Distribution and phenology of monarch butterfly larvae and their milkweed hosts in the South Central US

South Central US milkweeds (Asclepias) are critical adult nectar and larval food resources for producing the first spring and last summer/fall generations of declining eastern migratory monarch butterflies (Danaus plexippus). This study addresses multiple gaps in assessment of monarch conservation priorities for the South Central US through analyses of monarch larval host selectivity, phenology, and spatial density, as well as the phenology, niche modeled distribution, and land cover selectivity of important milkweed hosts. Results are synthesized to estimate seasonal milkweed resource areas. About 70% of monarch larval activity occurred from mid-March to mid-July (early season) and 30% from mid-August to late November (late season). Twenty-six wild milkweed (Apocynaceae) hosts were mapped, including four new records for North America. Important hosts included Asclepias a. ssp. capricornu, A. viridis, and A. oenotheroides, that were utilized more frequently during early season, and Asclepias latifolia, utilized more frequently during late season. Landscape host selectivity was positive for A. viridis and A. a. ssp. capricornu in late and early seasons, respectively, and negative for A. oenotheroides in late season. Milkweed land cover selectivity was positive for Developed-Open Space and Grassland Herbaceous, and negative for Cultivated Crops and Shrub/Scrub. Seasonal milkweed resource areas and larval spatial densities resolved interior and coastal corridors providing functional connectivity for monarch spring and fall migrations. A potential gap in milkweed land cover benefit was identified in South Texas. The novel merging of milkweed niche models with larval phenology, host selectivity, milkweed phenology, and land cover selectivity informs conservation assessment.

Unraveling the host-selective toxic interaction of cassiicolin with lipid membranes and its cytotoxicity

Corynespora cassiicola is the pathogen that causes Corynespora leaf fall (CLF) disease. Cassiicolin (Cas), a toxin produced by C. cassiicola, is responsible for CLF disease in rubber trees (Hevea brasiliensis). Currently, the molecular mechanism of the cytotoxicity of Cas and its host selectivity have not been fully elucidated. To gain insight into these issues, we analyzed the binding of Cas1 and Cas2 to membranes consisting of different plant lipids and their membrane-disruption activities. Our real-time observations with high-speed atomic force microscopy (HS-AFM) and confocal microscopy reveal that the binding and disruption activities of Cas1 and Cas2 are strongly dependent on the types of membrane lipids. The mixtures of DPPC with DPPA, MGDG, DGDG, and stigmasterol are more susceptible to membrane damage caused by Cas1 and Cas2 than DPPC alone or its mixtures with sitosterol, DGTS-d9, and DGTS. This difference derives from the stronger binding of the toxins to membranes with the former lipid composition. Cytotoxicity tests on rubber leaves of RRIV 1, RRIV 4, and PB 255 clones suggest that the toxins cause necrosis of rubber leaves, except for the strong resistance of PB 255 against Cas2. Cryo-SEM analyses of necrotic leaf tissues exposed to Cas1 confirm that cytoplasmic membranes are vulnerable to the toxin. Thus, the host selectivity of Cas toxin in CLF disease is attained by the lipid-dependent binding activity of Cas to the membrane, and the cytotoxicity of Cas arises from its ability to disrupt membranes.

Host Selectivity of Nerocila Orbignyi (Guerin-Meneville, 1832) (Isopoda, Cymothoidae) with a Record of a New Host from the Sea of Marmara (Turkey)

Nerocila orbignyi (Isopoda, Cymothoidae) is reported for the first time on Mugil cephalus Linnaeus, 1758 (Pisces, Mugilidae) from Bandırma Bay (the Sea of Marmara, Turkey) during 2020. This paper aims to present the morphological characters of male of N. orbignyi from Turkey. Hosts infested with N. orbignyi are commented according to taxonomical status (order, families), ecological behaviours (habitat selections, feeding habits, school-solitary), morphological characters (scale types) according to current records. It may be said that N. orbignyi has been reported more frequently on fish belonging to the Perciformes order and Mugilidae and Sparidae families. It may also be said that this parasite selects also the fishes with carnivorous, demersal, schools, and migratory character.

Identification of Echinococcus granulosus Genotypes G1 and G3 by SNPs Genotyping Assays

Echinococcus granulosus sensu lato (s.l.) is the causative agent of cystic echinococcosis in animals and humans. Different E. granulosuss.l. genotypes exhibit great diversity in their life cycle, host selectivity and pathogenicity. For this reason, the study of genetic variation within Echinococcus species is of importance for their epidemiological implication. We employed two SNP genotyping technologies to distinguish G1 and G3 E. granulosus sensu stricto (s.s.). genotypes. The genotypes of DNA samples (n = 28) extracted from hydatid cysts of different animal species were identified by amplification and sequencing of a fragment of the mitochondrial nad5 gene. Two SYBR green and three TaqMan real time PCR assays were developed for targeting of three nad5 informative positions (SNP758, 1123, and 1380) known to be able to discriminate G1 from G3. Genotyping by SYBR Green PCR based on cycle threshold (Ct) with melting temperature (Tm) analysis and performed on SNP1123 and SNP1380 failed to identify one DNA sample. TaqMan assays for SNP758, 1123 and 1380 effectively confirmed genotype identification obtained by Sanger sequencing. Our results demonstrated that the combination of the three Taqman assays developed in this study represents a valuable and cost effective tool alternative to DNA sequencing for E. granulosus s.s. genotyping.

Host (–)-(2R,3R)-2,3-Dimethoxy-1,1,4,4-tetraphenylbutane-1,4-diol and Guests Aniline, N-Methylaniline, and N,N-Dimethylaniline: A Selectivity Study

The compound (–)-(2R,3R)-2,3-dimethoxy-1,1,4,4-tetraphenylbutane-1,4-diol (DMT) forms 2 : 1 host : guest complexes with aniline, N-methylaniline, and N,N-dimethylaniline when recrystallized from these solvents. When the guests competed, as in binary and ternary mixtures, DMT proved to be remarkably selective for the alkylated guests, discriminating consistently against aniline. A host selectivity order of aniline << N-methylaniline < N,N-dimethylaniline was observed. Results from single-crystal diffraction, Hirshfeld surface, and thermal analyses were used to explain the observed preference order. This investigation shows that using the realm of supramolecular chemistry may have future application in the separation of these anilines.