Cost and efficacy comparison of integrated pest management strategies with monthly spray insecticide applications for German cockroach (Dictyoptera: Blattellidae) control in public housing

The long-term costs and efficacy of two treatment methodologies for German cockroach, Blattella germanica (L.), control were compared in the public housing environment. The "traditional" treatment for German cockroaches consisted of monthly baseboard and crack and crevice treatment (TBCC) by using spray and dust formulation insecticides. The integrated pest management treatment (IPM) involved initial vacuuming of apartments followed by monthly or quarterly applications of baits and insect growth regulator (IGR) devices. Cockroach populations in the IPM treatment were also monitored with sticky traps. Technician time and the amount of product applied were used to measure cost in both treatments. Twenty-four hour sticky trap catch was used as an indicator of treatment efficacy. The cost of the IPM treatment was found to be significantly greater than the traditional treatment, particularly at the initiation of the test. In the first month (clean-out), the average cost per apartment unit was $14.60, whereas the average cost of a TBCC unit was $2.75. In the second month of treatment, the average cost of IPM was still significantly greater than the TBCC cost. However, after month 4 the cost of the two treatments was no longer significantly different because many of the IPM apartments were moved to a quarterly treatment schedule. To evaluate the long-term costs of the two treatments over the entire year, technician time and product quantities were averaged over all units treated within the 12-mo test period (total 600 U per treatment). The average per unit cost of the IPM treatment was ($4.06). The average IPM cost was significantly greater than that of the TBCC treatment at $1.50 per unit. Although the TBCC was significantly less expensive than the IPM treatment, it was also less effective. Trap catch data indicated that the TBCC treatment had little, if any, effect on the cockroach populations over the course of the year. Cockroach populations in the TBCC treatment remained steady for the first 5 mo of the test and then had a threefold increase during the summer. Cockroach populations in the IPM treatment were significantly reduced from an average of 24.7 cockroaches per unit before treatment to an average 3.9 cockroaches per unit in month 4. The suppressed cockroach populations (<5 per unit) in the IPM treatment remained constant for the remaining 8 mo of the test.