Search Results (4)

Lance nematodes, Hoplolaimus spp., feed on the roots of many kinds of plants, including agronomic crops. In this study, morphological and molecular analyses of several Hoplolaimus species and populations are provided. We were able to collect and characterize the topotype materials of H. galeatus from Arlington, Virginia; H. stephanus syn. n. from Nichols, South Carolina; and H. concaudajuvencus from Pensacola, Florida, and several additional populations and species from the United States, Israel, and India. Phylogenetic analyses of several hundred sequences of the D2–D3 expansion regions of 28S rRNA, ITS rRNA, and COI genes of Hoplolaimus species obtained from published and original datasets were given. Fifty-three new D2–D3 of 28S rRNA, 43 new ITS rRNA, and 47 new COI sequences from 23 isolates of Hoplolaimus spp. and one isolate of Peltamigratus christiei were obtained in this study. New molecular identities for H. concaudajuvencus and H. galeatus were proposed. Hoplolaimus stephanus syn. n. was considered a synonym of H. galeatus based on the morphological and molecular similarity of these two species. Analysis of morphology and molecular data did not reveal significant differences among H. columbus syn. n., H. indicus syn. n., and H. seinhorsti, and the first two species were synonymized with H. seinhorsti. A new species, H. floridensis sp. n., was described from many locations in Florida, USA. It was separated from other representatives of the genus Hoplolaimus by its morphological and molecular characteristics. Maps with geographical distribution of several lance nematode species in North America were reconstructed based on published and original molecular identification of samples. Full article

Lance nematodes (Hoplolaimus spp.) feed on the roots of various plants, including key horticultural products. An investigation of the genetic diversity and structure of six Hoplolaimus species, utilizing the cytochrome c oxidase I (COI) of the mtDNA gene, was based on 174 sequences available on the NCBI. Based on the COI of mtDNA, the haplotype analysis revealed 44 haplotypes. Nucleotide diversity was low among all species of Hoplolaimus, except for H. magnistylus (π = 0.04915) and H. stephanus (π = 0.06746). In contrast, haplotype diversity (Hd) was high, especially for H. stephanus (Hd = 0.89) and H. pararobustus (Hd = 0.90). Phylogenetic analysis grouped the various populations into eight clades, and the result showed that H. magnistylus was placed in three different clades, which showed high variability in haplotype supported by the haplotype network. Neutrality tests and mismatch distribution based on the mtDNA supported the hypothesis of a constant population with no expansion in Hoplolaimus, except for H. concaudajuvencus (Tajima (D) = −0.84971) and H. columbus (Tajima (D) = −0.87674). In conclusion, genetic analysis showed a neutral evolution amongst the Hoplolaimus species. The result of the present study provides a better insight into the Hoplolaimus species toward species delimitation and managing this plant-parasitic nematode in various crops. Full article

The larvae of ermine moths from the Yponomeutidae family (Lepidoptera) feed on a range of species and varieties of fruit and ornamental trees. Some species of this family pose a serious threat to the environment, mainly because of the significant defoliation they cause but also due to the widespread use of insecticides used to control them. This study was designed to assess the sensitivity of Yponomeuta padella and Yponomeuta cagnagella larvae and pupae to a native strain of Steinernema feltiae ZAG15 nematodes under laboratory conditions and to test the biological activity of these nematodes against the larvae and pupae of these species in field studies. The following doses were used in the laboratory tests: 50 IJs/insect (Petri dish tests) and 100 IJs/insect (container tests). Petri dish and container tests were performed at 20 °C and 60% humidity. Mortality of two stages (larvae and pupae) was determined 3 days after treatment. In the field trials, the nematodes were applied at the following doses: 4000 IJs/web for the caterpillars of Y. padella and Y. cagnagella and 1000 IJs/web for the pupae of Y. padella and Y. cagnagella (this corresponded to approximately 200 IJs/insect). Nematodes were applied using a 1 L hand sprayer and a lance. The efficacy of the application was assessed after seven days. The results of our study showed that the larvae (81.7%) and pupae (88.3%) of Y. padella had a greater susceptibility to entomopathogenic nematodes (EPNs) than those of Y. cagnagella (50% and 33.3%, respectively). However, our promising laboratory results did not translate into results in field trials, where the application of EPNs proved to be ineffective. Full article

Cereal monocultures are very susceptible to many pests, especially to those living on leaves, which largely affects yield by decreasing its quality. The most dangerous of them is the cereal leaf beetle (Oulema melanopus L.). In cases of heavy infestation by its larvae, the surface of plants may be reduced by 50%, and sometimes even by 80%, with a main yield loss of 10–25%. The aim of the presented study was to assess the efficiency of a native isolate of Steinernema feltiae (Filipjev, 1934) and commercial preparation Larvanem (Heterorhabditis bacteriophora (Poinar, 1975)) in controlling the larvae of O. melanopus, and to reduce crops damage in the field. Nematodes were applied in a dosage of 2 million IJs/m² as a suspension of 11 litres per square metre. A hand sprinkler with field lance and flat-stream nozzles was used for applications at the lowest working pressure of 3000 hPa. The effectiveness of both nematode species was moderate: 47.8% for S. feltiae isolate and 49.5% for H. bacteriophora. The biggest reduction in leaf damage was found in crops treated with the commercial preparation, where the index of leaf infection was 32%, being more than twofold smaller than that for the control. Full article