The role of combination insectary plants and botanical pesticides in increasing arthropod populations of natural enemies and suppressing populations of s. frugiperda in corn

Spodoptera frugiperda is the main pest of corn with a high level of attack intensity. Utilization of natural enemies both predators and parasitoids can be lured using zinnia flowers could be an effective control technique in suppressing armyworm pest populations. Pests hate the smells and taste of botanical insecticides a mixed of maja fruit and giant milkweed leaves which contain secondary metabolites such as volatile, pectin, saponins and tannins. This study aims to determine the effect of zinnia flowers and the application of botanical insecticides in suppressing armyworm populations. This research was carried out in Padakkalawa, Mattirobulu District, Pinrang Regency and Universitas Hasanuddin’s Laboratory of Insect and Plant Disease Relations. The research observed pest intensity, larval population and natural enemies. The results showed that the highest attack intensity was observed in the control treatment with an average of 12.59%/plant. The highest observed larval population was in the control with an average of 2.13 individuals/plant. In observing natural enemy arthropods in all observation techniques, the highest population of natural enemy arthropods was in the combination treatment of zinnia flowers and botanical insecticides with the most species being Lasius niger or ants which was significantly different from the control treatment. The results showed that the combination of insect plants and the application of botanical pesticides had an effect on the population and attack intensity of S. frugiperda larvae and populations of natural enemy arthropods.


Introduction
Corn (Zea mays L.) is an important and main cereal crop in the world, also corn has a huge commodity in the world.In Indonesia, corn is an alternative carbohydrate after rice, besides is cultivated in the food sector, corn is also used as feed and a source of raw materials for production [1].Pests and diseases are the main cause of production problem of corn.In developing tropical and sub-tropical regions such as Indonesia, pests and diseases are the main obstacle to the stability of corn production [2].
The most common pest is caterpillar or S. frugiperda which is a new pest of corn in Indonesia.This pest originates from America and then spreads to Africa to Asia [3].In Indonesia, it has a very wide host range and is considered an invasive pest because it has a relatively short life cycle and can live in any environment even though it is not its natural ecosystem.S. frugiperda could be found in all growth of corn and caused the highest damage in the vegetative phase.S. frugiperda larvae able to damage roots, stems, leaves to cobs of corn and can cause significant yield losses if not handled properly.The failed harvest caused by S. frugiperda can reach losses of up to 80% [4].
Utilization of natural enemies can be used to suppress pest populations by using parasitoids such as Tricogramma spp, Apanteles spp and predators such as Ophionea ishii, Paederus furcipes, several types of ants, dragonflies, and several other types of natural enemies.Zinnia flowers are one of the Insecteary plant which are microhabitats that provide temporary shelter for predators and parasitoids, providing benefits for biotic ecosystem interactions [5].Refugia or Insectary plants is weeds that grow around cultivated plants, which have the potential to act as microhabitats for natural enemies for both predators and parasites, so that the conservation of ha is well created.Refugia has striking flowers and colors, fast and sustainable plant regeneration, seeds are easy to obtain, easy to plant, and can be intercropped with other plants [6]  Indonesia has rich variety of plants to use as botanical pesticides, for instance is Calabash fruit (Aegle marmelos).Maja fruit besides containing marmelosin also contains essential oils, pectin, saponins and tannins which are not liked by plant pests, Calabash fruit have a pungent odor and bitter taste so that they can repel pests, besides that they can interfere with the digestive function of insects [7].Giant milkweed plant (C.gigantea) can also be used as a botanical pesticides.Some researchers suggest that the leaves and stems of giant milkweeds function as insecticides, extracts and giant milkweeds can be used as botanical pesticides.The results of another study showed that crude extracts from C. gigantea leaves were effective as oviposition inhibitors and had the potential to be ovicidal with about 75% effectiveness against P. pallicornis [8].
Therefore, the purpose of this study was to determine the role of combination insectary plants and botanical pesticides in increasing arthropod populations of natural enemies and suppressing populations of s. frugiperda populations in corn.

Methodology
This research was conducted in Padakkalawa Village, Mattiro Bulu District, Pinrang Regency, South Sulawesi Province and the Laboratory of Insect and Plant Disease Relations, Faculty of Agriculture, Universitas Hasanuddin, Makassar.Started from October 2022 to January 2023.
This study used an experimental randomized block design (RBD) consisting of 4 treatments, and each treatment was repeated 5 times, there were 20 experimental plots, each replicate plot measuring 4.5 x 11m with the following treatments: T1 = Zinnia flowers and botanical pesticides T2 = natural treatment 2.1 Implementation Sowing of the zinnia plants was started 30 days before the corns were planted.After the zinnia plants were approximately 14 days old, the zinnia plants were then transferred to the study plot.
The land to be used as a research site must first be cleared of weeds and remnants of roots from previous crops, then loosened using a tractor.After that, 20 plots were made with a size of 4.5 x 11 m each, where each experimental plot had 3 beds with size 3 x 4.5 m.Two corn seeds were planting in 5cm holes with distance of 30 cm x 50 cm.Botanical insecticide spraying was started when the corn were 7 to 28 DAP, spraying was done once a week with a concentration of 5% using 15 liter sprayer.Treatment included watering, fertilizing and weeding.Watering is done every day if there is no rain, fertilization is done when the corn are old.Weeding is done by removing weeds that grow around the corn and zinnia.

