Detection and Characterization of QoI-Resistant Phytophthora cactorum and P. nicotianae Causing Leather Rot in Florida Strawberry

Phytophthora cactorum and P. nicotianae cause leather rot (LR) of fruit and Phytophthora crown rot (PhCR) in strawberry. LR occurs sporadically but can cause up to 70% fruit loss when weather is conducive. In Florida's annual strawberry winter production system, PhCR can be severe, resulting in plant stunting, mortality, and severe yield loss. Currently, azoxystrobin is labeled for control of LR but not for PhCR. The aims of this research were i) to determine the sensitivity of P. cactorum and P. nicotianae isolates from strawberry to azoxystrobin and ii) to investigate mechanisms of QoI-resistance present in P. cactorum and P. nicotianae based on the known point mutations within the cytb gene. Isolates of both Phytophthora spp. causing LR and PhCR were collected from multiple strawberry fields in Florida between 1997 and 2020. Isolates were tested for sensitivity to azoxystrobin at 0, 0.01, 0.1, 1.0, 10, and 50 µg/ml on potato dextrose agar (PDA) amended with SHAM (100 µg/ml). Isolates were separated into two groups, sensitive isolates, with the 50% effective concentration (EC50) values lower than 1.0 µg/ml, and resistant isolates having EC50 values higher than 50 µg/ml. P. cactorum and P. nicotianae resistance to azoxystrobin was found for isolates collected after 2010. The first 450 nucleotides of the mitochondrial cytochrome b (cytb) gene were sequenced from a selection of resistant and sensitive isolates of both species. The G143A mutation reported to confer resistance to azoxystrobin was found in all resistant P. cactorum isolates. However, in P. nicotianae, qualitative resistance was observed, but the isolates lacked all the known mutations in the cytb gene. This is the first report of resistance to azoxystrobin in P. cactorum and P. nicotianae.

Diagnoses of two new species of Parosphromenus (Teleostei: Osphronemidae) from Bangka Island and Kalimantan, Indonesia

We describe two new species of Parosphromenus from Indonesia based on morphological and molecular diagnoses. Parosphromenus juelinae, sp. nov., occurs on Bangka Island. Its unpaired fin coloration is similar to that of P. deissneri, but it differs from the latter in having a rounded caudal fin with a non-filamentous branched median ray and a smaller anal fin. Although the new species has the same caudal fin structure as P. bintan, it can be distinguished from the latter by its distinct unpaired fin coloration and the intense red color on the body flanks. Parosphromenus kishii, sp. nov., is found only in a single river system in Kalimantan Tengah. It is distinguished from all other congeners by the unique coloration of its caudal fin. A phylogenetic tree based on the cytochrome b (cytb) gene indicates that the two new species are distinct monophyletic groups constituting distinct phylogenetic branches from their congeners. Cytochrome b Genetic distances between Parosphromenus juelinae, sp. nov., and Parosphromenus kishii, sp. nov., and the other taxa in the phylogenetic tree range from 2.44% to 19.52% and from 8.65% to 17.28%, respectively.

A new species of Lasioseius (Acari: Blattisociidae) from Brazil with morphological and DNA barcode data

Lasioseius foliatisetus n. sp. is described based on the morphology and molecular markers of adult females collected in litter/soil samples of the Caatinga and Pantanal, extensive Brazilian biomes. This new species can be distinguished from other Lasioseius species mainly by having fixed cheliceral digit with three teeth in addition to apical tooth, most dorsal shield setae leaf-shaped, and ventrianal shield with seven pairs of setae (including Jv5) in addition to the circumanal setae. The determined nucleotide sequences of the CytB gene and of ITSS of Lasioseius foliatisetus n. sp. are the first data of these types deposited in a published database (GenBank) for a species of this genus. The phylogenetic tree generated in the analysis of ITSS sequences showed a clade constituted only by species of the superfamily Phytoseoidea, including L. foliatisetus n. sp.. The phylogenetic tree generated in the ML analysis based on CytB showed a separation of the blattisociid species (including L. foliatisetus n. sp.) in one clade and the phytoseiid species in another clade. The analysis of the 28S 1–3 domain by itself did not allow the separation of the new species here described from species of other blattisociid genera.

