Frequently Asked Questions

General information about the VDRC RNAi lines

GD lines can be on chromosome 1, 2 or 3. All KK lines are on chromosome 2. All lines on chromosomes 2 or 3 are balanced. Lines either homozygous lethal or sterile are kept over the balancers (CyO for the 2nd chromosome; TM3, Sb for the 3rd chromosome). Stocks that are viable have been made homozygous.

Sterile lines are kept over the balancers. In these stocks there are both homozygous (these flies are sterile) and heterozygous flies for the UAS-IR insertion (over the CyO or TM3). For your RNAi experiments please use flies over the balancers and screen the progeny against the balancer.

Lethal lines are kept over the balancers. In these lines all the flies are either over the CyO or TM3,Sb balancer depending on the insertion chromosome. In these stocks homozygous flies (no balancer) survive rarely.

Insertions on the 1st chromosome are not balanced, and we keep these strains by crossing the RNAi males to X-compound virgins. In this case only the males have red eyes, never the females. Since these virgins (C(1)DX / winscy, hs-hid) are rather weak, we suggest adding fresh virgins every time you flip the RNAi stock on fresh food to ensure survival of the line. Or even better, balance the line with the 1st chromosome balancer. You can get a stock of (C(1)DX / winscy, hs-hid) in the RNAi Toolkit Stocks section (Stock Number 60006).

The red eye color - marks the successful insertion of the UAS-IR in the genome. As long as you do not find a fly with white eyes, you can be sure that there is no contamination in the stock. The eye color can vary from dark red to very light red. The eye color can vary even within the same stock.

All the UAS-IR insertion sites for the GD library are mapped only to the chromosome (1, 2 or 3). We do not have data on specific location on the chromosome.

The phenotype (viable, lethal, sterile) referred to in our database for every line, is due to the insertion site of the UAS-IR, not due the induction with the Gal4.

RNAi Lines And Other Stocks

  1. Q: How many different RNAi lines do you have in your library?
    A: As of Jan 2017 the library comprises 16,763 transgenic Drosophila strains of the P-Element RNAi library (GD), 9,822 lines of the phiC31 (KK) RNAi library and 372 of the shRNA library, which together target 12,671 genes, or 91% of the Drosophila melanogaster protein-coding genome.
  2. Q: What flies should we use as a control for the RNAi lines?
    A: For the GD library, you should use the isogenic host strain w1118, which we injected the library into (VDRC ID 60000). For the KK library, the best control is the host line y,w[1118];P{attP,y[+],w[3`]} (VDRC ID 60100). For the shRNA library use the host strain (VDRC ID 60200) containing an empty pWALIUM20 vector (no hairpin sequence) integrated into the attP40 landing site, created in the same way and with same gene genetic background as the shRNA lines. You can find these lines in our library under 'Browse RNAi Toolkit Stocks'. Alternatively, we suggest using a VDRC RNAi line which is known NOT to function in the process or pathway being studied.
  3. Q: Does the viability phenotype you describe in your data refer to the phenotype due to the insertion site or induction with the Gal4?
    A: We refer to the phenotype due to the insertion site on the chromosome.
  4. Q: What are the ’RNAi Toolkit Stocks’?
    A: These are the stocks which have been used for creation of the GD, KK and shRNA libraries and also lines which are helpful for triggering RNAi and increasing its efficiency e.g. dicer2.
  5. Q: Can we get dicer2 flies from you?
    A: Yes, you can find them by clicking the ’Browse RNAi Toolkit Stocks’ button on our main page. Since January, 2008 you can also obtain these stocks from the Bloomington Drosophila Stock Center.
  6. Q: There are some interesting stocks which are marked as ’temporarily unavailable’ in your library. When will they be available again?
    A: Temporarily unavailable stocks are probably sick and being treated in hospital. Usually it takes 3-5 weeks until we can release them back and are ready to be ordered.
  7. Q: Only males of the lines I have received have red eyes. Females have white eyes and singed phenotype. After 3 generations I have not seen red eyed females?
    A: Your GD lines are insertions on the X chromosome. These lines are not balanced and we keep them by crossing the RNAi males to the X compound virgins.
  8. Q: Some numbers of the RNAi lines have disappeared from the original list. Are they lost?
    A: Some lines have been intentionally culled to streamline the collection, and a few have been lost over time due to the stock being too sick. The DNA construct is usually available for re-injection.
  9. Q: How can I donate/provide stocks to VDRC?
    A: Please contact us:
  10. Q: My Tagged FlyFos TransgeneOme (fTRG) lines have white eyes. Is this correct?
    A: Yes. The transgenes carry the 3xP3-dsred marker (Ejsmont et al., 2009). This is an eyeless derived promoter fragment resulting in dsRed expression in the developing eye and in the brain. This needs to be taken into account when working with the developing or adult brain. The eyes should appear white under the light microscope but red under fluorescence.

