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Bioefficacy of Marigold (Tagetes spp.) Oil as Biopesticide Against
Eggplant Fruit and Shoot Borer (Lepidoptera: Leucinodes orbonalis)
Cyrus C. Bautista, Jolina A. Enardecido, RAgr*, and Karlo C. Balabat
Monkayo College of Arts, Sciences, and Technology L.S. Sarmiento St., Poblacion, Monkayo, Davao de
Oro, Philippines, 8805
DOI:
https://doi.org/10.51244/IJRSI.2025.120800293
Received: 04 September 2025; Accepted: 10 September 2025; Published: 06 October 2025
ABSTRACT
Eggplant (Solanum melongena) is one of the most important vegetable crops in the Philippines, commonly grown
in backyard and commercial farms. It is widely consumed by most Filipinos due to its nutritive value. However,
its production is often affected by the eggplant fruit and shoot borer or EFSB (Leucinodes orbonalis), a pest
known to cause serious damage and yield loss. Local farmers commonly address this pest problem with synthetic
insecticides, however, excessive reliance on those synthetic chemicals poses environmental and health risks.
Hence, this study assessed marigold (Tagetes spp.), a promising repellant plant with insecticidal potential, as a
botanical-based biopesticide alternative for managing L. orbonalis larvae. This study investigates the efficacy
of non-phytotoxic marigold plant in oil-emulsion concentration to EFSB mortality. The experiment was done in
Completely Randomized Design (CRD), involving two experiments: a phytotoxicity experiment to test if the
marigold oil-emulsion would harm the young eggplant leaves; and a laboratory bioassay to observe the larval
mortality of EFSB treated with different marigold oil-emulsion concentrations (0.1%, 0.3%, and 0.5%) at 1, 2,
and 3 hour/s after treatment (HAT). The study showed that the concentrations used were non-phytotoxic as
observed on the marigold oil-emulsion solution-treated young leaves. Furthermore, the insect mortality
experiment showed that the higher the concentration, the higher the larval mortality, with 0.5% treatment
reaching 88.89% mortality in 3 HAT, which was statistically comparable to the chemical control with 100%
mortality. Based on these results, non-phytotoxic marigold oil-emulsion at 0.5% is a potential option for
managing L. orbonalis in eggplant, however, further study under field condition is needed before
recommendation as regular use.
Keywords: Botanical biopesticide, marigold oil, phytotoxicity, EFSB, Monkayo
INTRODUCTION
Eggplant (Solanum melongena) is a major solanaceous vegetable crop grown in many parts of the world, valued
for its nutritional and economic significance. The fruit is widely consumed due to its nutritive value such as
vitamins, minerals, antioxidants, and dietary fibers (Naeem & Ugur, 2019). According to Nayak et al., (2021)
eggplant plays an essential role in the diets of millions and is cultivated across more than 85 countries. In the
Philippines, eggplant is among the most widely grown and consumed vegetables, with national production of
248,151.43 metric tons in 2022. (Philippine Statistics Authority [PSA], 2023). It ranks high in terms of land area
cultivated and contributes significantly to farmers’ livelihoods and local food supply (Chupungco et al., 2014).
Depending on the variety, eggplant fruits vary in size and shape, ranging from long and slender to short and
round.
However, despite its agricultural importance, eggplant cultivation faces major challenges—most notably the
widespread infestation of eggplant fruit and shoot borer (EFSB), Leucinodes orbonalis (Hautea et al., 2016). In
fact, total national production of eggplant in 2023 was reported at 238,597 metric tons which is lower compared
to 2022 production (PSA, 2024). EFSB is one of the most damaging insect pests affecting eggplant production
in Asia and Southeast Asia (Srinivasan, 2008). The larvae of this pest bore into the shoots and fruits of the plant,
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causing wilting, internal damage, and rendering the fruits unmarketable. Infestation can lead to yield losses of
up to 67%, posing a serious threat to food security and farmer income (Quamruzzaman, 2021). In response,
farmers often rely heavily on chemical pesticides, applying them multiple times per week to control EFSB
populations. This overreliance raises significant concerns related to human health, pesticide resistance, and
environmental pollution (Lu, 2022).
