Introduction
⌅Hellula undalis (Fabricius, 1781), a member of the Lepidoptera order belonging to the
Pyralidae family, holds considerable status as a pest within warm
geographical regions across the globe (Labou et al. 2017Labou
B, Brévault T, Sylla S, Diatte M, Bordat D, Diarra K, 2017. Spatial and
temporal incidence of insect pests in farmers’ cabbage fields in
Senegal. Int J Trop Insect Sci. 37(4):225-33. https://doi.org/10.1017/S1742758417000200.
).
Its origin traces back to Europe; however, it has incited substantial
outbreaks in diverse Asian nations like India, Malaysia, and Vietnam (Kunjwal and Srivastava, 2018Kunjwal
N, Srivastava RM. Insect pests of vegetables, 2018. In: Omkar, editor.
Pests manag. Singapore: Springer Singapore, p. 163-221. https://doi.org/10.1007/978-981-10-8687-8_7.
; Tran et al., 2018Tran
TT, Le VV, Nguyen L, 2018. Study on damage situation of the cabbage
webworm, Hellula Undalis Fabricius (Lepidoptera: Crambidae) on green
mustards at the Mekong Delta. Can Tho Univ. J. Sci. 54: 115-24.
). The larvae of H. undalis exhibit an initial behaviour of tunnelling into the stems of nascent
shoots. These larvae undergo a transition as they get older and begin to
constipate the leaves and leaf stems. In the process, they construct a
silk enclosure around their feeding vicinity, within which accumulates
their excrement. The larvae of H. undalis initially bore into the
stems of growing shoots, while mature larvae mine the leaves and leaf
stems. They create a silk web around their feeding area, which becomes
filled with their waste material. During the pre-heading stage, a single
larva's feeding damage to a cabbage plant can result in multiple
non-marketable heads or even plant death. Remarkably, even the feeding
activity of a solitary larva on a cabbage plant during its pre-heading
phase can culminate in the demise of the plant or yield multiple heads
that lack market value (Sivapragasan, 2005Sivapragasan
A, 2005. Development of cabbage webworm, Hellula undalis (Fabr.) on
head cabbage, Brassica oleracea var. capitata. J Trop Agric Food Sci.
33:321-31.
).
Significant disadvantages resulting from overuse of pesticides include harm to native predators and ecosystem degradation (Khan et al., 2012Khan S, Guo L, Maimaiti Y, Mijit M, Qiu D, 2012. Entomopathogenic fungi as microbial biocontrol agent. Mol Plant Breed. 3(7). https://doi.org/10.5376/mpb.2012.03.0007.
; Khan et al., 2023Khan
BA, Nadeem MA, Nawaz H, Amin MM, Abbasi GH, Nadeem M et al., 2023.
Pesticides: impacts on agriculture productivity, environment, and
management strategies. In: Aftab T, editor. Emerging contaminants and
plants: interactions, adaptations and remediation technologies. Cham:
Springer International Publishing. p. 109-34. https://doi.org/10.1007/978-3-031-22269-6_5.
).
In the context of ecological well-being, the adoption of biocontrol
agents for the sustainable oversight of insect pests experiencing rapid
growth. Fungal bioagents that initiate infections within insects present
a potent avenue for ecologically considerate management of insect
pests. Biocontrol agents that possess noteworthy virulence traits, such
as entomopathogenic fungi, are swiftly emerging as credible substitutes
for synthetic pesticides (Islam et al., 2021Islam
W, Adnan M, Shabbir A, Naveed H, Abubakar YS, Qasim M et al., 2021.
Insect-fungal-interactions: A detailed review on entomopathogenic fungi
pathogenicity to combat insect pests. Microb Pathog. 159:105122. https://doi.org/10.1016/j.micpath.2021.105122
).
Global demand for the formulation of microbial bio-pesticides as
integral components of integrated pest management initiatives and the
increasing necessity for pesticides devoid of chemical constituents are
on the rise, as reported by Zaki et al. (2020)Zaki
O, Weekers F, Thonart P, Tesch E, Kuenemann P, Jacques P, 2020.
Limiting factors of mycopesticide development. Biol Control. 144:104220. https://doi.org/10.1016/j.biocontrol.2020.104220.
.
