Application of Various Concentrations of Mixed Extracts of Calotropis gigantea and Crescentia cujete Against Population and Attack Intensity of Leptocorisa acuta, Nephotettix virescens and Natural Enemy Populations of Rice Plants

Changes in land and pesticide are the main drivers of changes in the biodiversity of agricultural land, particularly natural enemies of insect pests. Leptocorisa acuta and Nephotettix virescens are the main pests of rice plants in Indonesia which are mostly controlled with pesticides. The use of extracts of natural ingredients Calontropis gigantea leaves and Crescentia cujete fruit is an alternative for controlling rice pests. The purpose of the study was to determine the mixed extracts of C. gigantea and C. cujete with various concentrations on the population and the attack intensity of Leptocorisa acuta and Nephotettix virescens as well as natural enemies population. This study consisted of six treatments, namely a concentration of 1%; 2.5%; 4%; 5.5%; 7% and farmer treatment. Observations were made visually and sweep net by taking samples diagonally in one plot was taken five plant sample points were and in one point consisted of four clumps of rice. The results showed that, in comparison to the farmers treatment, the population and attack intensity were low for all extract concentration treatments, and statistical analysis did not reveal any statistically significant differences between concentrations. In comparison to farmer treatment, the population of natural enemies was high in all extract treatments. When mixed extracts of C. gigantea and C. cujete are used for pest management of rice plants, the number and severity of pest attacks can be reduced without affecting natural enemies.


Introduction
Rice is still essential to life for humans and rural livelihoods because it is the most important agricultural priority product worldwide, especially in Indonesia [1].However, there are several factors that cause a decrease in rice productivity, it is pests and diseases, climate and cultivation techniques.Among these factors, pests are the main cause of decreased rice production.Leptocorisa acuta and Nephotettix virescens are pests that reduce output and quality [2].L. acuta, the notorious pest responsible for pecky rice, is common in major rice-growing areas and presents a high potential for damage.Leptocorisa species significantly damage rice agriculture in a number of Asian and Oceanian nations by drastically affecting production, grain quality, and seed viability [3].N. virescens is a vector of Rice dwarf virus (RDV) which causes reduced growth in the number of tillers and totally inhibits plant growth so that plants look stunted or short.Plant damage caused by N. virescens causes the leaves of the plants to turn 1230 (2023) 012093 IOP Publishing doi:10.1088/1755-1315/1230/1/012093 2 yellow or orange yellow which threatens rice yields and causes substantial economic losses [4].To control pests, farmers usually use synthetic pesticides.As a result, resistance, resurgence, death of natural enemies and of course can cause environmental pollution, because levels of synthetic pesticide residues can increase and kill organisms in the food chain [5,6,7].Very few pesticides used after DDT have long environmental half-lives, and none of them bioaccumulate in the same way as organochlorines did.Additionally, because the majority of synthetic pesticides affect non-target organisms like fish, plants, and animals, they pose a risk to human health.Furthermore, farmers in countries that are developing cannot afford them [8,9,10,11].It must therefore look for alternative technology that can reduce the use of this synthetic pesticide.Once they are affordable, target-specific, less harmful to human health, bio-degradable, and thus environmentally friendly, extract technology from plants containing bioactive substances such as biopesticides may meet those necessary standards and become the key to solving pest problems and promoting sustainable production.Biopesticides are pest control methods based on biochemicals produced by live insects, plants, and microorganisms [7,12,13].Plant extracts can be used to repel, poison, kill, stop feeding, and restrict the growth and development of insect pests.Calotropis gigantea and Crescentia cujete are two plants that could potentially serve as natural pesticides.C. gigantea has been used as an insecticide [4,5], medicinal plant [16], molluscacide, fungicide, and nematicide [17] because C. gigantea contains flavonoids, tannins, cardiac glycosides, and terpenoids [18].Secondary metabolites of this plant can cause ovicidal effects [8,9], oviposition deterrent [21], larvicidal and repellent [22] for insects.C. cujete contains saponins, flavonoid, cardenolides, tannins and phenol as well as the presence of hydrogen cyanide [23].Tannin compounds can affect insects in terms of oviposition, flavonoid compounds can inhibit the transport of leucine amino acids and are toxic to insects [22].Previous research shown a synergistic impact between C. gigantea and C. cujete in preventing the growth of Scirpophaga innotata and Cnaphalocrosis medinalis [24].Based on this research, a mixture of fermented C. gigantea and C. cujete was used to reduce pests and the effects it had on natural enemies, particularly rice plant predators.

Location
This study was carried out at the Faculty of Agriculture's Laboratory of Natural Pesticides at Hasanuddin University in Makassar and Loka Penelitian Penyakit Tungro.St. Bulo No. 101, Lanrang District, Sidrap Regency, Sulawesi Selatan -Indonesia.The study was conducted between June and October of 2021.

