Effectiveness of a nanoemulsion formulation of Piper aduncum L. extract and Cymbopogon nardus L. hydrosol in controlling the main pests of broccoli

Efektivitas formulasi nanoemulsi ekstrak Piper aduncum L. dan hidrosol Cymbopogon nardus L. untuk pengendalian hama utama tanaman brokoli

A nanoemulsion formulation of a mixture of Piper aduncum extract and Cymbopogon nardus hydrosol was evaluated for its effectiveness against the major broccoli pests, Crocidolomia pavonana and Plutella xylostella. The study was conducted in Alahan Panjang, West Sumatra, using a completely randomized design with four treatments (the nanoemulsion formulation, Bacillus thuringiensis, cypermethrin, and a control) and seven replications. Treatments were applied weekly from 21 to 70 days after planting (DAP). Larval population density and plant damage were recorded, and the data were analyzed using analysis of variance (ANOVA) followed by a least significant difference (LSD) test at a 5% significance level. Infestation by P. xylostella occurred earlier at 21 DAP, whereas infestation by C. pavonana began at 28 DAP. Overall, the population density of P. xylostella was higher than that of C. pavonana. The nanoemulsion formulation exhibited insecticidal activity, although its effectiveness was lower than that of cypermethrin and B. thuringiensis. The effectiveness rates against C. pavonana were 71.49%, 48.54%, 33.33%, and against P. xylostella were 73.49%, 60.88%, and 57.52% for cypermethrin, B. thuringiensis, and the nanoemulsion formulation, respectively.

INTRODUCTION

Broccoli (Brassica oleracea L. var. italica) contains high levels of fiber, minerals, and antioxidants, which are beneficial for health(Handayani & Ayustaningwarno, 2014). According to Statistic Indonesia(Statistik, 2023), cabbage and broccoli production in West Sumatra decreased by 17.62%, from 211,711 tons in 2020 to 174,387 tons in 2021. One of the contributing factors to this decline is the incidence of plant-disrupting organisms, including of plant pests, pathogens, and weeds. Pests and diseases are major causes of yield instability in cabbage and broccoli crops. Among the most damaging insect pests affecting these crops are cabbage head caterpillar (Crocidolomia pavonana Fab.) and the diamondback moth (Plutella xylostella Linn.), both of which are key pests of Brassicaceae crops(Jamtsho et al., 2021).

Farmers continue to rely on synthetic insecticides to control C. pavonana and P. xylostella, primarily due to their practicality, cost-efficiency, and quick action in reducing pest populations(Indiati & Marwoto, 2017). However, if used unwisely, synthetic insecticides can have adverse effects such as pest resistance, pest resurgence, and mortality of non-target organisms(Indiati & Marwoto, 2017). Insecticides, including carbamate and organophosphates, are extensively utilized in agriculture and have the potential to lethally affect various non-target organisms, such as earthworms, natural enemies (predators and parasitoids), and other ecologically significant species. Research indicates that the insecticides carbosulfan, carbofuran, and BPMC result in the mortality of the earthworm Eisenia fetida, with mortality rates ranging from 66% to 76% at elevated concentrations (300 mg/kg)(Kinasih et al., 2014). Therefore, botanical insecticides are considered a promising alternative, as they offer a more environmentally friendly approach and help mitigate the negative consequences associated with synthetic insecticide use.

Botanical insecticides offer several advantages, such as biodegradability, environmental friendliness, and a lower risk of inducing pest resistance(Yusuf, 2012). Several plant species possess the potential to be developed into effective insecticides. According to previous reports, spiked pepper (Piper aduncum L.) contains secondary metabolites such as dillapiole, alkaloids, flavonoids, phenolics, triterpenoids, steroids, saponins, and coumarins. P. aduncum acts as a contact poison, a stomach poison, and an antifeedant(Arneti, 2012). The secondary metabolites produced by P. aduncum are known to possess insecticidal activity(Safrida et al., 2020). Spiked pepper has been utilized as a plant-based insecticide in conventional formulations such as emulsifiable concentrate (EC) and wettable powder (WP). Botanical insecticides are generally considered environmentally friendly because they are biodegradable and tend to degrade rapidly in the environment after application. However, in EC and WP formulations still present several limitations, including phytotoxicity, the presence of residues on plant surfaces after application, and reduced adhesion or persistence on foliage(Lina, 2014). To overcome these limitations, nanoemulsion formulations have been developed to create more effective botanical insecticidal products.

