CHAPTER VII 

 SEX DETERMINATION 



Genetic research with the wasp Habrobracon 

 juglandis was begun at the University of Penn- 

 sylvania in 1916 by P. W. Whiting. Many phases 

 of this work have been developed since that 

 time but the central problem has always been 

 that of sex determination. 



In 1845 Dzierzon put forth the theory that 

 in the honey bee, drones (males) develop from 

 unfertilized eggs while workers and queens (fe- 

 males) come from fertilized eggs. This theory 

 was based on the fact that unmated and old queens 

 produce drone broods and that race-crossing re- 

 sults in drones like the maternal race while 

 the daughters are hybrid. Dzierzon (1854) stat- 

 ed that the drones of the second generation 

 from a cross resemble either the paternal or 

 the maternal race and that thcce two types oc- 

 cur in equal numbers. He, therefore, glimpsed 

 the fundamental gametic ratio twelve years be- 

 fore Mendel published his paper on peas. Dzier- 

 zon's Law applies to other insects of the order 

 Hymenoptera, including wasps, ants, ichneumon- 

 flies, chalcis-f lies, and saw-flies, but many 

 exceptions occur. P. W. Whiting (1918) working 

 v/ith the ichneumonoid wasp, Habrobracon, found 

 that in this form also haploid males are pro- 



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