2024

Newsletter “おかいこさま”

Overseas Distribution
NationalSpecial version for overseas researchers
Bio-Resource
Project“Silkworm”
National Bio-Resource Project “Silkworm” Newsletter
August 1, 2024
http://www.nbrp.jp/index.jsp

Bombyx mandarina (Oki)The Bombyx mandarina Oki strain is large and is collected from Oki Island, Japan. They have been
maintained at Kyushu University since 2022.

１

NBRP “Silkworm” resources
Kyushu University, the core institute of the NBRP “Silkworm,” rears over 500 mutant strains of B. mori annually, andwe are able to provide any mutant strain. Upon request, two Japanese strains (Oki and Sakado) of wild silkworms (B.
mandarina) are also available (p. 3–5). In addition, we have consomic and semiconosomic strains, in which one pair ofB. mori autosomes has been replaced with a B. mandarina chromosome (p. 3). Since last year, two types of BmN celllines have been prepared and are available for distribution(p. 6). We look forward to receiving your orders.
Silkworm strains: Classification by phenotype

European strain

otherClassification by phenotype and the number of each strain.
You can view the strains available for distribution and their features on the website. More than 500
silkworm strains are available for distribution. https://shigen.nig.ac.jp/silkwormbase/top.jsp

Characteristic phenotypes
a60

k31

c43

1

a60: Gene that affects the cuticle hardening at the first ecdysis.
Spontaneous; homozygotes hatch and develop normally during the first instar, and distinct albino features appear soon after the firstecdysis and die with shrinking. The cuticle layer has incomplete hardening and a porous structure. They are unable to eat leaves andmaintain body water. The independent spontaneous mutation al2 is like al. Symbol: alc43: Spontaneous; with a pink cocoon, and coexistence with Y, +C (or CI), and F is needed for manifestation. Symbol: F, Pk
k31: Spontaneous; with the dorsal and lateral sides of the larva that are covered with dark brown pigments, resulting in a whitelongitudinal band above the dorsal vessel. When in combination with p, they are almost white except for small black spots on the sideof the thorax, and in a p2 background, there is a wavy pattern on the side of the abdomen. Symbol: Um203

ｔ70

u42

m203: Includes many mosaic individuals, which is presumed to be caused by the presence of fragmented chromosomes.
t70: Adult silkworms usually live for approximately a week after emersence; however, the t70 strain is lethal within a few days. The
exact cause is unknown, but the responsible region is located on chromosome 25.
u42: Introduced from B. mandarina. Spontaneous; with a black spot on the apex of the wings, and when heterozygous, it is lessconspicuous, especially in females. Symbol: Ws2

Bombyx mandarina and other silk moths
B. mori are insects that were domesticated from wild silkworms (B. mandarina) over 5,000 years ago. We provide twostrains of B. mandarina that were collected from Sakado, Saitama Prefecture, and Oki, Shimane Prefecture. We present
the characteristics of the two strains.

SakadoOki

Introduction of the Sakado and Oki strains
NBRP “Silkworm” has two B. mandarina strains available for distribution. The Sakado strain was collected in Sakado City, Saitama
Prefecture, and the Oki strain was collected in Oki Island, Shimane Prefecture, and they have been reared at Kyushu University.
Sakado is the origin of the CT and T strains and is similar in size to the common Japanese B. mandarina, whereas Oki is larger thanSakado. Sakado is reared from summer to autumn, and Oki is reared in autumn.
Shinshu University is the curator of the wild silk moths. Information on Japanese wild silkworm
moths are available at https://shigen.nig.ac.jp/wildmoth/ .
More details are on pages 7–8.

Consomic and semi-consomic strains
We have consomic (CT) and semiconsomic (T) strains that have been constructed from the female Sakado strain of B.
mandarina. These strains have a single or a pair of B. mandarina autosomes and a female-specific sex chromosome (W),and the remaining chromosomes are from the standard strain p50 of B. mori. B. mandarina in Japan has fused
chromosomes that correspond to Chr14 and Chr27 of B. mori. Thus, there are no CT27 and T27. Details of these lines aresummarized in the article Journal of Insect Biotechnology and Sericology 90, 33–40 (2021).
DOI: https://doi.org/10.11416/jibs.90.2_033

T17WS
p50

Characteristics of the T17 strain: wing spot (WS) and chromosome composition.
The red chromosomes are from the Sakado strain of B. mandarina, and the blue chromosomes are from the p50 strain of B. mori.
The dominant traits on the B. mandarina chromosome are easy to determine.
The CT website has not yet been published. Kindly contact us via email or other means to request a distribution. Pricing is the same
as for regular eggs.