In nanoemulsion systems, two phases are involved: an organic phase and an aqueous phase. The organic phase contains plant-derived active compounds dissolved in a suitable solvent, while the aqueous phase consists of water and emulsifying agents to stabilize the emulsion. These two phases are mixed using a spontaneous emulsification technique to produce stable nanoemulsion(Lina et al., 2021). In addition to P. aduncum, citronella (Cymbopogon nardus L.) is also a potential source of plant-based insecticides. The distillation of citronella grass produces two types of liquid fractions: the essential oil itself and a by-product known as hydrosol. In this study, citronella hydrosol was used as the aqueous phase in the nanoemulsion formulation because it is environmentally friendly, readily biodegradable, and may enhance insecticidal activity compared with formulations using plain water. Hydrosol is a water-based distillation product that contains small amounts of active compounds originating from citronella essential oil, such as citronellal, citronellol, and geraniol(Saidi et al., 2021). Although present in low concentrations, these compounds exhibit biological activity, including repellent and antifeedant effects against insect pests(Lina et al., 2021). Therefore, the use of hydrosol not only serves as a carrier in the aqueous phase but also contributes additional bioactive compounds to the nanoemulsion system.

Plant-based insecticides, particularly those developed using nanotechnology, must be formulated in a stable form to ensure their efficacy. Nanoemulsion technology enables the reduction of particle size, thereby enhancing the efficiency and effectiveness of the active ingredients(Noveriza et al., 2017). Nanoemulsion formulations have been developed to improve the performance of botanical insecticides compared with earlier and commonly used formulations like EC and WP. These nanoparticle-based formulations offer several advantages, including enhanced penetration into leaf tissues, extended shelf life, resistance to sedimentation, low volatility, and improved physicochemical stability(Shakeel et al., 2008). A nanoemulsion formulation of P. aduncum extract has been shown to cause significant mortality in C. pavonana larvae, with an LC₉₅ value of 1.02%(Erlina et al., 2020). Furthermore, Lina et al. (2023a)(Lina et al., 2023) reported that nanoemulsion formulations of P. aduncum showed high larval mortality against Spodoptera frugiperda Smith. Recent studies have demonstrated that nanoemulsion-based botanical insecticides enhance the stability and bioactivity of active compounds, leading to increased larval mortality and physiological disruption in insect pests, including S. frugiperda (Campos et al. 2020; de Oliveira et el.2021).

Prior to commercialization, botanical insecticides must undergo thorough testing. Efficacy testing is a critical step in evaluating the performance of a pesticide product intended for commercial use(Fitriasari et al., 2009). This study aimed to evaluate the effectiveness of a nanoemulsion formulation containing P. aduncum extract and C. nardus hydrosol in controlling C. pavonana and P. xylostella on broccoli crops in Alahan Panjang.

MATERIALS AND METHODS

Time and place

This study was conducted in Nagari Alahan Panjang, Lembah Gumanti District, Solok Regency, from July to October 2023. Botanical insecticide nanoemulsions were formulated at the Insect Bioecology Laboratory, Department of Plant Protection, Faculty of Agriculture, Andalas University.

Making hydrosols

Hydrosols, also known as hydrolates, are byproducts of the essential oil distillation process and typically contain trace amounts of volatile compounds derived from the essential oil, generally less than 0.02%. These compounds originate from citronella essential oil and remain dispersed in the aqueous distillate during the distillation process. In this study, citronella (Cymbopogon nardus) hydrosol was used as the aqueous phase of the nanoemulsion formulation. The hydrosol was obtained from Laing Farmers, Solok Regency, West Sumatra, Indonesia.

