Long-term foliar persistence and efficacy of spinosad against beet armyworm under greenhouse conditions

BACKGROUND: The immediate lethality caused by spinosad has been widely studied on Spodoptera exigua (Hübner). However, long‐term effects can also provide valuable information on insecticide toxic action. Here, the persistence of spinosad on Capsicum annuum L. foliage and the lethal and sublethal effects of greenhouse‐aged foliar residues of this insecticide on third instars of S. exigua are reported. RESULTS: Foliage was collected at 0, 3, 5, 10, 20, 30, 40 and 50 days after application, and spinosad residues were measured. Residues decreased over time according to first‐order kinetics. The average rate constant and half‐life of disappearance were 4.44 × 10^?3 and 156 days and 5.80 × 10^?3 and 120 days for 60 and 120 mg L^?1 respectively. Larval mortality gradually decreased, corresponding to the residues, but was still appreciable (35 and 65% for 60 and 120 mg L^?1 respectively) when the larvae were fed with foliage collected 50 days after treatment. Subsequently, pupal development was reduced and varied between 20 and 60% and between 21 and 41% for 60 and 120 mg L^?1, respectively, in all ages of leaf residues that were bioassayed. At all time points, the consumption rate by the larvae was reduced between 62 and 84% for both concentrations that were bioassayed. CONCLUSION: It is concluded that, under the present greenhouse conditions, the degradation of spinosad was slower than that reported by other authors in the field, and, because of that, its residues could cause lethal and sublethal effects to S. exigua larvae. Copyright © 2011 Society of Chemical Industry     

Weak connectivity and population cohesiveness in rudderfish Kyphosus sandwicensis (Teleostei: Kyphosidae) inhabiting remote oceanic islands

1. Population connectivity has a fundamental role in metapopulation dynamics, with important implications in conservation. Easter Island (EI) and Salas y Gómez Island (SG) in the Pacific Ocean are ideal for the study of population connectivity because they are separated by 415 km and isolated from other islands in the Pacific Ocean by >2,000 km.
2. Considering that dispersal processes could play a critical role in the persistence of its populations, the connectivity pattern of the rudderfish Kyphosus sandwicensis was evaluated between EI and SG using both a population genetics and a biophysical modelling approach.
3. The variability in the control region of the mitochondrial DNA did not show a significant phylogeographical pattern, and the variability in 16 microsatellite loci suggested that individuals of K. sandwicensis located at EI and SG belong to the same genetic population. However, historical migration showed that 0.2% of the recruits at EI come from SG and that 0.15% at SG come from EI per year.
4. Using simulated larval release during September and a larval development of 30 days in the plankton, biophysical modelling did not detect migration between the islands. Furthermore, self-recruitment shows interannual variation ranging from 5 to 10% of the total released larvae.
5. Whereas the genetic data showed a lack of population genetic structure but low connectivity of K. sandwicensis between EI and SG, the biophysical modelling showed null movement of particles between the islands. Stochastic movement of larvae or adults could explain the pattern observed, with rafting as an example. These low-frequency and stochastic movements may be important in maintaining the cohesiveness between EI and SG.

     

Climate-based seed zones for Mexico: guiding reforestation under observed and projected climate change

Seed zones for forest tree species are a widely used tool in reforestation programs to ensure that seedlings are well adapted to their planting environments. Here, we propose a climate-based seed zone system for Mexico to address observed and projected climate change. The proposed seed zone classification is based on bands of climate variables often related to genetic adaptation of tree species: mean coldest month temperature (MCMT) and an aridity index (AHM). The overlay of the MCMT and AHM for the 1961–1990 period resulted in 63 climate-based zones. Climate change observed over the last three decades has resulted in an increase of + 0.74 °C for MCMT and a shift toward overall drier conditions across Mexico. By the 2050s, MCMT is expected to increase by + 1.7 °C and AHM shifts further towards drier conditions. We recommend moving seed sources from warm, dry locations towards currently wetter and cooler planting sites, to compensate for climate change that has already occurred and is expected to continue for the next decades. We contribute a straight-forward climate-based seed zone system that allows practitioners to match seed procurement regions with planting regions under observed and anticipated climate change. Our transfer recommendations using climate-based zones can be implemented within the existing seed zone system, which often span large climate gradients.     

