Male multiple matings and reproductive success in commodity-adapted strains of <Emphasis Type="Italic">Sitophilus oryzae</Emphasis>

Multiple matings occur in many species of stored-grain insect pests, such as the rice weevil Sitophilus oryzae (L.), with both female and male mating more than once and with more than one partner. Multiple female mating in S. oryzae increased lifetime fecundity by extending the period of time progeny were produced, but consequences of multiple male mating in S. oryzae were not yet studied although it is likely to increase male fitness by increasing offspring production. Here, the effects of polygynous mating on male mating behavior, success, and fitness were assessed in two strains of S. oryzae, one adapted to barley and another to wheat. Two insect strains were considered because they may differ in response depending on the host grain, which present distinct nutritional value to the insects. Mating by pairs formed between the two strains did not impact mating success, but wheat-adapted females exhibited longer mating duration, which was positively correlated with progeny production. Wheat-adapted males exhibited higher fertility than barley-adapted males. When male multiple matings were considered in successive polygynous matings, late matings led to lower non-cumulative values of progeny production, but higher cumulative performance, and wheat-adapted S. oryzae always performed better. Thus, male fitness and grain losses in wheat are higher than in barley, even when S. oryzae was adapted to the latter.     

Molecular characterization of two papaya ringspot virus isolates that cause devastating symptoms in Norte de Santander,Colombia

Papaya ringspot virus is an RNA virus that belongs to the genus Potyvirus, family Potyviridae and affects both papaya and cucurbits, causing great economic losses. PRSV isolates are divided into biotypes P and W; both biotypes naturally infect plants in the family Cucurbitaceae, whereas the P type also naturally infects papaya (Carica papaya L). In the present study, we report the full-length genome sequence of two PRSV-P isolates sampled from the Campo Hermoso (PRSV-CH) and Villa del Rosario (PRSV-VR) localities in Norte de Santander, Colombia. The genomes of these PRSV isolates are 10,326 nt in length and have a predicted ORF of 3344 aa. The identity among Colombian PRSV isolates is 96.9% and 97.3% at the nucleotide and deduced amino acid levels, respectively. PRSV isolates from China had the lowest identity at 78.3% and 89.2% (nucleotide-amino acid), whereas the highest identities were detected in PRSV isolates from Mexico, Venezuela and Hawaii. At the polyprotein level, the amino acid composition surrounding the active polyprotein cleavage sites differ in the Colombian PRSV sequences. The predicted cleavage site in P1/HC-Pro is LEQY/N – LEQY/S instead of MEQY/N. Both of the Colombian PRSV isolates have a putative recombination event in the P1 coding region, which is common in all PRSV isolates from the American continent. The new full-length PRSV sequences from Colombia provide a better understanding of the dynamics of papaya ringspot virus infections in papaya in Colombia and worldwide.     

Environmental influence on urban rodent bait consumption

Anticoagulant poisoning is a common rodent control method in urban areas, but rodents may exhibit versatile feeding behavioural habits in varying environmental conditions. This study has been conducted to determine those environmental factors that could directly influence bait consumption and which therefore may affect an urban rodent control plan carried out with chemical methods. In the city of Bologna (Italy), 2500 bait stations have been monitored in various urban biotopes and the bait consumption studied in relation to several environmental factors, using both bivariate and multivariate analysis. Results reveal that the rodent patch distribution triggers the avoidance of baits placed outside of their home-range, hence the importance on bait placement. The logistic regression model confirms that vegetation, harbourage and water supplies are important variables in determining bait consumption, probably because they may spatially and temporarily facilitate the agoraphobic rodent movement, ensuring undisturbed bait consumption. The role of predators (dogs and cats) and food competitors (synanthropic birds) remains insignificant. However, bait eating invertebrates may consume part of the bait. For a proper rodent control plan the first real need is to minimize the alternative food sources, which may compete with baits. Weather conditions in which rodents could possibly pass unnoticed (fog and rainfall) may encourage bait consumption, vice versa with a cold climate. The considered environmental factors have satisfactorily explained bait consumption, highlighting the importance of human influence. The study of environmental factors may be useful in categorizing several site-specific conditions where rodent control efforts should be targeted, enhancing any intervention by matching the correct and specific strategy.     