Preparation of P. aduncum

Piper aduncum was utilized as the primary source material for the plant-based insecticide. The P. aduncum fruits selected were green, hard-texture, and free of mold. The fruits were collected and transported the Insect Bioecology Laboratory, Department of Plant Protection, Faculty of Agriculture, Andalas University. They were cut into small pieces and placed on a paper-lined tray with a diameter of 60 cm. The fruits were air-dried at room temperature for approximately three weeks until the moisture content was reduced to below 12%. Finally, the dried P. aduncum fruits were pulverized into a fine powder using a blender(Lina et al., 2018).

Extraction of P. aduncum

The spiked pepper powder was extracted using the maceration method with ethyl acetate as the solvent. A total of 100 g of the powdered material was placed in an Erlenmeyer flask and soaked in ethyl acetate until the final volume reached 1 liter. The maceration process was carried out for 48 hours. The resulting extract was filtered using a glass funnel lined sequentially with Whatman No. 1 and No. 41 filter papers. The filtrate was then concentrated using a rotary evaporator at 45 °C and a pressure of 277 mbar(Lina, 2014). The concentrated extract was transferred into a storage bottle and stored in refrigerator until further formulation.

Nanoemulsion formulation

The P. aduncum nanoemulsion was prepared using the spontaneous emulsification method, comprising an aqueous phase (90%) and an organic phase (10%). The aqueous phase, consisting of 87% lemon grass hydrosol and 3% Tween 80, was subjected to a magnetic homogenization process and stirred for 30 minutes at 2500 rpm. The organic phase was prepared by mixing the P. aduncum extract (5%) and 96% ethanol (5%) in an Erlenmeyer flask. To formulate the emulsion, the organic phase was slowly dripped into the aqueous phase using a Mohr pipette under continuous magnetic stirring for 45 min(Lina, 2014). The obtained P. aduncum nanoemulsions were stored in a refrigerator until further use. Following formulation completion, droplet size was measured using a particle size analyzer, which confirmed that the nanoemulsion had a mean particle size of 104.2 nm(Lina et al., 2023).

Site selection and land preparation

This efficacy trial began with a survey of potential locations. Nagari Alahan Panjang located in Lembah Gumanti District, Solok Regency, West Sumatra, was selected as the experimental site due to its highland characteristics, which are typical for cabbage and broccoli production centers. The land was prepared by clearing rocks, grasses, shrubs, and trees. The prepared area was divided into 28 experimental plots, and planting beds were constructed manually using hoes. Each bed measured 10 m in length, 1.5 m in width, and approximately 30 cm in height, with a 50 cm spacing between beds. Organic manure was applied at a rate of 100 g per plant, and NPK fertilizer (16:16:16) was applied at a dose of 4 g per plant during transplanting.

Broccoli cultivation

Broccoli seeds of the Green Magic variety were used. At 21 days after sowing, the seedlings were transferred to the experimental plots, totalling 60 plants per plot. Broccoli seedlings were planted in each bed at a distance of 50 cm × 50 cm. Population monitoring and damage assessments for C. pavonana and P. xylostella were conducted on six randomly selected sample plants per plot. Sample plats were selected using a simple random sampling lottery technique.

Field applications

Spraying was initiated following the detection of P. xylostella larvae, which typically appear earlier in the growing season. Control actions to P. xylostella were taken once the pest population exceeded the economic threshold, defined as the presence of 0.5 larvae per plant or a cumulative total of five of third and fourth instar larvae per 10 plants(Winarto & Sebayang, 2015). The concentration of the botanical insecticide used in the field was determined based on prior laboratory toxicity tests, specifically at 2 × LC₉₅, equivalent to 2.04%(Erlina et al., 2020). For comparison, two commercial insecticides were applied at the manufacturer’s recommended dosages: Thuricide HP (active ingredient: Bacillus thuringiensis, biological insecticide) and Instop 311 EC (active ingredient: cypermethrin 311 g/l, synthetic insecticide.

All insecticides were applied using a knapsack sprayer at weekly intervals. As determined by calibration, the spray volume varied depending on the plant growth stage. The application volume was 2 l per plot at the early growth stage, 5 l per plot from 28 to 42 days after planting (DAP), and 10 l per plot from 49 to 70 DAP. The insecticide concentration used in the spray solution was 20.4 ml/l.