Species determination and CYTB-G143A monitoring of Ramulariopsis spp. isolated from cotton in Brazil

Ramularia leaf spot is a disease of major importance on cotton fields in Brazil due to its effects on yield and cotton fiber quality. Two Ramulariopsis (syn. Ramularia) species, R. gossypii and R. pseudoglycines, are reported as the causal agents of this disease, but it is unknown which species is the most prevalent in Brazilian cotton fields. The goal of this work was to determine the most frequent species occurring on field samples from a molecular monitoring program which sampled from all cotton growing regions in Brazil from 2017 to 2020 seasons. We also used molecular tools for genotyping a region of the Cytb gene for all sampled isolates. Sequencing of an ITS-rDNA region was used for Ramulariopsis species determination, and a DNA fragment from the Cytb gene was amplified, sequenced, and analyzed for all 165 isolates. The ITS-rDNA sequencing confirmed that all isolates belong to the Ramulariopsis, and most notably, all the SNPs observed in this region, are of the R. pseudoglycines species for all 165 isolates, thus all analyzed isolates were assigned to this species. The analysis of the Cytb gene fragment sequenced showed the presence of the G143A substitution, and absence of G137R substitution, in all 165 isolates.

Sensitivity of the U.S. wheat powdery mildew population to QoI fungicides and determination of the complete Blumeria graminis f. sp. tritici cytochrome b gene

Wheat powdery mildew, caused by Blumeria graminis f. sp. tritici, is managed primarily with cultivar resistance and foliar fungicides. Quinone outside inhibitors (QoIs), which target the mitochondrial cytochrome b (cytb) gene, are one of the two main fungicide classes used on wheat. While European populations of B. graminis f. sp. tritici are widely insensitive to QoIs, largely due to the cytb mutation G143A, the QoI sensitivity of the U.S. B. graminis f. sp. tritici population had never been evaluated despite years of QoI use on U.S. wheat. A total of 381 B. graminis f. sp. tritici isolates from 15 central and eastern U.S. states were screened for sensitivity to QoI fungicides pyraclostrobin and picoxystrobin. A modest range of sensitivities was observed, with maximum resistance factors of 11.2 for pyraclostrobin and 5.3 for picoxystrobin. The F129L, G137R, and G143A cytb mutations were not detected in the U.S. B. graminis f. sp. tritici population, nor were mutations identified in the PEWY loop, a key part of the Qo site. Thus, no genetic basis for the observed quantitative variation in QoI sensitivity of U.S. B. graminis f. sp. tritici was identified. Isolate sporulation was weakly negatively associated with reduced QoI sensitivity, suggesting a fitness cost. In the course of the study, the complete B. graminis f. sp. tritici cytb gene sequence was determined for the first time in the isolate 96224 v. 3.16 reference genome. Contrary to previous reports, the gene has an intron that appears to belong to intron group II, which is unusual in fungi. The study was the first QoI sensitivity screening of a large, geographically diverse set of U.S. B. graminis f. sp. tritici isolates, and while the population as a whole remains relatively sensitive, some quantitative loss of efficacy was observed.

A new species of Psammophis (Serpentes: Psammophiidae) from the Turpan Basin in northwest China

An adult sand snake specimen was collected during a herpetofaunal survey conducted in the Turpan Basin in northwest China. Phylogenetic analyses revealed that this specimen, along with other snake sloughs and skins collected from different localities in the Turpan Basin formed a clade that is sister to Psammophis lineolatus. This taxon exhibited substantial divergence from its congeners (P. lineolatus and P. condanarus) with uncorrelated p-distances ranging from 11.9 ± 0.9% to 15.8 ± 1.6% for the ND4 gene and from 10.2 ± 0.8% to 13.8 ± 1.1% for the Cytb gene. Given the genetic differences along with morphological differences, we describe the specimen from the Turpan Basin as Psammophis turpanensis sp. nov. We provide detailed morphological descriptions, and compare this specimen with five Asian sand snakes and the Afro-Asian Sand Snake, P. schokari. In addition, we provide brief comments on the biogeography of Psammophis in China.

