Abstract
The genetics of dieldrin-resistance in the German cockroach, Blattella germanica, were studied by exposing a batch of larvae (from a single female) to dieldrin and observing percentage knockdown at various intervals. Hybrids of Denken (susceptible) and Isago (resistant) colonies were intermediate in resistance as compared to both parents. In the progeny of F_2 (by mass mating) the segregation into three types, i. e. resistant, intermediate and susceptible individuals, occured in the ration 1 : 2 : 1. In the progeny of back-crosses with F_1 (hybrids) and P (susceptible or resistant), the ratio of susceptible and resistant individuals was 1 : 1. It is therefore concluded that dieldrin-resistance in the German cockroach is mono-factorial with partial dominance. The separation and establishment of pure dieldrin-resistant and -susceptible colonies from a mixed Kanda colony was successfully achieved by making use of discriminating dosages.