Variables observed

Population of C. pavonana and P. xylostella

Larval populations of C. pavonana and P. xylostella were observed visually by counting and recording the number of larvae on the broccoli leaves, stems, and heads of the six sample plants per plot. Observation were conducted at weekly. Intervals from 21–70 DAP. Data were subsequently tabulated and graphed.

Percentage of infested plants.

The percentage of infested plants was determined by counting the number of sample plants showing symptoms of damage or the physical presence of C. pavonana and P. xylostella larvae. Observations were conducted in the morning at weekly intervals from 21 DAP to 70 DAP. The percentage of attacks can be calculated using the following formula:

\documentclass{article} \usepackage{amsmath} \begin{document} \displaystyle P = \frac{A}{B} \times 100\% \end{document}

where P: percentage of infested plants (%); A: number of infested plants; and B: number of plants observed.

Insecticide effectiveness level.

Based on the efficacy standards, an insecticide is considered effective if it’s effectiveness value remains above 70% in at least half the observation periods plus one(Fertilizers & Pesticides, 2012). The effectiveness level of the tested insecticides (%) was calculated using Abbot’s formula as follows:

\documentclass{article} \usepackage{amsmath} \begin{document} \displaystyle EI = \frac{Ca - Ta}{Ca} \times 100\% \end{document}

where EI: effectiveness of the insecticide tested (%); Ca: target pest population in the control plot; and Ta: target pest population in the treatment plot after insecticide application.

Data analysis

Larval population data and the percentage of plants infested by C. pavonana and P. xylostella were analyzed using analysis of variance (ANOVA). When significance differences were detected, the data were further analyzed using a least significant difference (LSD) test at the 5% significance level using Statistis 8.

RESULTS

Larval populations of C. pavonana and P. xylostella

Observations of the larval populations of C. pavonana and P. xylostella consistently showed that untreated (control) populations were higher than those exposed to insecticides. Statistical analysis revealed that the botanical insecticide nanoemulsion formulation–containing a mixture of P. aduncum and C. nardus hydrosol (INN)–along with the biological insecticide B. thuringiensis (Bt) and the synthetic insecticide cypermethrin (IS), each produced population densities that were significantly lower than that of the control. For C. pavonana population, these significant differences were observed from 49 DAP onwards through 70 DAP (Table 1). Meanwhile, for P. xylostella significant population increase on control were noted earlier, occurring continuously from 28 DAP to 70 DAP (Table 2).

The lowest overall average larval density of C. pavonana was recorded in the IS treatment (0.12 larvae per plant), followed by Bt (0.22 larvae per plant) and INN (0.23 larvae per plant). All three treatments were significantly lower than the control, which had a density of 0.60 larvae per plant (Table 1). Similarly, for P. xylostella, the lowest average population density was found in the IS treatment (0.91 larvae per plant), followed by Bt (1.30 larvae per plant) and INN (1.32 larvae per plant), all of which were significantly lower than the control (3.97 larvae per plant) (Table 2).

Table 1.Larval population density of Crocidolomia pavonana on broccoli under differents insecticide treatment

Treatment	Population of C. pavonana larval (Mean ± SD)								Average
	21 DAP	28 DAP	35 DAP	42 DAP	49 DAP	56 DAP	63 DAP	70 DAP
Control	0.00±0 a	0.09±1.51 a	0.16±2.64 a	0.26±1.51 a	1.40±9.93 a	1.21±6.07 a	1.02±3.48 a	0.69±3.21 a	0.60
INN	0.00±0 a	0.09±1.13 a	0.11±0.98 a	0.19±2.26 a	0.30±2.54 b	0.69±3.18 b	0.59±1.71 ab	0.35±1.21 b	0.23
Bt	0.00±0 a	0.07±0.78 a	0.07±0.78 a	0.11±1.25 a	0.26±1.90 b	0.54±4.07 b	0.61±1.88 b	0.16±0.81 b	0.22
IS	0.00±0 a	0.02±0.37a	0.00±0 a	0.00±0 a	0.11±0.95 b	0.47±1.86 b	0.14±1.21 bc	0.28±1.38 b	0.12

