Pollen Alone or a Mixture of Pollen Types? Assessing Their Suitability for Mass Rearing of Neoseiulus cucumeris (Acari: Phytoseiidae) Over 20 Generations

The generalist predatory mite, Neoseiulus cucumeris (Oudemans) is known as one of the most effective natural enemies on many pests. This economically important biocontrol agent was reared for 20 generations on date palm and castor bean pollen as well as a mixture of pollen types, including date palm, castor bean, and almond. The performance of this predator was evaluated by comparing its life table parameters after different generations (G1–G20) fed on each diet in a laboratory at 25 ± 1°C, 60 ± 5% RH, and a photoperiod of 16:8 (L: D) h. The development time of the predator reared on all tested diets had no significant difference in G20. The intrinsic rate of increase (r) of N. cucumeris by feeding on the mixed pollen (0.197 day⁻¹) was significantly higher than that on castor bean, or date palm pollen (0.146 or 0.152 day⁻¹ in G1, respectively). Our results indicated that the predator’s performance was not affected by long-term feeding on the pollen diets, as well as there was no considerable difference between pollen alone and pollen mixture diets. Furthermore, mites reared on pollen diets had higher quality than those reared on natural prey, Tetranychus urticae Koch.     

Optimized conditions for determination of total soil organic matter in diverse samples by mass loss on ignition

Reliable measurement of soil organic matter (SOM) contents is crucial to assessment of soil health, productive longevity and the effects of climate change. In this study, the loss‐on‐ignition (LOI) method has been used to determine the SOM of dried soil samples with a wide range of clay, sand and silt contents from the Agricultural Laboratory Proficiency (ALP) program. Regressions of ALP participant data against LOI measurements at 350–650°C indicate that the extent of SOM oxidation depends more on the ignition temperature and time than on the sample compositions. Thus, LOI data from ignition at 350–550°C for 12 h relative to ignition at 650°C for 12 h converge at 650°C and the average coefficient of variance decreases to ≈ 4% at 650°C. Also examined are regressions of soil organic C from direct dry combustion as standards with LOI measured at 360°C for 2 h, LOI measured at 650°C for 12 h and with the Walkley‐Black procedure used in the ALP program.     

Cytology and pollen grain fertility in creeping bentgrass interspecific and intergeneric hybrids

Creeping bentgrass (Agrostis stolonifera L. or A. palustris Huds.) is a highly outcrossing allotetraploid species. It can form hybrids with a number of other Agrostis species and Polypogon genus. However, cytology and pollen grain fertility of the creeping bentgrass interspecific and intergeneric hybrids are not well known. In this research, chromosome pairing behaviors during meiosis I in F₁ and pollen viability of F₁ hybrids, as well as seed set rate and seed germination rate of backcrosses were studied in hybrids between creeping bentgrass, and other bentgrass species and three species of Polypogon genus. Abnormal chromosome pairing, laggard chromosomes, and premature segregation in F₁ hybrids were found. Pollen viability ranged from 1.6 to 48.5% amongst F₁ hybrids, significantly lower than that of the parents (85.5–94.1%). Some hybrids produced pollens of different sizes within the same anther. Seed set following backcrosses using F₁ hybrids as the male parent and creeping bentgrass as the recurrent parent was significantly lower than their parents. The study of chromosome paring behaviors and progeny fecundity are important in utilizing the alien genes to improve bio-stress and abio-stress resistance, and in assessing the potential transgene risks of creeping bentgrass.     

Characterization of Malaysian Pectobacterium spp. from vegetables using biochemical, molecular and phylogenetic methods

In August 2011, vegetable crops showing symptoms of maceration and water soaked lesions on their tuber, leaf, and fruit were collected from four major vegetable growing states in Malaysia including Pahang, Johor, Melaka and Selangor. The majority of the causal organisms isolated from infected tissues (52 strains) were identified as Pectobacterium spp. based on PCR amplification of the pectate lyase (pel) gene and amplification of the 16S-23S rRNA (ITS) with G1 and L1 primers. Physiological and biochemical assays divided Malaysian Pectobacterium species into two main groups: Pectobacterium wasabiae and Pectobacterium carotovorum subsp carotovorum. Partial sequence of PCR product from reaction of putative Pectobacterium spp. with 16S rRNA confirmed the results obtained from physiological and biochemical assays used for identification of the bacterium. Application of specific primers such as Eca1F/Eca2r, Br1f/L1r, EXPCCF/EXPCCR, and also ITS-PCR following by RFLP by restriction enzyme (RsaI) successfully differentiated Malaysian P. wasabiae and P. carotovorum subsp carotovorum isolates from other species and subspecies of Pectobacterium. Phylogenetic analysis of Malaysian isolates with housekeeping genes (mdh, gapA) grouped Malaysian P. carotovorum subsp carotovorum and P. wasabiae in the same cluster with P. carotovorum subsp carotovorum (Ecc380) and P. wasabiae (SCRI488) respectively.     

Effects of melatonin on oocyte maturation in PCOS mouse model

The purpose of oocyte in vitro maturation is generation of mature oocytes that could support future development. Efforts have been made to enhance oocyte developmental competence by developing optimal culture conditions. The present study is conducted to determine melatonin effects on quality of polycystic ovarian syndrome (PCOS) oocytes when it has been added during in vitro maturation, and immature oocytes were cultured in defined conditioned medium with and without different melatonin concentrations. Melatonin could significantly improve nuclear maturation of PCOS oocytes (81.1% vs. 56.3%, P < 0.05 were achieved with 10^?6 mol/L concentration). Cleavage rate was significantly higher in 10^?5 mol/L concentration compared to untreated oocytes in PCOS (54% vs. 35%, respectively) and it was significantly higher with 10^?6 mol/L concentration in the control group, 55% versus 38%, compared to untreated oocytes. This study showed that melatonin has the potential to induce oocyte nuclear maturation and guarantee fertilization potential. © 2016 Japanese Society of Animal Science     

Hygroscopic thickness swelling rate of composites from sawdust and recycled plastics

The thickness swelling rates of compression molded wood plastic composites (WPCs) prepared from 50% by weight sawdust and 50% by weight virgin and/or recycled plastics (HDPE and PP) were studied. Thickness swelling rates of the manufactured WPCs were evaluated by immersing them in water at room temperature and monitoring thickness changes for several weeks. A swelling model developed by Shi and Gardner (Composites Part A, 37:1276–1285, 2006) was used to study the thickness swelling process of WPCs. The parameter K _SR of the model can be used to quantify the swelling rate. The results indicated that composites containing PP had lower equilibrium thickness swelling and also shorter equilibrium time (time to reach equilibrium thickness swelling). The swelling model developed was a good predictor of the hygroscopic swelling process of wood plastic composites. Composites containing PP (virgin and recycled) had higher K _SR than those containing HDPE. The minimum and maximum K _SR values were observed in composites made of virgin HDPE and a mixture of recycled plastics, respectively. With increasing recycled plastic content K _SR linearly decreased.