3How to rear B. mandarina
B. mandarina is more sensitive to stress than B. mori. We present here how we rear and mate them.

abc

a: Incubation of eggs
B. mandarina eggs are maintained at a temperature of 25°C and a humidity of approximately 75% for 14 days.
b: Move newly hatched larvae to mulberry leaves
Use bird feathers to gently move the larvae to the mulberry leaves. B. mandarina eggs do not hatch simultaneously; therefore, thisshould be done over several days. The hatching rate is approximately 50%.
c: Larvae rearing immediately after hatching
They are reared on fresh and soft mulberry leaves that are used by the branch. The rearing temperature is 25°C.

dfe

d: Humidity controlLarvae do not eat dry leaves; therefore, they should be kept under high humidity conditions. However, high humidity causes moldgrowth, and rearing cages should be kept clean. Mulberry feeding is done once a day.
e and f: Cleaning of rearing cages
Remove larval excrement and leftovers daily, as this can cause disease. When moving larvae, move them with the mulberry and do
not touch them directly because this can cause ecdysis failure and disease.

gihg: Use of humidity retention bags
A bag that can maintain humidity (such as a vegetable bag) can be used as a substitute for rearing cages.
h: Third to last instar larvae
The final instar of B. mandarina is generally 4th instar. Some individuals of the Oki strain are nearly 7 cm in length.
i: Population density and mulberry feeding
If the number of individuals in the final instar is too large, the number of mulberry leaves may become insufficient, and the humidity
may become too high. It is better to maintain a small number of individuals.

4jkl

j: Wandering stage
Individuals who have eaten sufficient mulberry leaves necessary for the metamorphosis into pupae are active and very mobile. Caremust be taken to prevent escape.
k and l: Spinning period
Larva produces feces and urine with a lot of water before it creates a cocoon. The cocoon-making process requires a threedimensional frame. There are other frames that can be used, such as wavy paper or other materials, but generally, mulberry leaves areused to make the cocoons.

mnom and n: Cocoon of the Oki strain
After the cocoon is completed, it takes approximately five days for the larvae to become pupa. During this period, the cocoon should
not be moved. The cocoon size varies greatly among individuals, but in general, the cocoons of Oki tend to be larger.
o: Cocoon storage
Remove the paper, mulberry leaves, etc., and move only the cocoons to a separate room. However, if there is a possibility that thecocoons will be damaged, move them without removing them from the frame. The cocoons should be maintained at a temperature of
25°C and a humidity of approximately 60% until the emergence of the moths.

pqrp and q: Mating
After identifying the male and female moths, 1–2 pairs are placed in a bag to allow for mating to occur. The bags are punctured withsmall air holes, and the egg-laying status is checked 3–5 days later. Note that some pupae are in summer diapause, and the moths may
appear sluggishly.
r: Egg check
The first moths to emerge often produce non-diapause or unfertilized eggs; therefore, the eggs need to be checked.
Diapause eggs are used for the following year's rearing, and they should be treated in the same manner as B. mori. Diapause breakage
should be performed (cold treatment for about 3 months) according to the rearing time of the following year.

5European strains
Kyushu University also has some non-Japanese silkworm strains, including many European silkworm strains. We haveseven Spanish strains (S01, S02, S03, S04, S05, S06, and S13), two Italian strains (c42 and c44), and one French strain(u48). We introduce some of these strains here.

c44

u48

S01

c44: This Kyushu University strain produces the reddest-looking cocoons.
S01: This strain produces the deepest yellow cocoons, and the larvae and cocoons are larger.
u48: This strain originates from the Papillion noire in France and is a slightly darker moth.
1: OrderOrdering from the Silkworm base is simple. Silkworm strains andcharacteristics can be selected by viewing the photographs.
2: Material transfer agreement (MTA)
A contract must be signed before our resources can be used(silkworms, BmN cells, etc.). We also accept some commercial useagreements.
3: Invoice
An invoice will be generated once the shipping details and method
have been determined. This may take approximately a week to prepare.
4: Payment
The amount on the invoice in Japanese yen (JPY) should be paid.
Kindly note that you are responsible for any other external fees. Youcan pay by bank transfer or WISE.
5: Shipping
After confirming payment, we will ship the order. This takes
approximately one week, although the number of days varies
depending on the shipping area.

Overview of Distribution request

It takes approximately 4 weeks from order to arrival.
Please contact us at least one month before the date you wish to rear the silkworm.
Q＆AThe following is a list of frequently asked questions about distribution.
① Differences in shipping methods
We ship via EMS or FedEx. EMS has a shipping cost ofabout 3,150 yen (as of April 2024). If you are in an area witha hub airline, it will take approximately one week to arrive.
However, considerable delays occur during peak season.
FedEx has an indefinite shipping cost; however, it often
costs more than 10,000 yen. It arrives faster than EMS, andthe delivery days are more stable. Please indicate yourshipping preference when placing an order.

EMSFedEx

Place (JPY)

3,150

About 10,000

Shipping days

1~2weeks

3~10 days※Place and days vary depending on location and time of season② Two types of rates: academic and non-academic
Academic rates apply to educational and research
institutions when using the product for educational or
academic research purposes.

6③ More information on how to order
Ordering instructions and required documentation
are summarized in the Distribution request section of
our website.

When submitting a research article using
resources distributed by NBRP “silkworms,”
please clearly mention the use of NBRP
“silkworms” in your manuscript.