Influence of exercise on thermographically determined surface temperatures of thoracic and pelvic limbs in horses

OBJECTIVE: To determine the amount of time required for surface temperatures of thoracic and pelvic limbs in horses to return to pre-exercise temperatures after high-speed treadmill exercise, as detected via infrared thermographic imaging. DESIGN: Prospective study. ANIMALS: 6 Thoroughbreds. PROCEDURES: All horses had been trained on and conditioned to use of a high-speed treadmill. Baseline thermographic images were obtained 3 days prior to exercise (baseline). Horses were exercised on a treadmill at a walk for 5 minutes, a slow trot (3 m/s) for 5 minutes, a trot (5 to 6 m/s) for 5 minutes, and a slow gallop (6 to 8 m/s) for 5 minutes, then back to a trot for 3 minutes, a slow trot for 3 minutes, and a walk for 3 minutes prior to stopping. Thermal images were obtained immediately after stopping exercise (0 minutes) and 5, 15, 45, and 60 minutes and 6 hours after stopping exercise. Ambient temperature surrounding each horse was recorded. RESULTS: In all regions, significant differences in surface temperatures were detected between thermograms obtained before exercise and those obtained immediately after, 5 minutes after, and 15 minutes after exercise was stopped. There were no significant differences in surface temperatures between thermograms obtained before exercise and those obtained > or = 45 minutes after exercise was stopped. CONCLUSIONS AND CLINICAL RELEVANCE: In horses, images generated via infrared thermography are not influenced by exercise-generated heat > or = 45 minutes after exercise is stopped.     

Application of system of rice intensification practices in the arid environment of the Timbuktu region in Mali

Cereal production is chronically deficit in the Timbuktu region of Mali, sufficient for only 4.5 months of annual household consumption. Small-scale, village-based irrigation schemes, usually 30–35 ha in size, irrigated by a diesel motor pump, have become important to improve food security in this arid region. The NGO Africare has worked during the past 12 years with farmers in Goundam and Dire circles to establish irrigation schemes and provide them with technical assistance. In 2007, Africare undertook a first test of the System of Rice Intensification (SRI) in Goundam circle. After farmers observed a yield of 9 t ha⁻¹ of paddy compared to 6.7 t ha⁻¹ in the control plot there was interest in larger scale testing of the SRI system. In 2008, Africare, in collaboration with the local Government Agriculture Service and with support from the Better U Foundation, implemented a community-based evaluation of SRI with 60 farmers in 12 villages. Farmers in each village selected five volunteers, who each installed both SRI and control plots, side by side, starting the nurseries on the same day and using the same seed. For SRI plots, seedlings were transplanted one plant hill⁻¹ at the two-leaf stage (on average, 11.6 days old), with spacing of 25 cm × 25 cm between hills and aligned in both directions. This allowed farmers to cross-weed with a cono-weeder, on average 2.4 times during the season. In the control plots, farmers planted 3 plants hill⁻¹ with seedlings 29.4 days old and spaced on average 23.7 cm, not planted in lines. Weeding was done by hand. 13 t ha⁻¹ of organic matter was applied under SRI management, and 3 t ha⁻¹ in the control plots. Fertilizer use was reduced by 30% with SRI compared to the control. Although alternate wetting and drying irrigation is recommended for SRI, this was not optimally implemented due to constraints on irrigation management within the scheme; thus water savings were only 10% compared to the control. Average SRI yield for all farmers reached 9.1 t ha⁻¹, with the lowest being 5.4 t ha⁻¹ and highest being 12.4 t ha⁻¹. SRI yields were on average 66% higher than the control plots at 5.5 t ha⁻¹, and 87% higher than the yields in surrounding rice fields at 4.9 t ha⁻¹. Number of tillers and panicles hill⁻¹, number of tillers and panicles m⁻², and panicle length and number of grains panicle⁻¹ were clearly superior with SRI compared to control plants. Farmers tested five varieties, all of which produced better under SRI. The SRI system allowed for a seed reduction of 85–90%: from 40–60 kg ha⁻¹ for the control plots to 6.1 kg ha⁻¹ under SRI. Although production costs per hectare were 15% higher for SRI, revenue was 2.1 times higher than under the control. Farmers were very satisfied with these results. In 2009/2010, Africare and the Government’s agriculture service worked with over 270 farmers in 28 villages to scale up SRI practices and to test innovations, including composting techniques, optimization of irrigation, and techniques to reduce labor requirements and production costs. The good crop performance along with other advantages was confirmed in this third year with SRI yields of 7.7 t ha⁻¹ (n = 130 farmers) compared to 4.5 t ha⁻¹ in farmers’ fields.     

