Reproductive strategy ofPodisus nigrispinus females under different feeding intervals

An attempt was made to quantify the influence of prey scarcity on longevity and on the reproductive variables of females of the predatorPodisus nigrispinus (Dallas) (Heteroptera: Pentatomidae). The predators received prey (Alabama argillacea) of different sizes,viz., 50 mg (small prey) or 220 mg (large prey), for a period of 24 h, daily or every 2, 4, 8 or 16 days. In an additional trial, the predators were provided only with water or kept without food, in which latter condition they lived a significantly shorter time. Individuals that received large prey in excess (every day) and at 16-day intervals lived significantly less, while the longevity of those that fed on small prey did not differ significantly between feeding intervals. Predators that fed less frequently laid fewer eggs, with increased intervals between clutches. The results were more marked in females fed on small prey; however, evidence of trade-off between reproduction and survival was detected only in predators that received large prey. The results suggest a type of trade-off, where longevity is maintained at the expense of reproduction. This strategy can contribute to the establishment and survival ofP. nigrispinus in an environment of fluctuating food supply. http://www.phytoparasitica.org posting Dec. 11, 2007.     

Tissue‐print and squash real‐time PCR for direct detection of ‘Candidatus Liberibacter’ species in citrus plants and psyllid vectors

Huanglongbing (HLB) disease is seriously threatening and/or damaging the citrus industry worldwide. Accurate detection of the three species associated with HLB disease, ‘Candidatus Liberibacter asiaticus’, ‘Candidatus Liberibacter africanus’ and ‘Candidatus Liberibacter americanus’, is essential for the preventive control of the disease. Real‐time PCR is a useful tool for bacterial detection. However, nucleic acid purification steps limit the number of samples that can be processed by PCR. Universal detection of ‘Ca. Liberibacter’ species was achieved by direct tissue‐printing and spotting of plant leaf petiole extracts or squashing of individual psyllids onto paper or nylon membranes. Primers were designed and used with TaqMan chemistry for accurate detection of the bacterium in immobilized targets (prints of 10 overlapping leaf pedicels per tree, or squashed single vectors), by extraction with water and direct use for real‐time PCR. This simplified method was validated and could detect HLB‐liberibacters in 100% of leaves with symptoms and 59% of symptomless leaves collected from HLB‐infected trees. The use of direct assays as template showed good agreement with use of purified DNA (κ = 0·76 ± 0·052). The squash assay allowed detection of the bacterium in 40% of mature Diaphorina citri that fed on leaves of HLB‐infected trees with or without symptoms. A commercial ready‐made kit based on this technology showed 96% accuracy in intra‐laboratory performance studies. The simplified direct methods of sample preparation presented herein can be effectively adopted for use in rapid screening of HLB agents in extensive surveys, certification schemes or for epidemiological and research studies.     

Overyielding in mixed pine forests with belowground complementarity: impacts on understory

European Journal of Forest Research - The impact of biodiversity loss on the functioning of forest ecosystems has become a central issue in ecology. Most reports of the positive effects of tree...     

Chemical management of weeds in corn hybrids

Corn stands out among the cultivars because of its high importance in food, animal feed and raw materials for energy production. The quantity and quality of the harvested grain can be reduced, mainly due to inadequate weed management. Nowadays, weed control is accomplished with the use of herbicides as pre‐emergence and postemergence, applied alone or in a tank mix. This study aimed to evaluate the efficiency of the control of weeds and phytotoxicity of the herbicides that were applied in tank mix or isolated in the corn hybrids, Formula TL® and SYN 7B28 . Two experiments were conducted: in the 2012/2013 season (Formula TL®) and 2013/2014 season (SYN 7B28). There was a low initial phytotoxicity of all the tested herbicides in the initial evaluation; however, from 14 days after treatment, it was minimal. The weed control of Ipomoea indivisa, Urochloa plantaginea and Euphorbia heterophylla in both experiments was better, in general, when using the tank mixtures of atrazine + simazine + tembotrione and atrazine + simazine + mesotrione, respectively. The application of atrazine + simazine + tembotrione in the SYN 7B28 hybrids provided, with the exception of the thousand‐grain weight, the best expression of grain yield components, combining a low phytotoxicity and best control of the weeds. The Formula TL® hybrid presented the highest mass of a thousand grains and yield with the application of nicosulfuron + tembotrione. The yield average difference of the herbicide treatments and the unweeded control showed an increase of 27.66 and 34.59% in the grain yield of the corn hybrids, Formula TL® and SYN 7B28, respectively.     

