Abstract
Abstract BACKGROUND Caterpillars of moths and butterflies represent some of the most destructive agricultural pests and have become increasingly resistant to synthetic chemical insecticides. Manuka essential oil is known to be a potent alternative to synthetic insecticides, but its potential to control caterpillar pests remains underexplored. We evaluated the toxicity of manuka essential oil and its components against third‐instar larvae of Trichoplusia ni and Chrysodeixis includens . We also evaluated their potential phytotoxic effects against cabbage, soybean, and corn. RESULTS Manuka essential oil and one of its four fractions (fraction 2) were toxic to the two lepidopteran pests with fraction 2 being more toxic than the whole essential oil. Gas chromatography–mass spectrometry analysis revealed leptospermone, isoleptospermone, and flavesone to be the major components of fraction 2. Flavesone and manuka essential oil had similar toxicity to both caterpillar species, whereas leptospermone, isoleptospermone and grandiflorone, a triketone of manuka leaves, were more toxic to both caterpillar species than the whole essential oil. The median lethal dose (LD 50 ) values (μg/larva) for manuka essential oil, fraction 2, leptospermone, isoleptospermone, flavesone, and grandiflorone against T. ni were 50, 25, 20, 20, 45 and 18, respectively and 42, 32, 28, 20, 41, and 14, respectively against C. includens . Manuka essential oil and its constituents were phytotoxic to cabbage, soybean, and corn, with cabbage and corn being the most and the least affected plants, respectively. CONCLUSION These findings demonstrate that manuka essential oil and its components are promising biopesticides, but improved delivery systems are needed to reduce phytotoxicity. Published 2026. This article is a U.S. Government work and is in the public domain in the USA.
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Claims 20
Claim · model-written summary
Manuka essential oil and one of its four fractions (fraction 2) were toxic to the two lepidopteran pests.
- Taxon
- Manukae0
- Treatment
- Manuka essential oil and one of its four fractions (fraction 2)e0
- Interactor
- lepidopteran pestse0pest
- Outcome
- toxice0
Not reportedComparatorDirection
Verbatim
e0“Manuka essential oil and one of its four fractions (fraction 2) were toxic to the two lepidopteran pests”
Claim · model-written summary
Fraction 2 was more toxic than the whole manuka essential oil.
Verbatim
e0“fraction 2 being more toxic than the whole essential oil”
t0“manuka essential oil”
Claim · model-written summary
Gas chromatography-mass spectrometry showed leptospermone, isoleptospermone and flavesone to be the major components of manuka fraction 2.
Verbatim
e0“Gas chromatography–mass spectrometry analysis revealed leptospermone, isoleptospermone, and flavesone to be the major components of fraction 2”
t0“manuka essential oil”
Claim · model-written summary
Flavesone and manuka essential oil had similar toxicity to both caterpillar species.
Verbatim
e0“Flavesone and manuka essential oil had similar toxicity to both caterpillar species”
Claim · model-written summary
Leptospermone, isoleptospermone and grandiflorone were more toxic to both caterpillar species than the whole essential oil.
Verbatim
e0“leptospermone, isoleptospermone and grandiflorone, a triketone of manuka leaves, were more toxic to both caterpillar species than the whole essential oil”
Claim · model-written summary
The median lethal dose of manuka essential oil against T. ni larvae was 50 ug/larva.
Verbatim
e0“The median lethal dose (LD 50 ) values (μg/larva) for manuka essential oil, fraction 2, leptospermone, isoleptospermone, flavesone, and grandiflorone against T. ni were 50, 25, 20, 20, 45 and 18, respectively and 42, 32, 28, 20, 41, and 14, respectively against C. includens”
Claim · model-written summary
The median lethal dose of fraction 2 against T. ni larvae was 25 ug/larva.
Verbatim
e0“The median lethal dose (LD 50 ) values (μg/larva) for manuka essential oil, fraction 2, leptospermone, isoleptospermone, flavesone, and grandiflorone against T. ni were 50, 25, 20, 20, 45 and 18, respectively and 42, 32, 28, 20, 41, and 14, respectively against C. includens”
Claim · model-written summary
The median lethal dose of leptospermone against T. ni larvae was 20 ug/larva.
Verbatim
e0“The median lethal dose (LD 50 ) values (μg/larva) for manuka essential oil, fraction 2, leptospermone, isoleptospermone, flavesone, and grandiflorone against T. ni were 50, 25, 20, 20, 45 and 18, respectively and 42, 32, 28, 20, 41, and 14, respectively against C. includens”
Claim · model-written summary
The median lethal dose of isoleptospermone against T. ni larvae was 20 ug/larva.
Verbatim
e0“The median lethal dose (LD 50 ) values (μg/larva) for manuka essential oil, fraction 2, leptospermone, isoleptospermone, flavesone, and grandiflorone against T. ni were 50, 25, 20, 20, 45 and 18, respectively and 42, 32, 28, 20, 41, and 14, respectively against C. includens”
Claim · model-written summary
The median lethal dose of flavesone against T. ni larvae was 45 ug/larva.
Verbatim
e0“The median lethal dose (LD 50 ) values (μg/larva) for manuka essential oil, fraction 2, leptospermone, isoleptospermone, flavesone, and grandiflorone against T. ni were 50, 25, 20, 20, 45 and 18, respectively and 42, 32, 28, 20, 41, and 14, respectively against C. includens”
Claim · model-written summary
The median lethal dose of grandiflorone against T. ni larvae was 18 ug/larva.
