4.15. Evaluation of rearing success
The control mortality for evaluation of rearing success was already discussed (see 5.13. Control mortality). Researchers also measured physiological parameters such as body weight, body size, ovary development and flight performance to evaluate rearing methods. A comparison with sisters naturally reared in a colony provides information about the quality of the artificial diet and rearing condition. This comparison reveals that larvae reared in the laboratory are close to those reared in a colony. They have slightly reduced wing areas and thorax dry weights, but reach the age of foragers when introduced into a colony and engage in long persisting flights similar to those of naturally reared control bees (Brodschneider et al., 2009).
Another problem is the predictable production of individuals unambiguously belonging to the worker caste, which might be necessary for certain scientific questions. Early attempts to rear worker larvae in the laboratory frequently resulted in inter-castes (Rhein, 1933; Weaver, 1974; Rembold et al., 1974; Rembold and Lackner, 1981; Shuel and Dixon, 1986). Therefore, and also because larval nutrition affects ovary development (Hoover et al., 2006), the developmental stages of ovaries and number of ovarioles of laboratory-reared honey bees have been investigated (Weaver, 1955; Mitsui et al., 1964; Kaftanoglu et al., 2010). Also other characteristics such as developmental time, tongue length, spermatheca, chaetotaxy of metathoric legs, sting lancet, mandibular notch, weight at adult emergence and juvenile hormone titer are used for differentiation (Weaver, 1974; Asencot and Lensky, 1976, 1984; Shuel and Dixon, 1986; Kucharski et al., 2008; Kamakura, 2011).