TARGETING OVIPOSITION SITES AS A CONTROL STRATEGY FOR POPULATION REDUCTION IN PERIPLANETA FULIGINOSA (SERVILLE) (DICTYOPTERA: BLATTIDAE)

Abstract:
A focal point for pest management programs is often limiting the amount of insecticide to the minimum level while still maintaining the maximum benefit for population reduction. With that in mind we conducted a field study in 28 homes to evaluate the efficacy of applying insecticide to habitats identified as potential oviposition sites for the smokybrown cockroach, Periplaneta fuliginosa (Serville). We hypothesized that by targeting those sites we could significantly reduce the amount of insecticide applied while selectively reducing the number of reproductive females and newly eclosed nymphs in the population. The habitats were chosen based on laboratory generated data on oviposition site selection in the smokybrown cockroach in which, in decreasing order, peat, wall void and landscape marble chips were differentially preferred by females for deposition of oothecae. Three treatment strategies were evaluated and a control was included in the study. The treatments were exterior, interior/exterior, and interior/ exterior coupled with an insect growth regulator (IGR). The insecticides used were microencapsulated chlorpyrifos and fenoxycarb. Trapping was conducted at 1 week pretreatment, and 1,2,4,6,8,10, and 12 weeks post-treatment. There were no significant differences in population reduction for P. fuliginosa between the three treatments investigated, although all did vary significantly from the control. Mean numbers of cockroaches trapped from exterior, interior/exterior, and interior/exterior with IGR treatments were 13.1, 11.6, and 11.1. No smokybrown cockroaches were trapped inside the homes after treatment. Populations in untreated homes were, on the average, four times greater than in the treated homes. As one measure of the success of the control strategy we evaluated the percentage of the population for each treatment that were adult females. In the exterior, interior / exterior, and interior/exterior with IGR the percentages of the trapped population that were adult females were 19.2, 18.5, and 16.8% respectively. These percentages were all significantly less than the untreated control in which 29.7% of the population was female. These data indicate that insecticide applications to target oviposition sites for smokybrown cockroaches can significantly reduce populations while also reducing the amount of insecticide applied over a standard treatment program. We suggest that effective placement of insecticide to target reduction of reproductive females and eclosing nymphs in a population of smokybrown cockroaches is a successful pest management strategy.