Prospect of utilizing botanical pesticides for maize weevil Sitophilus zeamais (Motschulsky) management to preserve national maize production

Maize plays a strategic role in the national food map as well as a mainstay commodity in accelerating the realization of food self-sufficiency. It is because maize has wide adaptability and is relatively easy to cultivate. However, the attack of maize weevil obstructs the increase of maize productivity. This pest is the most destructive and reduces maize productivity as a national source of carbohydrates. The global policy of limiting the use of synthetic pesticides to control agricultural pests has become a topic of discussion in international forums today. It is due to the large number of deaths reported by synthetic pesticides. WHO reports that every year pesticide poisoning occurs between 44,000-2,000,000 people worldwide, and the highest poisoning rates occur in developing countries. In response to this, the government has made regulations through Government Regulation No.6 of 1995 concerning synthetic pesticides. It is contained in. Plant-based materials are very prospective to be used as active ingredients for environmentally friendly botanical pesticides. It has been identified that around 10,000 potential secondary metabolite components can be processed into active ingredients of botanical pesticides. This paper discusses the potential of botanical pesticides in Indonesia’s national plant treasures.


Introduction
Plant Pest Organism is one of the obstacles that must be seriously addressed in cultivating crops.The uncontrolled growth of PPO will cause other problems, including social, economic, and ecological.Several types of pests can inhibit crop production since they affect the quantity and quality of the crop.PPO can attack plants at all growth stages, from early growth to storage.Inadequate use of cultivation technology will result in low productivity and quality [1].
Pesticides or poison for pests [2] has so far been used by farmers for pest eradication.Pesticides play a very important role in the agricultural, plantation, forestry, and animal husbandry sectors for sustainable crop production.In addition, pesticides also play an important role in preventing and controlling pest attacks and their impacts to achieve the expected results, both in quality and quantity.These impressive results make pesticides the number one choice for farmers to protect against pest attacks.
Botanical pesticides are natural pesticides from plants containing active ingredients to control insect pests.According to historical records [3], the use of botanical pesticides has been practiced since three centuries ago, in 1690, when farmers in France used tobacco leaf juice to control ladybird pests on peaches.Furthermore, in the 1800s, powdered pyrethrum was used to control fleas [4,5].Those two 1230 (2023) 012087 IOP Publishing doi:10.1088/1755-1315/1230/1/012087 2 materials for controlling pest attacks have shown impressive results.In addition to reducing environmental pollution, the operational costs of using botanical pesticides that farmers and other users must incur are relatively cheap compared to chemical pesticides.However, because the reaction of botanical pesticides takes a short time, most farmers still rely on synthetic pesticides [6].
While only about 10,000 secondary metabolite products have been identified, the number of chemicals in plants that have the potential as botanical pesticides is estimated at around 400,000 species [7,8].Furthermore, it is estimated that around 1,800 species of plants containing botanical pesticides can be used for pest control.In Indonesia, plant species producing botanical pesticides are spread across 235 plant families with a total of 2,400 identified plant species [9,10].
Plants have developed and produced natural chemicals as a means of self-defense against insect pests.Plants contain many chemicals in the form of secondary metabolite compounds whose benefits are still unclear in plant metabolic processes.It was found that this group of compounds plays an important role in the process of interacting or competing, including self-protection from interference from competitors [11].Plants can use these secondary metabolite products as active ingredients in botanical pesticides [12,13] and as a defense against pest attacks.
The main problem in maize farming is the significant loss of yield due to the infestation of Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae) in storage [14,15].The S. zeamais was the most damaging pest of the many pests in crop storage [16,17].The destructive ability of this pest occurs in the active larval stage since the larvae bore and hide in the seeds.