Preparation of fermented C. gigantea and C. cujete extract
C. gigantea leaves and C. cujete fruit were fermented in a 1:1:0.2ratio with water and molasses.The combined components are then swirled until well combined, and the container is carefully closed.Allow to stand for 2 weeks.The extracted liquid and solid components are then separated after filtering the fermented extract.The fermented extract was subsequently put in a container, with the liquid version being utilized for field application.

Application in the field
The field experiment was conducted on a 3 × 5 meter patch.There were 18 rice plots in all, with six different treatments and three repeats.The plots were separated by 2 meters.The extract was sprayed over the rice surface at one-week intervals from 31 to 94 days.

Observation
Populations of natural enemies, pest populations, and the intensity of pest attacks were the subjects of observation.The experiment began one day before application, ended 30 days after rice planting, and was repeated ten times.Five subplots each plot served as observational sampled.There were two methods used to observe the insect population and natural enemies: a virtual approach that involved sweeping the net with eight swings and a method that used ten clumps of rice per plot.This observation took place in the morning.

Observation parameters
2.6.1 The average population of pests and natural enemies.Observation of average population were carried out by calculating the number of populations of main pests and natural enemies in each clump sample.The formula used to calculate the main pests and natural enemies are: 2.6.2.Attack intensity of pest.The strength of the primary pest attack in every clump was calculated to observe attack intensity.The formula for calculating the attack intensity of L. acuta and N. virescens is as follows: 2.7 Data analysis.Data analysis using a randomized group design then conducted the F test at α 0.05 and 0.01 levels.Further test using the HSD test.

Result and Discussion
Following the application of several concentrations of C. gigantea and C. cujete extracts to rice plants for 10 weeks, the results of observing the population and attack intensity of L. acuta and N. virescens attack showed a significant difference.The values followed by the same letter are not significantly different from each other at the P d" 0.05.
Table 1 shows that at the 31 to 52 DAP observations, no population of L. acuta was found.At the 59 DAP, 73 DAP, 87 DAP and 94 DAP observations there was no significant difference in each treatment then at the 66 DAP and 80 DAP observations there was a significant difference while in the 66 DAP observation the farmer treatment had the average population of the walang sangit was 3.00 significantly different at concentrations of 2.5% (1.67 individuals), 4% (1.83 individuals) and 7% (1.17 individuals) and not significantly different at concentrations of 1% (2.00 individuals) and 5 .5% (2.17 individuals).
Then at the 80 DAP observation, the farmer treatment had the highest average population of stink bugs, namely 11.17 individuals and was significantly different at all concentrations.The evolutionary relations between these compounds and the functional functions they play as signaling molecules are shown.Based on this, it is possible to believe that the presence of secondary metabolites that act as attractants can attract and increase the population of pollinating insects and natural enemies that also play a role in preying on insect pests, thereby indirectly reducing pest populations, which is directly proportional to the suppression of pest attack intensity [28].
Repellent is one of the effects caused by compounds contained in plants in the form of repelling insects against host plants.The use of repellents generally does not directly kill insects but rather serves to repel the presence of insects, which is caused by a pungent odor from the stimulus source [29].The repellent effect is generally obtained in plants with high alkaloid and terpenoid content [30].According to reports, the phytochemicals alter insect life cycles, limit larval survival, and affect growth [31].Saponins in G. gigantea and C. cujete can suppress pest populations and attack intensity.Saponins are found in a variety of plant parts, including the leaves, stems, roots, bark, and even the flowers [32].Some plants have very high saponin content, which is significantly affected through abiotic environmental factors.The antimicrobial, antioxidant, insecticidal, nematicidal, and molluscicidal properties of these chemicals are all present [33,34,35].Due to their function as repellents or deterrents, saponins directly affect the growth and reproduction of insect pests.By reducing food intake and changing food flow in the insect stomach as a result of toxicity and poor digestion, they raise death rates [36].Saponins impair digestion through changing the microbiota in an insect's stomach.They reportedly alter the digesting process in the insect gut by forming complexes with digestive enzymes including proteases.Saponins rupture the interior lining of gut mucosal cells because they have the potential to make membranes more permeable.Furthermore, they exhibit potent insecticide activity by developing structures with cholesterol that render insects toxic to cells and ecdysial failure [37].Because it is unable to produce sterol structures, insects must obtain the precursors for ecdysteroids from their diet, such as cholesterol or phytosterols.Saponins interfere with insect moulting and ecdysis, create an indigestible bond with sterols in diet, and impede sterol intake [38].

Conclusion
The population and intensity of pest infestations were dramatically decreased when C. gigantea and C. cujete extracts mixed with its secondary metabolites.Furthermore, natural enemies are unaffected by this mixture of extracts.

