Differences between a Resistant and a Non-Resistant Strain of the German Cockroach

Abstract

Comparisons were made between a chlordan-resistant strain of the German cockroach, Blattella germanica, from Texas and a non-resistant strain. The resistant strain was found to be highly resistant to chlordan (> 100 times), moderately resistant to lindane (>3.8 times), and only slightly resistant to tetraethyl pyrophosphate (>1.2 times). Fewer nymphs per female and fewer nymphs per egg case were produced in the resistant strain than in the non-resistant strain. The empty egg cases produced in the resistant strain were smaller in both length and width than those produced in the non-resistant strain. The weights of male and female roaches in the resistant strain were less than those of the corresponding sex in the non-resistant strain. All of these differences were significant.