The Turkestan cockroach, Blatta lateralis (Walker), has become the most important peridomestic species in urban areas of the Southwestern United States. The aim of this study was to evaluate the use of botanical compounds to control this urban pest. We tested the acute toxicity and repellency of six botanical constituents and three essential oils on Turkestan cockroach nymphs. Chemical composition of the essential oils was also determined. Topical and fumigant assays with nymphs showed that thymol was the most toxic essential oil constituent, with a LD50 of 0.34 mg/nymph and a LC50 of 27.6 mg/liter air, respectively. Contact toxicity was also observed in assays with trans-Cinnamaldehyde, eugenol, geraniol, methyl eugenol, and p-Cymene. Methyl eugenol and geraniol had limited fumigant toxicity. The essential oils from red thyme, clove bud, and Java citronella exhibited toxicity against nymphs. Cockroaches avoided fresh dry residues of thymol and essential oils. Chemical analysis of the essential oils confirmed high contents of effective essential oil constituents. Our results demonstrated that essential oils and some of their constituents have potential as eco-friendly insecticides for the management of Turkestan cockroaches.

A full-wave analysis of infinite periodic grid structures loaded with active devices is presented. The grid consists of arbitrary periodic metal patterns printed on one or both sides of a dielectric slab in free space. Since the structure is periodic, under equi-phase conditions it is sufMent to analyze a single unit cell. An expression is derived relating the radiated electric field to the surface current density on the metal, which is determined by the method of moments. The driving-point impedances are found for any active devices embedded in the grid structure. Using this analysis, the metal geometry can be optimized for designing active quasi-optical power-combining grids for the microwave and millimeter-wave regions.

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Numerical results for interacting single-patch and meander-slot antennas, as well as finite arrays of U-strip, U-slot, and meander slot antennas, show significant advantages in scattering characteristics in comparison to rectangular patch and slot antennas traditionally used for spatial power-combining applications. The results presented also exhibit the effect of several antenna design parameters on the frequency bandwidth and operating frequency of the system.