4.1. Maintenance of drones for instrumental insemination
Producing a large number of mature drones from select sources can be more challenging then queen rearing, especially if seasonal conditions are not optimal. Drones have a high rate of attrition and drift heavily among colonies. Free flying drones have better survival and have a prior opportunity to void faeces.
- Use strong, healthy, well-fed colonies for drone
a. Colonies headed by older queens tend to rear and maintain more drones.
b. Minimize colony stressors, especially exposure to pathogens, parasites and chemical residues (see the BEEBOOK papers on pests and diseases: Dietemann et al., 2013; Forsgren et al., 2013; Fries et al., 2013; de Graaf et al., 2013; Jensen et al., 2013; de Miranda et al., 2013; Sammataro et al., 2013).
- Drones require 12 -14 days post-emergence to sexually mature (Woyke and Jasinski, 1978).
- Maintain the identity of drone sources.
a. For free-flying drones, newly emerged drones can be emerged from field-collected combs placed in an incubator set at broodnest conditions (34°C, ~50% RH), marked, and returned to colonies to reach sexual maturity. Mark several times the number needed to ensure an adequate supply.
b. To confine drones, emerge drone brood above a queen excluder in a healthy, strong colony. Screening the top box (i.e. replacing the colony lid with screen mesh) may be used to collect the drones as mature drones are attracted to light.
- Collect drones in holding cages made of queen
excluder material (Fig. 4).
a. Drone flight times vary with the season and weather conditions. Watch the colonies in the local area to determine drone flight time.
b. Caged drones can be banked in queenless nursery colonies or queen cell builders (see Büchler et al., 2013 for more information on queen cell builders).
i. Minimize banking time as drones are perishable, overnight to a few days.
ii. Banked drones accumulate faeces that need to be voided.
- Release mature drones into a flight box for semen
collection (Fig. 4).
a. Bring in only the number of drones that can be collected in about 30-40 minutes (100 to 150), as inactive drones are difficult to evert.
b. Providing heat (a light above the flight box) and food (bee candy) will extend the active period of drones.