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  • Author: T. M. L. Le x
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A new root-knot nematode, Meloidogyne moensi n. sp. (Nematoda: Meloidogynidae), parasitizing Robusta coffee from Western Highlands, Vietnam

Summary

A new root-knot nematode, parasitizing Robusta coffee in Dak Lak Province, Western Highlands of Vietnam, is described as Meloidogyne moensi n. sp. Morphological and molecular analyses demonstrated that this species differs clearly from other previously described root-knot nematodes. Morphologically, the new species is characterized by a swollen body of females with a small posterior protuberance that elongated from ovoid to saccate; perineal patterns with smooth striae, continuous and low dorsal arch; lateral lines marked as a faint space or linear depression at junction of the dorsal and ventral striate; distinct phasmids; perivulval region free of striae; visible and wide tail terminus surrounding by concentric circles of striae; medial lips of females in dumbbell-shaped and slightly raised above lateral lips; female stylet is normally straight with posteriorly sloping stylet knobs; lip region of second stage juvenile (J2) is not annulated; medial lips and labial disc of J2 formed dumbbell shape; lateral lips are large and triangular; tail of J2 is conoid with rounded unstriated tail tip; distinct phasmids and hyaline; dilated rectum. Meloidogyne moensi n. sp. is most similar to M. africana, M. ottersoni by prominent posterior protuberance. Results of molecular analysis of rDNA sequences including the D2–D3 expansion regions of 28S rDNA, COI, and partial COII/16S rRNA of mitochondrial DNA support for the new species status.

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First evidence of retained sexual capacity and survival in the pyrethroid resistant Sitobion avenae (F.) (Hemiptera: Aphididae) SA3 super-clone following exposure to a pyrethroid at current field-rate

Abstract

The grain aphid Sitobion avenae is a prolific pest of cereal crops worldwide, controlled effectively with pyrethroid insecticides. However, the classic knock down resistance (kdr) mutation, L1014F on the S. avenae sodium channel gene, has been identified as the cause of the recently observed heterozygous (kdr-SR) resistance in the SA3 grain aphid super-clone. Results indicate that the kdr-SR SA3 clone can survive pyrethroid exposure above twice the normal field rate, continuing to reproduce thereafter. Additionally, the SA3 clone was found to be capable of producing sexual oviparous morphs, able to lay eggs following pyrethroid exposure. This demonstrates that possession of the L1014F mutation does not preclude the capacity to produce sexual morphs. This makes the adoption of an effective resistance management strategy imperative, within a wider integrated pest management (IPM) approach to control grain aphid.

Open access
Advanced Deformation Stages in Duplex Steel Investigated using Neutron and Synchrotron Radiation

Abstract

The grain scale of materials is an area still open for investigations within the field of materials science. The most helpful tools to perform this type of research are diffraction methods. Within the research project presented in this paper two experiments were carried out employing two different types of radiation: neutron (ISIS) and synchrotron (ESRF). The aim of the work was to describe the stress state in the necking zone during the occurrence of a damage phenomenon (Fig. 1.) in separate phase and to check the level of the homogeneity. The supplemental tools were the finite elements method and self-consistent modeling – it testified, confirmed and completed our experimental results and allowed us to formulate the justifiable conclusions.

Open access