Table 1 .
Effect of plant extract concentration on the population of L. acuta compared with farmer treatment.

Table 2 .
Effect of plant extract concentration on the attack intensity of L. acuta compared with farmer treatment.The values followed by the same letter are not significantly different from each other at the P d" 0.05.

Table 2
shows that the intensity of the attack of the walang sangit on the 94 DAP observation of the farmer treatment had an average attack intensity by the L. acuta, which was 5.12, significantly different from the concentration treatment of 7% (4.03 individuals) and 5.5% (3.36 individuals).The 7% concentration treatment was not significantly different at the 1% (3.70 individuals) and 4% (3.64 individuals) treatment and the 5.5% concentration treatment was not significantly different at the 2.5% concentration (2.93 individuals).

Table 3 .
Effect of plant extract concentration on the population of N. virescens compared with farmer treatment.
The values followed by the same letter are not significantly different from each other at the P d" 0.05.

Table 3
shows that in observation 31 no N. virescens population was found, N.

Table 4 .
Effect of plant extract concentration on the attack intensity of N. virescens compared with farmer treatment.The values followed by the same letter are not significantly different from each other at the P d" 0.05.

Table 4
shows that from the 31 to 38 DAP observations no N. virescens attack intensity was found, N. virescens populations began to appear on the 45 to 94 DAP observations.At the 45 DAP, 52 DAP, and 80 DAP observations there was no significant difference in each treatment then at the 59th DAP, 66 DAP, 73 DAP, 87 DAP and 94 DAP observations there was a significant difference in the 59 DAP observation of the farmer treatment had an average N. virescens intensity of 4.00 and was significantly different at all concentrations.The 66 DAP observations in the farmer treatment had an average N. virescens intensity of 7.00 which was significantly different in the treatment of 1% (3.33 individuals), 2.5% (4.67 individuals), 5.5% (5.00 individuals) and 7% (4.00 individuals) and not significantly different at 4% concentration (6.33 individuals).Observation of the 73 DAP control treatment (farmer treatment) had an average population of N. virescenss, namely 8.33, which was significantly different at the concentrations of 5.5% (6.67 individuals) and 7% (5.33 individuals) and not significantly different at the 4 concentration treatments.%(7.33 individuals).Treatment of 5.5%(6.

Table 5 .
Population of natural enemies in farmer and extract treatment

Table 5
[27]17]hat the highest natural enemy population observed in all extract concentration treatments and the lowest in the farmer treatment (control).Compared to controls, observations revealed that applying a mixture of C. gigantea and C. cujete extracts had an impact on a decrease in pest populations and the intensity of L. acuta and N. virescens attacks.This extract's ability to eradicate L. acuta and N. virescens suggested the existence of secondary metabolites such calcium oxalate, phenols, flavonoids, tannins, alkaloids and saponins.[15,17].Secondary metabolite compounds are produced by plants, one of which functions to defend themselves from unfavorable environmental conditions such as temperature, climate, as well as pest and plant disease disturbances[26].These secondary compounds have various functions and mechanisms to repel pests and can kill these pests.C. gigantea and C. cujete extracts also affected the number of populations of natural enemies of Ladybird beetles, Spiders, Damselflies and Rove beetles.The population of L. acuta in rice plants started to increase in the generative vase at age 59 DAP, peaked at age 73 DAP to reach a population of 87 DAP, and then started to decline at age 94 DAP.The fact that the extract treatment's attack intensity was lower than the controls suggests that the extracts use as a plant based pesticide significantly reduced the L. acuta's attack intensity.In rice plants, N. virescens first appeared during the vegetative phase, specifically at 38 DAP, reached its highest population between 59 and 80 DAP, and then started to decline at 87 DAP.This is due to N. virescens' attack, which peaked at the booting stage after beginning during the vegetative phase[27].While regarding the target intensity of attack of N. virescens indicates that the treatment of spraying the extract as a vegetable pesticide significantly affected the intensity of attack of N. virescens on rice.Because C. gigantea and C. cujete extracts contain several secondary metabolites that can act as attractants to natural enemies in addition to acting as insect repellents, antifeedants, and toxicants, they can have the effect of reducing pest populations and suppressing the intensity of pest attacks.In this situation, secondary metabolites serve as signaling substances that attract in natural enemies.Secondary metabolite chemicals including oil, colorful flavonoids, and tetraterpenes have a role in attracting pollinator insects or other natural enemies for seed dissemination.Volatile monoterpenes or essential oils present in plants act as a crucial defense mechanism for plants, especially in the face of insect herbivorous pests and fungi.Furthermore, this volatile terpenoid is a key in plant-plant interactions and attracts pollinators.