Ascodipteron sanmingensis sp. nov., a new bat fly (Hippoboscidae: streblid grade) from Fujian, China

The bat fly genus Ascodipteron Adensamer, 1896 currently contains 15 species, all of which occur in tropical and subtropical areas of the Eastern Hemisphere. A new species of endoparasitic bat fly, Ascodipteron sanmingensis sp. nov., was collected from the Great Himalayan Leaf-nosed Bat, Hipposideros armiger (Hodgson, 1853), during ecological studies on bats in Fujian, China. A new species, Ascodipteron sanmingensis sp. nov., is described, based on dealate neosomic females and is supported by molecular data from a 368 bp fragment of the cytochrome B (Cytb) gene. Habitus and diagnostic details, as well as the attachment sites on the host, are documented with photographs. A detailed comparison of the new species with related species is provided and the new species is accommodated in the most recent key to the world species of Ascodipteron.

Changes in DMI, SDHI, and QoI Fungicide Sensitivity in the Estonian Zymoseptoria tritici Population between 2019 and 2020

Zymoseptoria tritici (Zt) populations adapt under the selection pressure of fungicides applied for disease control. The primary objective of this study was to assess fungicide sensitivity in the Estonian Zt population. A total of 282 Zt isolates from 2019 and 2020 were tested for sensitivity to azoles (DMIs; prothioconazole-desthio, epoxiconazole, mefentrifluconazole) and succinate dehydrogenase inhibitors (SDHIs; boscalid, fluxapyroxad). The efficacy of the tested fungicides varied considerably between the Estonian counties, but the Zt population is mainly sensitive to DMIs. Additionally, the frequencies of CYP51 gene alterations varied; D134G, V136C, A379G, and S524T had increased, but V136A and I381V showed a moderate decrease in 2020 in comparison to 2019. Sensitivity to SDHIs was stable, but boscalid was less effective than fluxapyroxad. SdhC gene mutations C-T33N, C-T34N, and C-N86S were common, but not linked with SDHI fungicide sensitivity assay results. Otherwise, mutation B-N225I in the SdhB subunit occurred in isolates with reduced sensitivity to SDHIs. Sensitivity to strobilurins was evaluated by the mutation G143A in the CytB gene, which was present in nearly half of the population. The data presented confirm the ongoing evolution of fungicide sensitivity in the Zt population in Estonia and highlight the importance of knowledge-based decisions for optimizing anti-resistance strategies in the field.

Genetic differentiation of geographic populations of Rattus tanezumi based on the mitochondrial Cytb gene

Rattus tanezumi is a common domestic rat and host of the bubonic plague pathogen in China and Southeast Asia (SEA). The origin, genetic differentiation and dispersal of R. tanezumi have received increasing attention from researchers. The population genetics of R. tanezumi based on its mitochondrial cytochrome b gene have been studied to explain the origin, relationships and dispersal of populations. In this study, we captured a total of 229 rats; morphological and molecular biological identification cytochrome oxidase subunit I (COI) confirmed 131 R. tanezumi individuals collected from 6 provincial areas, and their Cytb gene sequences were analyzed. The results showed that the population in Mohan (MH), Yunnan, had the highest genetic diversity, while that in Ningde (ND), Fujian, had the lowest. Tajima’s D statistic for all populations was negative and nonsignificant, indicating the possible expansion of R. tanezumi populations. Low gene flow occurred between the Zhangmu (ZM) R. tanezumi population and other populations, and the genetic differentiation among them was high. Furthermore, our analyses revealed the ZM lineage was the oldest lineage among the groups and diverged ~1.06 Mya, followed by the Luoyang (LY) lineages (~0.51 Mya) and Yunnan lineage (~0.33 Mya). In southeastern Yunnan, the Jinshuihe (JSH) and MH populations were more closely related to the populations in southeastern China (Fuzhou (FZ), ND, Quanzhou (QZ), Nanchang (NC)) and inland areas (Chongqing (CQ), LY) than to those in other areas of Yunnan (Jiegao (JG) and Qingshuihe (QSH)), indicating that R. tanezumi may have spread from southeastern Yunnan to the interior of China. In summary, R. tanezumi may have originated in ZM and adjacent areas, spread to Yunnan, and then spread from the southeast of Yunnan inland or directly eastward from ZM to inland China.