Fly Extract

  1. Q: Do I have to register and have a VDRC login to order Fly Extract?
    A: No, our MTA relates to transgenic flies and DNA constructs, so this is not necessary to have a VDRC login and sign our MTA for ordering Fly Extract. However, you must fill out the ‘VDRC Fly Extract order form’ each time you place an order.
  2. Q: My institute cannot receive items on dry ice. Is it possible to send Fly Extract another way?
    A: Fly Extract can only be sent on dry ice to ensure it is in a frozen condition when it arrives.
  3. Q: Can I combine fly stocks and Fly Extract in a single order/shipment?
    A: Due to the different temperature and legal documentation requirements, orders of fly stocks/DNA constructs and Fly Extract will be treated as completely independent orders and cannot be sent in a combined shipment.
  4. Q: Can I pay for Fly Extract by credit card or cheque?
    A: You should pay the invoice upon receipt by wire transfer. It is not possible to pay the invoice by credit card or by cheque.


  1. Q: How long does it take to get the lines?
    A: The time taken to dispatch your order will depend on the size of the order. Orders with 300 items or less will be prioritized and dispatched within 2 weeks. For orders with a total of more than 300 items it may take up to 6 weeks for your order to be dispatched. Orders with more than 150 lines will be split and delivered in two or more shipments.
  2. Q: I would like to order 30 items (RNAi lines/other stocks/DNA). What are the transport costs by express courier?
    A: E.g. The shipment fees for 30-40 lines to the USA would be around € 60-70. Please contact your local delivery service for detailed information about shipping costs and see the link on VDRC website.
  3. Q: My order has 300 items or less and but was not dispatched within the stated 2 weeks. Will I be refunded?
    A: You will be refunded 50% of the total cost of your order to compensate for the slow delivery. You will be notified by email and your credit card will be refunded automatically.
  4. Q: My order contains more than 300 items. Why does it take up to 6 weeks to be dispatched?
    A: Smaller orders are charged a premium for dispatch within 2 weeks and are therefore prioritized. Larger orders will be completed after smaller orders have been dispatched and we are therefore unable to guarantee such a fast turnaround time.
  5. Q: How long does the shipment take once dispatched?
    A: In Europe the package is delivered within 2 working days. Shipments outside of Europe usually take few days longer e.g. Japan 2-3 days, USA/Australia up to one week.
  6. Q: Lines died during the shipment. Can you resend them?
    A: If you notify us within one week we will resend the lines but you will have to pay the shipping costs.
  7. Q: Do I need an import permit to get lines?
    A: Some countries (e.g. Australia, China) require a valid permit for importing transgenic Drosophila.
    In the USA, you need a “Letter of No Permit Required”.
    Please check the following link for detailed information:

    If you are located in Australia, please apply at the AQUIS (Australian Quarantine and Inspection Service) for an import license and send a copy of the confirmed permission to us.

    For importing lines into China, we need a permission for which you can apply for at the ’Bureau of Animal and Plant Health Inspection and Quarantine’ and a valid CR Number ’Customs Registration Number’.

