Deltamethrin and cypermethrin resistance status of Rhipicephalus (Boophilus) microplus collected from six agro-climatic regions of India

A cross sectional study was conducted to assess the prevalence of synthetic pyrethroids (SP) resistance in Rhipicephalus (Boophilus) microplus in India. Twenty-seven areas located in six agro-climatic regions were selected for the collection of engorged ticks using two stage stratified sampling procedure. Adult immersion test (AIT) and larval packet test (LPT) were optimized using laboratory reared susceptible line of R.(B.) microplus (IVRI-I) for determination of 95% lethal concentration (LC(95)) of deltamethrin (29.6 ppm in AIT and 35.5 ppm in LPT) and cypermethrin (349.1 ppm in AIT and 350.7 ppm in LPT). The AIT with a discriminating dose (2 × LC(95)) was used to detect deltamethrin and cypermethrin resistance in the field isolates of R.(B.) microplus. On the basis of the data generated on three variables viz., mortality, egg masses and reproductive index, the resistance level was categorized as I, II, III and IV. The overall prevalence of SP-resistant R.(B.) microplus among the sampled farms was 66.6% (18/27). Out of these 18 areas, resistance to deltamethrin at level I was detected in 08 areas (resistance factor=2.0-4.9), at level II in 09 areas (RF=5.2-11.8), at level III in 01 area (RF=34.9) and at level IV in 01 area (RF=95.7). The resistance to cypermethrin was detected in 16 areas and level of resistance was detected at level I in 10 areas (RF=2.06-4.64) and at level II in 06 areas (RF=5.13-9.88). The middle-gangetic and trans-gangetic plains revealed higher density of resistant ticks where intensive cross bred cattle population are reared and the SP compounds are commonly used. The data generated on acaricide resistant status in ticks will help in formulating tick control strategy for the country.     

Modeling carbon allocation in trees: a search for principles

We review approaches to predicting carbon and nitrogen allocation in forest models in terms of their underlying assumptions and their resulting strengths and limitations. Empirical and allometric methods are easily developed and computationally efficient, but lack the power of evolution-based approaches to explain and predict multifaceted effects of environmental variability and climate change. In evolution-based methods, allocation is usually determined by maximization of a fitness proxy, either in a fixed environment, which we call optimal response (OR) models, or including the feedback of an individual's strategy on its environment (game-theoretical optimization, GTO). Optimal response models can predict allocation in single trees and stands when there is significant competition only for one resource. Game-theoretical optimization can be used to account for additional dimensions of competition, e.g., when strong root competition boosts root allocation at the expense of wood production. However, we demonstrate that an OR model predicts similar allocation to a GTO model under the root-competitive conditions reported in free-air carbon dioxide enrichment (FACE) experiments. The most evolutionarily realistic approach is adaptive dynamics (AD) where the allocation strategy arises from eco-evolutionary dynamics of populations instead of a fitness proxy. We also discuss emerging entropy-based approaches that offer an alternative thermodynamic perspective on allocation, in which fitness proxies are replaced by entropy or entropy production. To help develop allocation models further, the value of wide-ranging datasets, such as FLUXNET, could be greatly enhanced by ancillary measurements of driving variables, such as water and soil nitrogen availability.     

The effect of oral metformin on insulin sensitivity in insulin-resistant ponies

Metformin may be an effective therapeutic option for insulin-resistant (I-R) horses/ponies because, in humans, it reportedly enhances insulin sensitivity (SI) of peripheral tissues without stimulating insulin secretion. To determine the effect of metformin on insulin and glucose dynamics in I-R ponies, six ponies were studied in a cross-over design by Minimal Model analysis of a frequently-sampled intravenous glucose tolerance test (FSIGT). Metformin was administered at 15 mg/kg bodyweight (BW), orally, twice-daily, for 21 days to the metformin-treated group. The control group received a placebo. A FSIGT was conducted before and after treatment. The Minimal Model of glucose and insulin dynamics rendered indices describing SI, glucose effectiveness (Sg), acute insulin response to glucose (AIRg) and the disposition index (DI). The body condition score (BCS), BW and cresty neck score (CNS) were also assessed. There was no significant change in SI, Sg, AIRg, DI, BW, BCS or CNS in response to metformin, or over time in the control group. There were no measurable benefits of metformin on SI, consistent with recent work showing that the bioavailability of metformin in horses is poor, and chronic dosing may not achieve therapeutic blood concentrations. Alternatively, metformin may only be effective in obese ponies losing weight or with hyperglycaemia.     