Table 2.Larval population density of Plutella xylostella on broccoli under differents insecticide treatment

Treatment	Population of larvae P. xylostella (Mean ± SD)								Average
	21 DAP	28 DAP	35 DAP	42 DAP	49 DAP	56 DAP	63 DAP	70 DAP
Control	0.07±0.78 a	0.61±2.56 a	0.76±3.86 ab	2.80±5.11 a	8.73±4.82 a	8.16±12.71 a	6.61±12.48 a	4.02±10.18 a	3.97
INN	0.16±0.88 a	0.42±2.37 b	0.97±2.79 a	1.19±3.33 b	3.28±6.82 bc	3.04±10.54 b	0.78±2.05 b	0.73±1.90 b	1.32
Bt	0.21±1.88 a	0.59±2.76 b	0.45±1.79 b	1.50±4.72 b	3.52±10.10 b	2.69±5.78 b	1.23±7.11 b	0.28±2.05 b	1.30
IS	0.14±0.89 a	0.21±2.21 b	0.59±1.98 ab	0.97±1.67 b	2.02±7.05 c	2.61±10.95 b	0.38±3.68 b	0.42±2.37 b	0.91

Throughout the observation period (21 to 70 DAP), larval population densities of both C. pavonana and P. xylostella fluctuated across all treatments. However, the control consistently maintained the highest population densities than the treated plots.

The population density of C. pavonana larvae peaked at 49 DAP, reaching 1.40 larvae per plant in the control group, whereas densities in the insecticide-treated plots remained significantly lower, 0.30, 0.26, and 0.11 larvae per plant in the INN, Bt, and IS treatments, respectively (Figure 1). Following this peak infestation, C. pavonana population densities generally decreased toward the end of the observation period (63 to 70 DAP) across all treatments, though the control group maintained the highest values.

Figure 1.Population development of the pest Crocidolomia pavonana after insecticide treatment. INN: nanoemulsion insecticide; IS: synthetic insecticide; Bt: Bacillus thuringiensis insecticide; C: control.

Similarly, the population density of P. xylostella larvae reached its peak at 49 DAP with the control group recording 8.73 larvae per plant, while the treated plots remained significantly lower (Figure 2). At 49 DAP, the IS, INN, and Bt treatments 2.02, 3.28, and 3.52 larvae per plant, respectively. The P. xylostella larval population densities subsequently declined from 56 to 70 DAP. Throughout the entire observation period, the control group had a higher population density than any of the insecticide treatments.

Figure 2.Population development of Plutella xylostella after insecticide treatment. INN: nanoemulsion insecticide; IS: synthetic insecticide; Bt: Bacillus thuringiensis insecticide; C: control.

Percentage of infested plants

The percentage of infested plants by C. pavonana and P. xylostella larvae was simultaneously assessed. The results showed that all insecticide treatments (INN, Bt, and IS) significantly reduced plant infestation compared with the control group continuously from 28 to 70 DAP (Table 3). Averaged across all observation periods, the control group demonstrated the highest infestation rate (70.66%). Among the treatments, INN resulted in the lowest overall infestation rate (27.85%), followed by Bt (37.49%) and IS insecticide (38.01%).

Table 3.Percentage of infested plants by Crocidolomia pavonana and Plutella xylostella simultaneously on broccoli plants after treatment

Treatment	Percentage of infested plants by C. pavonana and P. xylostella (% ± SD )								Average (%)
	21 DAP	28 DAP	35 DAP	42 DAP	49 DAP	56 DAP	63 DAP	70 DAP
Control	5.71±2.12 a	17.61±4.49 a	43.63±7.76 a	99.04±2.51 a	99.28±1.88 a	100±0.00 a	100±0.00 a	100±0.00 a	70.66
INN	5.47±1.58 a	10.23±1.78 b	28.81±9.09 b	46.68±10.3 b	51.44±8.32 b	52.88±7.14 b	53.59±7.28 b	55.02±7.43 b	27.85
Bt	5.23±1.78 a	9.52±1.85 b	25.95±5.25 b	45.60±5.56 b	52.51±8.45 b	53.22±8.25 b	53.22±8.25 b	54.89±5.93 b	37.49
IS	4.52±1.25 a	7.38±2.32 b	20.95±3.70 b	34.04±5.34 c	34.87±5.71 c	38.93±7.65 c	40.12±7.68 c	42.03±6.42 c	38.01