The entomopathogenic fungus satisfies the prerequisites for a potential natural factor inducing insect mortality (Boomsma et al., 2014Boomsma
JJ, Jensen AB, Meyling NV, Eilenberg J, 2014. Evolutionary interaction
networks of insect pathogenic fungi. Annu Rev Entomol. 59:467-85. https://doi.org/10.1146/annurev-ento-011613-162054
). Established models for investigating the biological regulation of pest populations through fungal entomopathogens encompass Beauveria bassiana (Bals.-Criv.) Vuill and Metarhizium anisopliae (Metchnikoff) Sorokin, both widely recognized for their pathogenic
effects on numerous insect species. These mycobiocontrol agents have
gained global utilization in the agricultural sector for the biocontrol
of insects (Sandhu et al., 2012Sandhu
SS, Sharma AK, Beniwal V, Goel G, Batra P, Kumar A, Malhotra S, 2012.
Myco-biocontrol of insect pests: factors involved, mechanism, and
regulation. J Pathog :3-12.
; Shehzad et al., 2021Shehzad
M, Tariq M, Mukhtar T, Gulzar A, 2021. On the virulence of the
entomopathogenic fungi, Beauveria bassiana and Metarhizium anisopliae
(Ascomycota: Hypocreales), against the diamondback moth, plutella
xylostella (L.)(Lepidoptera: Plutellidae). Egypt J Biol Pest Control
31(1):7.
; Shanker et al., 2023Shanker
R, Prajapati MR, Singh RP, Singh R, Singh J, Kumar P, 2023. Isolation,
molecular characterization of indigenous Metarhizium anisopliae
(Metchnikoff) isolate, using ITS-5.8 s rDNA region, and its efficacy
against the Helicoverpa armigera (Hubner)(Lepidoptera: Noctuidae). Egypt
J Biol Pest Control. 33(1):23. https://doi.org/10.1186/s41938-023-00670-7.
).
The present investigation was carried out to evaluate the effectiveness of a local isolate of M. anisopliae against the fourth instar larvae of H. undalis. These larvae were reared using a natural dietary regimen within controlled laboratory settings.
Material and methods
⌅Insect collection and rearing
⌅The cabbage plants infected with cabbage webworm (H. undalis) were collected from the Horticulture Experimental Field, Sardar Vallabhbhai Patel University of Agriculture and Technology in Meerut, Uttar Pradesh, India. Culture was reared on cabbage leaves (natural diet) in 25 ± 2°C, 65 ± 5% RH.
Metarhizum anisopalae culture
⌅Previously identified local isolate of M. anisopliae retrieved from lab (Shanker et al., 2023Shanker
R, Prajapati MR, Singh RP, Singh R, Singh J, Kumar P, 2023. Isolation,
molecular characterization of indigenous Metarhizium anisopliae
(Metchnikoff) isolate, using ITS-5.8 s rDNA region, and its efficacy
against the Helicoverpa armigera (Hubner)(Lepidoptera: Noctuidae). Egypt
J Biol Pest Control. 33(1):23. https://doi.org/10.1186/s41938-023-00670-7.
)
was cultured on Sabouraud dextrose agar medium. Inoculated petri dishes
were subjected to a 15-day incubation period upheld at a temperature of
25°C alongside a relative humidity ranging between 50% and 60%.
Subsequently, gather the conidia from the surface of the cultivated
material collected via careful scraping, employing a sterile solution
containing 0.01% Tween-80. Concentration of the resultant stock
suspension was quantified utilizing a hemocytometer and thereafter
conserved within a refrigerated environment for future utilization.
Efficacy of the fungal isolate against fourth instar larvae of H. undalis
⌅Fourth instar larvae of H. undalis were employed as the subject of investigation in present study. A total of 45 larvae, distributed into groups of 15 larvae each, were immersed for a duration of 20 seconds within a solution of varying concentrations (103, 104, 105, 106, 107, 108, 109, and 1010 spores ml−1) that had been meticulously prepared. The experimental setup was arranged within transparent plastic enclosures, adhering to a complete randomized design (CRD) and featuring four replications, all experiments conducted under ambient room temperature conditions. Additionally, the procedure was duplicated on two occasions to ensure the reproducibility of outcomes.
Mortality rate stemming from the distinct concentrations of M. anisopliae was recorded meticulously over a five-day period, and percentage
mortalities were subsequently computed utilizing Abbott's formula (Abbott, 1925Abbott WS, 1925. A method of computing the effectiveness of an insecticide. J Econ Entomol. 18(2):265-7. https://doi.org/10.1093/jee/18.2.265a
) as follows:
In this equation, the survival percentages derived from control group and treatment groups, reflecting the effect of the fungus on larval survival.
