1. Effectiveness and safety of some essential oils of
aromatic plants on the growth and silk production
of the silkworm Bombyx mori L.
Youssef Dewer and Mona M. Mahmoud
Journal of Entomology and Zoology Studies
Presented By
Muhammad Zeeshan Nazar

2. i. Importance
 Mulberry leaves play a key role in the production of silk industry as the
silkworms feed on it.
Introduction
 The silkworm is an important economic insect.
 Converts leaf proteins into the silk proteins
Sericulture industry depends not only on a high quantity but also on the
quality of leave (Tribhuwan S, Mathur SK. 1989).

3. ii. Pests of mulberry
 Mulberry foliage is susceptible to various insect pests.
 mealy bugs, armored scale insects, whiteflies and beetles
 These pests not only reduce the yield but also alter the biochemical
components.
 Generally, insecticide are not advisable for the mulberry.
Therefore, we apply botanicals for control of insect pests (Yamamoto M.
and Toda M. et al 2007).

4. iii. Essential oils
Essential oils (EOs) are volatile oil(s) that have strong aromatic components.
Commonly referred as plant secondary metabolites.
Functions
 Attractants or repellents for the insects and protecting themselves from
heat and cold.
 Sub-lethal effects including oviposition deterrence, anti-feedant activity
and repellent actions (Burt, 2004).

5.  The aim of the present study was to identify the safety and efficacy
of EOs from Fennel and Caraway on the productivity and development
of silkworms.
Objective

6. i. Insects culture and rearing conditions
 Silkworm eggs were obtained from the Sericulture Research Department,
Plant Protection Research Institute (PPRI), Agricultural Research Centre,
Giza, Egypt.
Materials and Methods
 Larvae were reared in the laboratory at
 25 ± 1.5 ºC
 75 ± 5 % relative humidity
 Newly hatched larvae were fed on fresh mulberry leaves (variety Romi)
until the 5th instar, which stage was used in our bioassays.

7. ii. Preparation of essential oils
• Essential oils were derived from two species of Mediterranean plants
 Caraway (Carum carvi)
 Fennel (Foeniculum vulgare)

8. 500 g
Hydro-distillation apparatus
Water
Seeds
Condenser
EO outlet
Stored at
4°C

9. iii. Insect Bioassay
 A series of dilutions of 1, 2, 4, 6 and 8% of the extracted oils were used.
 The dilutions were prepared from stock solutions of 50% by using distilled
water.
 Fresh dilutions were made and used to test the silkworm.
 Mulberry leaves were thoroughly washed with water and then dipped into
the test solution for around 1 min.

10. • Control leaves were dipped in distilled water with 0.1% Triton X-100.
• Both leaves were left to dry at room temperature.
• Both mulberry leaves were fed to the silkworm larvae (50 larvae/tray x 3
replicates x 10 treatments) up to cocoon formation.
• Mortality and survival were determined after 24 h of each exposure and
the numbers of dead larvae were counted cumulatively.
• Observations were also recorded on the cocoon parameters viz., cocoon
weight, pupae weight and shell weight.

11. iv. Experimental Measurements
• A sample of five mature experimented larvae was dissected and the silk
glands were drawn and weighed.
• The number of deposited and fertilized eggs per female moth was counted
and recorded.
v. Statistical analysis
The data as percentages were analyzed using methods described by Snedecor.
(Snedecor GW. 1956).

12. Results and Discussion
Results shows that :
The larval mortality percentage increased with increasing oil
concentrations.

13. Tretments Larval wt (g) Larval duration
(days)
Silk gland wt (g) Larval Mortality
(%)
Fecundity value
Fennel Oil Conc. [%]
1 3.064± 0.362 31 0.574± 0.142 15.38 370.4± 37.159
2 2.776± 0.352 32 0.409± 0.100 20 335.6± 23.835
4 2.488± 0.188 32 0.362± 0.070 23.08 330.4± 24.501
6 2.451± 0..303 33 0.304± 0.044 58.46 313.2±23.123
8 2.248± 0.243 34 0.307± 0.081 69.23 261± 13.076
Caraway Oil Conc. [%]
1 3.058± 0.224 31 0.592± 0.023 18.46 359.2± 18.198
2 2.957± 0.344 32 0.504± 0.104 20 362.8± 24.933
4 2.597± 0.260 33 0.432± 0.042 21.54 346.2± 31.276
6 2.215± 0.390 33 0.318± 0.073 46.15 276.2± 26.347
8 1.919± 0.271 34 0.234± 0.028 76.92 254± 29.656
Control 3.077± 0.153 32 0.559± 0.088 16.92 359± 9.772
L.S.D. “F-test” 18.643** .. 10.890** .. 16.395**

14. 0
0.5
1
1.5
2
2.5
3
3.5
1 2 4 6 8
Larvalweight(g)
Essential Oils Concentratiom (%)
Fennal
Caraway
Control
Fennel oil 3.064g at 1% Concentration
2.248g at 8% Concentration
Caraway 3.058g at 1% Concentration
1.919g at 8% Concentration
Control 3.077g
Larval weight

15. 0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
1 2 4 6 8
Silkglandweight(g)
Essential Oils Concentration (%)
Fennel
Caraway
Control
Fennel oil 0.592g at 1% Concentration
0.307g at 8% Concentration
Caraway 0.574g at 1% Concentration
0.234g at 8% Concentration
Control 0.559g
Silk gland weight

16. Fennel oil 15.4% mortality at 1% Concentration
69.2% mortality at 8% Concentration
Caraway 18.5% mortality at 1% Concentration
76.9% mortality at 8% Concentration
Control 16.9%
0
10
20
30
40
50
60
70
80
90
1 2 4 6 8
LarvalMortality(%)
Essential Oils Concentration (%)
Fennel
Caraway
Control
Larval Mortality

17. 0
50
100
150
200
250
300
350
400
1 2 4 6 8
FecundityValue
Essential Oils Concentration (%)
Fennel
Caraway
Control
Fennel oil 370.4 at 1% Concentration
261 at 8% Concentration
Caraway 359.2 at 1% Concentration
254 at 8% Concentration
Control 359
Fecundity Value

18. • No negative effects on the development and silk production of
silkworm.
• It would be useful to gain insight into the efficiency of a safe
management process.
• Contribute to the IPM in silkworm-breeding industry.
Conclusion

19.  Das PK, Vijaya Raghawan K, Jolly MS. Preliminary observation on the effect of feeding with washed and dusty
mulberry leaves on the performance of four races of silkworm, Bombyx mori (L.) National seminar on silk research
and development (Abstract) 1983; March 10-13, Bangalore. India p-111.
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Journal of Food Microbiology 2004; 94, 223-253.
 Snedecor GW. Statistical methods. 5th ed., lowa State University Press, lowa 1956; pp. 534.
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 Fournier A. Quantitative data on the Bombyx mori L. silkworm: a review. Biochimie 1979; 61, 283-320.
 Hiratsuka Ε. Researches on the nutrition of the silkworm. Bulletin Series Experimental Station in Tokyo 1920; 1,
275 - 315.
 Biram SNM, Tribhuwan S, Beera S. Occurrence of unfertilized eggs in the mulberry silkworm, Bombyx mori L.
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