Biomass and Defoliation Tolerance of 12 Populations of Pseudoroegneria spicata at Two Densities

Pseudoroegneria spicata(Pursh.) A. Löve is an important native grass of the rangelands of the Intermountain West, USA and is widely used in this region for restoration applications. High grazing preference, together with high grazing sensitivity, has reduced the abundance of this species, indicating the need for the development of grazing-tolerant plant materials. While a genotype may be defoliation tolerant at low density, e.g., in an experimental setting, an effective grazing-tolerant genotype must also display this trait at higher densities resembling those found in natural and restoration settings. We compared 12 restoration plant materials for response to spring-defoliation at high (25 plants · m^?2) and low (8 plants · m^?2) plant densities in a field experiment. Two consecutive years of spring-defoliation reduced shoot biomass 19% compared to the nonspring-defoliated control, and this reduction was similar for the two densities examined. Two populations, P-3 and Acc:238, were able to compensate for shoot biomass after 2 yr of spring-defoliation, while the remaining 10 populations undercompensated, as is commonly reported for cool-season grasses in arid and semiarid regions. While the association between control and spring-defoliated shoot biomass was marginally positive (R² = 0.26; P < 0.10), we found a stronger negative association (R² = 0.36; P < 0.05) between spring-defoliation tolerance and control shoot-biomass production. This suggests a possible trade-off between growth and defoliation tolerance (calculated as percentage of control biomass) among populations. Of the four commercially available plant materials in our study, the more recent prevariety germplasm, P-7, exhibited higher control shoot biomass and higher spring-defoliation tolerance than the older cultivars, Whitmar and Goldar. Anatone germplasm was intermediate but not statistically different from these other plant materials for these two traits.     

Subsequent nitrogen utilisation and soil water distribution as affected by forage radish cover crop and nitrogen fertiliser in a corn silage production system

Forage radish is a unique winter cover crop that is relatively new but becoming rapidly adopted in temperate, humid North America. Little is known about how the use of this cover crop may influence subsequent nitrogen availability, soil water accumulation in the soil profile in corn silage production system. In this present work, the average nitrogen uptake by silage corn increased significantly by 11.6% in cover plots compared with the no-cover control plots. The recovery efficiency and agronomic efficiency of applied nitrogen in silage corn declined in cover plots compared to no-cover plots. The average soil water storage in cover plots was significantly higher than in the control after corn sowing and at the harvest stage. With increasing nitrogen application level, the average corn grain yield increased significantly at 56 and 112 kg N ha^?1 by 13.1% and 39.8%, respectively. Planting a forage radish cover crop can facilitate growth of silage corn and markedly improve total nitrogen uptake of corn. Consideration should be given to nitrogen application rate and also to avoiding excessive nitrogen input in the subsequent crop following a cover crop, thereby truly improving subsequent fertiliser use efficiency.     

Experimental infection of cats (Felis catus) with Tritrichomonas foetus isolated from cattle

Tritrichomonas foetus is recognized as the causative agent of venereal trichomoniasis in cattle. It is characterized by embryonic and early fetal death and post-coital pyometra, and feline trichomoniasis, manifest as chronic, large bowel diarrhea. Many of the infected cats are less than 2 years old and specific routes of transmission remain unknown. We recently demonstrated that feline isolates of T. foetus can successfully infect heifers, resulting in pathologic changes similar, but not identical to those previously reported as representative of bovine trichomoniasis. In this study, we experimentally infected six cats less than 1 year of age with a bovine (D-1) isolate of T. foetus and one cat with a feline (AUTf-1) isolate of T. foetus. Within 2 weeks, the cat infected with the feline (AUTf-1) isolate was culture positive for trichomonads in weekly fecal samples. At the end of 5 weeks, only one cat infected with the bovine (D-1) isolate was fecal culture positive for trichomonads. At necropsy, the intestine of each cat was removed and divided into five sections (ileum, cecum, anterior, medial and posterior colon). Contents from each section were collected and cultured. The cat infected with the feline (AUTf-1) isolate was culture positive in the ileum, cecum, medial and posterior colon. Two cats infected with the bovine (D-1) isolate were culture positive in the cecum only. Additionally, each intestinal section was submitted to a pathologist for histopathological examination. The combined results indicate that there are demonstrable differences between the feline (AUTf-1) and bovine (D-1) isolates regarding their infectivity in cats.     

Studies on ‘zinc deficiency syndrome’ in Black Bengal goats (Capra hircus) fed with fodder (Andropogon gayanus) grown on soil treated with an excess of calcium and phosphorus fertilizer

Overliming and excessive application of superphosphate caused a zinc deficiency in the soil and so reduced the uptake of zinc by fodder plants. Bucks reared on such fodder had significantly (p<0.01) less zinc in their hair compared with controls and suffered from conditioned zinc deficiency syndrome with a significant (p<0.01) loss of body weight, stunted growth, alopecia, lethargy, abnormal (kyphotic) gait, anorexia, digestive and respiratory problems. Oral supplementation with zinc sulphate very rapidly improved these conditions to near normality. Histological examination of samples of skin and testis from the zinc-deficient bucks revealed formation of excessive keratin, retention of nuclei in the stratum corneum and reduction in the width of the stratum granulosum in the skin, while samples of testis indicated degenerative changes, including atrophy of the seminiferous tubules, hyperplasia of the germinal epithelium and thickening of the walls of blood ve ssels.     

Vitamin D3 supplementation of beef steers increases longissimus tenderness.