Verbatim
e0“The median lethal dose (LD 50 ) values (μg/larva) for manuka essential oil, fraction 2, leptospermone, isoleptospermone, flavesone, and grandiflorone against T. ni were 50, 25, 20, 20, 45 and 18, respectively and 42, 32, 28, 20, 41, and 14, respectively against C. includens”
Claim · model-written summary
The median lethal dose of manuka essential oil against C. includens larvae was 42 ug/larva.
- Taxon
- C. includens
Chrysodeixis includense0 - Treatment
- manuka essential oile0
- Outcome
- median lethal dose (LD 50 )e0
- Value
- 42e0
- Qualifier
- μg/larvae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The median lethal dose (LD 50 ) values (μg/larva) for manuka essential oil, fraction 2, leptospermone, isoleptospermone, flavesone, and grandiflorone against T. ni were 50, 25, 20, 20, 45 and 18, respectively and 42, 32, 28, 20, 41, and 14, respectively against C. includens”
Claim · model-written summary
The median lethal dose of fraction 2 against C. includens larvae was 32 ug/larva.
- Taxon
- C. includensChrysodeixis includense0
- Treatment
- fraction 2e0
- Outcome
- median lethal dose (LD 50 )e0
- Value
- 32e0
- Qualifier
- μg/larvae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The median lethal dose (LD 50 ) values (μg/larva) for manuka essential oil, fraction 2, leptospermone, isoleptospermone, flavesone, and grandiflorone against T. ni were 50, 25, 20, 20, 45 and 18, respectively and 42, 32, 28, 20, 41, and 14, respectively against C. includens”
Claim · model-written summary
The median lethal dose of leptospermone against C. includens larvae was 28 ug/larva.
- Taxon
- C. includensChrysodeixis includense0
- Treatment
- leptospermonee0
- Outcome
- median lethal dose (LD 50 )e0
- Value
- 28e0
- Qualifier
- μg/larvae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The median lethal dose (LD 50 ) values (μg/larva) for manuka essential oil, fraction 2, leptospermone, isoleptospermone, flavesone, and grandiflorone against T. ni were 50, 25, 20, 20, 45 and 18, respectively and 42, 32, 28, 20, 41, and 14, respectively against C. includens”
Claim · model-written summary
The median lethal dose of isoleptospermone against C. includens larvae was 20 ug/larva.
- Taxon
- C. includensChrysodeixis includense0
- Treatment
- isoleptospermonee0
- Outcome
- median lethal dose (LD 50 )e0
- Value
- 20e0
- Qualifier
- μg/larvae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The median lethal dose (LD 50 ) values (μg/larva) for manuka essential oil, fraction 2, leptospermone, isoleptospermone, flavesone, and grandiflorone against T. ni were 50, 25, 20, 20, 45 and 18, respectively and 42, 32, 28, 20, 41, and 14, respectively against C. includens”
Claim · model-written summary
The median lethal dose of flavesone against C. includens larvae was 41 ug/larva.
- Taxon
- C. includensChrysodeixis includense0
- Treatment
- flavesonee0
- Outcome
- median lethal dose (LD 50 )e0
- Value
- 41e0
- Qualifier
- μg/larvae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The median lethal dose (LD 50 ) values (μg/larva) for manuka essential oil, fraction 2, leptospermone, isoleptospermone, flavesone, and grandiflorone against T. ni were 50, 25, 20, 20, 45 and 18, respectively and 42, 32, 28, 20, 41, and 14, respectively against C. includens”
Claim · model-written summary
The median lethal dose of grandiflorone against C. includens larvae was 14 ug/larva.
- Taxon
- C. includensChrysodeixis includense0
- Treatment
- grandifloronee0
- Outcome
- median lethal dose (LD 50 )e0
- Value
- 14e0
- Qualifier
- μg/larvae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The median lethal dose (LD 50 ) values (μg/larva) for manuka essential oil, fraction 2, leptospermone, isoleptospermone, flavesone, and grandiflorone against T. ni were 50, 25, 20, 20, 45 and 18, respectively and 42, 32, 28, 20, 41, and 14, respectively against C. includens”
Claim · model-written summary
Manuka essential oil and its constituents were phytotoxic to cabbage, soybean and corn.
- Taxon
- cabbage, soybean, and corn
Brassica oleracea var. capitata
Glycine max
Zea mays subsp. mayse0 - Treatment
- Manuka essential oil and its constituentse0
- Outcome
- phytotoxice0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Manuka essential oil and its constituents were phytotoxic to cabbage, soybean, and corn, with cabbage and corn being the most and the least affected plants, respectively”
Claim · model-written summary
Cabbage and corn were the most and the least affected plants by manuka essential oil and its constituents, respectively.
- Taxon
- cabbage and cornBrassica oleracea var. capitataZea mays subsp. mayse0
- Treatment
- Manuka essential oil and its constituentse0
- Outcome
- the most and the least affected plantse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Manuka essential oil and its constituents were phytotoxic to cabbage, soybean, and corn, with cabbage and corn being the most and the least affected plants, respectively”
Claim · model-written summary
The authors conclude manuka essential oil and its components are promising biopesticides, but improved delivery systems are needed to reduce phytotoxicity.
Verbatim
e0“These findings demonstrate that manuka essential oil and its components are promising biopesticides, but improved delivery systems are needed to reduce phytotoxicity”
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