Statistical analysis
⌅The mortality percentage was subjected to computational analysis (Feng et al., 1992Feng
MG, Nowierski RM, Johnson JB, Poprawski TJ, 1992. Epizootics caused by
entomophthoralean fungi (Zygomycetes, Entomophthorales) in populations
of cereal aphids (Hom, Aphididae) in irrigated small grains of
southwestern Idaho, USA. J Appl Entomol 113(1-5):376-90. https://doi.org/10.1111/j.1439-0418.1992.tb00678.x
). Software application SPSS (version 21) was employed to ascertain the values of lethal time (LT50 and LT90), pivotal in causing mortality in 50% and 90% of the population, respectively (Finney, 1971Finney DJ, 1971 Probit analysis. Cambridge, UK: Cambridge University Press
).
Results and Discussion
⌅Entomopathogenic fungi play a crucial role in regulating insect populations. In particular, M. anisopliae is important as a natural control agent and source of mycoinsecticides
for the control of numerous lepidopteran pests worldwide (Asi et al., 2013Asi
MR, Bashir MH, Afzal M, Zia K, Akram M, 2013. Potential of
entomopathogenic fungi for biocontrol of Spodoptera litura Fabricius
(Lepidoptera: Noctuidae). J Anim Plant Sci. 23(3):913-8.
). Previous studies have extensively investigated the potential of M. anisopliae as a biological control agent (Lin et al., 2007Lin
H-F, Yang X-J, Gao Y-B, Li S-G, 2007. Pathogenicity of several fungal
species on Spodoptera litura. Ying Yong Sheng Tai Xue Bao [Ying Yong
Sheng Tai Xue Bao]. 18(4):937-40.
). The effectiveness of M. anisopliae as an entomopathogenic fungus has been demonstrated against a variety of insects, including Lepidoptera, Coleoptera, Hemiptera and others (Shehzad et al., 2021Shehzad
M, Tariq M, Mukhtar T, Gulzar A, 2021. On the virulence of the
entomopathogenic fungi, Beauveria bassiana and Metarhizium anisopliae
(Ascomycota: Hypocreales), against the diamondback moth, plutella
xylostella (L.)(Lepidoptera: Plutellidae). Egypt J Biol Pest Control
31(1):7.
; Kumar et al., 2023Kumar
A, Suroshe SS, Sonam GK, Saini GK, Singh J, 2023. Efficacy of
genetically transformed Metarhizium anisopliae against Spodoptera litura
and Aphis craccivora. Saudi J Biol Sci. 30(1):103493. https://doi.org/10.1016/j.sjbs.2022.103493
; Shanker et al ., 2023Shanker
R, Prajapati MR, Singh RP, Singh R, Singh J, Kumar P, 2023. Isolation,
molecular characterization of indigenous Metarhizium anisopliae
(Metchnikoff) isolate, using ITS-5.8 s rDNA region, and its efficacy
against the Helicoverpa armigera (Hubner)(Lepidoptera: Noctuidae). Egypt
J Biol Pest Control. 33(1):23. https://doi.org/10.1186/s41938-023-00670-7.
).
The aim of the present study was to evaluate the effectiveness of a locally identified isolate of the entomopathogenic fungus M. anisopliae against H. undalis larvae under controlled laboratory conditions. The results of this investigation provide insight into the potential of this fungus as a biocontrol agent for the control of H. undalis populations.
The efficacy of a M. anisopliae isolate against fourth instar larvae of H. undalis was investigated in this study. The experiment involved exposing the larvae to varying concentrations of M. anisopliae spores and monitoring mortality percentages at different time intervals. The results revealed direct relationship to the concentration of treatment with increasing spore concentrations leading to higher mortality rates. At the lowest concentration tested (1 × 103 spores ml-1), no mortality was observed within the initial 24 h, but over time, mortality rates increased to 41.66% after 120 h. As the spore concentration increased to 1 × 1010 spores ml-1, mortality percentages steadily increase to 86.88% after 120 h of exposure (p ≤ 0.05) (Table 1). These findings suggest that the effectiveness of M. anisopliae against H. undalis larvae is concentration-dependent.
