COMPARISONS BETWEEN THE RESPONSE OF GERMAN-COCKROACH FIELD-COLLECTED STRAINS (DICTYOPTERA, BLATTELLIDAE) TO VAPORS AND CONTACT WITH A CYFLUTHRIN FORMULATION

Research on differences in insecticide-induced behavior of German cockroach field-collected strains was continued. Late instar nymphs (5th-6th stadia) were drawn from the Fairbanks, an insecticide susceptible strain, and two pyrethroid resistant strains, the Jacksonville and Forest Green. Dispersal induced by vapors of a cyfluthrin flowable concentrate (FC) and the FC formulation base (blank) was compared with response to the FC and the FC blank when dry. Jacksonville nymphs avoided the dried FC, but not as strongly as Fairbanks strain nymphs. The AI played a major role in eliciting avoidance by Fairbanks strain nymphs but, in the Jacksonville strain, avoidance was due more to an ingredient(s) of the formulation base. Forest Green nymphs did not avoid the dried FC or the FC blank. Vapors of the FC and the FC blank caused rapid dispersal of all strains, but dispersal of resistant strain nymphs was slower than that of susceptible strain nymphs. Although Jacksonville nymphs responded more strongly to the dried formulation than Forest Green nymphs, the response to vapors was weaker than that of Forest Green nymphs. It is suggested that localized populations of the German cockroach have developed many different combinations of behavioral modifications and physiological/biochemical resistance.