Insecticide efficacy

Field evaluations indicated that the IS treatment was the most effective against C. pavonana, with an overall average efficacy of 71.49%. In contrast, INN treatment recorded the lowest efficacy among the treated groups at 33.33% with Bt showed intermediate efficacy at 48.54% (Table 4). A similar trend was observed for P. xylostella, the IS treatment was again the most effective, with an average efficacy at 73.70%, followed by Bt (60.88%), and INN treatment recorded the lowest average at 58,38% (Table 5). According to national efficacy standards, an insecticide is considered effective if its efficacy (EI) values exceeds 70% in more than half of the observations. The IS treatment met this criterion, exceeding 70% efficacy in five out of the eight observation periods for both C. pavonana and P. xylostella. Consequently, the synthetic insecticide was deemed effective, whereas both the Bt and INN botanical treatments failed to meet this threshold and were classified as ineffective under these field conditions. These results suggested that the biological and botanical formulations provided only moderate pest suppression under field conditions tested.

Table 4.Field efficacy of insecticide treatments against Crocidolomia pavonana larvae on broccoli

Treatment	Insecticide efficacy at each observation period (%)								Average (%)
	21 DAP	28 DAP	35 DAP	42 DAP	49 DAP	56 DAP	63 DAP	70 DAP
INN	0.00	0.00	28.57	27.27	77.96	43.13	41.46	48.27	33.33
Bt	0.00	25.00	57.14	54.54	81.35	54.90	39.53	75.86	48.54
IS	0.00	75.00	100	100	91.52	60.78	86.04	58.62	71.49

Table 5.Field efficacy of insecticide treatments against Plutella xylostella larvae on broccoli

Treatment	Insecticide efficacy at each observation period (%)								Average (%)
	21 DAP	28 DAP	35 DAP	42 DAP	49 DAP	56 DAP	63 DAP	70 DAP
INN	37.60	15.38	57.62	62.19	62.39	62.68	88.12	81.06	58.38
Bt	19.23	63.46	44.06	59.45	59.67	67.05	81.29	92.89	60.88
IS	65.38	51.92	64.44	77.26	76.83	70.55	94.24	89.34	73.70

DISCUSSION

In general, field observations of C. pavonana and P. xylostella larval populations, showed that untreated larval populations (control) were consistently higher than those subjected to insecticide treatments. Statistical analysis revealed that the INN, Bt, and IS treatments resulted significantly lower populations compared to the control group from 49 to 70 DAP for C. pavonana, and from 28 DAP to 70 DAP for P. xylostella.

Throughout the study, the larval populations of both pest species fluctuated significantly. Highest population occurred at 49 DAP, which aligns with findings by Kumarawati et al. (2013), who reported that the highest abundance of C. pavonana and P. xylostella larval populations on broccoli typically occurs between seven to eight weeks post-planting. Abiotic factors, particularly rainfall, influence these insect population dynamics(Murtiningsih et al., 2023). Low rainfall and intermittent drought periods when the plants were 42 - 56 DAP likely facilitated the increase in larval populations of C. pavonana and P. xylostella. Conversely, high rainfall intensity during the eighth week contributed to a decline in both pest populations by 63 DAP. Furthermore, larval abundance in the field is positively correlated with food availability, indicating that areas with more food sources tend to support higher larval populations (Kumarawati et al. 2013). At 49 DAP, broccoli plants experience the increase in leaf number. This vegetative growth increases in leaf number correlates with a heightened susceptibility to pest attacks, resulting in a rise in the populations of C. pavonana and P. xylostella during this observation period. Akter et al. (2025)(Akter et al., 2025) reported that leaf number in broccoli increases progressively during the vegetative stage, with observations commonly conducted up to around 49 days after planting (DAP).

