TY  - BOOK
AU  - Farzana M Sha
AU  - Thania Sara Varghese (Guide)
TI  - Bioactivity of essential oil from the tea tree Melaleuca bracteata F. Muell.  against stored product  pests
U1  - 632.6 
PY  - 2023///
CY  - Vellayani
PB  - Department of Agricultural Entomology, College of Agriculture
KW  - Agricultural Entomology
KW  - Tea tree
KW  - Bioactivity of essential oil
KW  - Melaleuca bracteata F Muell
N1  - MSc
N2  - The research work entitled “Bioactivity of essential oil from the tea tree
Melaleuca bracteata F. Muell. against stored product pests” was carried out at the 
Department of Agricultural Entomology, College of Agriculture, Vellayani during 
2020 to 2022 with an objective to isolate and characterize and evaluate the bioactivity 
and persistence of toxicity of M. bracteata essential oil against stored product pests viz. 
red flour beetle, Tribolium castaneum (Herbst) and pulse beetle, Callosobruchus 
chinensis (Linn.). 
The essential oil (EO) from M. bracteata was extracted by hydro distillation in 
clevenger type apparatus. Essential oil yield per 100g leaves was observed as 1.08 mL. 
The efficacy of tea tree essential oil was tested against the laboratorymaintained culture of T. castaneum and C. chinensis by contact, fumigant and repellent 
bioassays and the persistence of toxic activity of the essential oil on the test insects were 
also evaluated under laboratory conditions. 
In contact toxicity bioassay, the LC50 and LC90 values of the EO against T. 
castaneum were 25.16 % and 69.94 %, respectively at 24 hours after treatment (HAT). 
The LC50 and LC90 values of EO against C. chinensis were 0.05 % and 2.73 %, 
respectively at 24 HAT. In fumigant toxicity bioassay of T. castaneum, the LC50 and 
LC90 values of the EO were 7.7mLL-1
and 22.95mLL-1
at 24 HAT. The LC50 and LC90
values of EO against C. chinensis were 4.30 μLL-1
and 29.96 μLL-1
, respectively at 24 
HAT. 
In the case of T. castaneum, the maximum repellency observed was 93.75 % at 
5% concentration of EO. Cent per cent repellency was not observed here because of the 
fumigant effect at higher doses which scattered the released insects into both treated 
and untreated filter paper halves in Petri plates. In case of C. chinensis, the insects get 
repelled at a very low concentration. 100 per cent repellency was observed at 0.01% 
and 0.05% concentration of EO after 2 h and 45 min, respectively.
The toxic effect of M. bracteata EO persisted up to 34 days on C. chinensis
whereas upto 10 days for T. castaneum when exposed to LC90 values obtained from 
136
fumigant bioassay. The GC-FID and GC-MS profiling of the EO showed 46 
components where, methyl isoeugenol (69.64%) a phenylpropanoid was found to be 
major component followed by methyl cinnamate (8.73%) and methyl eugenol (7.40%), 
which may alone or synergistically with other constituents caused the insecticidal 
effects. 
Experiments on the effect of the EO on the detoxifying enzymes of T. 
castaneum and C. chinensis showed that the enzymes like cytochrome P 450, carboxyl 
esterase were significantly lower in essential oil treated insects, whereas the activity of 
glutathione S- transferase was found to be higher when compared to untreated insects. 
Similarly, the total protein content was also found lower in essential oil treated insects 
compared to the untreated insects. 
In the present investigation, M. bracteata was found to have a good essential oil 
yield of 1.08 per cent. The M. bracteata EO showed strong contact, fumigant and 
repellent toxicity against C. chinensis when compared to T. castaneum. Against C. 
chinensis, the toxic activity of the essential oil persisted up to 34 days. Methyl 
isoeugenol (69.53%) was found to be the major component in the essential oil, followed 
by methyl cinnamate (8.73%) and methyl eugenol (7.41%), which may alone or 
synergistically with other constituents caused the insecticidal effects. The essential oil 
in the present investigation has effects on the detoxification enzymes of the test insects

ER  -