Given the urgent need for safer and more sustainable pest management strategies, the use of botanical
biopesticides has gained increasing attention. Among these, marigold (Tagetes spp.), a widely available and
resilient plant in the Philippines is a promising candidate for natural pest control (Iamba, 2021). According to
Bakshi and Ghosh, (2022), marigold contains biologically active compounds such as α-terthienyl, which have
been shown to possess insecticidal, nematicidal, and antifungal properties. These compounds interfere with pest
physiology by damaging cell membranes, suppressing egg hatching, and disrupting reproductive processes
(Tudora et al., 2024).
Marigold plant is commonly utilized as insect repellent crop as demonstrated by several studies (Qasim et al.,
2023; Horgan et al., 2023; and Blassioli-Moraes et al., 2022). However, its effectiveness was limited due to its
limited life duration where it will undergo senescence along with the crops (Yang et al., 2017). Hence, this study
investigates the use of marigold oil-emulsion concentration as a natural treatment for controlling EFSB
infestation in eggplant. In fact, essential oils and oil-emulsion from marigold have demonstrated concentration-
dependent toxicity against a range of agricultural pests, including whiteflies, aphids, and plant bugs (Fabrick et
al., 2020; Mmbone, 2016; and Jakubowska et al., 2023).
By exploring a plant-based alternative to synthetic pesticides, the study aims to support the development of eco-
friendly, low-cost, and locally accessible pest management solutions. Generally, the study aimed to evaluate the
effectiveness of marigold (Tagetes spp.) extract as a botanical treatment against eggplant fruit and shoot borer
(Leucinodes orbonalis). Specifically, the study aimed to determine the phytotoxic effects of the different
marigold oil-emulsion concentration on the physical appearance of treated young eggplant leaves. The mortality
rate of EFSB larvae treated with the varying concentrations of marigold extract was also determined to identify
the optimal non-phytotoxic marigold oil-emulsion concentration that maximizes EFSB mortality. The findings
of this study may contribute to the ongoing efforts in promote organic agriculture, reduce chemical inputs, and
advance climate-resilient farming practices.
MATERIALS AND METHODS
The study was conducted at MonCAST Laboratory, Poblacion, Monkayo, Davao de Oro, over three months.
Phytotoxicity test was done to assess potential adverse effects of the marigold oil-emulsion solution on eggplant
young foliage, while the bioassay of non-phytotoxic marigold oil was done to evaluate its insecticidal effect
against EFSB larvae.
Collection and Rearing of EFSB (Leucinodes orbonalis)
Reared L. orbonalis larvae were collected from the nearby eggplant farms of Monkayo, Davao de Oro. A total
of 150 larvae at the 3
rd
instar stage were gathered for the study. The 3
rd
instar larvae were used since it is the
instar stage of target as this stage has already developed physiological systems, such as digestion, immunity, and
feeding behavior, damaging eggplant shoots and fruits. This ideal stage was necessary as it was the highest, near-
peak feeding activity of the larvae. Thereafter, the collected larvae were transferred into 25 ml plastic vials
containing fresh pieces of eggplant. Vials were secured by lids, and the food were replaced daily to avoid any
contamination of microorganisms until the larvae were on its 5
th
instar. Larvae ready for pupation were moved
to a glass jar filled with sand, then were covered with muslin cloth for security during their transformation. The
sand was sterilized to prevent contamination, and was maintained in a damp condition by frequent spraying of
water, required for the pupal survival (Figure 1).
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Figure 1. L. orbonalis collection and rearing: (a) collected eggplant fruits with EFSB larvae; and (b) larval (L)
and pupal (P) stages of the reared EFSB in a damped sand.
