Occurrence and distribution of lace bug, whitefly, and shoot fly pest species on cassava (Manihot esculenta) crops according to region in Paraná State, Brazil

The cassava (Manihot esculenta Crantz) crop is relevant for human livelihoods, particularly in poorer regions. It is consumed fresh or as industrialized flour, and the roots and aerial parts are also used to feed livestock. Pests may limit cassava production, which may endanger food security due to the socioeconomic importance of the crop. Reports of the occurrence of three insect guilds, lace bugs, shoot flies, and whiteflies have been recorded in Paraná State, Brazil, but the distinct species and their distribution are yet to be determined. This lack of information limits the development of strategies to mitigate pest damage. Surveys were conducted in 39 counties (four farms per county) distributed throughout the state that encompass the various socioeconomic regions. The collected material was properly packed and sent to the laboratory for identification, and the following species were identified: lace bugs Vatiga illudens Drake, 1922 and Vatiga manihotae Drake, 1922 (both Hemiptera: Tingidae); whiteflies Bemisia tuberculata (Bondar, 1923) and Aleurothrixus aepim (Goeldi, 1886) (both Hemiptera: Aleyrodidae), and the cassava shoot fly Neosilba perezi Romero & Ruppel, 1973 (Diptera: Lonchaeidae) in Paraná State. Lace bugs were not found in the samples in the eastern and southern portions of the state. V. illudens was more widespread than V. manihotae. The whitefly A. aepim was not observed in three counties (eastern, southern, and central regions), whereas B. tuberculata and the cassava shoot fly were found in all regions sampled in Paraná State. Suggestions for future investigations of pest management are proposed.

Phenotypic diversity and population structure of Ethiopian barley (Hordeum vulgare L.) landrace collections

Landraces play a key role in crop breeding by providing beneficial trait for improvement of related crops and their genetic diversity studies are very important for breeding program and identification of parental lines. In this study, 585 barley (Hordeum vulgare L.) landraces collected from 13 agro-ecological zones of Ethiopia were evaluated along with 10 cultivars for their phenotypic diversity and population structure in relation to agronomic traits, resistance to major diseases and barley shoot fly. Data on 22 agronomic traits, three major diseases and barley shoot fly resistance-related traits were recorded. Univariate and multivariate approaches such as principal component and cluster analyses were applied to assess the genetic diversity and population structure. The analysis of variance indicated significant genotypic main, accessions x year and accession x environment interaction effects for almost all the traits evaluated. However, the accessions x environment interactions were mainly due to changes in magnitude rather than crossover types of interactions. The diversity analysis indicated that the population was highly structured according to kernel row-type, region (geographic) origin and altitude classes. Since the population is highly structured, appropriate statistical models will be needed when this population is used for association mapping studies. Eight principal components (PCs) in principal component analysis (PCA) accounted for the variation of 83.01%. The most related traits were included in the same PC, implying that results from PCA could give clues as to the relationship among traits. Though variability existed within and among clusters, useful germplasm clustered together. These materials are important sources of germplasm for the improvement of agronomic, disease and insect pest resistance traits. Keywords: Barley, diseases, genetic diversity, landraces, multivariate, shoot fly