④ Invoice, payment, and shipping
Once the MTA has been signed and the shipping method is fixed, an invoice will be prepared. Please let us
know if you require an address or VAT number on the invoice. We can also generate separate shipping andresource invoices.
Payment Notes
1. Remittance fees are the client's responsibility.
2. Please make all payments in Japanese yen (JPY).
Shipping Notes
1. If you request delivery by FedEx, the shipment will be shipped pay-on-delivery.
2. Delivery is not possible during the summer (over 30°C) because the temperatures
are too high.
3. In areas where delivery takes longer, we only deliver during the winter.
4. Refunds and reshipments are not available if eggs hatch because of shipping problems.

⑤ How to rear B. mori
It is easier to rear B. mori than B. mandarina. For details on rearing B.
mori, kindly refer to previous publications(https://shigen.nig.ac.jp/silkwormbase/newsletter/No43_20190415.pdf).
In addition, we do not distribute mulberry and artificial diet overseas.
Please prepare the feed locally.
This QR code leads to information about how to rear B. mori. ⇒Japanese wild silkworm moths
Shinshu University, the sub-core facility of the NBRP “Silkworm,” maintains and distributes 6 wild silkworm species
including Samia cynthia pryeri Butler, Samia cynthia ricini Donovan, Antheraea yamamai Guérin-Méneville, Antheraea
pernyi Guérin-Méneville, Actias aliena Butler and Rhodinia fugax Butler.

7

Select the moth you are interested in and detailed information
about the moth will be displayed.

Note regarding the wild silkworm moth distribution request① Wild silkworm moths are difficult to rear, so the strains and number of individuals available for
distribution varies greatly.
② We are only shipping eggs due to the risk of insects escaping during shipping.
③ In some countries, we may not be able to ship to resource users.
④ Maximum care should be taken to prevent insects from escaping.

Introduction of providing silkworms resources●Kyushu University

Distribution
to request
Researchers
can inquire-Howby referencing
this table as a guide.

Strain nameStage

PeriodAntheraea
yamamaiegg(diapause)

Sep～nextJun～100eggs

larva

Jun～Sep～50 individualspupa

Jul～Oct～50 individuals

Adult

Aug～Oct～10 individuals

egg(non-diapause)

Apr～Aug～100eggs

Larva

Jun～Sep～50 individuals

pupa(diapause)

Sep～nextMay～50 individuals

Adult

May～Oct～10 individuals

egg(non-diapause)

yearround～1000eggs

larva

yearround～100 individuals

pupa(diapause)

yearround～100 individuals

Adult

yearround～10 individuals

For time-sensitive requests, please contact Kyushu University
directly.

D Introduction
Rearingscheduletoinsilkworm
2024th resources
Phase

Larval stage

Pupal stage1

May 10～Jun 1

Jun 2～Jun 102

Jul 2～Jul 24Jul 25～Aug 23

Aug 20～Sep 11

Sep 12～Sep 20

4

Oct 4～Oct 26

Oct 27～Nov
4日

5

Nov 22～Dec 14

Dec 15～Dec 23

6Jan 9～Jan 31

Feb 1～Feb
9日

Antheraea
pernyiSamia cynthia
ricini

We can provide DNA samples of B. mori and B.
mandarina.
Our institute maintains a DNA repository of B. morimutant strains (approximately 500) and B. mandarina
collected over 40 locations across Japan (Hokkaido toKagoshima). This resource offers researchers valuable
DNA material for studies where rearing live silkworms
is challenging or for investigations into geneticpolymorphisms within strains due to the individuallevel purification of DNA.

OfferAbout the newsletter "おかいこさま"
Silkworms have held a significant role in Japanese agriculture.
Traditionally, farmers meticulously raised silkworms, evenkeeping them in their home parlors, and bestowed upon them
the respectful title “Okaiko-sama（おかいこさま）” (“sama”
signifying respect). Silkworms hold a special place inJapanese culture. For generations, the Empress of Japan has
personally overseen the care of “Okaiko-sama” at the Imperial
Palace silkworm farm. This tradition underscores thesignificance of silkworms as a unique bioresource developedin Japan. In recognition of this heritage, we named ourinformation magazine dedicated to sharing recent
advancements in silkworm resources .
Newsletter “おかいこさま” Edited and published by●Shinshu University (Sub-core facility)
The Shinshu University sub-core facility curates acollection of saturniid species native to Japan,
including Rhodinia fugax, Actias aliena, Actias gnoma,
Saturnia janasii, Samia cynthia pryeri, and Aglia
japonica. For a complete species list, please visit ourwebsite.

The National Bio-Resource Project, Silkworm Resource Division,
Institute of Genetic Resources, Kyushu University Graduate School ofBioresources and Bioenvironmental Science, 744 Motooka, Nishi-ku,
Fukuoka 819-0395, Japan
Writer: Toshiaki Fujimoto

http://www.shigen.nig.ac.jp/wildmoth/index.jsp
Contact: Zenta Kajiura (zkajiur@shinshu-u.ac.jp)

E-mail: fujimoto.toshiaki.252@m.kyushu-u.ac.jp
Project leader: Tsuguru Fujii
Tel: +81-92-802-4821
E-mail: fujii.tsuguru.233@m.kyushu-u.ac.jp8