2.3.3. Microinjection of small volumes using the Nanoject device and other micro injectors
For very small injection volumes (<1 µl), the Nanoject injector (Drummond) can be used. It consists of a microinjection pipette with an automated microprocessor that can precisely inject a set volume. The injection tips are made from glass capillaries. This automated injection method eliminates vibration and thus minimizes tissue injury. It may therefore reduce deleterious effects on honey bees, compared to manual injections. The second advantage over manual injections is the high precision of the injector that will eliminate variations in injection volumes. The Nanoject injector has been successfully used on insects (e.g. Teixeira et al., 2008; Yamane and Miyatake, 2010). Furthermore, embryonic injections have been performed using a microscope with a micromanipulator and a microinjector (Narishige) with glass capillary (Sasaki and Ishikawa, 2000). Beye et al. (2002) injected honey bee eggs under a microscope using an Oxford micromanipulator (Singer) and a microinjector with borosilicate capillaries. Lozano et al. (2001) injected adult honey bee workers using a custom-made microinjection system consisting of a glass micropipette mounted on a microelectrode puller (Campden Instruments).
- Prior to injection, adult individuals should be
anaesthetised (see section 2.1).
Anaesthesia with CO2 is not recommended, given known CO2 driven physiological and behavioural modifications in honey bees (Ebadi et al., 1980; Koywiwattrakul et al., 2005).
- Immobilise the individual to be injected
This can be done by physical means (see section 2.2.1.) or by chilling them (section 2.2.2). Anaesthesia with CO2 is not recommended, given known CO2 driven
physiological and behavioural modifications in honey bees (Ebadi et al., 1980;
Koywiwattrakul et al., 2005).
- Inject the individual. The method of injection will depend on the device used (for methods see references in the introduction of this section).