Observation Parameters
Observations conducted every 7 days when the corn were 14 to 63 days after planting.There are three observation techniques, the first is visual observation, the second is by observation using a sweep net and the third is direct capture using a pitfall trap, then all the caught arthropods are put into a killing bottle and then taken to the laboratory to be identified.The observed are as follows: 1. S. frugiperda larvae attack intensity 2. Larvae population of S. frugiperda 3. Arthropod population of natural enemies in corn and zinnia flowers

Data Analysis
The data were analyzed using the ANOVA test of variance with a significant level of 5% and then tested with the BNT test if there were significant data.

Attack Intensity of S. frugiperda Larvae
The average attack intensity of S. frugiperda during 8 observations for all treatments showed in picture 1.During the observations it can be seen that the highest attack intensity of S. frugiperda larvae was in the control treatment with the highest attack intensity in the 5th observation with an intensity of 12.59%.The results of statistical analysis showed a significant difference with the combination treatment of zinnia flowers and botanical pesticides with the highest intensity occurring in the 5th observation with an intensity of 2.73%.It caused by the highest level of greed of S. frugiperda larvae occurs in the vegetative phase [9].One of the reason is that corn which growing shaped more trichomes on the leaves, making it difficult for the insect's mouthparts to reach the leaves [10].The average intensity of attack by S. frugiperda larvae on maize was lowest in the combined treatment of zinnia flowers and vegetable pesticides.The low population of larvae was due to the zinnia flowers which act as insecticides which trigger the presence of natural enemy arthropods to enter the plant ecosystem, apart from being a hiding place., flowering plants also produce nectar which is an additional food source for natural enemies so that their performance is maximized.Compared to ecosystems that do not have flowers, the population of natural enemy arthropods is very less [11].Giving plant extracts which are a mixture of A. marmelos and C. gigantea can also suppress the activity of S. frugiperda, C.gigantea leaf extract which is repellent to ladybugs which causes a lack of feeding activity of the larvae which causes the death of the S. frugiperda [12].

Larvae population of S. frugiperda
Based on the population of S. frugiperda larvae during observation.The highest larval population was in the control treatment with the highest population of S. frugiperda larvae in the 3rd observation with an average of 2.13 individuals/plant.The results of the analysis showed a significant difference with the combination treatment of zinnia flowers and botanical pesticides with the lowest intensity in the 3rd observation with 0.93 individuals/plant.The lowest average larval population on corn is in the combination treatment of zinnia flowers and botanical pesticides, zinnia flowers as the provider of food sources, shelter or reserve resources for natural enemies, besides being able to increase the number of natural enemy populations of 72% can also reduce pest populations by 74% [13].Provision of botanical pesticide extracts from a mixture of A. marmelos and C. gigantea which pests do not like because they are repellent.C. gigantea contains tannins and flavonoids which can inhibit the digestive system in insects so that both can suppress the activity of S. frugiperda larvae [14].

Arthropod populations Natural enemies
Arthropod populations of natural enemies using all observation techniques can be seen in table 1.The highest populations of natural enemy arthropods were found in the combined treatment of zinnia flowers and botanical pesticides.The results of statistical analysis showed significant differences with the control treatment.Arthropod natural enemies found consisted of 27 families and divided into 33 species, the highest species population was Lasius niger from the Formicidae family with a total of 432, then Paederus fuscipes from the Staphylidae family with a total of 332 and Oxyopes salticus species from a total of 331 families.
Average Larva Population S. frugiperda Arthropod populations of natural enemies in all observation techniques, the highest population of arthropods in each observation technique was found in the combined treatment of zinnia flowers and botanical pesticides.The high population of insects such as ants, tomcats, spiders and several other insects caused by zinnia flowers which can lure natural enemy arthropods, the presence of 1255 (2023) 012009 IOP Publishing doi:10.1088/1755-1315/1255/1/0120096 cobwebs on zinnia flowers which are on the edge of the beds can prevent pests from entering the land, their habitat.Insects such as spiders and ants can be found in various ecosystems, both those that are rarely traversed by humans or those that are frequently traversed [15].Zinnia flowers generally start flowering at the age of 21 DAP, have many stalks and leaves that are thick enough so that natural enemies can easily hide so that the population of natural enemy arthropods in a field that has zinnia plants is higher than land that does not have zinnia plants [16].

Conclusion
The result showed that zinnia flowers and botanical pesticides can reduce the attack intensity and population of S. frugiperda larvae.Zinnia flowers attracted natural enemy arthropods to suppress the intensity and population of S. frugiperda larvae.Botanical pesticides which made from extracts of A. marmelos and C. gigantea was repellent against pests which causing them to have digestive disorders, thus making the larval population and the intensity of larval attacks very low compared to the control treatment.The suggestion for further research is to add the types of flowers and the types of vegetable pesticides used.That is all and thank you.

Figure 1 .
Figure 1.Average attack intensity of S. frugiperda larvae each week.

Table 1 .
Arthropod populations of natural enemies in all observation techniques