After the adults emerge from the pupae, they were identified by sex based on their body size and the presence
of a tuft of hairs at the tip of the abdomen. A newly emerged pair, consisting of one male and one female moth
were placed into a glass jar (15 cm x 10 cm) that contained moist filter paper at the bottom. To create an
appropriate habitat, the glass jars were wrapped with black chart paper on the outside. Cotton swabs were soaked
in a 10% sugar solution, suspended from the top of each jar to provide nourishment for the adult moths. The
openings of the jars were covered with muslin cloth. In addition, a 100ml vial with a slice of eggplant fruit
dipped in distilled water, was introduced into each jar to mimic a natural setting and encourage insect oviposition,
following the procedure of Netam & Shewale, (2022) with slight modification based on available resources. The
larvae hatched from the eggs laid on the same day were used, repeating the process of rearing L. orbonalis up to
3
rd
instar to be used in the insect mortality experiment.
Marigold Buds Collection and Extraction Process
Marigold plants were grown in a prepared garden plot from the Municipal Agriculture Office (MAgrO) farm at
Mae-te, Salvacion, Monkayo, Davao de Oro. Fully bloomed flowers were harvested after approximately two
months and air-dried in a shaded, well-ventilated area to preserve oil content. Essential oils were extracted from
dried marigold flowers using a modified steam distillation unit (Figure 2), following the procedure of Rajeswara
Rao et al., (2006).
Figure 2. Improvised steam distillation setup with a flask-distiller (a), condenser (b), receiver-flask (c), heat
source-alcohol lamp (d), and distilled water (e); the dried flowers were loaded into the distiller with heat
vaporizing the volatile oil through a condenser cooling into liquid, then the product was separated through a
separator funnel.
a
b
L
P
P
L
L
L
L
P
P
P
P
P
c
a
e
d
b
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Dried flowers were placed in the plant chamber of a steam distillation unit. Steam was passed through the plant
material, releasing the essential oils, which were then condensed and collected. The oil was separated from the
hydrosol and stored in dark glass bottles to maintain quality. The temperature and pressure were monitored
throughout to protect sensitive compounds such as thiophenes, monoterpenes, and lutein esters. The temperature
was maintained at 15
0
C to 35
0
C at less than 1 psi. A total of 4 kilograms were harvested and were sun-dried to
get less than 0.9kg or at less than 25% of biomass. This drying process was necessary to concentrate the
compounds in the flower itself during the extraction process.
Formulation of Marigold Oil-Emulsion Solution
The marigold oil was formulated into a foliar spray with the addition of Polysorbate 80, a food-grade emulsifier
(4 mL), dissolved in warm distilled water (approximately 40°C). Marigold oil was then slowly incorporated into
the mixture while stirring continuously to achieve a uniform oil-emulsion concentration (Figure 3). The mixture
was diluted with distilled water to produce 100 mL solution of each treatment concentration (0.1%, 0.3%, and
0.5%).
Figure 3. Marigold oil-emulsion components: (a) the marigold oil at the surface above the water produced by
steam distillation process; and (b) marigold oil-emulsion solution.
Phytotoxicity Test of Marigold Oil on Eggplant Leaves
Phytotoxic symptoms such as chlorosis, necrosis, and leaf deformation were evaluated every hour, using the
visual phytotoxicity rating scale developed by Nalini and Parthasarathi (2018). The experiment was laid out
using a Complete Randomized Design (CRD) with 4 treatments, replicated 3 times, with 5 sample young
eggplant leaves per treatment. The treatments were as follows: T1 – Control; T2 – 0.1% marigold oil+ 4%
emulsifier in 100 mL distilled water; T3 – 0.3% marigold oil+ 4% emulsifier in 100 mL distilled water; and T4
– 0.5% marigold oil+ 4% emulsifier in 100 mL distilled water.
Bioassay of Marigold Oil Against EFSB
A laboratory bioassay was performed to assess the insecticidal activity of marigold oil-emulsion against L.