| Concentrations (spores ml-1) | Mortality percentage at different time interval (hours) | LT50 (Days) | LT90 (Days) | ||||
|---|---|---|---|---|---|---|---|
| 24 | 48 | 72 | 96 | 120 | |||
| 1 × 103 | 0.00 | 0.00b | 10.41b | 31.24a | 41.66a | 7.91 | 12.25 |
| 1 × 104 | 0.00 | 0.00b | 12.49b | 33.33a | 45.82a | 7.72 | 12.07 |
| 1 × 105 | 0.00 | 0.00b | 16.66ab | 41.66a | 49.99a | 7.53 | 11.88 |
| 1 × 106 | 0.00 | 0.00b | 20.83ab | 47.91a | 58.33a | 7.22 | 11.57 |
| 1 × 107 | 0.00 | 0.00b | 27.08a | 50.00a | 66.66a | 6.94 | 11.29 |
| 1 × 108 | 0.00 | 8.33a | 31.24ab | 54.16a | 77.08a | 6.61 | 10.95 |
| 1 × 109 | 0.00 | 12.49a | 35.41b | 66.66a | 83.33a | 6.47 | 10.91 |
| 1 ×1010 | 0.00 | 9.63a | 39.38a | 68.22a | 86.88a | 5.43 | 9.29 |
| Control | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | - | - |
Number
denote by same letter within the column are statistically non -
significant (Tukey’s test, p < 0.05) data show the mean of three.
The LT50 decreased as concentrations of the spore increased. The LT50 ranged from 7.91 days for the lowest spore concentration (1 × 103 spores ml-1) to 5.43 days for the highest spore concentration (1 × 1010 spores ml-1). Similarly, the LT90 exhibited a decreasing trend with higher spore concentrations. The LT90 values ranged from 12.25 days for the lowest spore concentration (1 × 103 spores ml-1) to 9.29 days for the highest concentration (1 × 1010 spores ml-1) (p ≤ 0.05) (Table 1). These findings highlight the potential of M. anisopliae as a biological control agent against H. undalis larvae under laboratory conditions.
Previously, similar studies were conducted involving different insects. For instance, Nguyen et al., (2007)Nguyen
NTH, Borgemeister C, Poehling H-M, Zimmermann G, 2007. Laboratory
investigations on the potential of entomopathogenic fungi for biocontrol
of Helicoverpa armigera (Lepidoptera: Noctuidae) larvae and pupae.
Biocontrol Sci Technol. 17(8):853-64. https://doi.org/10.1080/09583150701546375.
reported an 87.00% mortality rate in 4th instar larvae of H. armigera after a two-week exposure period. Additionally, Fite et al. (2020)Fite
T, Tefera T, Negeri M, Damte T, Sori W, 2020. Evaluation of Beauveria
bassiana, Metarhizium anisopliae, and Bacillus thuringiensis for the
management of Helicoverpa armigera (Hubner)(Lepidoptera: Noctuidae)
under laboratory and field conditions. Biocontrol Sci Technol.
30(3):278-95. https://doi.org/10.1080/09583157.2019.1707481
observed a 71.00% mortality rate at a concentration of 1 × 109 spores ml−1 after eleven days of post-treatment. Similarly, Rijal et al. (2008)Rijal
JP, Dhoj GCY, Thapa RB, Kafle L, 2008. Virulence of native isolates of
Metarhizium anisopliae and Beauveria bassiana against Helicoverpa
armigera in Nepal. Formos Entomol 28:21-9.
and Sabry et al. (2011)Sabry KH, Abdel-Raheem MA, El-Fatih MM, 2011. Efficacy of the entomopathogenic fungi Beauveria bassiana and Metarhizium anisopliae on some insect pests under laboratory conditions. Egypt J Biol Pest Control 21(1):33–8.
documented mortality rates of 65.33%, 86.67%, 60.00%, and 80.00% for
second and third instar larvae with a conidial concentration of 1 × 107 spores ml−1 after six, seven-, and ten-days post-treatment, respectively. Shanker et al. (2023)Shanker
R, Prajapati MR, Singh RP, Singh R, Singh J, Kumar P, 2023. Isolation,
molecular characterization of indigenous Metarhizium anisopliae
(Metchnikoff) isolate, using ITS-5.8 s rDNA region, and its efficacy
against the Helicoverpa armigera (Hubner)(Lepidoptera: Noctuidae). Egypt
J Biol Pest Control. 33(1):23. https://doi.org/10.1186/s41938-023-00670-7.
and Yanar et al. (2023)Yanar
O, Topkara EF, Sahin F, Yanar Y, Yanar D, Terzi Y, 2023. Efficacy of
Beauveria bassiana and Metarhizium brunneum isolates against the pine
processionary moth, Thaumetopoea wilkinsoni Tams, 1926 (Lepidoptera:
Notodontidae). Egypt J Biol Pest Control. 33(1):32. https://doi.org/10.1186/s41938-023-00679-y.
