A Comparision of Reproduction and Longevity in Pyrethroid-Resistant and Susceptible German Cockroach (Blattodea: Blattellidae) Field-Collected Strains

Abstract

Life histories of five field-collected strains of the German cockroach, Blattella germanica, were studied. Three were highly resistant to pyrethrins and allethrin; two were susceptible. Life history parameters of the susceptible strains and one of the resistant strains were closely similar. Two of the three resistant strains differed from the susceptible strains and from the third resistant strain. Differences from the latter strains included a longer interval between hatch of successive egg cases, fewer viable (hatched) egg cases per female, a more uneven pattern of maturation among nymphs from individual oothecae (egg cases), fewer adult progeny per egg case, and lower total numbers of adult progeny per life span of females. No significant difference occurred between the two resistant strains in any of the foregoing characteristics.