orbonalis larvae. Larvae were exposed to treated leaf materials. Mortality of EFSB was recorded at 1, 2, and 3
hours after treatment. The experiment was laid out using a Complete Randomized Design (CRD) with 5
treatments, replicated 3 times, with 10 sample EFSB larvae per treatment. The treatments were as follows: T1 –
Control; T2 – 0.1% marigold oil+ 4% emulsifier in 100 mL distilled water; T3 – 0.3% marigold oil+ 4%
emulsifier in 100 mL distilled water; T4 – 0.5% marigold oil+ 4% emulsifier in 100 mL distilled water; and T5
– chemical check (cypermethrin)
Data Gathered
Phytotoxicity Test
Phytotoxicity rating scores recorded every hour based on visible damage to eggplant leaves, 3 hours after
treatment (HAT), 6 HAT, and 9 HAT. Any changes in color, rotting, and shrinkage of the tested green chili
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pepper fruits after the application of the treatments was monitored and recorded daily using the rating scale used
by Nalini and Parthasarathi (2018) presented below:
Rating
Crop Responses/ Crop
Injury (%)
Verbal Description
0
0
No symptoms
1
1-10
Very slight discoloration
2
11-20
More severe, but not lasting
3
21-30
Moderate and more lasting
4
31-40
Medium and lasting
5
41-50
Moderately heavy
6
51-60
Heavy
7
61-70
Very heavy
8
71-80
Nearly destroyed
9
81-90
Destroyed
10
91-100
Completely destroyed
Source: Annals of Agrarian Science: 16(2), 108-115. DOI: 10.1016/j.aasci.2017.11.002 by Nalini and
Parthasarathi (2018)
Insect Mortality Rate
Mortality of L. orbonalis at 1 HAT, 2 HAT, and 3 HAT were recorded and the percent mortality rates were
obtained using the formula: mortality (%) = total number / number of dead × 100. Corrected insect mortality
rates were also used with the formula by Abbott, (1925): Corrected Mortality (%) = mortality in control (%) −
mortality in treatment (%) 100 − mortality in control (%) x 100
RESULT AND DISCUSSION
Effects of Marigold Oil-Emulsion Solution on Treated Young Eggplant Leaves
The study assessed the phytotoxic response of marigold oil on eggplant leaves under controlled condition.
Concentration of 0.1%, 0.3%, and 0.5% were tested, along with a control (untreated). The mean rate of
phytotoxicity assessment of eggplant leaves by different concentrations of marigold oil within 9 hours after
treatment is presented in Table 1. and the appearance of eggplant leaves 9 HAT is presented in Figure 4.
TREATMENT
HOURS AFTER TREATMENT
INITIAL
ns
3 HAT
ns
6 HAT
ns
9 HAT
ns
T1-Control
0.00
0.00
0.00
0.00
T2-0.1%
0.00
0.00
0.00
0.00
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T3-0.3%
0.00
0.00
0.00
0.00
T4-0.5%
0.00
0.00
0.00
0.00
Pr (> F)
0.00
0.00
0.00
0.00
Table 1. Mean phytotoxicity result of the different concentrations of marigold oil applied on young eggplant
leaves within 9 hours after treatment (HAT)
Means having the same letter superscripts are not significantly different at 5% level of significance using
Bartlett’s Test for Homogeneity of Variances; Values are means of three replications; ** – significant, and ns –
not significant.
Throughout the 9-hour observation period, none of the treatments caused chlorosis, necrosis, wilting, or visible
deformation. All phytotoxicity means remained at 0.00
± 0.00 and statistical analysis revealed no significant
differences across treatments (p = 0.00), with consistent variance among replicates. These findings strongly
indicate that marigold oil-emulsion solution, at the applied concentration does not disrupt the morphological or
physiological integrity of eggplant foliage. Thus, the concentrations of 0.1%, 0.3%, and 0.5% are non-phytotoxic
to eggplant leaves, even when compared with a synthetic insecticide (Cypermethrin). This suggests that
marigold-based formulations are safe for foliar application under the conditions tested and pose no risk of
phytotoxicity within the timeframe observed.
Figure 4. Appearance of young eggplant leaves treated with different levels of marigold oil within 9 hours after
treatment, (a) control (untreated), (b) 0.1%, (c) 0.3%, and (d) 0.5% marigold oil. All treated leaves showed no
toxicity symptoms.
In addition to its insecticidal properties, the phytotoxicity evaluation revealed no visible adverse effects on
eggplant (Solanum melongena) foliage across all treatments and time periods. All treatments, including the
highest concentration of marigold extract (0.5%) and the chemical control (Cypermethrin), consistently received
a phytotoxicity rating of 0.00, indicating an absence of harmful effects such as chlorosis, necrosis, wilting, or
leaf deformation. The analysis of variance confirmed no significant differences among treatments at any time
point (p = 0.00), suggesting that marigold oil-emulsion are safe for foliar application on eggplant within the
concentrations and timeframe tested.
