Self-compensation in semiconductors: The Zn vacancy in Ga-doped ZnO

Self-compensation, the tendency of a crystal to lower its energy by forming point defects to counter the effects of a dopant, is here quantitatively proven. Based on a new theoretical formalism and several different experimental techniques, we demonstrate that the addition of 1.4 × 10 exp 21-cm exp −3 Ga donors in ZnO causes the lattice to form 1.7 × 10 exp 20-cm exp −3 Zn-vacancy acceptors. The calculated VZn formation energy of 0.2 eV is consistent with predictions from density functional theory. Our formalism is of general validity and can be used to investigate self-compensation in any degenerate semiconductor material.Peer reviewe

Genetic diversity and host alternation of the egg parasitoid Oencyrtus pityocampae between the pine processionary moth and caper bug

Research ArticleThe increased use of molecular tools for species identification in recent decades revealed that each of many apparently generalist parasitoids are actually a complex of morphologically similar congeners, most of which have a rather narrow host range. Ooencyrtus pityocampae (OP), an important egg parasitoid of the pine processionary moth (PPM), is considered a generalist parasitoid. OP emerges from PPM eggs after winter hibernation, mainly in spring and early summer, long before the eggs of the next PPM generation occurs. The occurrence of OP in eggs of the variegated caper bug (CB) Stenozygum coloratum in spring and summer suggests that OP populations alternate seasonally between PPM and CB. However, the identity of OP population on CB eggs seemed uncertain; unlike OP-PPM populations, the former displayed apparently high male/female ratios and lack of attraction to the PPM sex pheromone. We studied the molecular identities of the two populations since the morphological identification of the genus Ooencyrtus, and OP in particular, is difficult. Sequencing of COI and ITS2 DNA fragments and AFLP analysis of individuals from both hosts revealed no apparent differences between the OP-PPM and the OP-CB populations for both the Israeli and the Turkish OPs, which therefore supported the possibility of host alternation. Sequencing data extended our knowledge of the genetic structure of OP populations in the Mediterranean area, and revealed clear separation between East and West Mediterranean populations. The overall level of genetic diversity was rather small, with the Israeli population much less diverse than all others; possible explanations for this finding are discussed. The findings support the possibility of utilizing the CB and other hosts for enhancing biological control of the PPMinfo:eu-repo/semantics/publishedVersio

The genus Brachygrammatella Girault (Hymenoptera: Trichogrammatidae)

Volume: 44Start Page: 289End Page: 29

Natural enemies and insect speciation

Volume: 36Start Page: 1End Page: 1

Dahmsia, a new genus of Mymaridae. (Hymenoptera: Chalcidoidea)

Volume: 51Start Page: 254End Page: 25

The genus Dicopus Enock (Hymenoptera: Mymaridae)

Volume: 50Start Page: 165End Page: 16

The genus Erythmelus in California (Hymenoptera, Mymaridae)

Volume: 25Start Page: 77End Page: 8

The suitability of insect-conditioned plant tissues as habitats for successive insect species

Volume: 24Start Page: 121End Page: 12