Possible genetic basis of pederin polymorphism in rove beetles (Paederus riparius)

In Paederus riparius, (+) females able to biosynthesize the unique hemolymph toxin pederin and (-) females lacking this ability co-occur in natural populations. Larvae descended from both types of females were reared in the laboratory and the imagoes were crossed in order to get information about a possible genetic basis of this polymorphism. The daughters of (+) mothers become (+) females or (-) females, while the progeny of (-) mothers comprises only (-) females. This suggests a matrilineal trait because pederin biosynthesis cannot be inherited from the father. The rather stable proportion of nearly 90% (+) females in collected females is not maintained, however, when the beetles are reared in the laboratory. This observation is discussed with regard to artificial rearing conditions, where individuals are kept separate and cannot prey on conspecifics.