In vitro antimicrobial activity of a commercial ear antiseptic containing chlorhexidine and Tris–EDTA

Minimum bactericidal concentrations (MBCs) of a commercial ear antiseptic containing chlorhexidine 0.15% and Tris–EDTA (Otodine^®) were determined by broth microdilution for 150 isolates representing the most common pathogens associated with canine otitis. The microorganisms were classified into three groups according to their levels of susceptibility. The most susceptible group included Staphylococcus pseudintermedius, Malassezia pachydermatis, Streptococcus canis and Corynebacterium auriscanis, which were generally killed by 1 : 64 dilution of the antiseptic product (MBC = 23/0.8 μg/mL of chlorhexidine/Tris–EDTA). The most resistant organism was Proteus mirabilis, which survived up to 1 : 8 dilution of the product (MBC = 375/12 μg/mL). Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus displayed intermediate MBCs ranging between 188/6 and 47/1.5 μg/mL. Interestingly, S. pseudintermedius was more susceptible than S. aureus, and no significant difference was observed between meticillin‐resistant and meticillin‐susceptible isolates within each species, indicating that antiseptic use is unlikely to co‐select for meticillin resistance. Although the concentrations required for killing (MBCs) varied considerably with microorganism type, the combination of chlorhexidine 0.15% and Tris–EDTA was active against all the pathogens most commonly involved in canine otitis.     

Dimensional analysis of milk fat globules in sow milk: effects of the lactation stage and fat content and comparison with vaccine milk

To assess the differences in the granulometry of milk fat globules between swine and bovine species, milk samples from 30 lactating sows were analyzed for fat globule dimensions and compared with cow milk samples. Results showed differences between the fat globules: sow milk presents reduced globule diameters compared with cow milk (volume-weighted diameter 2.62 vs. 3.27 µm, p < 0.001) and reduced interglobular distance. A positive relationship was observed between milk fat content and globule diameter, while a slight, insignificant inverse trend was detected between the day of lactation and fat globule diameter. These complex interactions between milk lipids, globule membrane proteins, and globule dimensions provide a better understanding of digestion/absorption phenomena in the design of milk replacers.

     

Perspectives on the use of a seaweed extract to moderate the negative effects of alternate bearing in apple trees

Summary

Alternate bearing is a serious problem in many apple varieties. In fact, each year, apple trees have to be thinned in order to ensure a correct and constant balance between the reproductive and vegetative tendencies of the plant. In organic fruit growing, there is no alternative to the expensive and time-consuming process of hand-thinning. Under these conditions, the use of natural bio-stimulants which enhance the efficiency of nutrient uptake, plant fitness to different pedoclimatic conditions, and plant tolerance to stress, offers new opportunities to reduce the negative effects of alternate bearing. The aim of this work was to evaluate the effects of Actiwave^®, a metabolic enhancer derived from the alga, Ascophillum nodosum, on ‘Fuji’ apple trees affected by experimentally-imposed alternate bearing. The experiments were carried in open field conditions over four consecutive years. Although the effect of Actiwave^® was erratic from year-to-year, the compound generally reduced those problems linked to alternate bearing. Actiwave^® had its most significant effect on alternate bearing plants that were also affected by nutrient deprivation due to the absence of fertilisation. In these trees,Actiwave^® decreased the oscillations in yield between “on” and “off” years and increased the average fruit weight on plants affected by too-high a crop load. Treated trees also showed higher leaf chlorophyll contents (increased by 12%), with a consequent increase in the rates of photosynthesis and respiration. On the other hand, under standard conditions, in well-fertilised balanced plants, Actiwave^® did not have any significant effect. This evidence corroborates the hypothesis that Actiwave^® may be a useful tool to reduce alternate bearing in organic and low-input farming.     

Clarifying the identity of the main ellagitannin in the fruit of the strawberry, Fragaria vesca and Fragaria ananassa Duch

Although the composition of strawberry fruit has been extensively studied, especially for the most abundant phenolic compounds, agrimoniin has never been univocally identified as one of the most abundant phenolic compounds in the fruit. In this study agrimoniin was isolated in the fruit of Fragaria vesca and its structure characterized. Furthermore, its presence was definitively established to be the main ellagitannin in both F. vesca and Fragaria ananassa D. fruit. The presence of sanguiin H-6 and lambertianin C as minor compounds was confirmed in both F. vesca and F. ananassa D. samples. For the first time here is reported the full NMR assignments for agrimoniin. These data should represent a point of reference for NMR analysis of this and other structurally related ellagitannins. Finally, the establishment of an HPLC protocol for separation provided information making it possible to avoid confusion with sanguiin H-6, the main ellagitannin in Rubus species, which is also present in strawberries but at a much lower concentration.