The objectives of these experiments were to determine 1) the effectiveness of supplemental vitamin D3 (VITD) on altering plasma and muscle calcium levels, 2) whether VITD supplementation improves Warner-Bratzler shear force (WBS) values of steaks from feedlot beef steers, and 3) the tenderness response curve of longissimus steaks from steers supplemented with VITD. In Exp. 1, 20 crossbred steers were assigned randomly to one of four treatment diets consisting of either 0, 2.5, 5.0, or 7.5 x 106 IU of VITD per day for 10 d. Blood samples were obtained daily during this supplementation period and 5 d thereafter (d 11 to 15). Between d 6 and 13, a linear increase (P < .01) in ionized plasma calcium concentrations was observed in steers supplemented with VITD. Compared to unsupplemented steers, serum calcium concentrations of the steers receiving 7.5 x 106 IU of VITD per day were increased 8 to 48%. In Exp. 2, longissimus samples from crossbred steers (n = 118) that were supplemented with either 0 or 5 x 106 IU of VITD per day for 7 d were obtained and aged for 7, 14, or 21 d. Following the initial 7-d postmortem aging period, VITD supplementation lowered (P < .01) WBS (.58 kg) and increased sensory tenderness rating (.6 units) compared to cuts originating from unsupplemented steers. In Exp. 3, 44 steers were supplemented with either 0 or 7.5 x 106 IU of VITD per day for 10 d immediately prior to slaughter. Results indicated that plasma and longissimus calcium concentration were higher (P < .05) for steers that received supplemental VITD. Compared with unsupplemented cuts, VITD supplementation improved WBS of cuts aged for either 7 or 14 d (P = .02 and P = .07, respectively). Sensory panelists rated samples from VITD supplemented steers as more tender than their unsupplemented counterparts. Activation of calpain proteases could be responsible for the observed tenderization due to the supplementation of VITD.     

Probiotic efficiency of Bacillus sp. in Labeo rohita challenged by Aeromonas hydrophila: assessment of stress profile,haemato‐biochemical parameters and immune responses

Fish are always susceptible to a wide variety of deadly pathogens which cause a huge loss in aquaculture industries. In this investigation, we have demonstrated the in vivo probiotic efficiency of Bacillus sp. MVF1 (GenBank Acc. No. KP256503) in Labeo rohita challenged with pathogenic strain of Aeromonas hydrophila (MTCC 1739). To check the probiotic potential of the selected bacterial strain, fish were divided into four groups: control, D1, D2 and D3. A total of 100 days (70 days probiotic feeding + 71th day sampling and 28 days challenged test + 29th day sampling) of feeding trial was conducted. To establish the probiotic potential of Bacillus sp. MVF1, certain haematological parameters (haemoglobin, total erythrocyte and leucocyte count), serum biochemical parameters (total protein, albumin and globulin), immune parameters (serum lysozyme and total IgM levels) and hepatic stress profile (malondialdehyde production, superoxide dismutase and catalase activity) have been measured. Our results demonstrated that red blood cell number, white blood cell number and haemoglobin content were much higher in D2 group fish compared to other groups and control fish. Similarly, total protein contents, albumin concentration, globulin concentration, lysozyme activity and IgM production were also recorded to be highest in D2 group fish. This finding clearly indicated the probiotic potential of Bacillus sp. MVF1 in L. rohita. Furthermore, our results also demonstrated that 1 × 10⁷ CFU g^?1 feed (D2) provides better immunity compared to 1 × 10⁵ (D1) and 1 × 10⁹ (D3). Due to beneficial effects, the bacterium Bacillus sp. MVF1 might be useful in aquaculture industries to reduce the disease susceptibility.     

Effect of plastic mulch on water flow and herbicide transport in soil cultivated with pineapple crop: A modeling study

In Hawaii, pineapple is typically grown in raised beds covered with impervious plastic mulch. Field measurements of a commonly used herbicide (bromacil) mass beneath mulch-covered pineapple beds and inter-bed open areas revealed that open areas contained a mass of bromacil about 3.5 times greater than was originally applied, based on label instructions, to the entire field. The broadcast bromacil ended up in the inter-bed open areas through water runoff from the plastic mulch covering the pineapple beds. The objective of this study was to evaluate the impact of surficial management on water dynamics and bromacil concentration in the soil on a pineapple plantation using the one- (1D) and two-dimensional (2D) flow and transport models. Flow and transport processes were simulated in a 2D vertical cross-section perpendicular to the plant rows. The 1D simulation was limited to the open inter-bed areas. Several simulation scenarios were proposed to evaluate the effect of plastic mulch on bromacil transport in soil. In our simplified approach, the water and solute boundary fluxes for the non-covered areas were increased to simulate the water and solute contribution from the plastic mulch surface. The simulation results were compared with field observations of soil water potentials and resident bromacil concentration profiles. The field and laboratory-measured hydraulic and transport parameters were used for all simulation scenarios. Reasonably good agreement between the model-predicted and observed soil water potentials and bromacil concentration profiles was obtained. Biased 1D and 2D results were predicted when the water runoff from plastic mulch was neglected. The 1D approach to quantify bromacil transport beneath the inter-bed open areas seemed to be sufficient in case the water runoff from the mulch was taken into account.