Characterization of the bacterial population of the genital tract of adult cats

OBJECTIVE: To characterize the bacteria of the genital tract in adult cats; assess the effect of estrus, mating, and administration of progestins on those microorganisms in females; and evaluate whether results of bacteriologic culture of vaginal swabs are affected by cleansing of the vulva prior to sampling or by repeated sampling. ANIMALS: 66 female and 29 male cats undergoing routine ovariohysterectomy or castration. PROCEDURE: Specimens were obtained from vaginal and uterine or preputial mucosae with swabs moistened with sterile saline (0.9% NaCl) solution. In 9 cats, vaginal specimens were obtained before and after cleansing of the vulva with ethanol; in 7 female cats, 2 vaginal speci mens were obtained in immediate succession. RESULTS: Aerobic bacteria were most commonly isolated from cats' vaginas and prepuces; anaerobic bacteria were isolated frequently from males (41%) but rarely from females (5%). Generally, culture results were not affected by cleansing of the vulva or repeated vaginal sampling. The bacterial population of the vaginas of cats was influenced by stage of the estrous cycle but not by mating or administration of progestins. Bacteria were not isolated from the uterus of any cat. CONCLUSIONS AND CLINICAL RELEVANCE: In cats, bacteria of the genital tract in females are predominantly aerobic; in males, aerobic and anaerobic bacteria are found. The bacterial population of the vagina is affected by stage of the estrous cycle. Pure growth of bacteria in culture of genital tract specimens is a normal finding; antimicrobials should only be administered if clinical signs of genital infection are present.     

Algal-Derived Halogenated Sesquiterpenes from Laurencia dendroidea as Lead Compounds in Schistosomiasis Environmental Control

Schistosomiasis has been controlled for more than 40 years with a single drug, praziquantel, and only one molluscicide, niclosamide, raising concern of the possibility of the emergence of resistant strains. However, the molecular targets for both agents are thus far unknown. Consequently, the search for lead compounds from natural sources has been encouraged due to their diverse structure and function. Our search for natural compounds with potential use in schistosomiasis control led to the identification of an algal species, Laurencia dendroidea, whose extracts demonstrated significant activity toward both Schistosoma mansoni parasites and their intermediate host snails Biomphalaria glabrata. In the present study, three seaweed-derived halogenated sesquiterpenes, (−)-elatol, rogiolol, and obtusol are proposed as potential lead compounds for the development of anthelminthic drugs for the treatment of and pesticides for the environmental control of schistosomiasis. The three compounds were screened for their antischistosomal and molluscicidal activities. The screening revealed that rogiolol exhibits significant activity toward the survival of adult worms, and that all three compounds showed activity against S. mansoni cercariae and B. glabrata embryos. Biomonitored fractioning of L. dendroidea extracts indicated elatol as the most active compound toward cercariae larvae and snail embryos.     