These results are consistent with previous studies indicating the non-phytotoxic nature of marigold oil-emulsion,
such as research by Taye et al. (2012), which reported that marigold oil did not have phytotoxic effects on tomato
plants while effectively managing root-knot nematode populations. Furthermore, the presence of bioactive
compounds like flavonoids and phenolics in marigold oil-emulsion, as identified by Parklak et al. (2023),
suggests that these compounds contribute to plant tissue protection without causing harm.
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Bioassay of Marigold Oil-Emulsion Solution Against EFSB
All treatments recorded a uniform mean larval mortality rate of 0% at initial start of the study, indicating
consistent and unaffected larval activity across treatments before any exposure of the marigold oil. The absence
of variability rendered statistical analysis indicating that all third instar stage of larvae were alive at the start of
the treatment (Figure 5). This confirms experimental uniformity and proper randomization.
Early signs of larval mortality began to appear, particularly in 0.1% marigold oil reached to 11.11%, while 0.3%
and 0.5% both reached a mortality of 22.22%, and the chemical control at 44.45% (Table 2). However, the
difference was not statistically significant with p value of 0.2557. This suggest that although the larvae had
begun interacting with the treatment, the toxic compound were likely still within the lag phase of physiological
response. This lag phase of physiological response was described by Isman (2020) as delayed toxicity onset,
which means that plant-derived insecticides often display slower kinetics compared to synthetic neurotoxins,
which contributes to delayed mortality observation.
Table 2. Mean mortality rate of the EFSB (3
rd
instar) affected by the different concentrations of marigold oil
within 3 hours
Means having the same letter superscripts are not significantly different at 5% level of significance using
Bartlett’s Test for Homogeneity of Variances; Values are means of three replications; ** - significant at 5% level
and ns – not significant.
Figure 5. Physical appearance of the EFSB affected by the different concentration of marigold oil-emulsion
solution within 3 hours of observation, (a) Control (untreated)-alive borer determined by its mobility and pinkish
color, (b) 0.1% oil, (c) 0.3% oil, (d) 0.5% oil-dead borers having sunken upper body, and (e) chemical check
(cypermethrin)-dead borer in swelled pinkish-white body.
TREATMENT
HOURS AFTER TREATMENT
INITIAL (%)
ns
1 HAT (%)
ns
2 HAT (%)
**
3 HAT (%) **
T1-Control
0.00
ns
0.00
ns
0.00
c
0.00
c
T2-0.1%
0.00
ns
11.11
ns
11.11
c
44.45
b
T3-0.3%
0.00
ns
22.22
ns
55.56
b
77.78
ab
T4-0.5%
0.00
ns
22.22
ns
44.44
b
88.89
a
T5- Chemical Check
0.00
ns
44.45
ns
100.00
a
100.00
a
Pr (> F)
0.00
0.2557
0.0001
0.0011
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In botanical treatments such as marigold oil, bioactive compounds like thiophenes, flavonoids, or terpenoids
require time to accumulate within the insect’s system before eliciting visible toxic effects. This early stage is
often marked by sub-lethal stress responses at the cellular level, such as enzyme inhibition or oxidative
imbalance, which are not yet sufficient to induce mortality. In contrast, the chemical insecticide (T5) began
showing stronger efficacy, likely due to faster systemic penetration and neurotoxic action. The control (T1)
remained at 0.00% observed in Figure 6, confirming that mortality observed in other treatments was treatment-
induced and not a result of environmental or procedural stress.
Figure 6. The alive representative samples from the control group, showing a pinkish hue of hemolymph,
indicating that they are thriving.
