Influence of Repellency on the Efficacy of Blatticides. IV. Comparison of Four Cockroach Species

Abstract

Laboratory experiments were made to compare 4 domiciliary cockroach species, the German, Blattella germanica (L.); American, Periplaneta americana (L.); oriental, Blatta orientalis L.; and brown-banded, Supella supellectilium (Serville), in the influence of repellency on the efficacy of insecticides as determined by comparing the rate of mortality when the insects were continuously confined to the insecticides with the rate of mortality when they were able to avoid them. The descending order of repellency was Drione® (1% pyrethrins, 10% technical piperonyl butoxide, 38.12% amorphous silica aerogel, 1.88% ammonium fluosilicate, 49% petroleum base oil) > Baygon® ( o -isopropoxyphenyl methylcarbamate) > diazinon > chlordane> sodium fluoride > boric acid, which was also in the descending order of their toxicity to the cockroaches. When 3 species of cockroaches were tested for their relative susceptibility to 6 insecticides, 1% Baygon was the most effective against American and oriental cockroaches and second only to pyrethrins against the German cockroach in the continuous exposure test, in which the insects were confined with the residues. In choice-box tests 1% Baygon performed poorly against German and American cockroaches because of its high repellency, but it was strikingly superior to all other insecticides against the oriental cockroach. Even at 0.5%, Baygon is so toxic to the oriental cockroach that this relatively sluggish insect receives a fatal dose from initial contacts with the insecticide before being able to initiate evasive behavior. The special efficiency of Baygon in the control of oriental cockroaches, indicated by the choice-box tests, was confirmed in field tests against this species. Boric acid powder performed well in all field tests also against the oriental cockroach and was superior to 1% diazinon + 0.2% dichlorvos in base oil. At 136 g/manhole, Drione apparently killed all active stages of the American cockroach when the powder was blown into sewerage systems with sufficient force and air volume to penetrate through all laterals. The sewer lines are a closed system, and the experiment demonstrated the potential of a highly toxic insecticide when cockroaches are unable to escape from it. In a 4-story apartment building with 42 apartments, it appeared from circumstantial evidence that the entire building was infested, via the wall voids, from an apartment on the 3rd floor that was heavily infested with brown-banded cockroaches. The infestation was controlled with Drione. In other experiments boric acid was found to be effective in controlling brown-banded cockroaches.