plant leaves.The  The results of observations on the types of pests in the vegetative phase of plants in 2021 were O. furnacalis with the lowest average larvae found was 0.02 larvae/plant in Suri 4 and the highest in Numbu was 1.36 larvae/plant.The lowest average larvae of S. inferens was 0.20 larvae/plant at UPCA S1, and the highest was at Numbu at 1.28 larvae/plant.The average larvae of S. frugiferda ranged from 0.08 to 0.92 larvae/plant (Table 2).These pests were the same as those found in the vegetative phase of plants in 2022: O. furnacalis with the lowest average number of larvae of 0.20 larvae/plant in Suri 3, and the highest of 1.16 larvae/plant found in Numbu.The average number of S. inferens larvae was the lowest 0.20 larvae/plant found in Super 2 and the highest was 0.68 larvae/plant in Numbu.The lowest mean larvae of S. frugiferda was 0.03 larvae/plant in Soper 6 and the highest was 0.52 larvae/plant in Super 1 (Table 3).According to Siregar et al. [6], in the vegetative phase of sorghum plants found, among others, H. armigera, Mythimna separata, and Chilo partyellyus.The results of observations on the types of pests in the plant generative phase in 2021 were O. furnacalis with the lowest average larvae found was 2.04 larvae/panicle in Suri 3 and the highest was 3.08 larvae/panicle on Numbu.Besides O. furnacalis, Nola sorghiella larvae were also found with an average of 1.60 larvae/panicle on UPCA S1 and 3.67 larvae/panicle on Super 2 (Table 4).Observations on the generative phase of plants in 2022 found the types of pests O. furnacalis, N. sorghiella, and Helicoverpa sp. with the average larvae of O. furnacalis was 0.76 larvae/panicle on Soper 7, and 1.31 larvae/panicle on Numbu.The larval average of N. sorghiella was 0.24 larvae/panicle in Numbu and Kawali, and the highest larval average of 1.12 larvae/panicle was found in Soper 7 (Table 5).In the generative phase, the young larvae of O. furnacalis damaged the young sorghum seeds, then the 3rd instar larvae damaged/bored the stalk of the sorghum panicle, when the panicle was opened it was found that there were more than 3 larvae/panicle (Figure 5).According to Siregar et al. [6], the types of pests found in the generative phase include Aphis sp., H. armigera, S. frugiperda.The results of observations on Aphis sp. in 2021 and 2022 in the vegetative and generative phases of all varieties can be seen in (Figures 6 & 7).In Figure 6 (2021), the observations show that in the vegetative phase (when the plant is 30 DAP) the population score is between 1.8 in Mandau and 2.9 in Soper 6.The population score increases with increasing plant age in the generative phase for all varieties with a population score between 3.1 in UPCA S1 and 4.2 in Suri 4. This is in accordance with that reported by Siregar et al. [6], Aphis sp. has been found in sorghum plantations at 20 DAP to 60 DAP. Figure 7 (the year 2022) shows the population score of Aphis sp. at the vegetative phase (when the plant was 30 DAP) was between 1.8 in Super 1 and 3.7 in Super 2. The population score increased with increasing plant age (generative phase) between 3.1 in Kawali and 4.3 in Soper 7. The development of Aphis sp. in sorghum is influenced by plant genotype [15] and climate [16].

Conclusion
The types of sorghum pests in 2021 and 2022 in the vegetative phase are the same: Ostrinia furnacalis, Sesamia inferens, Sodoptera frugiferda, and Aphis sp.
The types of sorghum pests in 2021 and 2022 in the generative phase are the same: Ostrinia furnacalis, Nola sorghiella, and Aphis sp.In the generative phase in 2022, Helicoverpa sp. was also found.

Figure 3 .
Figure 3. Symptoms of S. frugiperda attack in the vegetative phase of the plant (Photo: Nonci, 2021).

Figure 6 .
Figure 6.Aphis sp population score. in the vegetative and generative phases in 2021.

Figure 7 .
Figure 7. Aphis sp population score. in the vegetative and generative phases in 2022.

Table 2 .
The average population of sorghum pest larvae in the vegetative phase in 2021.

Table 3 .
The average population of sorghum pest larvae in the vegetative phase in 2022.

Table 4 .
The average population of sorghum pest larvae in the generative phase in 2021.

Table 5 .
The average population of sorghum pest larvae in the generative phase in 2022.