    Some other countries may also require permissions for importing transgenic Drosophila. Please check your local importing terms. Please double-check the validation of the import permission. The VDRC will not replace lines which have been refused at the customs because of missing or expired importing documents.
  8. Q: Why do you use only DHL/FedEx and not postal service?
    A: We have a long and good experience with these courier services and also most of the researchers have their own accounts set up with them.
  9. Q: Can you send me the DHL/FedEx Tracking Number?
    A: After we shipped the flies we will send you the tracking number by e-mail.
  10. Q: Is it possible for the VDRC to supervise the shipment?
    A: No, VDRC will provide you with an e-mail notification and the tracking number of the package the day the lines are shipped, but we cannot phone the customs, USDA or change the shipping address after the package has been sent off.
  11. Q: Is it possible to combine several orders in one shipment?
    A: Please enquire:


  1. Q: How long does it take to approve my account?
    A: It takes around 2 working days upon arrival of your signed MTA.
  2. Q: I have created a VDRC account a while ago and sent the MTA form. My account is still not active. Why?
    A: It could be due to the following reasons: (1) MTA did not arrive. (2) The signatures are not valid. The MTA needs to be signed by a legal representative from your institution. (3) You forgot to write the VDRC user name on the MTA and we cannot identify you.
  3. Q: I placed an order yesterday and forgot to order a few lines. Can I add these lines to the existing order or should I place a second order?
    A: Unfortunately we cannot modify an existing order. Within 24h you can cancel the order with full refund and place another order with additional (or fewer) lines.
  4. Q: Can I replace some RNAi lines which are still pending with other ones?
    A: Unfortunately we cannot modify an existing order.
  5. Q: Is there a way to order the lines and save the content of the shopping cart?
    A: Our website does not offer a shopping cart management, but we recommend storing the Transformant ID of the desired lines in a list and to upload the list at a later date.
  6. Q: Can we order DNA constructs?
    A: Yes, since October 2010 it is possible to order the DNA constructs which we used to create our GD library.
  7. Q: Is it possible for VDRC to place an order for me?
    A: Sorry, but we cannot place an order for you. You have to do it yourself using the VDRC website.
  8. Q: Can I come and pick up the lines directly at the VDRC?
    A: Yes of course. After placing the order, please send us an email to notify us. As soon as your order is ready to ship, we will contact you and make an appointment for picking up the lines.
  9. Q: Can I perform my screen on-site at the VDRC?
    A: We have a limited capacity for researchers to perform their screens using VDRC lines on-site. Please send an email to to enquire.
  10. Q: I received my order and the fly food in some of the vials is moldy. What can I do to get rid of the mold?
    A: Just put the flies on fly food with NIPAGIN (15% sol, 12ml per 1l liquid fly food) added. This ensures that the next generation of flies is totally free of mold and does not contaminate your stocks.


  1. Q: Can we get a discount price if we order many lines?
    A: Our price system is very attractive for large orders. Please see our payment conditions.
  2. Q: My credit card is valid but was rejected during the payment process. Why?
    A: For security reasons we have no possibility to get detailed information about user transactions from financial institutes. Therefore we recommend you to try again later and if it does not work to check with your bank.
  3. Q: During the payment with my credit card the system asks for a password. What password?
    A: Your credit card is activated with the ’Verified by Visa’ service which improves the security of online payment transactions. Therefore you need a password to verify your credit card transactions. Please contact your bank.
  4. Q: What is a VAT Number in the registration form?
    A: The Value Added Tax, or VAT, in the European Union is a general, broadly based consumption tax assessed on the value added to goods and services. Every European Institution needs a VAT number for tax purposes.
  5. Q: I did not receive all ordered items and my credit card was already charged. Will I get a refund?
    A: Yes of course, you will get full refund for all the items we could not deliver. You will be notified and your credit card will be automatically refunded.
  6. Q: Can I pay for orders of more than 300 lines by credit card?
    A: Sorry, payment for orders of more than 300 lines is only possible with a Purchase Order code by wire transfer.
  7. Q: I do not have the invoice/credit note for one of my orders anymore. Can you resend it
    For your convenience, you can download the invoice/credit note in your account. Please follow these steps:

    1. Login with your username / password.
    2. Click on the arrow next to your name on the top right and select My Account.
    3. Select My Orders in the menu to the left and you will get a list of your orders.
    4. Click on the 'View Order' button to display an order.
    5. Select the Invoices tab and then click on Print Invoice to download the invoice.