The suppression of larval populations of C. pavonana and P. xylostella across treatments can be attributed to the specific active compounds in each formulation (Kumarawati et al. 2013). Dillapiole, a major active compound in P. aduncum, can inhibit the activity of the cytochrome P450 detoxification enzyme, which plays a role in reducing the toxicity of toxic compounds or metabolites in the larval body(Bernard et al., 1995). Previous studies have demonstrated that spiked piper extracts can cause 100% mortality in C. pavonana(Syahroni & Prijono, 2013) and 98 % mortality in P. xylostella(Lina et al., 2018). Although, the major bioactive compounds of C. nardus, such as citronellal and geraniol, are primarily present in the essential oil fraction. However, small amounts of these compounds can be carried over into hydrosol during the distillations. These carried-over compounds likely contribute to the overall insecticidal activity of the formulation by disrupting cellular metabolism and respiratory processes in insect(Araújo et al., 2023). Therefore, the combined antifeedant and toxicological effects of P. aduncum extract and C. nardus hydrosol mixture can also cause a decline in the larval populations of C. pavonana and P. xylostella(Erlina et al., 2020).

The biological insecticide B. thuringiensis (Bt) contains δ-endotoxin crystals that are lethal and can reduce the populations of C. pavonana and P. xylostella. The toxin bind to specific receptors on midgut epithelial cell, leading to pore formation, cell lysis, and gut paralysis. According to Hariyani et al. (2014)(Hariyani et al., 2014), B. thuringiensis formulations can suppress the larval populations of C. pavonana and P. xylostella by > 45%. The disadvantages of the insecticide B. thuringiensis are its sensitivity to ultraviolet light and ease of washing; therefore, its active ingredients do not last long in the field(Bahagiawati, 2002). In contrast, the synthetic insecticides with the active ingredient cypermethrin (IS) are known to have high acute toxicity and persistence, and can rapidly kill C. pavonana and P. xylostella larvae, thereby reducing pest infestation. Cypermethrin is a synthetic pyrethroid insecticide that acts on the insect nervous system by modifying the gating kinetics of voltage-gated sodium channels, resulting in prolonged depolarization, repetitive nerve firing, paralysis, and ultimately insect death(Field et al., 2017).

Application of INN, Bt and suppressed the attack of C. pavonana and P. xylostella. The results showed that the percentage of plants infested with C. pavonana and P. xylostella the same time, and broccoli plants were treated with a lower insecticide than those without insecticide treatment. The percentage of infested plants is closely related to the number of C. pavonana and P. xylostella larval populations; the higher the number of larvae, the higher the percentage of infested plants will increase(Hasnah, 2009). The percentage of infested plants increased significantly at 42 DAP and peaked at 70 DAP because of the high C. pavonana and P. xylostella populations. This aligns with Kumarawati et al. (2013), who stated that the highest percentage of plants infested with C. pavonana and P. xylostella larvae occurred in the tenth week after planting.

Based on the efficacy standard, it was found that the plant-based insecticide formulation of a nanoemulsion mixed with P. aduncum extract and C. nardus hydrosol was less effective in controlling C. pavonana and P. xylostella because it had an effectiveness percentage below 70% for five times in eight observations. The ineffectiveness of botanical insecticides is caused by the active ingredients contained in the insecticide, which cannot last long during field application because they are quickly degraded by sunlight and easily washed by rain. According to Badan Meteorologi, Klimatologi dan Geofisika (BMKG) data, the Gumanti Valley experienced rainfall amounts of 513 mm, 344 mm, and 463 mm during the planting period from July to October 2023. This indicates that these months fall into the category of wet months with significant rainfall. Therefore, the application of natural insecticides should be more frequent to increase the effectiveness of the active ingredient(Kardinan & Suriati, 2012)

CONCLUSION

The efficacy evaluation of a botanical insecticide nanoemulsion formulation of P. aduncum extract and C. nardus hydrosol demonstrated comparable activity to B. thuringiensis insecticide, although its control of C. pavonana and P. xylostella on broccoli plant was still lower than that of synthetic insecticides.

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