Subsoil compaction by heavy sugarbeet harvesters in southern Sweden: III. Risk assessment using a soil water model

Due to its persistence, subsoil compaction should be avoided, which can be done by setting stress limits depending on the strength of the soil. Such limits must take into account soil moisture status at the time of traffic. The objective of the work presented here was to measure soil water changes during the growing period, use the data to calibrate a soil water model and simulate the soil susceptibility to compaction using meteorological data for a 25-year period. Measurements of soil water content were made in sugarbeet (Beta vulgaris L.) from sowing until harvest in 1997 on two sites classified as Eutric Cambisols in southern Sweden. Sampling was carried out at 2-week intervals in 0.1 m layers down to 1 m depth, together with measurements of root growth and crop development. Precompression stress of the soil at 0.3, 0.5 and 0.7 m depth was determined from uniaxial compression tests at water tensions of 6, 30, 60 and 150 kPa and adjusted as a logarithmic function of the soil water tension. Soil water content was simulated by the SOIL model for the years 1963–1988. Risk calculations were made for a wheel load of 8 t and a ground pressure of 220 kPa, corresponding to a fully loaded six-row sugarbeet harvester. Subsoil compaction was expected to occur when the major principal stress was higher than the precompression stress. The subsoil water content was very low in late summer, but increased during the autumn. At the end of August, there was practically no plant available water down to 1 m depth. There was in general good agreement between measured and simulated values of soil water content for the subsoil, but not for the topsoil. In the 25-year simulations, the compaction risk at 50 cm depth was estimated to increase from around 25% to nearly 100% between September and late November, which is the period when the sugarbeet are harvested. The types of simulation presented here may be a very useful tool for practical agriculture as well as for society, in giving recommendations as to how subsoil compaction should be avoided.     

Influence of supraphysiological cortisol manipulation on predator avoidance behaviors and physiological responses to a predation threat in a wild marine teleost fish

The stress axis in teleost fish attempts to maintain internal homeostasis in the face of allostatic loading. However, stress axis induction has been associated with a higher predation rate in fish. To date, the physiological and behavioral factors associated with this outcome are poorly understood. The purpose of the present study was to investigate the impact of experimental cortisol elevation on anti‐predator behavior and physiological responses to predator presence. We hypothesized that semi‐chronic cortisol elevation would increase susceptibility to predation by increasing stress‐induced risk‐taking behaviors. To test this hypothesis, schoolmaster snapper were given cocoa butter implants without cortisol (sham) or with cortisol (50 mg/kg body weight) and tethered to cover. Fish were exposed to either a lemon shark or control conditions for 15‐min. Space use and activity were recorded throughout and fish were terminally sampled for blood. Cortisol implantation, relative to shams, resulted in higher blood glucose and plasma cortisol concentrations with a lower plasma lactate concentration. Shark exposure, relative to controls, elicited higher blood glucose and lactate concentrations but had no effect on plasma cortisol concentration. No interactions were detected between shark exposure and cortisol treatment for any physiological trait. Behavioral metrics, including shelter use and activity, were unaffected by either cortisol implantation or shark exposure. Physiological responses to cortisol implantation likely resulted from enhanced gluconeogenic activity, whereas alterations under predator exposure may have been the product of catecholamine mobilization. Further work should address context‐specific influences of stress in mediating behavioral responses to predation.     

Campylobacter-induced interleukin-8 responses in human intestinal epithelial cells and primary intestinal chick cells

Campylobacter (C.) jejuni and C. coli can cause gastrointestinal disorders in humans characterized by acute inflammation. Inflammatory signals are initiated during interaction between these pathogens and human intestinal cells, but nothing is known about the stimulation of avian intestinal cells by Campylobacter. Interleukin-8 (IL-8) as a proinflammatory chemokine plays an important role in mobilizing cellular defence mechanism. IL-8 mRNA expression in both human intestinal cells (INT 407) and primary intestinal chick cells (PIC) was determined by quantitative real-time RT-PCR. The secretion of IL-8 protein by INT407 was measured using ELISA. Although C. jejuni and C. coli are considered to be harmless commensals in the gut of birds, the avian Campylobacter isolates investigated were able to induce the proinflammatory IL-8 in PIC as well as in INT407. In an in vitro system, C. jejuni as well as C. coli were able to induce IL-8 mRNA in PIC. Relation between the virulence properties like toxin production, the ability to invade and to survive in Caco-2 cells and the level of IL-8 mRNA produced by INT 407 and PIC after infection with Campylobacter strains was also investigated.