Statistically significant treatment effects emerged by 2 HAT (p = 0.0001). The chemical standard (T5) achieved
complete larval mortality (100.00%), significantly higher than all botanical treatments. Among the marigold
extract concentrations, T3 (0.3%) and T4 (0.5%) yielded 55.56% and 44.44% mortality, respectively, both
significantly greater than T2 (0.1%, 11.11%) and the control (0.00%). By 2 HAT, the Least Significant
Difference (LSD) test was identified by which means differ. Group “a” or T5 (chemical control) is the most
effective treatment, significantly different from all other treatments. Group “b”, T3 and T4 (0.3% and 0.5%
concentration) were intermediate in efficacy, not significantly different from each other, but significantly better
than T2 and T1. Group “c”, T1, and T2 (control and 0.1%) were the least effective, statistically similar to each
other, and significantly lower than all other treatments.
After 3 hours of treatment, mortality continued to rise with both concentration and time. T5, maintained full
efficacy (100.00%) and remained statistically similar to the highest marigold extract – treatment 4 at 88.89%.
T3 (0.3%) showed slightly lower but still considerable mortality (77.78%), while T2 reached 44.45%. The
control consistently recorded 0.00 mortality. Statistical groupings at this time point confirmed a clearer
stratification: T5 and T4 shared comparability, T3 was included in group (ab), and T2 and T1 remained
significantly lower (c). These trends underscore both the time-dependent nature of larval susceptibility and the
concentration-dependent potency of marigold oil-emulsion.
The increasing efficacy over time supports the hypothesis that phytochemical compounds in marigold, such as
thiophenes and flavonoids, require adequate exposure or ingestion to exert cytotoxic effects. These constituents
accumulate within insects over time and disrupt metabolic and cellular functions rather than producing
immediate mortality (Kannan et al., 2024). The visible blackening of L. orbonalis larvae in T4, as depicted in
Figure 7, is indicative of oxidative stress and associated metabolic disruption. This observation aligns with
known insecticidal modes of action for Tagetes spp., including mitochondrial dysfunction, enzyme inhibition,
and neurotoxic interference (Fasbrick et al., 2020). Moreover, the sulfur-containing thiophene α – terthienyl,
abundant in Tagetes species, excerpts potent biocidal activity through oxidative damage and apoptotic pathways
(Ghosh and Bakshi, 2022).
Figure 7. The effect of marigold oil-emulsion solution at 0.5% on L. orbonalis, showing blackening of the insect
due to the oxidation and degradation of cellular components after (a) 1 hour, (b) 2 hours, and (c) 3 hours.
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The findings of this study demonstrate that marigold (Tagetes spp.) oil-emulsion exhibit significant insecticidal
activity against the larvae of Leucinodes orbonalis, with effectiveness determined by both concentration and
exposure time. After two hours of treatment, the results revealed statistically significant differences among the
various treatments (p = 0.0001). The chemical control treatment (T5) achieved complete larval mortality
(100.00%), whereas the 0.3% marigold extract (T3) and the 0.5% extract (T4) demonstrated intermediate
efficacy with mortality rates of 55.56% and 44.44%, respectively. These rates were significantly higher than
those observed with the 0.1% extract (T2) and the negative control (T1), indicating that even lower
concentrations of marigold oil-emulsion can be effective against the pest.
As the study progressed, by the final observation period, the 0.5% marigold extract (T4) achieved an impressive
mortality rate of 88.89%, which was statistically comparable to the chemical control. This suggests that higher
concentrations of marigold oil-emulsion could provide a level of effectiveness approaching that of traditional
synthetic insecticides. These results align with previous research indicating the potential of marigold oil-
emulsion as bioinsecticides. For example, Calumpang and Ohsawa (2015) found that volatile organic compounds
from T. erecta flowers disrupt host-finding behavior in L. orbonalis, contributing to reduced pest infestation
rates. Similarly, Salinas-Sánchez et al. (2012) documented the insecticidal activity of T. erecta oil-emulsion
against Spodoptera frugiperda, highlighting the broad-spectrum potential of marigold-based solutions.
Moreover, analysis conducted by Kour and Riat (2021) also highlighted other parts of the marigold plant, such
as the leaves, instead of the flower part used in this study. The study uses oil distilled from Tagetes spp. leaves,
and showed high mortality against mosquito larvae. Another similar study, which features insecticidal activity
of Tagetes against mosquito used multiple parts of the plant, and was more effective compared to extracts from
Cymbopogon nardus (Srivastava et al., 2023). Other study that uses another extraction method (solvent
extraction) emphasizes strong acaricidal activity towards Tetranychus truncatus, both ovicidal and adulticidal,
even at low concentration up to 0.2% (Vannathara et al., 2023).
