AN APTEROUS MUTATION IN BRUCIIUS* 



J. K. BREITENBECHER, 

 MARINE BIOLOGICAL LABORATORY, WOODS HOLE, MASS. 



There appeared in my cultures of Bruchus qnadrimaculatus 

 Fabr., the "four-spotted cowpea-weevil," a mutation entirely 

 void of wings. It was discovered at Cold Spring Harbor on 

 August 5, 1918, in seven females. The wild stocks from which 

 these wingless females emerged had passed through twenty- 

 five generations of selective breeding. This mutation could have 

 only come from a single pair. The culture was obtained from 

 Raleigh, North Carolina, on January 18, 1916, and had been 

 examined daily for various mutations. It is known therefore that 

 at no previous time had any such apterous beetles appeared. 

 During the eight years of breeding this insect no more such 

 mutations have been observed among the thousands of weevils 

 examined. The appearance of this Bruchid's wings is not unlike 

 that described by Metz ('14) for apterous Drosophila. Even 

 though the cultures of this apterous insect died out, due possibly 

 to some genital defect, there are some genetic interpretations of 

 value which may be made. 



This apterous beetle was first discovered in seven females 

 which made their appearance during two days from one wild 

 culture bottle. Because they were the first mutants observed in 

 such great numbers, they were at first thought considered 

 abnormalities or freaks rather than mutations. But when they 

 again emerged in the F 2 from apterous females mated with wild 

 males from another North Carolina culture, it was evident that 

 this trait was a recessive one. 



Concerning the origin of mutations in Drosophila Lancefield 

 ('18) states that if a mutation occurred in the early oogonial 

 stages several with the new gene should appear. This answers 

 the question why several of the mutants could have been revealed. 

 The fact that they were all of one sex might add evidence to such 



1 Contribution from the Zoological Laboratory of the University of Oklahoma, 

 Second Series, No. 46. 



1 66 