Natural ingredients as bioactive compounds of botanical pesticides
Natural ingredients that contain bioactive compounds can be classified into three, namely (a) natural ingredients containing anti-phytopathogenic compounds (agricultural anti-biotics), (b) natural ingredients containing phytotoxic compounds or compounds that regulate plant growth (phytotoxins, plant hormones, (ended by etc.), and (c) natural ingredients containing active compounds against insects (insect hormones, pheromones, anti-oxidants, repellents, attractants, and insecticides) [18].In general, the mechanism of botanical pesticides in protecting plants from pests is by inhibiting the reproductive process of insect pests, especially in female insects; reducing the appetite of pests; causing insects to refuse food; interfering with the development of eggs, larvae, and pupae; inhibits the breeding and molting of insects.
Based on the mode of action (MoA), botanical pesticides can be classified into (a) repellant, namely a group of botanical pesticides that prevent the presence of insects through a pungent odor; (b) antifeedant, which is a group of botanical pesticides that prevent insects from eating plants; (c) inhibit the reproduction of female insects; (d) nerve poison; and (e) disrupting the hormone system in the insect's body; and (f) attractants [19].
With the incessant movement back to nature and organic farming, plant-based pesticides are very prospective to be developed.This is because botanical pesticides contain many chemical compounds that are able to slow down insect resistance [20].
The use of pesticides, including botanical pesticides, is closely related to their toxicity [21].Unfortunately, very few researchers have conducted studies on the toxicity (both acute and chronic) of botanical insecticides to non-target organisms.Research on non-target organisms is very important to develop standardized botanical pesticides [22].Patchouli and cajuput essential oils have been studied for their biosafety against non-target organisms, namely predatory insects from the Reduviidae family, namely Sycanus annulicornis.The result showed that both essential oils were safe [23].Peppermint essential oil formulated in nanoemulsion has shown no toxicity to Artemia salina L. and Tenebrio molitor L. as non-target organisms [24].Due to their natural origin, many botanical pesticides are reported to have no adverse impact on natural enemies of pests and non-target organisms.Because they are relatively safe against non-target insects, botanical pesticides can prevent resurgence to reduce the risk of a secondary pest outbreak.
In addition to some of the advantages above, vegetable insecticides have other advantages such as being able to minimize harm to human health and livestock due to residues left behind; not damaging the environment, groundwater, and surface water supplies; reducing farmers' dependence on agricultural chemicals; cost less; easy to manufacture by the farmers themselves; does not cause poisoning in plants (phytotoxicity); synergistic and compatible when combined with other control techniques; easily degraded; and supports the sustainability of small-scale agriculture [25][26][27].
However, botanical pesticides also have drawbacks.Botanical pesticides are made from natural materials which are less stable, so they are easily degraded by physical, chemical, and biotic influences from the environment [28][29][30].It also requires a higher frequency of use than synthetic chemical pesticides, reducing the practicality aspect.Moreover, most organic compounds are non-polar, making them difficult to dissolve in water and require emulsifying agents.Besides that, the content of active ingredients is relatively low, therefore it takes quite a lot of material sources.If bioactive ingredients are obtained from flowers, seeds, fruit, or plant parts that grow seasonally, it will result in uncertainvailability, becoming an obstacle to further development [31].
To obtain concentrations and/or effective doses, long studies are required, starting from testing in the laboratory to the field.Some of the weaknesses of other vegetable pesticides include, some of the active ingredients work slowly in controlling pests so they must be formulated in a mixture or combined with other control techniques, are less persistent so that additional frequency of application is needed, and cannot be stored for a long time [32].
Several plants have been studied for their potential to control the maize weevil S. zeamais.These beetles are known to cause damage to corn, rice, sorghum, and other food products at the storage level [33].This weevil diminishes weight, damages the entire kernel, and promotes the spread of mold by increasing moisture.Furthermore, extreme circumstances may result in total degradation of the grain bulk [34].

Conclusion
Natural ingredients containing bioactive compounds can be classified into three, namely a) natural ingredients containing anti-phytopathogenic compounds (agricultural antibiotics), b) natural ingredients containing phytotoxic compounds or compounds that regulate plant growth (phytotoxins, plant hormones, etc.), and c) natural ingredients containing active compounds against insects (insect hormones, pheromones, anti-oxidants, repellents, attractants, and insecticides).The advantage of botanical pesticides is that these materials are easily decomposed in nature, so they do not pollute the environment (environmentally friendly).They are also safe for humans and livestock since the residues are easily lost, do not poison or damage plants, the doses used do not cause too much risk, and do not cause insect resistance.However, botanical pesticides also have disadvantages, such as being easily decomposed; having slow working power, so they must be applied frequently; being unable to be stored for a long time, and being less practical since we have to make it first and it takes time to make the pesticides.

Table 1 .
Potential plants have been used as botanical pesticides to control Sitophilus zeamais.