The Impact of Temperature Variations
on Silkworm Growth Rate and Cocoon Production
1- Objectives
The main object of this report is to
find out how different temperature conditions affect the overall growth,
molting and cocoon formation of the silkworm larvae.
2- Introduction
Silkworms (Bombyx mori) are
basically cold-blooded insects whose metabolic rates primarily depend on
environmental temperatures. Optimal temperatures (23–26°C) accelerate growth
whereas extreme conditions affect their development adversely. This study is an
attempt: to examine, via experiment, how controlled temperatures influence
larva growth speed and silk yield; and to determine what ideal temperatures are
best for silkworm’s metabolism.
3- Material and Apparatus
- 15 healthy silkworm larvae (of 3rd instar)
- Fresh mulberry leaves
- Thermometers
- Digital scale (.01g precision)
- 3 temperature-controlled environments:
- Group A: (Room temperature)
- Group B: (Heated incubator)
- Group C: (Cool cabinet)
4- Procedure
A total of 15 larvae were collected and divided into 3 groups (5 in each container). They were supplied with equal amount of fresh mulberry leaves at the same time each day. The learners recorded the following data of worms on daily basis:
- Length (from head to tail)
- Mass (weight of each entire group)
- Molting events (skin shedding turns)
- Cocoon formation (counted days)
The experiment continued until all
larvae were transformed into cocoons. Finally, total cocoons of each group were
collected separately and weighed to reach final conclusions.
5- Data Analysis
Table 1: Average Larval Growth (Day 1–10)
| Temp. Group | Avg. Length (cm) | Avg. Mass (g) | Days to Molt | Days to Cocoon |
|---|---|---|---|---|
| 25°C (Control) | 2.8 → 6.5 | 1.2 → 8.7 | Day 4 | Day 22 |
| 30°C (Warm) | 2.8 → 7.1 | 1.2 → 9.3 | Day 3 | Day 18 |
| 20°C (Cool) | 2.8 → 4.9 | 1.2 → 6.1 | Day 6 | Day 28 |
Table 2: Cocoon Yield
| Group | Avg. Cocoon Weight (g) | Silk Quality |
|---|---|---|
| 25°C | 1.45 | Shiny, firm |
| 30°C | 1.20 | Fragile, uneven |
| 20°C | 1.60 | Dense, but smaller |
Discussion
Growth Speed:
The group of larvae put in warm
conditions (30°C) grew fastest reached 7.1 cm in length but produced weaker and
lighter in weight cocoons. On the other hand, the larvae kept at (20°C)
recorded slowest growth but developed into denser cocoons.
Molting:
The warmer were the temperatures, the
faster was molting.
Cocoon Quality:
The larvae kept at (25°C) turned into
the best quality shiny and firm cocoons whereas those fostered at (30°C)
produced uneven and brittle silk of lowest quality.
Conclusion
The study at lab has proved that
temperature variations impact silkworm development significantly. A cross in
optimal temperature limits (23–26°C) may result in the production of bad
quality silk.
Precautions
- Handle larvae gently with soft brushes
- Replace mulberry leaves every 12 hours
- Clean containers daily to avoid mold
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