Application of Soluble Chitosan in vitro and in the Greenhouse to Increase Yield and Seed Quality of Potato Minitubers

The aim of this work was to investigate whether the application of soluble chitosan in potato micropropagation can improve microplant quality in vitro, help acclimatisation ex vitro, and increase yield and seed quality of minitubers. Potato cv. Désirée microplants were treated in vitro with soluble chitosan added to the semisolid tissue culture medium in different concentrations. Microplants were subsequently transferred to the greenhouse and sprayed with chitosan solutions or remained unsprayed. Untreated microplants were also established ex vitro and sprayed with chitosan, or left unsprayed as a control. Morphological and physiological parameters of plant growth were assessed in vitro and ex vitro. Plantlet quality was evaluated using a ranking system. Minitubers derived from greenhouse plantlets were planted in the field in subtropical conditions, and growth and yield parameters evaluated. The chitosan concentration most beneficial to the in vitro growth of microplants varied between years. In treatments with the best in vitro growth, minituber number and yield in the greenhouse was also increased. Foliar chitosan application at the acclimatisation phase stabilised the effect of in vitro treatment on yield parameters. The seed quality of minitubers derived from chitosan treatments in vitro alone and in combination with foliar treatment at acclimatisation was improved, giving rise to field plants with increased tuber numbers and yields. The combination of chitosan in vitro and foliar application during the acclimatisation phase ex vitro had a greater effect on minituber seed quality than the concentration applied in vitro.     

Use of oxytocin to attain cervical dilation for transcervical embryo transfer in sheep

The aim of this work was to determine whether a cervical dilation protocol (CDP) composed of only oxytocin can be used to perform transcervical (non-surgical) embryo transfer in sheep (NSET) without affecting the viability of the corpus luteum (CL). Likewise, we evaluated whether a cervical transposing test with a Hegar dilator (CT Hegar test), performed at oestrous time, could be used to screen ewes for NSET (greater or lower chances to transpose the cervix). For that, oestrous and ovulation synchronization was performed in 25 Santa Inês ewes to induce the dioestrous condition. Animals went through the following CDP in a crossover design: E + OX, oestradiol benzoate (100 µg intravenously [IV]) and oxytocin (100 IU IV); OX, oxytocin (100 IU IV); and SAL, saline solution (IV). Using a Hegar dilator, cervical transposing attempts were performed at oestrous (D0) and dioestrous time (D8). The viability of the CL (morphology, luteal blood flow and progesterone values) was evaluated by ultrasonography (colour Doppler and B-mode) and by serum progesterone measurement from D7 to D13. The cervical transposing rate was lower for the SAL group (64%; 16/25; p < .05) and did not differ between the E + OX (88%; 22/25, p > .05) and OX (84%; 21/25, p > .05) groups. No treatment affected the CL viability. The CT Hegar test showed a high sensitivity (85.7%–93.3%), satisfactory accuracy (72%–84%), low false-negative rate (6.7%–14.6%), but high false-positive rate (46%–66.7%). In conclusion, a CDP protocol composed exclusively of oxytocin can lead to good cervical transposing rates and does not affect the viability of the CL. In addition, a screening test (CT Hegar) performed at oestrus can identify ewes for which cervical transposing will likely not occur at NSET.     

Hematological and splenic Doppler ultrasonographic changes in dogs sedated with acepromazine or xylazine

Objective

To evaluate the onset and duration of hematological changes and the use of Doppler ultrasound (spleen) in dogs sedated with acepromazine or xylazine.