On the other hand, there are several studies that uses different botanical biopesticides against L. orbonalis and
showed similar efficacy. One of these were the Citrus limon and Aloe vera in methanolic leaf extracts that
showed 82.61% and 78.26% mortality against L. orbonalis, respectively according to Pavani et al., (2023).
Another study from Ullah et al., (2022), uses the same positive control (cypermethrin) but with different extracts,
specifically neem oil, showed great results in controlling shoot and fruit infestation. These studies showed that
extracts from different plants have a significant ability to control EFSB, although the availability of plant
material is an important consideration.
CONCLUSION
The phytotoxicity assessment further demonstrated that marigold oil-emulsion at 0.1%, 0.3%, and 0.5%
concentrations are non-phytotoxic to eggplant (Solanum melongena) leaves. No signs of chlorosis, necrosis,
wilting, or deformation were observed at any concentration or time point, indicating the oil-emulsion’ safety for
foliar application under the tested conditions. Together, these results support the potential of marigold extract as
an effective and safe botanical alternative for managing L. orbonalis in eggplant cultivation. The bioassay results
indicated that marigold (Tagetes erecta) oil-emulsion possess insecticidal properties against Leucinodes
orbonalis larvae, with efficacy increasing in both concentration and exposure time. At 3 hours after treatment
(HAT), the 0.5% marigold extract achieved 88.89% larval mortality, statistically comparable to the chemical
insecticide Cypermethrin (100%). The 0.3% extract also showed substantial activity (77.78%), while the 0.1%
extract produced only moderate effects (44.45%), and the control consistently showed no larval mortality. These
findings suggest that higher concentrations of marigold extract can offer near-equivalent control to synthetic
insecticides within a short period post-application.
RECOMMENDATION
The development of improved formulations of marigold extract is encouraged. Creating stable and user-friendly
products, such as emulsifiable concentrates or wettable powders, could enhance the practicality, storage, and
application of marigold-based insecticides for farmers. These advancements would also support the
commercialization and broader adoption of botanical pest control products. The use of marigold oil-emulsion
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should be considered within the framework of Integrated Pest Management (IPM) strategies. By incorporating
botanical insecticides like marigold oil-emulsion into IPM programs, farmers can reduce their reliance on
synthetic chemicals, lessen the risk of pesticide resistance, and promote environmentally sustainable farming
practices. The proven efficacy and safety of marigold oil-emulsion position them as a promising component of
these integrated approaches. Furthermore, marigold oil-emulsion demonstrate significant potential as a safe and
effective biopesticide against L. orbonalis, making it essential to further develop and integrate them into pest
management systems. Furthermore, the study recommends for future research on the biochemical components
of the marigold oil; its effects on the different plants to determine and evaluate its phytotoxicity; as well as its
effects on different insect pest and microorganisms to be fully utilized as a natural alternative of synthetic
pesticides.
ACKNOWLEDGMENT
The authors express their sincere gratitude to Monkayo College of Arts, Sciences, and Technology (MonCAST)
for providing the assistance necessary to conduct this study. Special thanks are also extended to the MonCAST
4-H Club for their support, and for those colleagues who contributed valuable insights during the course of this
study. The lead author also acknowledged the guidance and mentorship of Jolina A. Enardecido RAgr, whose
advice greatly strengthened the quality of this work, and to his co-author Karlo C. Balabat for his contribution
to this endeavor.
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Ethical Considerations
Authors of this paper were permitted to conduct the study as one of the institutional research outputs noting that
all experimental procedures were performed in accordance with the institutional and scientific guidelines.
Conflict of Interest
The authors declare that there are no conflicts of interest, financial or otherwise that could have influenced the
design, execution, interpretation, or reporting of this research.
Data Availability
The data supporting the findings of this study are available from the corresponding author upon reasonable
request, as the dataset is not publicly archived.
