The insecticidal activities of 13 Lamiaceae plant oils and their components against adult German cockroaches, Blattella germanica L. (Blattodea: Blattellidae), were evaluated using fumigant and contact bioassay. Among the tested oils, basil, pennyroyal, and spearmint showed the strongest insecticidal activities against adult B. germanica. Insecticidal activity of pennyroyal was 100% against male B. germinica at 1.25 mg concentration in fumigant bioassay. Basil and spearmint revealed 100% and 100% insecticidal activity against male B. germinica at 5 mg concentration, but their activities reduced to 80% and 25% at 2.5 mg concentration, respectively. In contact toxicity bioassy, basil, pennyroyal, and spearmint oils exhibited 100%, 100%, and 98% mortality against female B. germanica at 1 mg/♀, respectively. Among the constituents identified in basil, pennyroyal and spearmint oils, insecticidal activity of pulegone was the strongest against male and female B. germanica.

Twelve Lamiaceae plant essential oils (EOs) and their components were evaluated for their fumigant and contact toxicities. Inhibition of AChE by the major components of active EOs was also assessed. Strong fumigant toxicity was observed from EOs of Mentha piperita and Perilla frutescens. Menthone and menthol, and perilla aldehyde were identified as major components of the above two EOs, respectively. The LC50 (mg/L) values of M. piperita, P. frutescens, menthone, menthol and perilla aldehyde were 3.87, 2.44, 5.76, 1.88, and 0.99 against male, and 4.10, 3.31, 5.13, 1.94, and 1.15 against female, respectively. Strong contact toxicity was observed from the EOs of Satureja montana and Thymus zygis. Thymol and carvacrol were major components of these two EOs. The LD50 (μg/fly) values for contact toxicity of S. montana, T. zygis, thymol and carvacrol were 2.95, 2.93, 1.63, and 1.30 for male, and 4.59, 5.09, 2.68, and 2.60 for female, respectively. Among the five major components, perilla aldehyde showed most active inhibition activity against AChE of both sexes of SWD.

We observed the pollen grains and fruits of six Isodon taxa distributed in Korea using a light microscope and a scanning electron microscope. The muri thickness on the surface of the pollen grains distinguishes Isodon serra from other taxa: the thickness of I. serra is ca. 0.6 μm, while the thicknesses of other taxa are 0.37~0.49 μm. I. inflexus var. canescens has a relatively nutlet small (about 0.93×0.83 mm) compared to other Korean Isodon taxa (about 1.15~1.37×1.02~1.17 mm). Characteristically, a nutlet of I. inflexus var. microphyllus has non-glandular hairs distributed all over its surface. However, I. serra has non-glandular hairs distributed only on the top of the nutlet while it has glandular hairs broadly distributed over the entire nutlet. We suggested that these characters of the pollen and fruit surfaces can be included in the key to Korean Isodon as diagnostic characters to distinguish the above taxa from other Korean taxa.

The taxonomy of the Isodon excisus complex, which comprises I. inflexus var. inflexus, var. transiticus, var. macrophyllus, var. microphyllus, and var. canescens, has been ambiguous and problematic because their morphological characters are variable. To elucidate the taxonomic structure of the I. inflexus complex in Korea, 42 characters were measured from 70 OTUs representing the I. inflexus complex and were analyzed by a principle component analysis (PCA). The principle component axes 1, 2, and 3 (PC1, PC2, and PC3) represents 55.7% of the total variance. The characters showing high loading values for PC1, which have of absolute loading values higher than 0.7, were characters related to the leaf base and leaf teeth and the length of corolla tube. The length of the broadest part to the apex in the leaf, the density of non-glandular hairs on the lower surface of the leaf, and the length and width of the calyx were highly related to PC2 with the absolute loading values higher than 0.7. PC3 does not have any characters which have absolute loading values higher than 0.5. Three-dimensional scatter plots of the OTUs for the PC1, PC2, and PC3 axes showed that there are three taxa in the complex. Each area of I. inflexus var. inflexus, var. transiticus, and var. macrophyllus was completely overlapped, demonstrating that this taxon is I. inflexus var. inflexus. Areas for var. microphyllus and var. canescens were separated from that of var. inflexus in both cases. Therefore, we recognized three varieties, which are I. inflexus var. inflexus, var. microphyllus and var. canescens in the I. inflexus complex in Korea. This result also indicates that I. inflexus var. inflexus has a wide range of morphological variation. The recognition of var. microphyllus and var. canescens is also supported by the result of recent SEM studies of the fruit surfaces of Korean Isodon.

Agastache rugosa, a member of the mint family (Labiatae), is a perennial herb widely distributed in East Asian countries. It is used in traditional medicine for the treatment of cholera, vomiting, and miasma. This study assessed the genetic diversity and population structures on 65 accessions of Korean mint A. rugosa germplasm based on inter simple sequence repeat (ISSR) markers. The selected nine ISSR primers produced reproducible polymorphic banding patterns. In total, 126 bands were scored; 119 (94.4%) were polymorphic. The number of bands generated per primer varied from 7 to 18. A minimum of seven bands was generated by primer 874, while a maximum of 18 bands was generated by the primer 844. Six primers (815, 826, 835, 844, 868, and 874) generated 100% polymorphic bands. This was supported by other parameters such as total gene diversity (HT) values, which ranged from 0.112 to 0.330 with a mean of 0.218. The effective number of alleles (NE) ranged from 1.174 to 1.486 with a mean value of 1.351. Nei's genetic diversity (H) mean value was 0.218, and Shannon's information index (I) mean value was 0.343. The high values for total gene diversity, effective number of alleles, Nei's genetic diversity, and Shannon's information index indicated substantial variations within the population. Cluster analysis showed characteristic grouping, which is not in accordance with their geographical affiliation. The implications of the results of this study in developing a strategy for the conservation and breeding of A. rugosa and other medicinal plant germplasm are discussed.