asserted that the highest concentration exhibits greater efficacy against the insect. The LT50 values varied with conidial concentrations, with Tahir et al. (2019)Tahir HM, Basheer T, Ali S, Yaqoob R, Naseem S, Khan SY, 2019. Effect of pesticides on biological control potential of Neoscona theisi (Araneae: Araneidae). J Insect Sci 19(2):17. https://doi.org/10.1093/jisesa/iez024.
and Fite et al. (2020)Fite
T, Tefera T, Negeri M, Damte T, Sori W, 2020. Evaluation of Beauveria
bassiana, Metarhizium anisopliae, and Bacillus thuringiensis for the
management of Helicoverpa armigera (Hubner)(Lepidoptera: Noctuidae)
under laboratory and field conditions. Biocontrol Sci Technol.
30(3):278-95. https://doi.org/10.1080/09583157.2019.1707481
reporting 6.20 days and 3.71 days at 1 × 109 spores ml−1, respectively. Moreover, Nahar et al. (2008)Nahar
PB, Kulkarni SA, Kulye MS, Chavan SB, Kulkarni G, Rajendran A,
Deshpande MV, 2008. Effect of repeated in vitro sub-culturing on the
virulence of Metarhizium anisopliae against Helicoverpa armigera (Lepidoptera: Noctuidae). Biocontrol Sci Technol 18(4):337–55.
and Nguyen et al. (2007)Nguyen
NTH, Borgemeister C, Poehling H-M, Zimmermann G, 2007. Laboratory
investigations on the potential of entomopathogenic fungi for biocontrol
of Helicoverpa armigera (Lepidoptera: Noctuidae) larvae and pupae.
Biocontrol Sci Technol. 17(8):853-64. https://doi.org/10.1080/09583150701546375.
found LT50 values of 3.4 days and 3.00 days for a conidial concentration of 1.0 × 107 ml−1, respectively. This study represents the first experimental finding aimed at evaluating the efficacy of M. anisopliae against the larvae of H. undalis under laboratory conditions. Due to the absence of comparable findings,
the current results are contextualized by drawing parallels with other
members of the same family, Pyralidae. The virulence of different
concentrations of M. anisopliae on H. undalis larvae exhibited similarities to outcomes reported by Ramanujam et al. (2015)Ramanujam
B, Poornesha B, Yatish KR, Renuka S, 2015. Evaluation of Pathogenicity
of Different Isolates of Metarhizium anisopliae (Metchnikoff) Sorokin
against maize stem borer, Chilo partellus (Swinhoe) using laboratory
bioassays. Biopestic Int 11:89-95.
. Specifically, a concentration of 107 conidia/ml resulted in a mortality rate of 90% in Chilo partellus, a member of the same family, after 10 days of inoculation.
Conclusion
⌅The results showed that the application of M. anisopliae spore suspension resulted in a significant increase in larval mortality compared to the control group. This result is consistent with previous research that has suggested insecticidal properties of Metarhizium species against various insect pests. The mortality rate observed in the treatment group supports the potential of this locally identified isolate as a biopesticide to control H. undalis infestations.
Data availability
⌅All data are available in the manuscript and the materials used in this work are of high transparency and grade.
Acknowledgements
⌅The authors acknowledge the Vice Chancellor, Sardar Vallabhbhai Patel University of Agriculture and Technology, Meerut-250110, Uttar Pradesh, CoE in Agri Biotech., Council of Science and Technology, Uttar Pradesh and Bioinformatics facility, Department of Biotechnology, India and Bio Control Lab, Department of Entomology, SVPUAandT, Meerut for providing the facilities to carry out this research work.
Competing interests
⌅The authors declare that they have no conflict of interest.
Authors’ contributions
⌅Malyaj R. Prajapati: Data curation, Formal analysis, Investigation, Methodology, Writing – original draft, Writing – review and editing. Ravi Shanker: Investigation, Methodology. Reetesh Pratap Singh: Data curation, Investigation, Methodology. Rajendra Singh: Conceptualization, Funding acquisition, Project administration, Supervision. Pankaj Kumar: Conceptualization, Funding acquisition, Project administration, Supervision, Writing – review and editing. Jitender Singh: Visualization, Writing – review and editing. Mahesh Kumar Bharti: Writing – review and editing. L. K. Gangwar: Writing – review and editing.
Funding
⌅The authors received no specific funding for this work.