Two new species of egg parasitoids, Oobius saimaensis Yao and Mottern new species and Oobius fleischeri Yao and Duan new species (Hymenoptera: Encyrtidae), are described from eggs of Agrilus fleischeri Obenberger, 1925 (Coleoptera: Buprestidae). Agrilus fleischeri is a phloem-feeding woodborer of poplar (Populus Linnaeus; Salicaceae) in northeastern China. These two species can be distinguished morphologically as O. fleischeri has five tarsomeres and O. saimaensis has four tarsomeres. Although O. saimaensis is morphologically similar to its sympatric congener O. agrili Zhang and Hang, 2005, an important natural enemy of the invasive emerald ash borer, Agrilus planipennis Fairmaire, 1888, molecular phylogenetics and morphological data indicate that they are distinct species. Phylogenetic relationships among the new species and other closely related species are also inferred by using DNA sequence data from several ribosomal and mitochondrial genes. In addition, we expand the known distribution of Oobius primorskyensis Yao and Duan, 2016 to include South Korea.

Studies of insect host-parasitoid relationships are often confounded by the difficulties associated with species delimitation in taxonomically challenging groups. Eurytomidae (Hymenoptera) are common parasitoids associated with galls induced by Cynipidae (Hymenoptera) and are difficult to identify due to their small size, morphological conservatism, and unreliable published host records. This study tests the species limits of eurytomids associated with galls induced by Diplolepis Geoffroy (Hymenoptera: Cynipidae) in Canada using an integrative taxonomy approach including adult morphology, the mitochondrial gene cytochrome c oxidase I, host records, and geographical range. Incongruences between morphological and molecular data were found within the Eurytoma discordans Bugbee complex, as Eurytoma discordans, Eurytoma acuta Bugbee, and Eurytoma calcarea Bugbee were shown to be new synonyms. The results also revealed the presence of cryptic species within Eurytoma spongiosa Bugbee. Furthermore, issues that have impeded ecological and biological studies of eurytomids associated with rose galls such as host specificity and sex association were resolved using DNA barcodes, providing new insights into the evolutionary history of this difficult group.

A new theta geometry was developed for microscale bending strength measurements. This new “gap” theta specimen was a modification of the arch theta specimen that enabled microscale tensile testing. The gap theta specimen was demonstrated here on single-crystal silicon, microfabricated using two different etch processes. The resulting sample strengths were described by three-parameter Weibull distributions derived from parameters determined using established arch theta strengths, assuming a specimen-geometry and -size invariant flaw distribution and an approximate loading configuration.

Single-crystal silicon test specimens, fabricated by lithography and deep reactive ion etching (DRIE), were used to measure microscale deformation and fracture properties. The mechanical properties of two specimen geometries, both in the form of a Greek letter Θ (theta), were measured using an instrumented indentation system. The DRIE process generated two different surface structures leading to two strength distributions that were specimen geometry independent: One distribution, centered about 2.1 GPa, was controlled by 35 nm surface roughness of scallops; the second distribution, centered about 1.4 GPa, was controlled by larger, 150 nm, pitting defects. Finite element analyses (FEA) converted measured loads into strengths; tensile elastic measurements validated the FEA. Fractographic observations verified failure locations. The theta specimen and testing protocols are shown to be extremely effective at testing statistically relevant (hundreds) numbers of samples to establish processing–structure–property relationships at ultrasmall scales and for determining design parameters for components of microelectromechanical systems.