GENETICS OF ALPHA-AMYLASE IN SITOPHILUS-ORYZAE (L) (COLEOPTERA, CURCULIONIDAE)

Crossing experiments with geographic strains of Sitophilus oryzae (L.) that differ in α-amylase isozyme composition were used to determine the gene system for coding these enzymes in this species. Savannah strain is monomorphic and has two isozymes designated RW-1 and RW-2. Japan and Tanzania-90 strains are also monomorphic but both lack RW-1. All F1 progeny of reciprocal crosses of Savannah with either Japan or Tanzania-90 have both isozymes. Two phenotypes were found in F2 progeny from mass F1 self crosses. Depending on the cross, there is a 3:1 ratio of Savannah phenotype (RW-1 + RW-2) to either the Japan or Tanzania-90 phenotype (RW-2). Overall results suggest that two structural genes control synthesis of the two amylase isozymes in this weevil. The gene RW-2 (hereafter referred to as Amy-2) is found in all three strains whereas the gene RW-1 (hereafter referred to as Amy-1) has an active allele (Amy-1A) expressed in Savannah and a null allel (Amy-10) in Japan and Tanzania-90. © 1990.